Academic literature on the topic 'Potassium deficiency'

Plants have developed mechanisms to adapt to the potassium deficient conditions over the years. In Arabidopsis thaliana, expression of a potassium transporter HAK5 is induced in low potassium conditions as an adaptive response to nutrient deficiency. In order to understand the mechanism in which HAK5 is regulated, the full-length cDNA overexpressor gene hunting system was employed as a screening method. Of 40 genes recovered, At4g18280 was found to be dramatically induced in response to potassium-deficiency and salt stress. Plants overexpressing this gene showed higher HAK5 expression and enhanced growth. These plants were also less sensitive to potassium-deficiency in terms of primary root growth. Taken together, these data suggest that this novel component, At4g18280, contributes to regulation of HAK5 and, consequently, tolerance to potassium-deficiency in plants.

This study shows that aquaporin-2 regulation is disrupted by a small fall in plasma potassium levels and the response is influenced by sexual dimorphism in renal potassium handling. The findings provided new insights into the mechanisms by which water balance is altered in dietary potassium deficiency and support defining the disorder as “potassium-dependent nephrogenic diabetes insipidus.”

Ixoras (Ixora L.) growing in calcareous sandy soils are highly susceptible to a reddish leaf spot disorder. Symptoms appear on the oldest leaves of a shoot and consist of irregular diffuse brownish-red blotches on slightly chlorotic leaves. Symptoms of K deficiency, P deficiency, and both K and P deficiency were induced in container-grown Ixora `Nora Grant' by withholding the appropriate element from the fertilization regime. Potassium-deficient ixoras showed sharply delimited necrotic spotting on the oldest leaves, were stunted in overall size, and retained fewer leaves per shoot than control plants. Phosphorus-deficient plants showed no spotting, but had uniformly brownish-red older leaves and olive-green younger foliage. Plants deficient in both elements displayed symptoms similar to those observed on landscape plants. Symptomatic experimental and landscape ixoras all had low foliar concentrations of both K and P.

Master of Science
Department of Agronomy
David B. Mengel
Over the last decade low (< 130 mg kg -1) soil test potassium (K) levels and increased crop K deficiency have become a major concern in the clay-pan soils of southeast Kansas. The use of more intense crop rotations and the increased production of high K extracting crops (e.g. soybeans (Glycine max L.)) has significantly increased K removal from these soils. In addition, the traditional use of the nutrient sufficiency-based fertilizer recommendations has resulted in K application rates being substantially lower than removal rates. Because of these practices, many soils that had naturally elevated K availability 25 years ago have declined in K content. More troubling is the extreme yearly variation of soil test exchangeable K levels reported in the region, which has many producers and consultants concerned about proper K management. This study was initiated to examine the extent of K soil test variation and to determine if the variability is impacting plant K availability by analyzing soybean leaf K content and crop yield. A major objective of our research is to identify the mechanism(s) driving these changes in soil test K levels and K availability to crops during the growing season. The long-term goal is to be able to design a soil sampling system and develop alternative K fertilizer recommendation strategies that could alleviate K deficiency impacts on crop yield. Evaluation of different K fertilizer application practices including rate of application and broadcast or surface band methods of application were studied as tools to correct soybean K deficiency. The direct and residual impacts of K fertilization and placement were also evaluated on corn (Zea mays L.) grown in the rotation with the soybeans. Results observed from this research showed that monthly soil samples taken during three crop years at multiple locations have ammonium acetate exchangeable K levels that indeed change dramatically. The data we collected together with data accumulated by farmers and crop consultants showed significant fluctuation in exchangeable K levels of up to 50% on a yearly and even on a monthly basis. Levels seem to demonstrate seasonal changes: higher in the spring months and then decline in the summer and fall. Potassium soil test levels also appear to follow a similar trend as monthly precipitation and soil moisture status. During wet months soil levels tend to increase and then decline during drier months, however, this is not a perfect relationship and other factors are likely to be involved in regulating soil test K levels. No clear effect of K fertilization or method of placement on soybean or corn yields was observed during the study. However, soybean leaf samples revealed that on very low (< 90 mg kg -1) soil test sites surface band applied fertilizer increased leaf K concentrations compared to broadcasted applications. Furthermore, the corn study revealed no distinct difference between using a split annual or biannual fertilizer application system. Maintaining soil test K levels above 130 mg kg -1 using a spring soil test appears to be a successful strategy for avoiding K deficiency. Traditionally most soil sampling occurs in late summer or fall when soil conditions are dry. Our data has demonstrated that during this period one should expect to encounter low soil test results that may not be true indicators of soil K levels during the spring planting months. With that said, spring soil sampling can be difficult to do in a timely fashion due to weather, as well as potential labor restrictions. Another critical point is to not switch back and forth between spring and fall sampling dates. Staying consistent with your sample timing will minimize the seasonal variability that is frequently experienced. Additionally, adopting a build and maintain fertilizer recommendation philosophy rather than a nutrient sufficiency-based recommendation approach is a better nutrient budgeting method to avoid having removal rates exceeding nutrient additions. The best K management proposal would be to consider using a build and maintain approach in combination with basing fertilizer rates on spring soil test K levels.

