Journal articles on the topic 'Yield decline'
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Ahmad, Mirza Junaid, Kyung-Sook Choi, Gun-Ho Cho, and Sang-Hyun Kim. "Future Wheat Yield Variabilities and Water Footprints Based on the Yield Sensitivity to Past Climate Conditions." Agronomy 9, no. 11 (November 11, 2019): 744. http://dx.doi.org/10.3390/agronomy9110744.
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This article analyzed the wheat yield variabilities and water footprints under projected future climate based on wheat yield sensitivity to past (1980–2017) trends of maximum temperature (Tmax), minimum temperature (Tmin), solar radiation (Rn) and rainfall (P) for the semi-arid condition of Punjab, Pakistan. The past and projected future trends of the climate variables were identical featuring prominent Tmin rise than Tmax accompanied by Rn and P declines. Based on the past influences and the projected future trends of the climate variables, Tmin was the principal driver of wheat yield decline followed by the Tmax, P and Rn. Wheat evapotranspiration and net irrigation water requirement declined due to the influence of both decrease of growing season length and Rn for the first half of 21st-century, and this trend reversed during the second half of 21st-century. These phenomena were caused by different degree of climate warming between the two-time slices. Due to future wheat yield decline and a gradual rise in green water scarcity the blue and grey water footprints rise consistently particularly during 2nd-time slices. CO2 enrichment showed limited mitigation potential of nullifying the warming-induced threats on future wheat yield and water footprints.
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Jefferson, P. G., and F. Selles. "The decline in hay yields: A Saskatchewan perspective." Canadian Journal of Plant Science 87, no. 5 (December 1, 2007): 1075–82. http://dx.doi.org/10.4141/cjps07128.
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Yield data collected by Statistics Canada show that annual hay yields have been declining in several Canadian provinces including Saskatchewan for the past 31 yr. Data from Saskatchewan provincial statistics on Beef Cow number, Area Harvested for Hay, Value of Land and Buildings, and Fertilizer Price Index were used to examine the relationships between hay yield and these variables. Weather from 16 sites across Saskatchewan’s agricultural region for the April, May, and June (AMJ) period was also examined from 1973 to 2003. Precipitation during AMJ was positively correlated to hay yield, but the difference between maximum and minimum temperatures (Δtemperature) was negatively correlated. Fertilizer Price Index was negatively correlated to hay yield, suggesting that producers are reducing fertilizer input to this crop resulting in lower yields. Step-wise regression analysis suggested that fertilizer cost was the most important variable, which explained 38% of the variation in hay yield. When fertilizer price was combined with Δtemperature, the Value of Land and Buildings and AMJ precipitation, 65% of the variation in Saskatchewan hay yield could be explained. Examination of census data on tame forage and tame pasture acres by district did not support the hypothes is that more hay has been seeded in lower yield regions of the Province. We speculate that climate change is negatively affecting Saskatchewan’s ability to produce hay, particularly since low inputs of fertilizer and infrequent stand rejuvenation are commonly practiced on forage crops. This problem needs more in-depth analysis to confirm the cause(s) of this decline and avoid a future scenario where low hay yields make ruminant livestock production economically unsustainable in Western Canada. Key words: Forage yield, precipitation, temperature, fertilizer
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Lamb, M. C., J. I. Davidson, and C. L. Butts. "Peanut Yield Decline in the Southeast and Economically Feasible Solutions." Peanut Science 20, no. 1 (January 1, 1993): 36–40. http://dx.doi.org/10.3146/i0095-3679-20-1-10.
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Abstract Peanut (Arachis hypogaea L.) yields in the Southeast declined 368 kg/ha during the 1980's and 596 kg/ha in the late 1980's when compared to the 1974-1979 period. The peanut yield decline was correlated with significant meteorological and policy changes in the Southeast during each time period. Meteorological changes were statistically estimated to decrease peanut yield by 137 kg/ha and 194 kg/ha in the 1980's and late 1980's, respectively. The effect on peanut yields from changes in agricultural policy and management decisions was estimated at -166 kg/ha and -225 kg/ha during the respective time periods. Field data gathered during crop years 1987-1990 reflected the meteorological and policy changes during the late 1980's in both non-irrigated and irrigated peanut fields. EXNUT, an expert systems model for peanut irrigation and pest management, was evaluated in 1987, 1988, 1989, and 1990 against expert farmers in the Southeast and increased peanut yields by 204 kg/ha. Evaluation of EXNUT demonstrated one example of how expert system technology can offer economically feasible solutions to the peanut yield decline in the Southeast.
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Magarey, RC. "Microbiological aspects of sugarcane yield decline." Australian Journal of Agricultural Research 47, no. 3 (1996): 307. http://dx.doi.org/10.1071/ar9960307.
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Sugarcane is an important Australian crop earning over $1.8 billion in export revenue annually. The crop is grown as a monoculture, and much of the production area has been continually cropped for over 60 years. Increasing production trends plateaued in the 1970s and soil based constraints now reduce industry income by $200~1 annually. The condition, termed sugarcane yield decline (YD), is similar to replant diseases in other crops. Large growth responses to soil fumigation, soil solarisation, and the application of fungicides, suggest that soil microbiology is intimately involved. Research has identified a previously unclassified oomycete, Pachymetra chaunorhiza, as a new sugarcane root pathogen. Additional root pathogens identified include Pythium arrhenomanes and various nematode species. Other organisms which appear to be involved in YD, are discussed.
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Sandhu, Harpinder, Benjamin Waterhouse, Stephane Boyer, and Steve Wratten. "Scarcity of ecosystem services: an experimental manipulation of declining pollination rates and its economic consequences for agriculture." PeerJ 4 (July 5, 2016): e2099. http://dx.doi.org/10.7717/peerj.2099.
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Ecosystem services (ES) such as pollination are vital for the continuous supply of food to a growing human population, but the decline in populations of insect pollinators worldwide poses a threat to food and nutritional security. Using a pollinator (honeybee) exclusion approach, we evaluated the impact of pollinator scarcity on production in four brassica fields, two producing hybrid seeds and two producing open-pollinated ones. There was a clear reduction in seed yield as pollination rates declined. Open-pollinated crops produced significantly higher yields than did the hybrid ones at all pollination rates. The hybrid crops required at least 0.50 of background pollination rates to achieve maximum yield, whereas in open-pollinated crops, 0.25 pollination rates were necessary for maximum yield. The total estimated economic value of pollination services provided by honeybees to the agricultural industry in New Zealand is NZD $1.96 billion annually. This study indicates that loss of pollination services can result in significant declines in production and have serious implications for the market economy in New Zealand. Depending on the extent of honeybee population decline, and assuming that results in declining pollination services, the estimated economic loss to New Zealand agriculture could be in the range of NZD $295–728 million annually.
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Zandstra, Bernard H., Sylvia Morse, Rodney V. Tocco, and Jarrod J. Morrice. "Response of Asparagus to Repeated Application of Residual Herbicides." HortTechnology 23, no. 1 (February 2013): 109–13. http://dx.doi.org/10.21273/horttech.23.1.109.
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Asparagus (Asparagus officinalis) is a perennial crop that has a 12- to 20-year production life in the field. Herbicides are applied in the spring each year and again after final harvest in early summer. Asparagus yield declines with age, and herbicides may contribute to yield decline. An experiment was established in 2004 and maintained for seven years with the same herbicide treatments applied each spring to determine herbicide effects on marketable spear yield. Spring-applied diuron, metribuzin, terbacil, sulfentrazone, halosulfuron, mesotrione, and clomazone had no adverse effect on yield or quality over the seven years of the experiment. Flumioxazin reduced yearly average marketable yield compared with standard treatments, and some spears developed lesions early in the season after rainfall. Asparagus yield from most treatments declined more than 50% from 2004 to 2010.
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Jefferson, Paul G., and Kathy Larson. "The relationship between Saskatchewan hay yield and changing cropping practices." Canadian Journal of Plant Science 94, no. 7 (September 2014): 1157–60. http://dx.doi.org/10.4141/cjps-2014-024.
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Jefferson, P. G. and Larson, K. 2014. The relationship between Saskatchewan hay yield and changing cropping practices. Can. J. Plant Sci. 94: 1157–1160. A previously reported decline in Saskatchewan hay yield statistics was re-examined with additional data. The decline in hay yield was confirmed in the new analysis, but the rate of decline was lower than previously reported. Several agronomic and economic variables were examined for their relationship to hay yield and precipitation use efficiency. Precipitation use efficiency for hay yield was correlated to summerfallow area, which has declined by 75% in Saskatchewan during the study period. Perennial hay crops are deep-rooted and therefore able to exploit soil water and nutrients at depth in previously summerfallowed land that was unavailable to grain and oilseed crops. We suggest that declining hay yield is due to less summerfallow land in modern Saskatchewan crop rotations.
