Effects Of Potassium Deficiency Research Articles

Effects of potassium deficiency on photosynthesis, chloroplast ultrastructure, ROS, and antioxidant activities in maize (Zea mays L.)

Potassium (K) deficiency significantly decreases photosynthesis due to leaf chlorosis induced by accumulation of reactive oxygen species (ROS). But, the physiological mechanism for adjusting antioxidative defense system to protect leaf function in maize (Zea mays L.) is unknown. In the present study, four maize inbred lines (K-tolerant, 90-21-3 and 099; K-sensitive, D937 and 835) were used to analyze leaf photosynthesis, anatomical structure, chloroplast ultrastructure, ROS, and antioxidant activities. The results showed that the chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), photochemical quenching (qP), and electron transport rate of PSII (ETR) in 90-21-3 and 099 were higher than those in D937 and 835 under K deficiency treatment. Parameters of leaf anatomical structure in D937 that were significantly changed under K deficiency treatment include smaller thickness of leaf, lower epidermis cells, and vascular bundle area, whereas the vascular bundle area, xylem vessel number, and area in 90-21-3 were significantly larger or higher. D937 also had seriously damaged chloroplasts and PSII reaction centers along with increased superoxide anion (O2−) and hydrogen peroxide (H2O2). Activities of antioxidants, like superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), were significantly stimulated in 90-21-3 resulting in lower levels of O2− and H2O2. These results indicated that the K-tolerant maize promoted antioxidant enzyme activities to maintain ROS homeostasis and suffered less oxidative damage on the photosynthetic apparatus, thereby maintaining regular photosynthesis under K deficiency stress.

Effects of potassium deficiency on the enzymatic changes in developing cotton fibers

Although effects of potassium (K) on cotton growth have been explored extensively, the effects of K deficiency on the physiological changes closely related to cotton fiber development are lacking. Thus, a 2-year field experiment was conducted with two cotton cultivars (Simian 3 and Siza 3) under 0 kg K2O ha−1 (K deficiency) and 300 kg K2O ha−1 (K sufficiency). The results showed that tonoplast adenosine triphosphatase (V-ATPase), pyrophosphatase (PPase), plasma membrane H+-ATPase (PM H+-ATPase), phosphoenolpyruvate carboxylase (PEPC), sucrose synthesis (SuSy) and vacuolar invertase (V-INV) were highly sensitive to K deficiency. The decreases in those enzymes resulted in low malate and soluble sugar contents, which together with low K concentration declined the driving force for fiber elongation, leading to significantly lower fiber length in the 0 kg K2O ha−1 treatment. The activity of sucrose phosphate synthase (SPS) was obviously increased by K deficiency before 20 days post anthesis (DPA), which could partly explain the acceleration of fiber cellulose synthesis and the increase in fiber strength in the 0 kg K2O ha−1 treatment in the early stage. However, SPS activity was decreased by K deficiency after 20 DPA and SuSy activity was reduced by K deficiency at any sampling date, resulting in low fiber strength in the end. Compared with Simian 3, the enzymes V-ATPase, PPase, PM H+-ATPase, PEPC and SuSy during fiber elongation stage were more sensitive to K deficiency in Siza 3, and the enzymes SuSy and SPS during fiber-thickening stage were more sensitive to K deficiency in Siza 3, which were the important reasons causing greater decreases in final fiber length and final fiber strength for Siza 3 than Simian 3 under K deficiency.

Effects of potassium deficiency on root morphology, ultrastructure and antioxidant enzyme system in sweet potato (Ipomoea batatas [L.] Lam.) during early growth