In the field crops are subject to a wide variety of biotic and abiotic stresses. In order to manage crop protection effectively it is important that we understand not only the way plants respond to these stresses, but the way in which these responses interact. High levels of fertilisers and pesticides are often applied to maintain soil nutritional status and prevent disease in modern intensive farming systems. Potassium (K) is an essential element for plant growth and development, and is required for a wide variety of processes within the plant. These processes can be broadly divided into biophysical processes such as stomatal opening and cell extension and biochemical processes such as protein synthesis and enzyme activation. K starvation has been shown to lead to increased levels of the stress hormone jasmonate (JA) and related compounds in Arabidopsis thaliana plants which in turn modulates the plant’s defence against herbivorous insects and probably other pests or pathogens (Armengaud et al., 2004; Troufflard et al., 2010). In order for these results to be applicable to agriculture it is important to assess whether crop plants respond to K in a similar manner as the model plant. In this project the effect of K-deficiency on growth, metabolite concentrations, transcript levels and pathogen susceptibility of barley were investigated. Plants were grown in full-nutrient (control) or K-free hydroponic culture. The physiological, biochemical and transcriptional effects of K-deprivation were accessed over a time course of 20 days. Roots and shoots from plants grown in K-free nutrient solution had significantly lower K concentration than those grown in the control solution after 3 and 6 days respectively. A significant reduction in growth was seen as early as 6 days after K withdrawal. K-starvation led to a slight decrease in nitrogen metabolism, while hexose sugars strongly accumulated. By day 9 a significant increase in the expression of JA marker genes was seen in plants grown in K-free nutrient solution. Thus, despite possible differences in downstream events an induction of JA biosynthesis in response to K-deficiency occurs in both Arabidopsis and barley. Detached leaf segments were used to assess the effect of K-deficiency on infection of barley by two fungal pathogens with different strategies for nutrient acquisition. K-deficient barley plants were less susceptible to the biotroph Blumeria graminis f. f. sp. hordei (powdery mildew) and more susceptible to the hemi-biotroph Rhynchosporium secalis. Treatment of detached leaves with methyl-jasmonate (Me-JA) also led to less B. graminis infection, but had no effect on the R. secalis infection, indicating that JA increase in response to K-deficiency influences B. graminis but not R. secalis infection. The study therefore provides strong evidence that the effect of K-deficiency on pathogen susceptibility is determined by the JA-sensitivity of the pathogen.