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Bi, J., J. A. Blanco, B. Seely, J. P. Kimmins, Y. Ding, and C. Welham. "Yield decline in Chinese-fir plantations: a simulation investigation with implications for model complexity." Canadian Journal of Forest Research 37, no. 9 (September 2007): 1615–30. http://dx.doi.org/10.1139/x07-018.
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A variety of competing hypotheses have been described to explain yield decline in Chinese-fir ( Cunninghamia lanceolata (Lamb.) Hook.) plantations. The difficulty in implementing field experiments suggests ecosystem modeling as a viable option for examining alternative hypotheses. We present a conceptual model of Chinese-fir yield decline and explore its merits using the ecosystem-based FORECAST model. Model results suggest that yield decline is caused primarily by a decline in soil fertility, largely as a consequence of slash burning in conjunction with short rotations. However, as tree leaf area declines, there is a transition (over subsequent rotations) from seed rain based competition to bud bank based competition, increasing the competitive impact of minor vegetation on tree growth. Short rotations increase understory survival between rotations and may cause a gradual shift from tree dominance to shrub/herb dominance over subsequent rotations. These effects are most evident on nutrient-poor sites, but understory competition poses a significant yield decline risk on good sites as well. We conclude that sustainable production in Chinese-fir plantations requires the avoidance of activities that compromise soil fertility and increase understory competition. The risk and severity of yield decline would be reduced by increasing rotation lengths and avoiding plantations on infertile sites.
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Clements, Jeff C., Josefin Sundin, Timothy D. Clark, and Fredrik Jutfelt. "Extreme original data yield extreme decline effects." PLOS Biology 21, no. 2 (February 6, 2023): e3001996. http://dx.doi.org/10.1371/journal.pbio.3001996.
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Arumugam, Surendran, Ashok K.R., Suren N. Kulshreshtha., Isaac Vellangany, and Ramu Govindasamy. "Yield variability in rainfed crops as influenced by climate variables." International Journal of Climate Change Strategies and Management 7, no. 4 (November 16, 2015): 442–59. http://dx.doi.org/10.1108/ijccsm-08-2013-0096.
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Purpose – This paper aims to explore the impact of climate change on yields and yield variances in major rainfed crops and measure possible changes in yields under projected climate changes in different agro-climatic zones of Tamil Nadu, India. Although many empirical studies report the influence of climate change on crop yield, only few address the effect on yield variances. Even in such cases, the reported yield variances were obtained through simulation studies rather than from actual observations. In this context, the present study analyzes the impact of climate change on crops yield and yield variance using the observed yields. Design/methodology/approach – The Just-Pope yield function (1978) is used to analyze the impact of climate change on mean yield and variance. The estimated coefficient from Just-Pope yield function and the projected climatic data for the year 2030 are incorporated to capture the projected changes in crop yield and variances. Findings – By the year 2030, the yield of pulses is estimated to decline in all the zones (Northeast, Northwest, Western, Cauvery delta, South and Southern zones), with significant declines in the Northeast zone (6.07 per cent), Cauvery delta zone (3.55 per cent) and South zone (3.54 per cent). Sorghum yield may suffer more in Western zone (2.63 per cent), Southern zone (1.92 per cent) and Northeast zone (1.62 per cent). Moreover, the yield of spiked millet is more likely to decrease in the Southern zone (1.39 per cent), Northeast zone (1.21 per cent) and Cauvery delta zone (0.24 per cent), and the yield of cotton may also decline in the Northeast zone (12.99 per cent), Northwest zone (8.05 per cent) and Western zone (2.10 per cent) of Tamil Nadu, India. Originality/value – The study recommends introducing appropriate crop insurance policies to address possible financial losses to the farmers. Prioritizing area-specific stress-tolerant crop varieties without complementing yield would sustain crops cultivation further.
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Dalla Lana, Felipe, Pierce A. Paul, Claudia V. Godoy, Carlos M. Utiamada, Luís Henrique C. P. da Silva, Fabiano V. Siqueri, Carlos A. Forcelini, et al. "Meta-Analytic Modeling of the Decline in Performance of Fungicides for Managing Soybean Rust after a Decade of Use in Brazil." Plant Disease 102, no. 4 (April 2018): 807–17. http://dx.doi.org/10.1094/pdis-03-17-0408-re.
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An apparent decline of fungicide performance for the control of soybean rust in Brazil has been reported but the rate at which it has occurred has not been formally quantified. Control efficacy and yield response to three fungicides applied as single active ingredients (a.i.)—azoxystrobin (AZOX), cyproconazole (CYPR), and tebuconazole (TEBU)—and four applied as mixtures—AZOX+CYPR, picoxystrobin + CYPR, pyraclostrobin + epoxiconazole, and trifloxystrobin + prothioconazole (TRIF+PROT)—were summarized using network meta-analytic models fitted to mean severity and yield data from 250 trials (10-year period). The effect of year was tested on both variables in a meta-regression model. Overall control efficacy ranged from 56 to 84%; the three single-a.i. fungicides performed the poorest (56 to 62%). Yield increase for single-a.i. fungicides was as low as 30% but ranged from 47 to 65% for the premixes. Significant declines in both variables were detected for all fungicides except TRIF+PROT. For TEBU, control efficacy (yield response) declined the most: 78% (18%) to 54% (8%) from 2004–05 to 2013–14. The recent surge of resistant populations of Phakopsora pachyrhizi to both demethylation inhibitor and quinone outside inhibitor fungicides is likely the driving force behind a significant decline after 4 years of fungicide use.
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GUBBELS, G. H., C. G. CAMPBELL, and R. C. ZIMMER. "INTERACTION OF CULTIVAR, SEEDING DATE AND DOWNY MILDEW INFECTION ON VARIOUS AGRONOMIC CHARACTERISTICS OF BUCKWHEAT." Canadian Journal of Plant Science 70, no. 4 (October 1, 1990): 949–54. http://dx.doi.org/10.4141/cjps90-117.
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Field studies were conducted over 5 yr to determine the effect of seeding date on agronomic characteristics and disease reaction of buckwheat (Fagopyrum esculentum Moench). Two large-seeded, mid-season buckwheat cultivars, Manor and a semi-dwarf line, G410 or G474, and a small-seeded early-maturing cultivar, CM 169, were grown at Morden and Portage la Prairie during the period 1983–1985 at early, mid- and late June or early July seeding dates. In 1986 and 1987, Manor was grown at three seeding dates, with and without a fungicide treatment to control downy mildew (Peronospora ducometi Siemaszko and Jankowska). In the 1983–1985 experiments, seed yield generally declined with delay in seeding. The smallest decline occurred in the early-maturing cultivar CM 169. From first to last seeding, yield decreases were 38, 44 and 18% for Manor, the semi-dwarf lines and CM 169, respectively. In 1985, downy mildew infection increased linearly to a small degree with delay in seeding and was negatively correlated with seed yield. However, it was considered a minor factor in the response of yield to seeding date. In 1986 and 1987, mildew infection was minimal. The fungicide treatment had no effect on seed yield. Seed yields decreased with delay in seeding as in the previous tests. It was concluded that seed yield declined markedly with delay in seeding from early to late June, more so in the later-maturing cultivars and the declines were independent of mildew infection.Key words: Buckwheat, Fagopyrum esculentum Moench., seeding date, downy mildew, Peronospora ducometi Siemaszko & Jankowska
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Kim, Don H., and Marcelo Ochoa. "International Yield Spillovers." Finance and Economics Discussion Series 2021, no. 001 (January 11, 2021): 1–59. http://dx.doi.org/10.17016/feds.2021.001.
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This paper investigates spillovers from foreign economies to the U.S. through changes in longterm Treasury yields. We document a decline in the contribution of U.S. domestic news to the variance of long-term Treasury yields and an increased importance of overnight yield changes—a rough proxy for the contribution of foreign shocks to U.S. yields—over the past decades. Using a model that identifies U.S., Euro area, and U.K. shocks that move global yields, we estimate that foreign (non-U.S.) shocks account for at least 20 percent of the daily variation in long-term U.S. yields in recent years. We argue that spillovers occur in large part through bond term premia by showing that a low level of foreign yields relative to U.S. yields predicts a decline in distant forward U.S. yields and higher returns on a strategy that is long on a long-term Treasury security and short on a long-term foreign bond.
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NAVEEN P. SINGH, BHAWNA ANAND, K.V. RAO, and RANJITH P.C. "Spatial and temporal assessment of climate impact on agriculture in plateau region, India." Journal of Agrometeorology 22, no. 3 (November 10, 2021): 353–61. http://dx.doi.org/10.54386/jam.v22i3.296.