Potassium (K+) deficiency is an important abiotic stress which has severe influence on the growth and development of sweet potato. To investigate the difference on root morphology, ultrastructure and antioxidant enzyme system at early growth stage, two representative sweet potato cultivars (Ipomoea batatas [L.] Lam.) with different K+ deficiency tolerance capacities were hydroponically cultivated under normal K+ (control) and K+ deficiency (−K) treatments. The results showed that after 14 days of treatment, the root length, surface area, volume, and average diameter of Ningzishu 1 (sensitive to K+ deficiency) were significantly decreased under −K treatment, by comparison, those corresponding decreases of Xushu 32 (tolerant to K+ deficiency) were lower and not significant (except for root length). In addition, the proportion of fine roots (diameter 1.0 mm) of Xushu 32 seedlings increased significantly under condition of K+ deficiency. Through transmission electron microscopy observations, it can be found that Xushu 32 seedlings showed a more complete root cellular structure and slighter oxidative damage than Ningzishu 1 under −K treatment. Moreover, the hydrogen peroxide content and malondialdehyde content in the root of Xushu 32 seedlings was significantly lower than that of Ningzishu 1, and the variations of superoxide dismutase, peroxidase, and catalase activities were pronouncedly less than those of Ningzishu 1. These differences between the two cultivars indicated that the stronger root morphology and nutrients absorption ability, and the better root cellular structure and physiological role of Xushu 32 seedlings could alleviate the damage of K+ deficiency stress. Thus, it might be a potential mechanism for cultivar tolerance to low K+ in sweet potato.

Effects of potassium deficiency on photosynthesis and photoprotection mechanisms in soybean (Glycine max (L.) Merr.)

Potassium is an important nutrient element requiring high concentration for photosynthetic metabolism. The potassium deficiency in soil could inhibit soybean (Glycine max (L.) Merr.) photosynthesis and result in yield reduction. Research on the photosynthetic variations of the different tolerant soyben varieties should provide important information for high yield tolerant soybean breeding program. Two representative soybean varieties Tiefeng 40 (tolerance to K+ deficiency) and GD8521 (sensitive to K+ deficiency) were hydroponically grown to measure the photosynthesis, chlorophyll fluorescence parameters and Rubisco activity under different potassium conditions. With the K-deficiency stress time extending, the net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of GD8521 were significantly decreased under K-deficiency condition, whereas the intercellular CO2 concentration (Ci) was significantly increased. As a contrast, the variations of Tiefeng 40 were almost little under K-deficiency condition, which indicated tolerance to K+ deficiency variety could maintain higher efficient photosynthesis. On the 25th d after treatment, the minimal fluorescence (F0) of GD8521 was significantly increased and the maximal fluorescence (Fm), the maximum quantum efficiency of PSII photochemistry (Fv/Fm), actual photochemical efficiency of PSII (ϕPSII), photochemical quenching (qP), and electron transport rate of PSII (ETR) were significantly decreased under K+ deficiency condition. In addition, the Rubisco content of GD8521 was significantly decreased in leaves. It is particularly noteworthy that the chlorophyll fluorescence parameters and Rubisco content of Tiefeng 40 were unaffected under K+ deficiency condition. On the other hand, the non-photochemical quenching (qN) of Tiefeng 40 was significantly increased. The dry matter weight of Tiefeng 40 was little affected under K+ deficiency condition. Results indicated that Tiefeng 40 could avoid or relieve the destruction of PSII caused by exceeded absorbed solar energy under K-deficiency condition and maintain natural photosynthesis and plant growth. It was an essential physiological mechanism for low-K-tolerant soybean under K-deficiency stress.

Effects of Potassium Deficiency on Root Growth of Cotton Seedlings and Its Physiological Mechanisms