La déficience en potassium dans les parcelles de cotonnier est un phénomène répandu et en recrudescence. Le problème est d’autant plus marqué en Afrique sub-saharienne que les sols sont pauvres et les systèmes de culture peu intensifs. Les principaux effets de la carence en potassium référencés dans la littérature sont une réduction de la surface foliaire, une réduction de l’assimilation et une modification des règles de répartition des assimilats entre les compartiments de la plante (tiges, racines, fruits et feuilles). Les connaissances à l’échelle cellulaire sur le rôle du potassium sont nombreuses mais paradoxalement peu de modèles permettent l’intégration de ces résultats à l’échelle du plant et du peuplement. La raison provient de la multiplicité des mécanismes affectés et de la complexité à les intégrer à l’échelle du plant ou du peuplement. L’objectif de notre travail est de caractériser les effets de la carence en K sur la croissance et le développement du cotonnier avec suffisamment de variables intermédiaires explicatives pour pouvoir proposer un schéma conceptuel compatible avec les concepts utilisés dans les modèles de croissance de cette plante. Cet objectif implique ainsi de porter nos investigations à plusieurs échelles (peuplement, plante, organes, organites) et sur des variables-clés du fonctionnement physiologiques des plantes utilisées dans la modélisation courante telles que la photosynthèse ou le statut hydrique. Nos recherches nous ont aussi amené à mesurer d’autres variables non inclues dans les modèles courant, afin d’affiner notre compréhension du fonctionnement des plantes carencées (teneurs en sucres, vitesses de carboxylation, ouvertures stomatiques …). Pour satisfaire à ces objectifs, deux types complémentaires d’expérimentations ont été menés : 1) des essais en pleins champs, en condition pluviale strictes ont été conduits au Bénin, deux années de suite, sur deux sites différents : à Aplahoué en 2004 et à Savalou en 2005. Il s’agit d’essais comparant différents niveaux de fertilisation en potassium. L’objectif de ces essais était d’étudier les effets de la carence à l’échelle du peuplement. 2) Par la suite, une expérimentation en serre et en hydroponie a été conduite (Bordeaux, 2006) dans l’objectif d’analyser finement les processus affectés à l’échelle du plant et de l’organe. Les essais en peuplement comme l’essai en serre ont permis d’obtenir des gammes de teneur en potassium variées, grâce à des niveaux d’alimentation variés (3 niveaux au champ, 4 en serre). Les teneurs planchers des plantes les plus carencées se situaient aux alentours de 8 à 10 mg Kg-1, ce qui contraste avec les teneurs maximum mesurées qui avoisinaient les 30 mg g-1. L’indice foliaire des traitements carencés des essais en peuplement est inférieur aux témoins en raison d’un moins grand nombre de feuilles et d’une taille individuelle réduite. Dans les essais en serre, une importante réduction de la surface foliaire est aussi observée mais la part de la réduction de la surface individuelle dans la réduction de la surface totale est plus prononcée. L’analyse des dynamiques de croissance des surfaces foliaires montre que l’accroissement relatif des feuilles est identique quel que soit les niveaux de carence mais que la taille des organes à l’émergence est plus petite pour les plants carencés. En revanche, les entrenœuds des plants carencés ont à la fois une taille réduite à l’émergence et une croissance relative plus faible. A l’échelle du peuplement aucune différence d’efficience de conversion de la lumière n’est observée en conséquence, les réductions de biomasse sèche observée sont entièrement dues à une diminution de l’efficience d’interception du rayonnement. En revanche, l’efficience de conversion du rayonnement interceptée de l’essai en serre est affectée par la carence en K mais uniquement pour le traitement le plus carencé
Potassium deficiency is a common phenomenon in cotton parcels. This problem is quite important in sub-Saharan Africa, where soils are poor and cropping systems are very low intensive. The main effects of potassium deficiency referenced in scientific literature are: (a) a reduction in leaf area, (b) a decrease in nutrient assimilation, and (c) a modification of nutrient repartition amongst compartments (i.e. stems roots, fruits, and leaves). Even though knowledge at the cellular level on the role of potassium is wide, ironically, only but a few models integrate results at the plant or stand levels. The reason comes from the multiplicity of mechanisms used and the complexity of integrating them throughout the plant or stand. The objective of our work is to characterize the effects of K-deficiency on the growth and development of cotton plants by including sufficient intermediate explanatory variables to provide a comparable scheme with the concepts used in growth models for this plant. This objective implies that our research focuses on different scales (i.e. stand, plant, organ, cell) and on physiological variables used in current models such as photosynthesis or water status. Our research had also led us to measure other variables not included in current models, to refine our understanding of the mechanisms of how deficient plants grows (i.e. sugar rates, carboxylation speed, stomata opening…). To meet these objectives, two complementary types of experiments were conducted: (i) field trials were performed in Benin on two different sites, Aplahoué in 2004 and Savalou in 2005, with strict rainfall conditions to compare different levels of potassium-fertilization and describe the effects of K-deficiency at the stand level. (ii) and a greenhouse hydroponic experiment was done in Bordeaux, France in 2006 to analyze the processes used throughout the plant and the organ. The field and the greenhouse tests had different levels of potassium fertilisation (2 to 3 levels in the field, 4 in the greenhouse) and gave us wide ranges of potassium contents in leaves. The minimum value of the leaf K content for the deficient plants were around 8 to 10 mg kg-1, which contrasts with the maximum values measured that were around 30 mg g-1. Potassium levels for the most deficient plants were around 8 to 10 mg Kg-1, while the highest levels measured were 30 g Kg-1. The leaf area index of deficient treatments is inferior to that of controls due to a lower number of leaves and smaller leaf sizes. In the greenhouse test, an important decrease of leaf area is observed but the proportion of the reduction due to a reduction in individual leaf size is more pronounced than in the filed experiments. The temporal analysis of the leaf area growth shows that the relative increase in size of the individual leaves is the same whatever the level of K-deficiency but that the size of the organs at emergence from apical buds is smaller for K-deficient plants. In counterpart, internodes of K-deficient plants have smaller lenght at emergence and a decreased relative growth rate. At stand level, no difference of light conversion efficiency is observed. As a result, observed reductions of dry biomass are essentially due to a decrease in light interception. However, radiation use efficiency in greenhouse tests are affected by K-deficiency but only for the most K-deficient treatment. Measures on gas exchanges made in greenhouse experiment also shows that photosynthesis is affected only for the most K-deficient treatments. This reduction is due to two concomitant effects: poor stomatal opening and a reduction in the maximum velocity of carboxylation. The relative distribution in biomass for all the tests is modified by the potassium-deficiency, benefiting leaves at the expense of the heterotrophic organs. This effect is observed at the plant level through an increase in the specific leaf weight and a relative decrease in stem and root biomass

Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 8, 2008) Includes bibliographical references.

For cotton (Gossypium hirsutum L.) to grow and develop normally, plants need to uptake the necessary amount of nutrients and use those nutrients in a beneficial fashion. It is recognized that cotton needs a certain tissue concentration of ions to achieve and maintain growth rates (Siddiqi et al., 1987). One of the most essential and abundant nutrients in cotton is potassium (K), second only by mass to nitrogen (N) (Marschner, 1995; Oosterhuis et al., 2013). Potassium exists in the soil in four separate pools and moves through soil to roots mainly through diffusion (Rengel & Damon, 2008; Samal et al., 2010; Ogaard et al., 2001). Potassium plays a vital role in plant growth and metabolism.

The objectives of this study were to determine the Michaelis-Menten parameters for the high-affinity transport system (HATS) and low-affinity transport system (LATS) uptake mechanisms of cotton, observe how K is partitioned throughout the cotton plant over a growing season with differing K fertilization rates, and to determine if cultivars differed in values from currently available indices formulated for N-status detection from active sensors. It also set out to determine if these N-sensitive indices were sensitive to leaf K concentration and available K2O in the soil, and to evaluate the role these indices play in predicting yield. It was hypothesized that a high K hydroponic environment would lead to more K uptake by cotton roots, which would lead to an increase in VMAX and KM. It was also hypothesized that with increased K fertilization, there would be greater K uptake and larger shift to reproductive components due to the plant having more than enough K in all other parts enabling it to send more to the reproductive components, and that greater K rates would lead to higher yields across all cultivars. It was believed that normalized difference vegetation index (NDVI) would more accurately predict leaf K, available K2O, and yield than normalized difference red edge (NDRE), that NDVI and NDRE would more accurately determine the K parameters chosen than canopy chlorophyll content index (CCCI), due to the strong influence of the red-edge band in the index and that yield would be most accurately predicted by the CCCI, due to yield being influenced by both chlorophyll content and biomass, and the CCCI involving the red-edge band to reflect chlorophyll content and the near infrared band to detect biomass.