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Using large-scale district-level data, the study examined the impact of climate change on crop yields during the period 1966-2011and predictsthe likely changes in yield sacross agro-climatic zones in Plateau Region. The future projections reveal that by 2080s, cotton yield is expected to decline by 7.18 percent in Western Plateau & Hills.By the end of the century, sorghum yield is projected to decline up to 19 percent in Central Plateau & Hills and increase by 18 percent in Western Plateau & Hills. Under midterm period, rapeseed & mustard yield is likely to reduce by 3.44 percent in Western Plateau & Hills. By 2050s maize yield is expected to reduce by 3.33 percent in Central Plateau & Hills. By 2080s, wheat yield is projected to decline by 5.44, percent in SouthernPlateau & Hills. The results suggest that impact of climate change on crop yield varies across regions, hence it is pertinent to formulate adaptation strategies and farm practices suitable to the crop and location specific needs that mitigate the likely exposure of food production and livelihoods to climate variations.
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Blaise, D., J. V. Singh, and M. V. Venugopalan. "Effect of continuous application of manures and fertilizers on productivity of cotton-sorghum rotation." Acta Agronomica Hungarica 51, no. 1 (April 1, 2003): 61–67. http://dx.doi.org/10.1556/aagr.51.2003.1.8.
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Field experiments were conducted from 1985 through 2001 on medium deep vertisol to determine the effect of the continuous application of manure and fertilizers on a two-year cotton-sorghum rotation. The results indicate that the response to N was greatest during the initial years, while after five to six rotation cycles the yield levels declined to the zero level in the N and NK plots. The application of P along with N prevented the decline in seed cotton and sorghum grain yields. The effect was more pronounced at the higher level. K application did not result in any yield increase. Balanced fertilizer at the higher level (N90P19K37) resulted in a significant yield increase over the recommended dose (N60P13K25); however, the percentage increase declined with duration, indicating a decline in factor productivity. Seed cotton yields were the highest when part of the fertilizer N was applied from an organic source (farmyard manure: FYM). Of the eight years, a significant response was observed in four years at the lower level (N30P13K25 + 5 t FYM ha-1) and six years at the higher level (N45P19K37 + 7.5 t FYM ha-1), while in sorghum a response was only observed in two years. The cotton crop should, therefore, be preferred to sorghum for the application of organic manure. In areas where no organic manure is available, N60P13K25 is sufficient for cotton, while sorghum needs to be fertilized at 1.5 times the recommended dose (N90P19K37).
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Foster, William E., and Bruce A. Babcock. "Commodity Policy, Price Incentives, and the Growth in Per-Acre Yields." Journal of Agricultural and Applied Economics 25, no. 1 (July 1993): 253–65. http://dx.doi.org/10.1017/s1074070800018812.
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AbstractWe estimate the influence of policy-induced price changes and of technology supply on North Carolina flue-cured tobacco yields. The decline in land rent and effective output price that accompanied a 1965 policy change from acreage allotments to poundage quotas caused a 12 percent decrease in yields. Farmer yields were more responsive to yield-increasing technologies under acreage allotments than under poundage quotas. Annual yield growth was 0.5 percent under poundage quotas and 4.32 percent under acreage allotments. The growth rate decline is attributable to changes in relative prices and to a slowdown in the supply of available technologies.
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Grace, PR, JM Oades, H. Keith, and TW Hancock. "Trends in wheat yields and soil organic carbon in the Permanent Rotation Trial at the Waite Agricultural Research Institute, South Australia." Australian Journal of Experimental Agriculture 35, no. 7 (1995): 857. http://dx.doi.org/10.1071/ea9950857.
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The Permanent Rotation Trial at the Waite Agricultural Research Institute in South Australia was established on a red-brown earth in 1925, with predominately cereal-long fallow rotations on 34 adjacent plots. The trial was upgraded in 1948 to include a greater proportion of pasture leys in the rotations and currently contains 11 treatments. The trial is unreplicated; however, each phase of a sequence is represented each year. Seven of the original rotations have remained in an unbroken sequence since 1925: continuous wheat (W), wheat-fallow (WF), wheat-peas (WPe), wheat-pasture-fallow (WPaF), wheatoats- fallow (WOF), wheat-barley-peas (WBPe), wheat-oats-pasture-fallow (WOPaF). For the 11 rotations, soil organic carbon (SOC) in the top 10 cm declined from 2.75% in 1925 to a mean value of 1.56% in 1993. One plot, which had reverted to permanent pasture in 1950, showed the smallest decline with an SOC content of 2.46% in 1993. The greatest declines in SOC were in the 4 original rotations that included fallow phases in the sequence (mean value of 1.22%). In the WF rotation the SOC content had declined from 2.75 to 1.04% during 68 years of cropping. Associated yield decreases showed that the treatment could not sustain production. Soil organic C declined linearly with increasing frequency of fallows and decreasing frequency of pasture in the rotations. Average grain yields (1925-93) in the 7 original sequences ranged from 2.64 t/ha in WOPaF to 0.89 t/ha in the continuous W plot. The linear decline in yields for WBPe, WPaF, WPe, and WOF treatments indicate a convergence in the 1990s under current management, with an average yield of 1.54 t/ha in 1993 and average SOC in the top 10 cm of 1.32%. We hypothesise that the gradual increase in grain yields from the continuous W plot since the 1960s is the result of a gradual build-up of light fraction organic material, which assists in the maintainence of structure and nutrient availability.
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Obiefuna, J. C. "The effect of monthly planting on yield, yield patterns and yield decline of plantains (Musa AAB)." Scientia Horticulturae 29, no. 1-2 (June 1986): 47–54. http://dx.doi.org/10.1016/0304-4238(86)90030-0.
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Botwright, T., N. Mendham, and B. Chung. "Effect of density on growth, development, yield and quality of kabocha (Cucurbita maxima)." Australian Journal of Experimental Agriculture 38, no. 2 (1998): 195. http://dx.doi.org/10.1071/ea97037.
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Summary. The effect of plant density on growth, development, yield and quality of kabocha (buttercup squash) (Cucurbita maxima) was examined during 1992–93, at a field site in Cambridge, Tasmania. Plant densities ranged between 0.5 and 4.7 plants/m2. Marketable and total yields were fitted to a yield–density model. Total yield followed an asymptotic trend, approaching 33 t/ha at 4.7 plants/m2, while marketable yield had a parabolic relationship with density. Marketable yield increased to a maximum of 18 t/ha at 1.1 plants/m2, while declining at higher densities because of increased numbers of undersized fruit. Yield of vine marked and callused fruit did not vary with density, but represented a significant proportion of the total yield at all densities. High plant density reduced vegetative growth per plant due to competition for limited resources; as shown by decreased leaf area, number and length of vines, and plant dry weight. Yield tended to decline at high densities because of fewer female flowers and increased fruit abortion per plant. Plants at low densities had more vegetative growth but decreased yields, as increased abortion of fruit relative to the higher plant densities left only 1–2 large fruit per plant. Economic returns varied with plant density. At high densities, variable costs increased (particularly due to high seed cost) while gross income declined reflecting the relationship between marketable yield and plant density. The gross margin therefore declined at high densities.
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Dewhurst, R. J., and C. H. Knight. "An investigation of the changes in sites of milk storage in the bovine udder over two lactation cycles." Animal Science 57, no. 03 (December 1993): 379–84. http://dx.doi.org/10.1017/s1357729800042703.
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AbstractThe objective of this work was to investigate phenotypic sources of variation in the sites of storage of milk within the udder. Ten primiparous and 10 multiparous dairy cows were studied over two successive lactations in order to investigate the effects of age, parity and stage of lactation. Cistern and alveolar milk volumes were estimated at a standard 8 h after a normal morning milking by catheter drainage and machine milking with oxytocin respectively. Measurements were made at approximately 9, 20, 30 and 42 weeks of the initial lactation and weeks 1, 4, 7, 10, 20 and 34 of the subsequent lactation. In the initial lactation, there was a significant difference between primiparous and multiparous animals in the rate of decline of total daily milk yield (P< 0·001). Cistern milk yield (kg/8 h) from multiparous animals declined over the lactation whilst that for primiparous animals was maintained. The effect was shown as a significant interaction effect (P< 0·05). For both multiparous and primiparous animals cistern proportion (cistern yield divided by total milk yield at 8h after a normal milking), increased over the lactation (P< 0·001). This was largely a consequence of the reduced total milk yield. Eleven animals were studied through the subsequent lactation. Cistern yield followed a lactation curve of similar form to that for total yield. The decline in cistern yield over this lactation was much greater than the decline with multiparous animals in the previous year. This may, in part, reflect a faster decline in total daily yield. Stage of lactation and parity must be taken into account if a standardized evaluation of cistern characteristics is to be obtained.
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Manning, Rob, and Ian R. Wallis. "Seed yields in canola (Brassica napus cv. Karoo) depend on the distance of plants from honeybee apiaries." Australian Journal of Experimental Agriculture 45, no. 10 (2005): 1307. http://dx.doi.org/10.1071/ea02170.