For the purpose of dissecting the mechanism of root growth in response to potassium (K) deficiency in cotton ( Gossypium hirsutum L.), young seedlings of NuCOTN99B grown in half-strength modified Hoagland's solution with low K nutrient (0.05 mmol L −1) were investigated for the root configuration, content of endogenous free indole acetic acid (IAA), and amount of ethylene released from the roots 4 d after treatment. Compared with the treatment with moderate K nutrient (0.50 mmol L −1, control), the K deficient treatment significantly inhibited root length and the formation of lateral roots. The reduced lateral roots mainly resulted from the shortened branched root zone, and there was no change in the lateral root density. Under K deficient condition, the greatest reductions for root length, total root surface area, and root volume occurred in fine roots (0.05 mm ≤ diameter < 0.20 mm), followed by the coarse roots (diameter [.tau] 0.45 mm) and the middle roots (0.25 mm ≤ diameter < 0.45 mm). The fine roots were more important in nutrient uptake than the middle and the coarse roots. Thus, the K starving damage was greater in cotton seedlings than the growth inhibition of roots. When the cotton seedlings exposed to K deficient media for 4 d and 10 d, the total root length and the total root surface area were 35.7–38.0% and 47.7–50.6% of the values of the control plants; whereas the K accumulation was approximately 25% and 16% to the control values, respectively. As expected, the endogenous free IAA content in the roots grown in K deficient media reduced by 50%, whereas the amount of ethylene released from roots increased by nearly 6-fold, which partially explained the inhibition of lateral root formation and root elongation by K deficiency.

Effects of potassium deficiency on potassium, polyamines and amino acids in mouse tissues

Sexual dimorphism in potassium content was found in plasma, kidney, heart and skeletal muscle of CD1 mice. We observed that feeding mice with a K +-deficient diet had an uneven and gender-dependent effect on organ weight and tissue potassium concentrations. Treatment produced a marked decrease in plasma, pancreas and skeletal muscle K + levels in both sexes, and a reduction in kidney, liver and heart potassium concentrations in females. Moreover, K + deficiency produced a 2–3-fold increase in the concentrations of cationic amino acids, such as arginine and lysine in both heart and skeletal muscle of the two sexes, a slight increase (∼37%) in renal arginine in the male mice. The concentrations of these amino acids in plasma and other tissues in both sexes remained unaltered. Polyamine levels in heart, liver, skeletal muscle and pancreas from male and female mice were not affected by K + deficiency. However, in the male kidney potassium deficiency was accompanied by an increase of putrescine and spermidine concentration, and a reduction of putrescine excretion into the urine, even though renal K + concentration was not significantly affected and ornithine decarboxylase activity was dramatically decreased. The general lack of correlation between tissue potassium decrease and the increase in organic cations suggests that it is unlikely that the changes observed could be related with an attempt of the tissues to compensate for the reduction in cellular positive charge produced by the fall in K + content. The mechanisms by which these changes are produced are discussed, but their physiological implications remain to be determined.

Development of a protocol to study the effects of potassium deficiency in cotton under controlled environmental conditions

Cotton (Gossypium hirsutum L.) was grown in two separate experiments in a growth chamber to develop an experimental protocol for studying the effects of potassium (K) deficiency in cotton under controlled environmental conditions. Hydroponic culture techniques were implemented in the first study and sand culture techniques in the second study. Potassium was regulated in these studies by substituting all K salts with the corresponding Na salts. Leaf areas, tissue dry weights and tissue K and sodium (Na) concentrations were recorded. These studies indicated additional Na in the nutrient solutions containing less K resulted in increased tissue Na concentrations, which may have substituted for K in the plant and delayed the development of a K deficiency. Therefore, a modified solution was developed and utilized for studying the effects of K deficiency on cotton growth under controlled environmental conditions.

Effects of Potassium Deficiency on Leaf Growth, Related Water Relations and Accumulation of Solutes in Leaves of Soybean Plants.

The influence of potassium (K) deficiency on leaf water and osmotic potentials, and concentrations of major solutes was determined to assess their contributions to the leaf growth of soybean plants grown in solution cultures containing 5.0 and 0.2 mM KCl. A deficient supply of K restricted leaf growth due to decreased mesophyll cell numbers and cell enlargement, though water content, water and osmotic potentials of the expanding leaves were not affected by the treatment. The osmolarity of the expanding leaves showed very similar values in both treatments, though the K+ concentration in the K-deficient plants was remarkably lower than that of the control. In response to the K-deficiency, some cations, anions, sugars and amino acids accumulated in the expanding leaf, compensating the decrease in K concentration approximately 92%. These findings suggest that the leaf growth depression observed in the K-deficient plant occurred when the water relations of the K-deficient leaves are maintained close to that of the control.