Secondary salinisation has rendered over 100 million hectares of land throughout the world, and over 5 million hectares in Australia, unsuitable for conventional agriculture. The utilization of salinised land and its associated water resources for mariculture is an adaptive approach to this environmental problem with many potential economic, social and environmental benefits. Despite this, inland mariculture is yet to develop into an industrial-scale, rural enterprise. The main aim of this study was therefore to identify and address some of the technical and biological limitations to the development of an inland finfish mariculture industry. Three technical aspects essential to the development of an Australian inland mariculture industry were reviewed; potential sources of water, the species suitable for culture in these water sources and the production systems available to produce them. Based on factors such as their quantity, quality and proximity to infrastructure, the most appropriate water sources were deemed to be groundwater obtained from interception schemes and waters from operational or disused mines. In terms of species, mulloway (Argyrosomus japonicus) were identified as having many positive attributes for inland mariculture, including being temperate and therefore having the ability to be cultured year-round in the regions where the majority of secondary salinity occurs. Seasonal production of barramundi (Lates calcarifer) in ponds in the temperate climatic zones has potential, but may be more appropriate for those salinised water sources located in the warmer parts of the country. Rainbow trout (Oncorhynchus mykiss) were also identified as having excellent potential provided water temperature can be maintained below the upper lethal limit and also have potential for seasonal production, perhaps in rotation with barramundi. In terms of production systems, pond-based culture methods were found to have many advantages specific to inland mariculture. Static ponds enable culture in areas with low groundwater yield and more cost-effective potassium supplementation compared with flow through ponds. Static ponds also largely overcome the issues associated with the disposal of salt-laden and eutrophied waste water; however yields from static ponds are typically low and limited by the nutrient input into the pond. In response to the yield constraints of static pond culture, a new culture technology known as the Semi-Intensive Floating Tank System (SIFTS) was designed, patented and constructed in collaboration with the aquaculture industry and tested in a static inland saline pond in the wheatbelt of Western Australia. This technology was designed to reduce nutrient input into ponds by the collection of settleable wastes and to provide large volumes of well-oxygenated water to the target species, to ameliorate the loss of fish from low dissolved oxygen during strong microalgal blooms. The three species identified above has having excellent potential for inland mariculture (mulloway, rainbow trout, and barramundi) were grown in SIFTS held within a 0.13 ha static, inland saline water body (salinity 14 ppt) over a period of 292 days, yielding the equivalent of 26 tonnes/ha/year (total for all three species). Rainbow trout were grown with an FCR of 0.97 from 83 to 697 grams over 111 days (SGR, 1.91%/day) between June and September, when average daily water temperatures ranged from 12.3„aC to 18.2„aC. Over the same time period, mulloway grew only from 100 to 116 grams, however, once temperatures increased to approximately 21„aC in October, feed intake increased and mulloway grew to an average size of 384 grams over 174 days with an SGR and FCR of 0.68 %/day and 1.39, respectively. Barramundi stocked in November with an average weight of 40 grams increased to 435 grams in 138 days (SGR 1.73%/day) with an FCR of 0.90. The SIFTS significantly reduced nutrient input into the pond by removing settleable wastes as a thick sludge with a dry matter content of 5 to 10%. The total quantity of dry waste removed over the 292 day culture period was 527 kg (5 tonnes/ha/yr), which was calculated to contain 15 kg of nitrogen (144 kg/ha/yr) and 16 kg of phosphorus (153 kg/ha/yr). The release of soluble nutrients into the pond resulted in blooms of macro- and micro- algae which caused large and potentially lethal diurnal fluctuations in dissolved oxygen within the pond, however, comparatively stable levels of dissolved oxygen were maintained within each SIFT through the use of air lift pumps. It is well documented that saline groundwater is deficient in potassium which, depending on the extent of the deficiency, can negatively impact on the performance of marine species, including fish. The physiological effects of this deficiency on fish, however, have not been previously described. As such, I conducted a bioassay investigating the physiological effects of a hypersaline (45 ppt) groundwater source containing 25% of the potassium found in equivalent salinity seawater (i.e. 25% K-equivalence) on juvenile barramundi. Histopathological examination of moribund fish revealed severe degeneration and necrosis of skeletal muscles, marked hyperplasia of branchial chloride cells and renal tubular necrosis. Clinical chemistry findings included hypernatraemia and hyperchloridaemia of the blood plasma and lowered muscle potassium levels. It was concluded from this study that the principal cause of death of these barramundi was skeletal myopathy induced by unsustainable buffering of blood plasma potassium levels from the muscle. Although such hypokalaemic muscle myopathies have been previously described in mammals and birds, this was the first description of such myopathies in fish. It was hypothesized from the results described above that the physiological effects of potassium deficiency are dependent on salinity and that they would be ameliorated by potassium supplementation. These predictions were tested in a subsequent study which measured the effects of potassium supplementation between 25% and 100% K-equivalence on the growth, survival and physiological response of juvenile barramundi at hyperosmotic (45 ppt), near-isosmotic (15 ppt) and hyposmotic (5 ppt) salinities. Unlike those juvenile barramundi reared at 45 ppt and 25% K-equivalence in the previous study, those reared in 50% K-equivalence water at 45 ppt in this study survived for four weeks but lost weight; whereas at 75% and 100% K-equivalences fish both survived and gained weight. Homeostasis of blood plasma potassium was maintained by buffering from skeletal muscle. Fish reared in 50% K-equivalence at this salinity exhibited muscle dehydration, increased branchial, renal and intestinal (Na+-K+)ATPase activity and elevated blood sodium and chloride, suggesting they were experiencing osmotic stress. At 15 ppt, equal rates of growth were obtained between all K-equivalence treatments. Buffering of plasma potassium by muscle also occurred but appeared to be in a state of equilibrium. Barramundi at 5 ppt displayed equal growth among treatments. At this salinity, buffering of plasma potassium from muscle did not occur and at 25% K-equivalence blood potassium was significantly lower than at all other K-equivalence treatments but with no apparent effect on growth, survival or (Na+-K+)ATPase activities. These data confirmed the hypothesis that proportionally more potassium is required at hyperosmotic salinities compared to iso- and hypo- osmotic salinities and also demonstrated that barramundi have a lower requirement for potassium than other marine and estuarine species being investigated for culture in inland saline groundwater. In addition to ongrowing fish, saline groundwater has potential for hatchery production. Specific advantages include the vertical integration of inland saline farms and the production of disease-free certified stock through isolation from the pathogens and parasites found naturally in coastal water. To determine the potential of utilizing inland saline groundwater for hatchery production, barramundi larvae were reared from 2 to 25 days post hatch in 14 ppt saline groundwater with either no potassium supplementation (38% K-equivalence) or full potassium supplementation (100% K-equivalence). Growth, survival and swimbladder inflation of these larvae were compared against those grown in control treatments of seawater (32 ppt) and seawater diluted to 14 ppt. Those reared in saline groundwater with 38% K-equivalence exhibited complete mortality within 2 days, whilst those held in groundwater with full supplementation survived at a rate equal to both control treatments (pooled average 51.1 ¡Ó 0.5%). At 25 days post hatch, there was no significant difference in larval length or dry weight between those grown in the 14 ppt control treatment and those in the saline groundwater with full potassium supplementation. There were no significant differences in swim bladder inflation between any of the surviving treatments (average 93.3 ¡Ó 2.5%). This is the first description of rearing barramundi larvae both in low salinity seawater and in saline groundwater, and demonstrates that the requirement for potassium by larval barramundi is higher than for juveniles of the same species. In addition to a deficiency in potassium, saline groundwater in Western Australia often contains an elevated concentration of manganese relative to seawater as a result of anaerobic reduction of manganese oxides or the pedogenic weathering of manganese-bearing rock. The effects of elevated manganese on marine or estuarine fish have not been described and a study was therefore conducted to determine if manganese, at a concentration typical of that found in saline groundwater, has any impact on fish. The effects of 5 mg/L of dissolved manganese on juvenile mulloway at salinities of 5, 15 and 45 ppt were determined by comparing the survival, growth and blood and organ chemistry with those grown at the same salinities without manganese addition. Survival of mulloway at 45 ppt in the presence of 5 mg/L of manganese (73 ¡Ó 13%) was significantly lower than all other treatments, which achieved 100% survival. Those fish grown in seawater without manganese exhibited rapid growth, which was not affected by salinity (SGR = 4.05 ¡Ó 0.29%/day). Those fish grown at 5 ppt and 45 ppt in the presence of manganese lost weight over the two week trial (SGR 0.17 ¡Ó 0.42 and -0.44 ¡Ó 0.83%/day, respectively), whilst those at 15 ppt gained only a small amount of weight (SGR 1.70 ¡Ó 0.20%/day). Growth was therefore affected by manganese and by the interaction of manganese and salinity, but not salinity alone. Manganese was found to accumulate in the gills, liver and muscle of the fish. No gill epithelial damage or other significant histological findings were found, however, significant differences in blood chemistry were observed. Blood sodium and chloride of manganese exposed fish were significantly elevated in hyperosmotic salinity (45 ppt) and depressed at hyposmotic salinity (5 ppt) compared with unexposed fish; consistent with manganese causing apoptosis or necrosis to chloride cells. Blood potassium was significantly elevated and liver potassium significantly reduced at all salinities in the presence of manganese. These findings are consistent with manganese interfering with carbohydrate metabolism. There were no differences in blood sodium, chloride or potassium across salinities in fish not exposed to manganese, demonstrating mulloway are capable of efficient osmoregulation across this salinity range.