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This research examined the benefits of placing hives of honeybees (Apis mellifera L.) in canola (Brassica napus L.) at a density of approximately 1 hive/ha. We tested 3 main hypotheses. First, deploying honeybees increases the yield of seed. Second, that the benefits of honeybee pollination decline the further plants are from an apiary. Third, poorly pollinated plants should channel more resources into larger seeds, whereas plants benefiting from insect pollination should produce more but smaller seeds. The experiment confirmed all 3 hypotheses. Yields of seed increased by more than 20% or by 400 kg/ha, whereas the yield declined in plots located more than 200 m from the apiary. There are several explanations for the increased yield, including an enhanced production of fertile pods and, therefore, more seed, particularly small seed.
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Doyle, AD, RW McLeod, PTW Wong, SE Hetherington, and RJ Southwell. "Evidence for the involvement of the root lesion nematode Pratylenchus thornei in wheat yield decline in northern New South Wales." Australian Journal of Experimental Agriculture 27, no. 4 (1987): 563. http://dx.doi.org/10.1071/ea9870563.
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Factors responsible for a decline in wheat yields in some paddocks in the Gunnedah (northern New South Wales) area were investigated in a series of field experiments. Yield decline is not apparent on soils cultivated for less than 10 years, and barley and sorghum crops are not affected. Plant nutrition apparently is not a major factor in the decline, because, although there was a small response to zinc application in 1 experiment, wheat yields were not significantly increased by the application of N, P, K, Cu, Mg, B, Mn, Mo or S in a paddock where the yield of wheat was half that of the surrounding barley crop. Fumigation of the soil with methyl bromide increased wheat cv. Timgalen yield by 78% to equal that of barley cv. Clipper in a second experiment. Large numbers of root lesion nematodes (Pratylenchus thornei) were associated with unfumigated wheat plots, with smaller numbers present on barley plots. In a third experiment, the grain yields of all of the 9 cereal genotypes tested were increased when sown with 4 kg/ha of aldicarb. The relative yield increase associated with aldicarb showed good correlation with the reputed tolerance of the genotypes to P. thornei. Pratylenchus thornei occurred to a depth of 120 cm. Aldicarb did not affect P. thornei numbers below 15 cm, while methyl bromide controlled P. thornei to depths of 30-90 cm. Aldicarb virtually eliminated P. thornei from the surface 10 cm of soil, but had no effect on the incidence of the fungal diseases common root rot (Bipolaris sorokiniana) or crown rot (Fusarium graminearum). Soil fumigation with methyl bromide controlled B. sorokiniana and F. graminearum as well as P. thornei and gave yields 9% higher than did treatment with aldicarb. In another experiment, ethylene dibromide (2.7-10.8 L/ha) had no consistent effect on the yield of wheat or numbers of P. thornei while terbufos (0.6 and 1.2 kg/ha) gave a small reduction in P. thornei numbers and a small increase in yield. These data indicate that P. thornei is at least partially responsible for wheat yield decline in parts of northern New South Wales.
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Radford, B. J., C. M. Thornton, B. A. Cowie, and M. L. Stephens. "The Brigalow Catchment Study: III. Productivity changes on brigalow land cleared for long-term cropping and for grazing." Soil Research 45, no. 7 (2007): 512. http://dx.doi.org/10.1071/sr07062.
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Productivity of grain crops and grazed pastures inevitably declines without soil nutrient replacement and may eventually make these enterprises unprofitable. We monitored these declines in north-eastern Australia during 23 years after clearing 2 of 3 adjacent brigalow catchments, in order to define the productivity levels of developed brigalow land over time. One catchment (11.7 ha) was used for grain production and another (12.7 ha) for beef production from a sown buffel grass pasture. There was no upward or downward trend in annual rainfall amounts throughout the study period. In the cropped catchment, grain yield from 14 winter crops without added nutrients declined significantly in 20 years from 2.9 to 1.1 t/ha.year on the upper-slope clay soil (92 kg/ha.year) and from 2.4 to 0.6 t/ha.year on the Sodosol (88 kg/ha.year). Crop production per year declined by 20% between 2 successive 10-year periods. Wheat grain protein content also declined with time, falling below the critical value for adequate soil N supply (11.5%) 12 years after clearing on the Sodosol and 16 years after clearing on the clay soil. Such declines in grain quantity and quality without applied fertiliser reduce profitability. The initial pasture dry matter on offer of 8 t/ha had halved 3 years after clearing, and a decline in cattle liveweight gain of 4 kg/ha.year was observed over an 8-year period with constant stocking of 0.59 head/ha. Due to fluctuating stocking rate levels of 0.3–0.7 head/ha over the trial period, liveweight productivity trends are attributed to the multiple effects of stocking rate changes and fertility decline. The amount of nitrogen exported from the cleared catchments was 36.1 kg/ha.year in grain but only 1.6 kg/ha.year in cattle (as liveweight gain). Total soil N at 0–0.3 m declined by 84 kg/ha.year under cropping but there was no significant decline under grazing. The soil nutrients removed during grain and beef production need to be replaced in order to avert productivity decline post-clearing.
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Gilreath, James P., Carlene A. Chase, and Salvadore J. Locascio. "Crop Injury from Sublethal Rates of Herbicide. II. Cucumber." HortScience 36, no. 4 (July 2001): 674–76. http://dx.doi.org/10.21273/hortsci.36.4.674.
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Cucumber (Cucumis sativus L.) growth and yield in response to application of sublethal rates of 2,4-D at several developmental stages were evaluated in field studies during two seasons. In Expt. 1, prebloom applications of 2,4-D amine reduced plant vigor and increased foliar epinasty as rates increased from 0 to 112 g·ha-1. Early and total fruit yields also declined linearly as 2,4-D rates increased; 112 g·ha-1 2,4-D reduced early yield by 25% and total yield by 20%. In Expt. 2, plant vigor declined with increasing rates of 2,4-D applied at all four stages of development from first true leaf to early fruit enlargement; however, response at stage 1 differed with time after application. Epinasty increased with 2,4-D rate when applied at all developmental stages; however the severity of the response varied with time after application for stages 1, 2, and 3, but not for stage 4. Averaged over all developmental stages, vine length, fresh weight, and yield decreased linearly as rates increased. Early and total yields with 112 g·ha-1 were 22% and 19% lower than those of nontreated plants, respectively. Growth inhibition and yield decline, pooled across 2,4-D rates, were greater when exposure occurred at the earlier stages of development. Chemical name used: (2,4-dichlorophenoxy)acetic acid (2,4-D).
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Dabbert, Stephan, and Patrick Madden. "The transition to organic agriculture: A multi-year simulation model of a Pennsylvania farm." American Journal of Alternative Agriculture 1, no. 3 (1986): 99–107. http://dx.doi.org/10.1017/s0889189300001028.
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AbstractPrior research has shown that an established organic farm can be as profitable as a conventional farm under certain circumstances. However, organic farming systems often require a transition period before they are fully established after a changeover from conventional farming. Yields may decrease and recover only slowly during this transition period and less profitable crop rotations may be required to establish an organic system. Previous studies have ignored the income trend during the transition phase, and comparisons of organic and conventional farms have been faulted for lack of similarity in management and other resources. The study reported here used a multi-year simulation model to investigate the trend in income of a 117-hectare crop-livestock farm in Pennsylvania (called the Kutztown farm) during this transition process. A baseline model of the Kutztown farm under conventional management (CONB) was found to earn an income (returns over cash operating cost) of $61,900. The transitional models developed were an upper-yield case assuming no yield decline during the transition (TRANS) and a lower-yield case assuming severe yield decline in the first year after the change-over from conventional management and a subsequent linear recovery of yields over a three-year period (TRANS-L). Income was found to be severely depressed by a yield decline during the transitional phase. The first year of TRANS-L resulted in a 43% reduction in income. The scenario without a yield decline (TRANS) resulted in a 13% lower income compared to the baseline (CONB) model. Both transitional models led to an established organic situation with stable organic yields and an income of $57,400 or 7% less than under conventional management. It was found to be more profitable to sell the crops and purchase manure than to feed the crops to beef in a fattening enterprise. At small herd sizes (100 head) the reduction in income caused by the feeding operation was moderate ($1,300), but with a larger operation (213 head) the income sacrifice increased tenfold.
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Fallahi, Esmaeil, D. Ross Rodney, and Zahra Mousavi. "Growth, Yield, and Fruit Quality of Eight Lemon Cultivars in Arizona." Journal of the American Society for Horticultural Science 115, no. 1 (January 1990): 6–8. http://dx.doi.org/10.21273/jashs.115.1.6.
Full textAbstract:
Tree growth, yield, and fruit quality of eight lemon cultivars [Citrus limon (L.) Burro. f.] on macrophylla (Alemow) (C. macrophylla Wester) rootstock were compared when grown in sandy soil in the arid climate of south-western Arizona. `Foothill Lisbon' had higher cumulative yield and titratable acids than `Monroe Lisbon', `Prior Lisbon', `Eureka', and `Villafranca', and had larger fruit than other `Lisbon' cultivars. `Prior Lisbon' produced a larger tree canopy with lower yield efficiency than all other cultivars and did not show any decline due to sieve tube necrosis 12 years after planting. Overall, `Eureka' cultivars and `Villafranca' had lower relative cumulative yields, canopy volumes, total soluble solids content, titratable acids, and seed content, but higher tree decline than `Lisbon' cultivars. Overall, `Foothill Lisbon', in spite of carrying exocortis viroid, produced good yields and fruit quality and `Prior Lisbon' had a satisfactory growth-performance.