Effects of potassium deficiency on tomato growth and mineral nutrition at the early production stage

The effects of potassium deficiency on hydroponically grown tomato were investigated at the early production stage (23 leaves, 3 trusses). Two types of potassium deficiency were applied : the permanent deficiency lasted for 23 days whereas the 10-day temporary deficiency was followed by a 7-day period of potassium supply resumption. Growth was assessed through non-destructive measurements. Permanent potassium deficiency resulted in growth slow-down before visual symptoms appeared on the adult leaves (leaves 12 to 17), but the older leaves (next to the first truss) were not affected. Temporary potassium deficiency reduced the growth rate, but, after potassium supply resumption, the plants recovered a growth pattern which was similar to that of the control plants. The potassium of the older leaves appeared to be less mobilizable than that present in the adult leaves where the visual deficiency symptoms appeared. Potassium uptake kinetics during the potassium supply resumption period were investigated on the plants submitted to temporary deficiency. In tomato plants which had been temporarily deprived of potassium before being transferred onto a standard nutrient solution, potassium uptake was faster than in the control plants. This result is to be related to the plant ability to recover a normal growth pattern. As a result of the occurrence of K-Mg and K-Na antagonisms, the sum of the cations was maintained at a constant value in some plant organs.

Effects of potassium deficiency on water relations and photosynthesis of the tomato plant

Potassium deficient (−K) and potassium sufficient (+K) plants were exposed to four days of water stress. Well watered −K and +K plants had comparable rates of transpiration. But +K plants had a larger leaf area and depleted the soil moisture to a greater extent on day 1 of stress. For days 2 and 3 their transpiration rate, leaf water potential and relative water content fell below those of −K plants. Well watered −K plants had a significantly lower rate of photosynthesis than +K plants. Photosynthesis of −K plants was more sensitive to reduction in plant water potential than that of +K plants. Reduction of photosythesis in −K leaves was due to impairment of photosynthetic capacity and not to stomatal closure. Growth was significantly reduced in −K plants.

Effects of potassium deficiency and simulated acid rain, alone and in combination, on the ultrastructure of Scots pine needles

The effects of potassium deficiency and artificial acid precipitation, alone and in combination, on Scots pine (Pinussilvestris L.) needles were studied using transmission electron microscopy. The seedling material was grown in quartz sand culture and watered with nutrient solution containing 45, 20, 10, or 5 mg of potassium/L; the concentration of other nutrients was constant and equally available for all seedlings. A portion of the seedlings from each group received consecutive acidified water spraying of pH 4.5, 4.0, 3.5, and 3.0, each for 4 days with a 3-day resting period between applications. The potassium deficiency caused an increase in the proportional vacuolar space and severe vesiculation of the tonoplast. Irregularly shaped lipid structures increased in number in the cytoplasm, and lipid bodies also appeared in the vacuoles and occasionally in the chloroplasts. The symptoms related to potassium deficiency were more severe in the transfusion parenchyma cells than in the mesophyll. The lowest level of potassium produced almost complete disorganization of the cellular structures in the transfusion parenchyma tissue, but severe changes were also seen in the mesophyll. The simulated acid rain treatment caused the formation of protrusions in the chloroplasts and an increase in irregularly shaped lipid structures in the cytoplasm throughout the mesophyll tissue, but no clear symptoms were observed inside the bundle sheath. In general, the changes caused by acid rain in the chloroplasts were slight and did not cause serious disorganization of these organelles. When the seedlings were exposed to combination treatment, the typical symptoms of both exposures were observable. The results suggest that the stresses caused by potassium deficiency and short-term foliar acid rain treatment can be distinguished in the needle ultrastructure.

Effects of potassium deficiency on growth and protein synthesis in skeletal muscle and the heart of rats.