L’un des rôles majeurs concernant les interactions bénéfiques entre les plantes et les champignons est l’amélioration de la nutrition des plantes en échangeant des nutriments, grâce à une meilleure exploration du sol et une meilleure absorption de l’eau et des ions. Par conséquent, la symbiose ectomycorhizienne, établie entre des espèces de plantes ligneuses et des champignons du sol, est cruciale pour que la plante puisse absorber efficacement les minéraux peu disponibles dans les écosystèmes forestiers. Des études physiologiques, des projets de séquençage de génomes récents et des analyses transcriptomiques ont permis de progresser dans l’identification et la caractérisation de transportomes de champignons symbiotiques. Le potassium (K+) est le cation le plus abondant dans les cellules de plantes et il participe à divers processus cellulaires et physiologiques. L’amélioration de la nutrition potassique par la symbiose ectomycorhizienne a été démontrée dans des conditions de carence en K+ en utilisant le couple-modèle Pinus pinaster et Hebeloma cylindrosporum. Des questions sont soulevées pour identifier les systèmes de transport fongiques impliqués dans l’absorption des nutriments du sol et dans leur transfert vers la plante au niveau de l’interface symbiotique entre le champignon et la plante, appelé le réseau de Hartig. Deux types de transporteurs potassiques, Trk et HAK, ont été identifiés comme des candidats pour effectuer l’absorption de K+ à partir du sol à l’aide des hyphes extraracinaires, et deux types de canaux potassiques, Shaker et TOK, qui eux pourraient jouer un rôle dans le relargage du K+ au niveau des hyphes du réseau de Hartig vers l’apoplasme des cellules racinaires. Dans ma thèse, je me suis focalisée sur les trois canaux TOK (« Two-pore Outward K+ ») d’H. cylindrosporum, une famille de canaux spécifiques aux champignons. Ces trois canaux TOK appartiennent à deux sous-familles, ce qui pourrait indiquer des rôles différents dans la nutrition potassique et la symbiose. L’un des trois canaux semble particulièrement intéressant en raison de son induction lors de la mycorhization. Le but de ma thèse a donc été de compléter les précédents résultats sur leur caractérisation, expression, localisation et de participer à la création de nouveaux outils pour analyser leur(s) rôle(s) physiologique(s). En perspective, mes résultats contribueront à une meilleure compréhension des rôles spécifiques des membres de cette famille TOK originale au sein du champignon et au sein de la symbiose
A major role of mutualistic interactions between plants and fungi is the improvement of plant nutrition by an exchange of nutrients, due to a better exploration of the soil and a better absorption of water and ions. Therefore, ectomycorrhizal symbiosis, established between woody plants and soil fungi, is crucial for the plant to efficiently take up poorly available nutrients in forest ecosystems. Physiological studies, recent genome sequencing projects and transcriptome analyses have allowed progress towards the identification and characterization of the fungal symbiotic transportome. Potassium (K+) is the most abundant cation in plant cells and is involved in various cellular and physiological processes. Improvement of K+ nutrition by ectomycorrhizal symbiosis has been shown under K+ shortage conditions using the model couple Pinus pinaster and Hebeloma cylindrosporum. Questions are raised to identify the fungal transport systems involved in the uptake of nutrients from the soil and in their transfer towards the plant at the symbiotic fungus-plant interface, called Hartig net. Two types of K+ transporters, Trk and HAK, have been identified as candidates to perform K+ uptake from the soil by extraradical hyphae, and two types of K+ channels, Shaker-like and TOK, that may release K+ by the hyphae of the Hartig net into the plant apoplasm. In my PhD, I focused my research on the three TOK (Two-pore Outward K+) channels of H. cylindrosporum, a channel family specific for fungi. These three TOK channels belong to two different subfamilies, which may imply different roles in potassium nutrition and in symbiosis. One member seems to be especially interesting because of its induction by mycorhization. My PhD aimed to complete the previous results on their functional characterization, expression, localization, and to contribute to the establishment of tools to analyze their physiological roles. In perspective, my results will contribute to a better understanding of the specific roles of these original TOK channel members within the fungus and within the symbiosis