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Tautges, Nicole E., Jacob M. Jungers, Lee R. DeHaan, Donald L. Wyse, and Craig C. Sheaffer. "Maintaining grain yields of the perennial cereal intermediate wheatgrass in monoculture v. bi-culture with alfalfa in the Upper Midwestern USA." Journal of Agricultural Science 156, no. 6 (August 2018): 758–73. http://dx.doi.org/10.1017/s0021859618000680.
Full textAbstract:
AbstractIntermediate wheatgrass (Thinopyrum intermedium; IWG) is a perennial cereal crop undergoing development for grain production; however, grain yield declines of >75% are often observed after year 2 of the perennial stand and may be linked to soil nutrient depletion. Intercropping IWG with a perennial legume such as alfalfa (Medicago sativa) could benefit nutrient cycling while increasing agroecological diversity. Intermediate wheatgrass was established at five environmentally diverse sites in Minnesota, USA in (1) bi-culture with alfalfa, (2) non-fertilized monoculture and (3) monoculture fertilized annually in the spring with 80 kg N/ha. At northern sites where alfalfa growth was favoured, IWG grain yields were reduced in year 2 by growing IWG in bi-culture with alfalfa, relative to the monoculture systems. Across all sites IWG grain yield decreased by 90% in the non-fertilized monoculture, 80% in the fertilized monoculture and 65% in the bi-culture from year 2 to 4 and plant macronutrient concentrations decreased by 25–70%. In year 4, IWG grain yield was similar or greater in the bi-culture than the fertilized monoculture at three of the five sites and alfalfa biomass was correlated positively with grain yield, harvest index and nutrient uptake in the year 4 bi-culture. Chemical-nitrogen fertilization increased grain yields in year 2 but did not mitigate the decline in yields as stands aged. Intermediate wheatgrass in the bi-culture had similar yields and nutrient uptake and lower yield declines than the chemically fertilized stand at sites where alfalfa growth was maintained throughout the life of the stand.
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Asseng, Senthold, Davide Cammarano, Bruno Basso, Uran Chung, Phillip D. Alderman, Kai Sonder, Matthew Reynolds, and David B. Lobell. "Hot spots of wheat yield decline with rising temperatures." Global Change Biology 23, no. 6 (November 10, 2016): 2464–72. http://dx.doi.org/10.1111/gcb.13530.
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Heinicke, Stefanie, Katja Frieler, Jonas Jägermeyr, and Matthias Mengel. "Global gridded crop models underestimate yield responses to droughts and heatwaves." Environmental Research Letters 17, no. 4 (March 18, 2022): 044026. http://dx.doi.org/10.1088/1748-9326/ac592e.
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Abstract Extreme events can lead to crop yield declines, resulting in financial losses and threats to food security, and the frequency and intensity of such events is projected to increase. As global gridded crop models (GGCMs) are commonly used to assess climate change impacts on agricultural yields, there is a need to understand whether these models are able to reproduce the observed yield declines. We evaluated 13 GGCMs from the Inter-Sectoral Impact Model Intercomparison Project and compared observed and simulated impact of past droughts and heatwaves on yields for four crops (maize, rice, soy, wheat). We found that most models detect but underestimate the impact of droughts and heatwaves on yield. Specifically, the drought signal was detected by 12 of 13 models for maize and all models for wheat, while the heat signal was detected by eleven models for maize and six models for wheat. To investigate whether the difference between simulated and observed yield declines is due to a misrepresentation of simulated exposure to heat or water scarcity (i.e. misrepresentation of growing season), we analysed the relationship between average discrepancies between observed and simulated yield losses, and average simulated exposure to extreme weather conditions across all crop models. We found a positive correlation between simulated exposure to heat and model performance for heatwaves, but found no correlation for droughts. This suggests that there is a systematic underestimation of yield responses to heat and drought and not only a misrepresentation of exposure. Assuming that performance for the past indicates models’ capacity to project future yield impacts, models likely underestimate future yield decline from climate change. High-quality temporally and spatially resolved observational data on growing seasons will be highly valuable to further improve crop models’ capacity to adequately respond to extreme weather events.
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Lakitan, Benyamin, David W. Wolfe, and Richard W. Zobel. "Flooding Affects Snap Bean Yield and Genotypic Variation in Leaf Gas Exchange and Root Growth Response." Journal of the American Society for Horticultural Science 117, no. 5 (September 1992): 711–16. http://dx.doi.org/10.21273/jashs.117.5.711.
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Greenhouse experiments were conducted in 1987 and 1988 to evaluate the effect of timing of a 4-day flooding stress on growth and yield of snap bean (Phaseolus vulgaris L. cv. Bush Blue Lake 274, BBL). Plant survival was reduced when flooding was imposed at postflowering growth stages, but most plants survived when flooded before flowering or when reproductive development was prevented by deflowering. Early yields of surviving plants were very low in all flooded treatments, regardless of timing, in both years. Total yield response to timing of flooding was linear in 1987, with lowest yields when flooding was imposed at later growth stages. The trend was not linear in 1988, but in both years the latest flooding treatment (36 days after planting) had few surviving plants and no measurable pod yield. Additional greenhouse experiments revealed that leaf conductance of BBL and another bean cultivar, Luna (LN), declined within the first day of flooding. This decline was concomitant with one in leaf water potential and photosynthesis (Pn) in BBL, but decline of these responses occurred 1 to 2 days later for LN. After 4 days of flooding, Pn fell to near 0 for BBL, and to 15% of the prestress value for LN. Pn of both cultivars had recovered to 18.5 μmol·m-2·s-1 10 days after termination of flooding. LN had a larger adventitious root biomass, higher percentage of adventitious roots, and a consistently lower leaf: root ratio than BBL during recovery.
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Song, Libing, and Jiming Jin. "Effects of Sunshine Hours and Daily Maximum Temperature Declines and Cultivar Replacements on Maize Growth and Yields." Agronomy 10, no. 12 (November 26, 2020): 1862. http://dx.doi.org/10.3390/agronomy10121862.
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In this study, the crop environment resource synthesis maize (CERES-Maize) model was used to explore the effects of declining sunshine hours (SSH), decreasing daily maximum temperature (Tmax), and cultivar replacements on growth processes and yields of maize in Northern China, a principal region of maize production. SSH were found to decrease at 189 of 246 meteorological stations in the northern provinces of China over the period of 1994–2012, and a decrease in Tmax was also seen at many of these stations. The most significant decrease in these two climate variables occurred during June to September, a period for summer maize growth. For this study, seven crop field stations in the ShaanXi province, in the Guanzhong Plain, were selected, all of which showed a downward trend in SSH and Tmax over the period of 1994–2012. The CERES-Maize model was first calibrated and validated against yield observations for these stations over the same period, and the yield simulations matched very well with observations. The model was then driven by the detrended SSH and Tmax data, and the simulations were compared with those with a trend in these two input variables. The decline in SSH was found to reduce the maize yield by 8% on average over these stations due mostly to limited root growth, and the decline for shorter SSH reduced the yield more than that for longer SSH. Meanwhile, the decrease in higher Tmax increased the yield by extending the growth period, while the decrease in lower Tmax reduced the yield by lowering the thermal time. In addition, the observed yield showed a significant upward trend, and our modeling results indicate that this increase can be attributed mainly to the frequent cultivar replacements over our study period. The replaced cultivars usually had a longer growth period than the prior ones, which compensated for the yield loss due to fewer SSH. Net maize production decreased with the combined effects of the declines in SSH and Tmax on yields. This study quantifies the contribution of changes in climate and cultivars to maize growth processes and yields and provides strong insights into maize production under a complex dynamic climate system.
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Karim, Md Fazlul, Xiang Zhang, and Ru Li. "Dynamics of Shrimp Farming in the Southwestern Coastal Districts of Bangladesh Using a Shrimp Yield Dataset (SYD) and Landsat Satellite Archives." Sustainability 11, no. 17 (August 26, 2019): 4635. http://dx.doi.org/10.3390/su11174635.