The effects of potassium deficiency on growth, K content and protein synthesis have been compared in 4-13-week-old rats. When maintained on K-deficient fodder (1 mmol/kg) rats ceased to grow within a few days, and the incorporation of [3H]leucine into skeletal muscle protein in vivo was reduced by 28-38%. Pair-feeding experiments showed that this inhibition was not due to reduced energy intake. Following 14 d on K-deficient fodder, there was a further reduction (39-56%) in the incorporation of [3H]leucine into skeletal muscle protein, whereas the incorporation into plasma, heart and liver proteins was not affected. The accumulation of the non-metabolized amino acid alpha-aminoisobutyric acid in the heart and skeletal muscles was not reduced. The inhibitory effect of K deficiency on 3H-labelling of muscle protein was seen following intraperitoneal (10-240 min) as well as intravenous (10 min) injection of [3H]leucine. In addition, the incorporation of [3H]phenylalanine into skeletal muscle protein was reduced in K-depleted animals. Following acute K repletion in vivo leading to complete normalization of muscle K content, the incorporation of [3H]leucine into muscle protein showed no increase within 2 h, but reached 76 and 104% of the control level within 24 and 72 h respectively. This was associated with a rapid initial weight gain, but normal body-weight was not reached until after 7 weeks of K repletion. Following 7 d on K-deficient fodder the inhibition of growth and protein synthesis was closely correlated with the K content of the fodder (1-40 mmol/kg) and significant already at modest reductions in muscle K content. In vitro experiments with soleus muscle showed a linear relationship between the incorporation of [3H]leucine into muscle protein and K content, but the sensitivity to cellular K deficiency induced in vitro was much less pronounced than that induced in vivo. Thus, in soleus and extensor digitorum longus (EDL) muscles prepared from K-deficient rats, the incorporation of [3H]leucine was reduced by 30 and 47% respectively. This defect was completely restored by 24 h K repletion in vivo. It is concluded that in the intact organism protein synthesis and growth are very sensitive to dietary K deficiency and that this can only partly be accounted for by the reduction in cellular K content per se. The observations emphasize the need for adequate K supplies to ensure optimum utilization of food elements for protein synthesis and growth.

Studies in the mineral nutrition of Japanese mint

The outstanding effects of potassium deficiency on Japanese mint during winter and rainy seasons were marked accumulation of ammonia, amide and nitrate nitrogen with corresponding decrease in protain ntioen indicating arrested protein synthesis at ammonia- and amide formation stages as these fractions showed large proportion in the pool of soluble-N. The accumulation of soluble-nitrogen could be correlated with high respiration rate. Further, potassium-deficient plants had lowe value of ‘rest’-N and tootal N in winter and vice a versa in rainy season. In spite of an increased per cent essential oil content (ml/100 g dry weight), the total essential oil production (ml/plant) was low. In general, rainy season plants had higer percentage of essential oil and total oil/plant but showed lower values of all the forms of nitrogen.

Maintenance of cochlear function with synthetic blood and effects of potassium deficiency

We have recently described a method for the vascular perfusion of the guinea pig cochlea with synthetic blood, using the flurocarbon FC 47 as oxygen carrier [Wada et al., Laryngoscope (1979) (to be published)]. We have now determined that the endolymphatic potential (EP) and the cochlear microphonics can be maintained at normal or near normal levels for perfusion periods exceeding 300 and 150 min, respectively. However, the compound action potential (N1) cannot be maintained for longer than 60 min. This finding may be of considerable significance for blood substitute technology in general, since N1 could be the most sensitive indicator of adverse effects of synthetic blood known to date. In other experiments we found that the EP can be maintained at normal levels for 25.3 ± 6.9 (SD) minutes by K+‐free vascular perfusion. By contrast, the EP starts to decline immediately if perilymph is replaced by K+‐free media [Marcus et al., J. Acoust. Soc. Am. Suppl. 1 65, S13(A) (1979)]. The possible implications of these findings with regard to the mode of generation of the EP will be discussed. [Supported by the NIH and NSF.]

Effects of Mineral Nutrition on Endogenous Cytokinins in Plants of Sunflower (Helianthus annuusL.)