Cette thèse de doctorat porte sur la régulation du cotransporteur K+-Cl- de type 4 (KCC4) par la « WNK lysine deficient protein kinase 4 » (WNK4), une sérine-thréonine kinase qui a été découverte en 2001. Le cotransporteur KCC4 fait partie de la famille des cotransporteurs cation-Cl- (CCC) qui compte neuf membres. Le cotransporteur KCC4, et les autres isoformes de type KCC, sont des protéines de surface qui couplent l’efflux du Cl- à celui du K+ de manière électroneutre. Ce faisant, ils régulent le Cl- intracellulaire (Cl-i), le volume cellulaire (Vi) et la réabsorption basolatérale du Cl- dans les épithélia. Bien qu’ils soient activés par une augmentation du Cl-i et du Vi, les intermédiaires signalétiques impliqués demeurent mal caractérisés à ce jour. À cet effet, WNK4 pourrait correspondre à l’un de ces intermédiaires puisqu’elle régule plusieurs systèmes de transport, dont les KCC. Les objectifs de cette thèse étaient donc de déterminer si WNK4 régule l’activité de KCC4 suite à des changements de Vi et de Cl-i, et si c’est le cas, par quels mécanismes. Pour répondre à ces objectifs, nous avons adopté une approche structure-fonction par laquelle des mutations ont été introduites dans les protéines KCC4 ou WNK4. L’effet de ces mutations a été analysé dans le système d’expression hétérologue des ovocytes de Xenopus laevis grâce à des études fonctionnelles, d’expression de surface, d’immunofluorescence et de phosphorylation. Nos travaux ont permis de montrer pour la première fois que WNK4 et PP1 sont bel et bien impliquées dans la régulation de KCC4 suite à une augmentation du Vi, mais que contrairement à des hypothèses avancées antérieurement, PP1 agirait en aval plutôt qu’en amont de WNK4, et qu’elle agirait aussi sur KCC4 par l’intermédiaire d’autres intervenants signalétiques. Nous avons aussi identifié deux résidus dans le domaine C-terminal de KCC4 qui soutiennent l’effet de WNK4 et de PP1. En somme, ces travaux pourraient permettre d’identifier de nouvelles voies de signalisation impliquées dans la régulation de KCC4 par WNK4 et PP1 et, par conséquent, d’offrir d’autres cibles thérapeutiques pour traiter des désordres électrolytiques.
This Ph.D. thesis focuses on the regulation of K+-Cl- cotransporter type 4 (KCC4) by WNK lysine deficient protein kinase 4 (WNK4), a serine threonine kinase that was discovered in 2001. The cotransporter KCC4 belongs to the cation-Cl- cotransporter (CCC) family that includes nine members. This transporter, along with the three other KCC isoforms, corresponds to cell surface proteins that couple elctroneutral efflux of Cl- with that of K+. In doing so, KCC family members regulate intracellular Cl- (Cl-i), cell volume (Vi) and basolateral reabsorption of Cl- across a variety of epithelia. Although they are activated by an increase in Cl-i and Vi, the signaling intermediates involved remain largely unknown to date. In this regard, WNK4 could correspond to one such intermediate given that it regulates several transport systems including KCC. On the basis of these premises, the main objectives of this thesis were to determine whether WNK4 regulates KCC4 activity during changes in Cl-i and Vi and if so, through which mechanisms. To address these objectives, I exploited a structure-function approach in which mutations were introduced in both KCC4 or WNK4 and in which the effect of such mutations were analyzed in the Xenopus laevis expression system through functional, expression, immunofluorescence studies and phosphorylation. My studies allowed to show for the first time that WNK4 et PP1 are indeed involved in KCC4 regulation during an increase in Vi, but that in contrast to previous assumptions, PP1 would act downstream instead of upstream of WNK4, and that it would also act on KCC4 through additional signaling intermediates. Lastly, we have identified two residues in the C-terminus of KCC4 that mediate the effect of WNK4 and PP1. Taken together, these results could help identifying new signaling pathways of KCC4 regulation by WNK4 and PP1, and thus offer other therapeutic targets to treat electrolyte disorders.