Full textAbstract:
The shrimp-farming area and shrimp yield are continuously changing in the southwestern coastal districts of Bangladesh. The three southwestern coastal districts, Bagerhat, Satkhira, and Khulna, along with Rampal, a subdistrict of Bagerhat, contribute 75% of the total shrimp yield of Bangladesh. However, the shrimp yield and farming area have declined in Bagerhat district, and the cause of this decline is uncertain. In this research, the differences in the shrimp yield were quantified using a shrimp yield dataset (SYD) and k-means classification. A supervised image classification approach was applied to quantify the spatiotemporal changes and identify the influencing factors behind the declining shrimp-farming area and yield in Rampal, Bagerhat district, using Landsat satellite archives. K-means classification reveals that, between 2015 and 2017, the shrimp yield in Bagerhat district declined significantly compared to Satkhira and Khulna. The satellite-based monitoring results affirm that the shrimp-farming area of Rampal also decreased rapidly, from 21.82% in 2013 to 6.52% in 2018. This research estimates that approximately 70% of the shrimp-farming area was lost in Rampal since December 2013. Hence, the findings of this research might motivate the responsible bodies to declare the shrimp-farming coastal area as a “shrimp zone” and implement an active policy to protect the vulnerable shrimp-farming industry and shrimp farmers, considering it is the second-largest export earning source in Bangladesh after ready-made garments.
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Azhgaliyeva, Dina. "The Effect of Oil Revenue Funds on Social Welfare." Public Finance Review 46, no. 4 (December 18, 2016): 692–712. http://dx.doi.org/10.1177/1091142116681838.
Full textAbstract:
Recently, it has become popular among oil-producing countries to establish oil revenue funds, which are believed to stabilize the economy and provide intergenerational redistribution. Oil revenue funds differ depending on rules, such as accumulation rules and withdrawal rules. Numerical simulations show that funds can improve intergenerational social welfare, though not always. Which rule yields the highest intergenerational social welfare depends on countries’ parameters such as gross interest rate, relative risk aversion, and growth rate of oil production. Some rules may be unaffordable for a government budget. If oil production does not decline, funds following expenditure-based accumulation rules yield higher social welfare than funds that follow other rules. If oil production declines, the permanent oil income model or “Bird-in-Hand” can yield the highest social welfare.
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Zhao, Luochao, Xia Sun, Xueyang Wang, Sheng Qin, Yunhui Kong, and Muwang Li. "Bombyx mori Vps13d is a key gene affecting silk yield." PLOS ONE 17, no. 7 (July 7, 2022): e0270840. http://dx.doi.org/10.1371/journal.pone.0270840.
Full textAbstract:
Bombyx mori is an important economic insect, its economic value mainly reflected in the silk yield. The major functional genes affecting the silk yield of B. mori have not been determined yet. Bombyx mori vacuolar protein sorting-associated protein 13d (BmVps13d) has been identified, but its function is not reported. In this study, BmVps13d protein shared 30.84% and 34.35% identity with that of in Drosophila melanogaster and Homo. sapiens, respectively. The expressions of BmVps13d were significantly higher in the midgut and silk gland of JS (high silk yield) than in that of L10 (low silk yield). An insertion of 9 bp nucleotides and two deficiencies of adenine ribonucleotides in the putative promoter region of BmVps13d gene in L10 resulted in the decline of promoter activity was confirmed using dual luciferase assay. Finally, the functions of BmVps13d in B. mori were studied using the CRISPR/Cas9 system, and the mutation of BmVps13d resulted in a 24.7% decline in weight of larvae, as well as a 27.1% (female) decline and a 11.8% (male) decline in the silk yield. This study provides a foundation for studying the molecular mechanism of silk yield and breeding the silkworm with high silk yield.
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Cooper, JL. "Effect of time sowing and cultivar on the development and grain yield of irrigated wheat in the Macquarie Valley, New South Wales." Australian Journal of Experimental Agriculture 32, no. 3 (1992): 345. http://dx.doi.org/10.1071/ea9920345.
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Field experiments over 2 seasons in the Macquarie Valley of central New South Wales compared yields under irrigation of 5 wheat varieties with a wide range of maturities sown from 8 April to 27 August.Early maturity wheats (Yecora and Avocet) sown prior to 6 May suffered frost damage, while the winter wheats (WW33G and Burgas) sown after 29 July were not fully vernalised and most tillers failed to produce heads. There was a curvilinear relation between time of sowing and grain yield. Excluding the treatments which suffered frost damage, the earliest time of sowing (8 April) produced the highest yield, with a 6.4% yield reduction between 8 April and 8 May. The yield reduction increased with later sowing date: 13.3, 19.3, and 26.5% during May, June, and July. Anthesis in mid September produced the highest yields for all varieties. Treatments which flowered earlier than mid September suffered frost damage. For each day later than 15 September that anthesis occurred, the mean yield fell by 1.3% or about 68 kg/ha.day. Date of anthesis had no detectable effect on the rate of individual grain growth (1.3 mg/grain.day), but the later anthesis occurred, the shorter the duration of grain development and the lower the final grain weight. Rising temperatures, not moisture stress, seems to be the factor causing the decline in yield with late sowing. This experiment was irrigated to eliminate moisture stress but the decline in yield was similar to that reported for dryland crops.
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MEROT, Anne, Guillaume Coulouma, Nathalie Smits, Elsa Robelot, Christian Gary, Lucia Guerin-Dubrana, Jouanel Poulmach, Xavier Burgun, Anne Pellegrino, and Marc Fermaud. "A systemic approach to grapevine decline diagnosed using three key indicators: plant mortality, yield loss and vigour decrease." OENO One 57, no. 1 (January 27, 2023): 133–49. http://dx.doi.org/10.20870/oeno-one.2023.57.1.5575.
Full textAbstract:
Grapevine decline, a major global viticulture issue, is defined as a multi-year decrease in vine productivity and/or increase in vine mortality. Although grapevine trunk diseases are one of the most-studied causes, decline is multifactorial and associated with more than 70 factors, including abiotic and biotic hazards. With so many factors to consider, the phenomenon difficult to understand, especially for winegrowers. Our study aims to make it easier to determine and assess grapevine decline by focusing on three key indicators: yield, mortality and vegetative vigour. We investigated the relationships between these indicators from both a temporal and spatial perspective to propose a set of diagnostic indicators. Thus, we conducted a winegrowers’ survey, an historical analysis of grapevine decline and field measurements of the abovementioned indicators on plot networks in three major French winegrowing regions (see graphical abstract): Bordeaux, Cognac and Languedoc. We found that farmers’ perceptions of decline were consistent with an objective characterisation of decline based on in-field measurements of the indicators. Although vine mortality progressively spread over the years, neither the survey nor the historical analysis showed a direct link between decline and yield loss. Rather, large yearly fluctuations in yield, which did not systematically decrease over time, account for this finding. As a result, the mortality rate and the normalised difference vegetation index (NDVI) indicators were shown to be earlier indicators of grapevine decline than yield loss (yield achievement ratio, YAR). We performed a multifactorial analysis of the overall data set from the three regions to deepen our understanding of the variety of declining situations and the underlying environmental and management factors contributing to decline. Finally, two ground-based NDVI indicators and an image-analysis methodology using aerial photographs were proposed as easy-to-obtain indicators of grapevine decline. NDVI indicators were linearly correlated to both YAR and mortality rate. This study provides a better understanding and promising tools for early diagnosis of grapevine decline.
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McKenzie, D. C., A. L. Bernardi, K. Y. Chan, H. I. Nicol, L. W. Banks, and K. L. Rose. "Sodicity v. yield decline functions for a Vertisol (Grey Vertosol) under border check and raised bed irrigation." Australian Journal of Experimental Agriculture 42, no. 3 (2002): 363. http://dx.doi.org/10.1071/ea00119.
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The grain yields of 2 soybean crops and a canola crop were related to topsoil and subsoil properties that are known to affect soil aggregate stability in water. A broad range of soil conditions was produced by applying gypsum and lime at various rates to a Vertisol that was naturally sodic throughout the soil profile. The observations were made under both ‘border check’ and ‘raised bed’ irrigation. Soil factors that influence dispersibility and crop growth were considered as part of a stepwise regression analysis. For the 2 soybean crops under border check irrigation, surface exchangeable sodium percentage (ESP) explained 72 and 63%, respectively, of the grain yield variation. For the canola crop that followed, a combination of pH, ESP and electrical conductivity (in that order) explained 75% of the variation in grain yield. Grain yields for the 3 crops declined as the soil became more sodic, particularly on the flat border check area. For soybeans (flat area), the critical values of ESP at which surface sodicity caused a 50% yield decline (ESP50) were strongly influenced by the post-planting climatic conditions. When there was heavy rain just after germination of the soybean seedlings, the ESP50 value was 8.6. The more sodic areas developed a thick crust that impeded seedling emergence. However, in the following year, when conditions remained dry after planting, the ESP50 value was 10.7. Under bed irrigation, the influence of ESP on yield was only minor after the first year of cropping. There was evidence of soil structure improvement from salt that was deposited in the beds via the irrigation water. Subsoil chemical properties that affect structural stability had more of an influence on crop yield under beds than under the flat areas.
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JONES, M. J., and M. SINGH. "Long-term yield patterns in barley-based cropping systems in Northern Syria. 1. Comparison of rotations." Journal of Agricultural Science 135, no. 3 (November 2000): 223–36. http://dx.doi.org/10.1017/s0021859699008205.