The effects of inorganic nutrients on the levels of endogenous cytokinins in plants of sunflower (Helianthus annuus L.) grown in sand culture were studied. Low levels of nitrogen resulted in rapid decreases in the levels of cytokinins extracted from leaves, buds, roots, and root exudates. Similar effects were observed with phosphorus deficiency, but the effects of potassium deficiency on the cytokinin content of leaves was less marked. The cytokinin content was higher in plants supplied with nitrogen as nitrate than in those supplied with ammonium sulphate or ammonium nitrate. The decline in cytokinin levels in derooted shoots and detached leaves could be reversed by supplying them with nutrient solution. Although leaves on intact plants may normally be dependent upon the supply of cytokinins from the roots, isolated leaves have the capacity for cytokinin production when supplied with inorganic nutrients.

Some Effects of Potassium Deficiency on Water Relations of French Prune1,2

Abstract In chlorotic, K-deficient leaves of prune (Prunus domestica L. cv. Agen), leaf water potentials were greater and transpiration less than in green, K-sufficient leaves. These results bring into question the role of leaf desiccation as the primary factor in the browning of K-deficient leaves.

Effects of Potassium Deficiency on Cotyledon Photosynthesis and Seedling Development in Cucumis sativus L.

Effects of Potassium Deficiency on Cotyledon Photosynthesis and Seedling Development in Cucumis sativus L.

Some Effects of Potassium Deficiency on Seedling Development

Some Effects of Potassium Deficiency on Seedling Development

Effects of Potassium Deficiency on the Photosynthesis and Respiration of Leaves of Sugar Beet under Conditions of Low Sodium Supply

Sugar beet plants (Beta vulgaris L. cv. F58-554H1) were germinated and cultured under standardized environmental conditions. The effects of K deficiency on photosynthetic and respiratory CO(2) exchange rates of attached leaves were studied under conditions of low Na supply by withholding both Na and K from the culture medium at cut-off (28 days after planting). Potassium and Na concentrations in the leaf blade and petiole decreased rapidly during the 8 days after cut-off, then more slowly.Photosynthetic CO(2) uptake per unit leaf area decreased rapidly with time after cut-off to 23% of the control rate in 17 days. Mesophyll resistance to CO(2) (r(m)) increased sharply after cut-off, r(m) eventually attaining 8.3 sec cm(-1). Leaf (mainly stomatal) diffusion resistance, r(1)', also increased rapidly from 4 days after cut-off, reaching 1.9 sec cm(-1) 13 days later. The photorespiratory evolution of CO(2) into CO(2)-free air decreased progressively after cut-off, but the rate of dark respiratory CO(2) evolution increased. It was concluded that withholding Na as well as K at cut-off increased the deleterious effects of K deficiency on photosynthesis and stomatal opening.

Effects of Potassium Deficiency on the Photosynthesis and Respiration of Leaves of Sugar Beet

Sugar beet plants (Beta vulgaris L. var. F5855441) were germinated and cultured under standardized environmental conditions for 28 days. Potassium deficiency was then induced by withholding K from the culture solution. Changes in CO(2) and water vapor exchange rates and surface temperatures of individual attached leaves were measured with time after K cut-off, along with changes in the concentrations of the leaf minerals K, Na, Ca, Mg, Fe, Mn, Cu, and Zn. During the 1st week after K cut-off the concentration of Na in the leaf blade increased from 200 to 1000 milliequivalents per kilogram dry matter while K decreased from 1500 to 300 milliequivalents per kilogram. During the subsequent 2 weeks, both Na and K concentrations decreased. The concentrations of other leaf minerals, except Mn, were little affected by K cut-off. Photosynthetic CO(2) uptake per unit area decreased linearly with time after cut-off and attained one-third of the control rate after 21 days. Low K apparently decreased photosynthesis through an increase in mesophyll resistance to CO(2) (r(m)) from 2.8 to 5.3 seconds per centimeter in 21 days. Leaf (mainly stomatal) diffusion resistance (r'(1)) increased only slowly during the first 15 days from 0.3 to 0.5 second per centimeter, eventually reaching 1.6 seconds per centimeter at 21 days. Low K progressively decreased the photorespiratory evolution of CO(2) into CO(2)-free air, but steadily increased the rate of CO(2) evolution in dark.