Glutathione levels in phloem sap of rice plants under sulfur deficient conditions

Glutathione which is an abundant reduced sulfur compound in plants is considered to play important roles in the transmission of the sulfur nutrient status between organs within the plant body and in the long-distance transport of reduced sulfur. We determined the concentrations of glutathione, γ-glutamylcysteine (γ-EC), sulfate in the rice phloem sap collected by the insect laser technique. Phloem sap was collected from the plants cultured in sulfur-deficient and control solutions. The concentration of glutathione in the rice phloem sap was higher than that of sulfate in both control and sulfur-deficient plants. Under sulfur-deficient condition, the concentration of glutathione in the phloem sap did not decrease, whereas the sulfate concentration decreased significantly. The pattern of changes in γ-EC concentration was similar to that of glutathione. These data indicate the presence of mechanisms for the maintenance of a constant glutathione concentration in the phloem sap in rice plants under sulfur deficiency, whereas the sulfate concentration was found to be relatively unstable.     

Impact of sulfate nutrition on the utilization of atmospheric SO2 as sulfur source for Chinese cabbage

The ability of Chinese cabbage (Brassica pekinensis) to utilize atmospheric sulfur dioxide (SO₂) as sulfur (S) source for growth was investigated in relation to root sulfate (SO ) nutrition. If seedlings of Chinese cabbage were transferred to a sulfate‐deprived nutrient solution directly after germination, plants became rapidly S‐deficient. Plant‐biomass production was decreased and the shoot‐to‐root ratio decreased. Sulfate deprivation resulted in a substantial decrease in total S, sulfate, organic‐S, and water‐soluble nonprotein thiol contents and in an increase in amino‐acid content of both shoot and root. The sulfate‐uptake rate of the root was strongly increased, whereas nitrate‐uptake rate was decreased. Upon resupply of sulfate, the onset of S‐deficiency symptoms was prevented, and growth was restored, whereas sulfate and nitrate‐uptake rates were quite similar to those of the sulfate‐sufficient plants. A 6‐day exposure to 0.12 µL L^–1 SO₂ of sulfate‐sufficient plants did not affect plant‐biomass production, shoot‐to‐root ratio, S and nitrogen (N) compounds of shoot and root, or sulfate and nitrate uptake by the root. Exposure of sulfate‐deprived plants to SO₂ resulted in enhanced total S, organic‐S, and water‐soluble nonprotein thiol contents of the shoot. The contribution of SO₂ as S source for biomass production depended on the duration of the sulfate deprivation. If Chinese cabbage was transferred to a sulfate‐deprived nutrient solution and simultaneously exposed to SO₂, then plants benefited optimally from the foliarly absorbed S. The development of S‐deficiency symptoms was prevented, and shoot‐biomass production was quite similar to that of sulfate‐sufficient plants. However, upon SO₂ exposure root‐biomass production was even higher than that of sulfate‐sufficient plants, whereas sulfate uptake was still enhanced. Evidently, upon SO₂ exposure there was no strict and direct shoot‐to‐root signaling in tuning sulfate uptake by the root and its transport to the shoot to the need for growth, via down‐regulation of sulfate uptake and normalizing shoot–to–root biomass partitioning.     

Genotypic differences in effects of cadmium on growth and nutrient compositions in wheat

Abstract

A solution culture study was conducted to determine the genotypic difference in the effects of cadmium (Cd) addition on growth and on the uptake and distribution of Cd and other 11 nutrients in wheat plants. Cadmium addition at a rate of 1 mg L^?1 significantly reduced root and shoot dry matter production, shoot height, root length, chlorophyll content, and tillers per plant. On the average of 16 wheat genotypes used in study, Cd concentrations of Cd‐treated plants were 48.1 and 459 μg g^?1 dry weight (DW) in shoots and roots, respectively, and retained 77.91% of total Cd taken up in the roots. On the whole, Cd addition reduced the concentration of sulfur (S), phosphorus (P), magnesium (Mg), molybdenum (Mo), manganese (Mn), and boron (B), and increased iron (Fe), irrespective of the plant parts. The effect of Cd on the concentration of potassium (K), calcium (Ca), and copper (Cu) differed in shoots and roots. The significant difference existed among 16 wheat genotypes in their response to Cd in terms of growth and nutrient concentrations. Genotype E81513, which showed relatively less inhibition in growth, had the lowest shoot Cd concentration and more Cd accumulation in roots, while Ailuyuang had the highest Cd concentration and accumulation in shoot with lower Cd concentration in root. The significant interaction was found between Cd treatment and genotype for all nutrient concentrations in both shoot and root, except S and Zn in root.     