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Trials, reflecting the feed needs in dry Mediterranean environments of small-ruminant production systems based on barley, were established at two sites in Syria in 1982. They compared various 2-course rotations of barley with feed legumes, fallow or more barley. This paper summarizes a 14-year sequence of results from an incomplete factorial combination of four rotations (B-V, B-L, B-F, B-B) of barley with vetch (Vicia sativa), lathyrus (Lathyrus sativus), fallow, and barley, with two fertilizer regimes, zero control and biennial NP applied to the barley phase, in terms of long-term mean yields, production stability and yield trends over time.On a 2-year rotational basis, most barley was produced by barley-only rotations, and differences between B-F and B-B were small; but, in terms of total biomass production, feed legume rotations (B-V and B-L) outyielded barley-only rotations by 29% at one site and 19% at the other. Responses to biennial fertilization were large but did not interact significantly with rotation treatment. The crude protein status (%N) of barley grain and straw was strongly determined by seasonal rainfall, but that of the grain could be enhanced, irrespective of rainfall, by a preceding feed-legume crop; and, altogether, the total mean crop nitrogen output of legume-based rotations exceeded that of barley-only rotations by 80% and 64% at the two sites. The inclusion of legumes thus enhances both quantity and quality of feed production.Annual yield fluctuations, attributable mainly to rainfall difference, were greater at the drier site. No consistent effect from fertilizer was observed, but at the wetter site rotation differences were appreciable, with B-F rotation giving the most stable yields. A number of time trends in yield values were tentatively identified. On a relative basis, some widening over time of the gap between fertilized and unfertilized treatments was observed in feed-legume yields at both sites and barley yields at the wetter site; over 14 years, yields in unfertilized plots had apparently declined relative to those receiving biennial NP. But, apart from a probable decline in lathyrus productivity compared to that of common vetch, changes in relative yield performance between rotations were difficult to detect. Regression models developed to describe absolute yield trends indicated a real decline over time in barley grain yields in continuous barley (B-B) at both sites and in unfertilized plots of all four rotations at the wetter site.
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ABDUL HARIS A, PRAGYAN KUMARI, VANDANA CHHABRA, and SANDEEP BISWAS. "Modeling the impact of anticipated climate change on wheat yields in two different agro-climatic zones of eastern India." Journal of Agrometeorology 13, no. 2 (December 1, 2011): 116–18. http://dx.doi.org/10.54386/jam.v13i2.1353.
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Wheat is the major cereal crop of winter season in the Indo-gangetic plains of India. The study is aimed to analyze impact of climate change on wheat varieties viz. K-9107 and HD-2733, under two different agroclimatic zones using simulation model InfoCrop. Model was calibrated and validated for Patna and Ranchi centres. Sensitivity analysis indicated declining yield trend with increase in temperature. Wheat yields simulated for future climate change scenario HADCM3 A2 for different time periods viz. 2020, 2050 and 2080. Simulated wheat yield showed decline from 3 to 38 percent for Patna and 3 to 28 percent for Ranchi. Due to higher temperature in future scenario the days to anthesis, days to maturity and grain number showed decline for both the locations.
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MacNish, GC. "Changes in take-all (Gaeumannomyces graminis var. tritici), Rhizoctonia root rot (Rhizoctonia solani) and soil pH in continuous wheat with annual applications of nitrogenous fertiliser in Western Australia." Australian Journal of Experimental Agriculture 28, no. 3 (1988): 333. http://dx.doi.org/10.1071/ea9880333.
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Experiments were conducted to test the hypotheses that: (i) continuous cropping with wheat would lead to a decline in take-all, (ii) ammonium nitrogen would reduce take-all compared with nitrate nitrogen, and (iii) that both sources of nitrogen would lead to a decline in soil pH. Attempts were also made to confirm that rhizoctonia root rot would vary unpredictably in continuous wheat and would be reduced by nitrogen. Wheat was grown without nitrogen (Nil) or with sodium nitrate (SN) or ammonium sulfate (AS) for 11, 10 and 9 consecutive years at Newdegate, Esperance and Mount Barker respectively. Rates of nitrogen were 50, 25 and 45 kg ha-1 at Newdegate, Esperance and Mount Barker respectively. A decline in take-all incidence was established at Newdegate, and plots treated with AS generally had a lower take-all incidence than did plots without nitrogen or treated with SN. At Esperance, a decline in take-all incidence was established only in AS treated plots. Take-all incidence was lower in plots treated with AS than plots without nitrogen or treated with SN in 6 years out of 10 at Esperance. No take-all decline was observed at Mount Barker and take-all incidence was rarely lower in plots treated with AS than in those without nitrogen or treated with SN. All treatments reduced soil pH at Newdegate and Esperance, which were weakly buffered sites, but at Mount Barker (a highly buffered site) only AS reduced pH. Rhizoctonia root rot was not found at Mount Barker. At Newdegate and Esperance it first occurred in the eighth and fifth crops respectively. Incidence peaked at about 60% of plants being affected in the ninth crop at Newdegate and 95% in year 7 at Esperance, and then declined to less than 5% at both sites. Applications of nitrogen had no effect on incidence of rhizoctonia root rot. Yields varied considerably between sites and years. Combining results for all years at each site showed that AS increased yield at all sites and SN increased yields at Newdegate and Mount Barker compared with no nitrogen. The continued use of AS at Mount Barker eventually had an adverse effect on yield.
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Masasi, Blessing, Saleh Taghvaeian, Randy Boman, and Sumon Datta. "Impacts of Irrigation Termination Date on Cotton Yield and Irrigation Requirement." Agriculture 9, no. 2 (February 19, 2019): 39. http://dx.doi.org/10.3390/agriculture9020039.
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Optimization of cotton irrigation termination (IT) can lead to more efficient utilization and conservation of limited water resources in many cotton production areas across the U.S. This study evaluated the effects of three IT timings on yield, fiber quality, and irrigation requirements of irrigated cotton in southwest Oklahoma during three growing seasons. The results showed cotton yield increased with later IT dates, but this response was highly dependent on the amount and timing of late-season precipitation events. Only a few fiber quality parameters were significantly different among treatments, suggesting a more limited impact of IT on fiber quality. When averaged over the three study years, the lint yield was significantly different amongst all treatments, with an average increase of 347 kg ha−1 from the earliest to the latest IT. Additionally, the seed yield and the micronaire were similar for the two earlier IT treatments and significantly smaller than the values under the latest IT treatment. The differences in fiber uniformity and strength were also significant amongst IT treatments. Strong positive relationships were found between yield components and average late-season water content in the root zone. Lint and seed yields plateaued at an average late-season soil matric potential of about −30 kPa and had a quadratic decline as soil moisture depleted. When benchmarked against the latest IT treatment, the earlier IT treatments achieved average reductions of 16–28% in irrigation requirement. However, this water conservation was accompanied with considerable declines in yield components and micronaire and smaller declines in fiber length, uniformity, and strength.
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Clements, R. O., P. J. Murray, B. R. Bentley, and I. F. Henderson. "Herbage yield and botanical composition over 20 years of a predominantly ryegrass sward treated frequently with phorate pesticide and three rates of nitrogen fertilizer." Journal of Agricultural Science 115, no. 1 (August 1990): 23–27. http://dx.doi.org/10.1017/s0021859600073871.
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SUMMARYPlots at Hurley, UK, sown to perennial ryegrass (Lolium perenne) in 1968 were given 188, 376 or 752 kg N fertilizer/ha per year. Half of each plot at the lowest and highest rate of N fertilizer was given a severe pesticide (phorate) treatment at frequent intervals. Plots were cut and their herbage yield was assessed on five occasions during each of the following 20 years. There was no indication of a long-term decline in total annual herbage yield at any rate of N fertilizer use. The severe pesticide regime enhanced yield by an average of 14·6%/year during the first 11 years, but tended to have little effect or to reduce yields subseque7tly. Initially (1969) all treatment plots comprised at least 85% perennial ryegrass, but this proportion declined to between 67% (medium N) and 40% (high N) by 1989. Apart from ryegrass, the main sward components were species of the grasses Agrostis, Poa, and Elymus and traces of the broad-leaved species Stellaria media and Taraxacum officinale.
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Song, Zhaoxia, Yubo Wang, and Hongyan Mu. "Metabolic Flow Analysis of Hydrogen Production from Glucose by Dark Fermentation Based on Stoichiometric and Thermodynamic Evaluation." Journal of Biobased Materials and Bioenergy 16, no. 3 (June 1, 2022): 519–25. http://dx.doi.org/10.1166/jbmb.2022.2192.