Mineral nutrients have marked effects on plant health by providing the building blocks for plant growth, as well as for mitigating abiotic and biotic stress factors, particularly disease development. Even if mineral nutrition field studies are conducted to study pest management, they are at the mercy of complex soil, water, and climatic conditions not amenable to strict experimental control. Therefore, a hydroponic method of growing lettuce was developed and growth curves were established for the macronutrients nitrogen (N), phosphorus (P), and potassium (K). Lettuce plants were grown at varying levels of each nutrient: 2.5, 5, 10, 20, 40, 80, 160, and 320 mg N/L; 0.5, 1, 2, 4, 8, 16, 32 and 64 mg P/L; and 0, 2.5, 5, 10, 20, 40, 80 and 160 mg K/L. Due to inadequate results lettuce was grown again at 0, 10, 20, 40, 80, 160, 320 and 640 mg L K. Optimal levels of N, P, and K were 160 mg/L, 4.0 mg/L, and 80 mg/L respectively. C:N ratios were also looked at for the N experiment. The overall result was consistent with results from similar studies. Unlike similar hydroponic studies done with other plants, micronutrient levels did not become deficient at high phosphorus levels suggesting phosphorus toxicity. These growth curves can be used to test lettuce resilience to various biotic and abiotic stresses.

The most important principle in understanding disorders of water balance is that sodium balance is determined by the adequacy of the effective circulating volume, while water balance is determined by osmoregulation and the interplay between vasopressin activity, renal concentrating and diluting ability, and thirst. Disorders of sodium balance can be determined only by clinical examination. Orthostatic hypotension implies volume depletion and sodium deficiency. Edema implies volume excess and sodium excess. Potassium is predominantly an intracellular cation. The intracellular balance of potassium is regulated by endogenous factors such as acidemia, sodium, adenosine triphosphatase, insulin, catecholamines, and aldosterone. Clinically, it is absolutely critical to follow a stepwise approach to acid-base disorders. Metabolic acidosis is defined as a primary disturbance in which the retention of acid consumes endogenous alkali stores. This is reflected by a decrease in bicarbonate. Metabolic alkalosis is defined as a primary disturbance in which plasma bicarbonate is increased. The signs and symptoms of metabolic alkalosis include weakness, muscle cramps, hyperreflexia, alveolar hypoventilation, and arrhythmias.

AbstractSeveral methods exist for evaluating plant nutritional status. Looking for visual deficiency symptoms is perhaps the simplest approach, but once symptoms appear, crop performance has already been compromised. Several other techniques have been developed. All of them require correlation studies to provide plant performance interpretations. Reflectance is a remote sensing technique that detects changes in light energy reflected by plant tissue. It has proven successful in detecting nutrient deficiencies but does not yet have the ability to discriminate among more than one deficiency. Chemical assays of leaf tissue, known as tissue tests, require destructive sampling but are the standard against which other assessments are compared. Sufficiency ranges provide concentrations of each nutrient that are considered adequate for crop growth and development. They consider nutrients in isolation. Other approaches have been developed to consider how the concentration of one nutrient in tissue impacts the concentrations of other nutrients. These approaches strive to develop guidelines for maintaining nutrient balance within the plant. All approaches require large data sets for interpretation.