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In batch tests, the biohydrogen yield from glucose declined gradually from 3.00 mol/mol to 2.00 mol/mol along with the substrate level increasing from 15 g/L to 60 g/L, respectively. The mechanism was revealed through stoichiometric and thermodynamic evaluation. In accordance with quantitative evaluation of the e− equivalent (e−-eq) balances, the decline of hydrogen yields generally accompanied with more e−-eq converting directly from acetate formation to butyrate and ethanol formation. Meanwhile, the acetate/butyrate ratio decreased from 2.1 to 0.6 with the increment of substrate concentration. Likewise, improved yield of the byproduct ethanol (from 0.16 mol/mol to 0.61 mol/mol) was obtained with the rising substrate concentration. It could be attributable to the decrease of Gibbs free energy from −3.9 KJ/e−-eq to −5.6 KJ/e−-eq, which indicated that the higher substrate concentration was more favorable for the fermentation.
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Jasmin, Jean-Nicolas, Marcus M. Dillon, and Clifford Zeyl. "The yield of experimental yeast populations declines during selection." Proceedings of the Royal Society B: Biological Sciences 279, no. 1746 (September 5, 2012): 4382–88. http://dx.doi.org/10.1098/rspb.2012.1659.
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The trade-off between growth rate and yield can limit population productivity. Here we tested for this life-history trade-off in replicate haploid and diploid populations of Saccharomyces cerevisiae propagated in glucose-limited medium in batch cultures for 5000 generations. The yield of single clones isolated from the haploid lineages, measured as both optical and population density at the end of a growth cycle, declined during selection and was negatively correlated with growth rate. Initially, diploid populations did not pay this cost of adaptation but haploidized after about 1000–3000 generations of selection, and this ploidy transition was associated with a decline in yield caused by reduced cell size. These results demonstrate the experimental evolution of a trade-off between growth rate and yield, caused by antagonistic pleiotropy, during adaptation in haploids and after an adaptive transition from diploidy to haploidy.
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Lewthwaite, S. L., P. J. Fletcher, J. D. Fletcher, and C. M. Triggs. "Cultivar decline in sweetpotato (Ipomoea batatas)." New Zealand Plant Protection 64 (January 8, 2011): 160–67. http://dx.doi.org/10.30843/nzpp.2011.64.5976.
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The sweetpotato (Ipomoea batatas) crop is propagated vegetatively by field transplanting adventitious sprouts produced on storage roots retained from the previous seasons harvest This system promotes the persistence and accumulation of both viruses and spontaneous mutations A phenomenon known as cultivar decline has been reported internationally where the root yield and appearance of commercially grown sweetpotato cultivars appear to deteriorate over successive growing seasons The relative contributions of virus infection and plant mutation to cultivar decline are uncertain but both issues are addressed through the use of virustested tissue cultured propagation systems This study assessed the degree of decline for cultivars Owairaka Red and Beauregard within the New Zealand biophysical production environment Storage root yield decreased significantly with increasing field exposure for both cultivars (P
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Feng, Fan, Pengfei Dang, Xuan Pu, Xiaoxia Wen, Xiaoliang Qin, Yinglong Chen, and Kadambot H. M. Siddique. "Contribution of Proximal and Distal Grains Within Spikelets in Relation to Yield and Yield Components in the Winter Wheat Production Region of China From 1948 to 2012." Agronomy 9, no. 12 (December 5, 2019): 850. http://dx.doi.org/10.3390/agronomy9120850.
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Grain number and weight within a spikelet are major yield components which determine the grain yield in wheat. The objective of this study was to explore genetic gains in grain performance within wheat spikelets at the individual grain level and its effect on grain yield and evaluate genetic progress in stem internode length and other yield-related traits. We conducted field experiments across three growing seasons in the western Yellow and Huai Valley of China; incorporating 17 bread wheat cultivars released from 1948 to 2012. Yields were significantly correlated with year of release. Yield gains equated to 3.95 g m−2 yr−1 in response to increases in total grain weight per m2 (GW) in proximal (G1 and G2) and distal (G3 and G4) grains, despite a decline in the proportional contribution of proximal grains to yield and increase in the proportional contribution of distal grains to yield with year of release. Grain number per m2 (GN), thousand-grain weight (TGW), and harvest index (HI) increased with year of release, but plant height decreased. Both grain number per spikelet of proximal and distal grain contributed to the increase in total GN. However, the contribution ratio of GN in proximal grains to total GN declined, and the proportion in distal grains increased. Average single grain weight (SGW) increased linearly at G1, G2, G3, and G4 with year of release and contributed to the increase in TGW. The G3 and G4 grain positions had much lower individual grain weights but increased at a faster rate than G1 and G2. At G1, G2, and G3 grain positions, from bottom to top spikelets, the newly released cultivars had the heaviest grains and the old cultivars had the lightest grains. New cultivars had more spikelets than old cultivars and the number of grains (proximal and distal grains) in the apical spike increased with year of release. The length of five internodes decreased significantly with year of release, more so in the upper than lower internodes, all of which contributed to the decline in plant height. In summary, increasing the number and weight of distal grains could increase grain yield, TGW, and GN.
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Pradhan, Gautam P., P. V. Vara Prasad, Allan K. Fritz, Mary B. Kirkham, and Bikram S. Gill. "Response of Aegilops species to drought stress during reproductive stages of development." Functional Plant Biology 39, no. 1 (2012): 51. http://dx.doi.org/10.1071/fp11171.
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Drought stress is an important abiotic factor limiting wheat yield. Thirty-one accessions of Aegilops species belonging to five species were screened to identify species/accessions tolerant to drought stress and to measure traits associated with the tolerance. Plants were grown at full irrigation, 25/19°C day/night temperature and an 18 h photoperiod. At anthesis (Feekes 10.5.1), drought stress was imposed by withholding water for 16 days. Controls were continuously irrigated. Drought stress decreased chlorophyll content, grain number, individual grain weight and grain yield by 31, 25, 68 and 76% compared with the control. Aegilops geniculata Roth had greater tolerance to drought stress for yield (48% decline from control) compared with other species (>73% decline from control). The tolerance was associated with higher grain number spike–1 and heavier grains. A. geniculata, GenBank accession number TA 10437, was highly tolerant to drought stress with <20% yield decline and a drought stress susceptibility index (DSI) <0.5, whereas TA 1802, TA 2061, TA 1814, TA 1819 were identified as moderately tolerant to drought stress (20–40% yield decline and DSI < 1.0). Our results suggest a presence of genetic variability among Aegilops species that can be utilised in breeding wheat for tolerance to drought stress at reproductive stages.
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Mahmood, Aqib, Iftikhar Ali, Wei Wang, Syed Tahir Ata-Ul-Karim, Bing Liu, Leilei Liu, Yan Zhu, Weixing Cao, and Liang Tang. "Individual and Combined Effects of High-Temperature Stress at Booting and Flowering Stages on Rice Grain Yield." Agronomy 12, no. 12 (December 6, 2022): 3092. http://dx.doi.org/10.3390/agronomy12123092.
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Extreme temperature events as a consequence of global climate change result in a significant decline in rice yield. A two year phytotron experiment was conducted using three temperature levels and two heating durations to compare the effects of heat stress at booting (BT), flowering (FL), and combined (BT + FL) stages on rice yield and yield components. Compared with T1 (Tmean of 27 °C), heat stress at BT + FL and BT stages produced more regenerated tillers and compensated more for yield loss than heat stress at FL. Heat stress at BT + FL stages alleviated spikelet sterility and yield loss of original tillers compared to heat stress at FL. The greater variation of yield per plant (YPP) under heat stress at flowering as compared to BT and BT + FL stages was accompanied by a higher decrease in spikelet fertility, while, at BT and BT + FL stages, spikelet number per plant and 1000-grain weight also contributed well to variation in yield. Furthermore, heat stress during BT and BT + FL stages caused a significant decline in spikelet fertility of the upper part of panicles, followed by middle and lower parts, while heat stress at the FL stage responded inversely. For every 1 °C day increase in heat degree days at BT, FL, and BT + FL stages, YPPO (only original tillers) declined by 2.9%, 2.5%, and 6.0%, and YPPT (including original + regenerated tillers) decreased by 5.8%, 2.7%, and 2.2%, respectively. The projected alleviation effects under BT + FL stages of heat stress in contrast to single-stage heat stress would help to accurately estimate rice yield under extreme temperature events, as well as to develop a heat-tolerant rice cultivar.
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Shin, Sang-Ouk, Won-Young Han, Byung-Won Lee, Hyun-Jin Park, Jin-Woo Bae, Kyung-Jin Choi, and In-Seok Oh. "Major Factors for Affecting to Soybean Yield Decline in South Korea." Journal of the Korean Society of International Agricultue 27, no. 4 (November 30, 2015): 489–96. http://dx.doi.org/10.12719/ksia.2015.27.4.489.
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Johnson, Nancy Collins, Philip J. Copeland, R. Kent Crookston, and F. L. Pfleger. "Mycorrhizae: Possible Explanation for Yield Decline with Continuous Corn and Soybean." Agronomy Journal 84, no. 3 (May 1992): 387–90. http://dx.doi.org/10.2134/agronj1992.00021962008400030007x.
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