AbstractPotassium (K) demand by crops is almost as high as that of nitrogen (N) and plays a crucial role in many plant metabolic processes. Insufficient K application results in soil K mining, deficiency symptoms in crops, and decreased crop yields and quality. Crop K demands vary with crop types, growth patterns, nutrient needs at different physiological stages, and productivity. Science-based K application in crops needs to follow 4R Nutrient Stewardship to ensure high yield, improved farm income, and optimum nutrient use efficiency. Studies around the world report widespread K deficiency, ranging from tropical to temperate environments. Long-term experiments indicate significant yield responses to K application and negative K balances where K application is either omitted or applied suboptimally. Limited understanding of K supplementation dynamics from soil non-exchangeable K pools to the exchangeable and solution phases and over-reliance on native K supply to meet crop demand are major reasons for deficit of K supply to crops. Research on optimum timing of K fertilizer application in diverse climate–soil–crop systems is scarce. The common one-time basal K management practice is often not suitable to supply adequate K to the crops during peak demand phases. Besides, changes in crop establishment practices, residue retention, or fertigation require new research in terms of rate, time, or source of K application. The current review assesses the synchrony of K supply from indigenous soil system and from external sources vis-à-vis plant demand under different crops and cropping systems for achieving high yield and nutrient use efficiency.

Enhanced forest growth may respond to demand of woody resources and contribute to the climate change mitigation. Forest soil treatment with fertilizers, as well as drainage and thinning enhance forest growth. The analysis of needles is an established method in forest science to identify the nutrient status in the forest stand and need for forest soil enrichment with fertilizers. The aim of this research is to estimate the efficiency of forest soil enrichment with wood ash and ammonium nitrate in order to eliminate nutrient deficiency in forest stands. Forest soil was enriched with wood ash fertilizer or ammonium nitrate in 2016–2017. The current year needles were collected from fertilized and control plots, from three trees in each plot. The samples were collected in the period 2018–2019. Total nitrogen (g kg-1), calcium (g kg-1), magnesium (g kg-1), and potassium (g kg-1) were analyzed in the collected samples. The chemical properties of collected needles were compared at the individual object level to estimate the impact of fertilizer on forest stand. A statistically significant increase in the concentrations of potassium and phosphorus was detected in some plots treated with wood ash and ammonium nitrate. In addition, a correlation analysis conducted between the variables of chemical properties of needles and soil showed few significant correlations between nutrient content in needles and in soil samples.

Research was carried out at the Lithuanian Research Centre for Agriculture and Forestry’s (LAMMC) Joniškėlis Experimental Station on a clay loam Endocalcari Endohypogleyic Cambisol. The study was aimed to explore the aboveground mass of perennial forage legumes: red clover (Trifolium pratense L.) and lucerne (Medicago sativa L.), and their mixtures with festulolium (x Festuliolium), used as green manure, qualitative parameters and compatibility with cereals on the basis of nutrients nitrogen (N), phosphorus (P) and potassium (K). The deficiency of other nutrients (P, K) and intensity of green manure mineralization can lead to N absorption. It has been determined that winter wheat takes one kg of N together with 0.2 kg P and 0.6 kg K. Spring wheat requires a similar amount of P but a higher amount of K. Average winter wheat grain yield can be 4.0 t ha-1 on a clay loam Cambisol in organic cropping system. NPK content – 134 kg ha-1 is needed for such productivity (grain + straw). This content is lower for spring winter growing. P:N and K:N ratios are more favourable in perennial forage legume mixture with festulolium, as compared to legume alone. To obtain grain yields of 4 t ha-1 of winter wheat and 3 t ha-1 of spring wheat in balanced organic crop rotation it is sufficient to apply 3.0 and 2.0 t ha-1 DM of pure legume mass as green manure. “Cut-and-carry” fertilisers do not satisfy the wheat demand for P.

Assessment of plasma vWF abnormalities by clinical coagulation laboratories is difficult because the available test systems for vWF antigen quantification and multimer analysis are expensive, laborious, and require days, radioactive anti-vWF antibodies and autoradiographic methods. We have devised simple, rapid, sensitive alternative techniques for vWF quantification and multimer analysis that can be readily installed in clinical laboratories. Plasma vWF antigen quantification is by a 2 hour enzyme immunoassay that accurately detects levels as low as 0.23% of normal. Plasma vWF to be quantified is bound to polyclonal monospecific antihuman vWF attached to small glass beads, and anti-human vWF conjugated with alkaline phosphatase is added to make an insoluble "sandwich." A substrate solution consisting of phenylphosphate and 4-amino-antipurine is added, followed by potassium ferricyanide. Optical density (at 490-510 nm) of the red color that develops is directly proportional to the plasma concentration of vWF antigen. Plasma vWF multimeric analysis is by a one-day electrophoretic immunobiot procedure. Plasma vWF multimer forms are solubilized in SDS-urea-Tris-EDTA, separated by horizontal 1% agarose gel electrophoresis, and transferred to a cationic membrane. Other protein binding sites on the membrane are blocked with milk proteins, and the membrane is overlaid with anti-vWF IgG linked to alkaline phosphatase. vWF multimers are then displayed as blue bands by soaking the membrane in an alkaline solution of the histochemical stain, fast blue RR (commonly used for leukocyte alkaline phosphatase scoring) dissolved in naphtol AS-MX phosphate. These simple, non-radioactive procedures performed together permit the rapid distinction of classical (Type I) von Willebrand's disease (vWD), characterized by low vWF antigen and normal multimers, from the Type II vWD syndromes, characterized by a relative deficiency of the largest plasma vWF forms. Unusually large vWF multimers, present in remission plasma of patients with chronic relapsing thrombotic thrombocytopenic purpura (TTP), are also easily detected using this rapid system of multimer analysis.