Does the Sulfur Assimilation Pathway Play a Role in the Response to Fe Deficiency in Maize (Zea mays L.) Plants?

Abstract

The finding that the methionine is the sole precursor of the mugineic acid family phytosiderophores induced us to evaluate whether sulfur assimilation pathway has a role in plant response to Fe deficiency. Maize plants were grown for 10 days in nutrient solution (NS) containing 80 µM Fe in the presence (+S) or absence (?S) of sulfate. After removing the root extraplasmatic iron pool, half of the plants of each treatment (+S and ?S) were transferred to a new Fe deficient NS (0.1 µM final Fe concentration) (?Fe). The remaining plants of each pre‐culture condition (+S and ?S) were transferred to a new NS containing 80 µM Fe (+Fe). Leaves were collected 4 and 24 hours from the beginning of Fe deprivation period and used for chemical analysis and enzyme assays. Results showed that iron content in the leaves was lower in plants grown in S‐deficiency than in those grown in the presence of the macro‐nutrient. Iron deprivation produced an increase in the level of SH compounds in both nutritive conditions (+S and ?S). These observations are suggestive of some relationship between S nutrition and Fe uptake. For this reason, we next investigated the influence of Fe availability on S metabolism through the evaluation of changes in ATPs and OASs activity, the first and the last enzyme of S assimilation pathway respectively. Results showed that S‐starvation increased the activity of both enzymes, but this effect disappeared in plants upon Fe deficiency suggesting that S metabolism is sensitive to Fe availability. Taken together these evidences suggest that S metabolism is sensitive to soil Fe‐availability for plant nutrition and support the hypothesis of S involvement in plant response to Fe deprivation.     

Molybdenum Stress Modulates Enzymes Responsive to Oxidative Stress and Affects Seeds Viability and Vigor in Chickpea

The importance of molybdenum (Mo) for plant growth is disproportionate with respect to the absolute amounts required by most plants. Chickpea (Cicer arietinum L.) cv. K-75 plants were raised in refined sand in glasshouse at graded levels from 0.002 to 1 µM for 100 days. Mo deficiency symptoms appeared as interveinal chlorosis of middle and old leaves. Compared with the control (0.2 µM Mo), dry matter, yield and seed protein decreased at low and excess Mo. The concentration of Mo in leaves and seed as well as the activity of nitrate reductase (NR) increased with an increase in Mo supply. The activities of antioxidative enzymes stimulate at both low and excess Mo supply. Low and excess Mo decreased the lipid peroxidation status in chickpea leaves, suggesting its antiperoxidative nature. The values of deficiency, threshold of deficiency and threshold of toxicity of Mo were, respectively, 0.38, 1.2 and 15 µg g^?1 in leaves of chickpea.     

Sulfur composition of soybeans as affected by macronutrient deficiencies

Abstract

Results of solution culture experiments on effects of N, P, and K deficiencies on S constituents of leaf blades, total S concentrations, and S uptake by soybean plants are reported. Nitrogen deficiency decreased the concentration of soluble protein S, had little effect on nonsoluble S, and increased concentrations of soluble nonprotein S, sulfate S, reduced non‐protein S, and total S of soybean leaf blades. Soluble protein and S content of soluble protein decreased under N‐deficient conditions. For whole plants, S concentration and S uptake increased while dry weight was unaffected by N deficiency.

Phosphorus deficiency did not significantly affect S constituents of soybean leaf blades or whole plants. However, S concentrations and S uptake tended to decrease when P was deficient.

Potassium deficiency increased nonsoluble S concentrations in leaf blades and total S concentrations in whole plants but lowered dry weight per plant. Other S fractions of the leaf blades and S uptake per plant were not significantly affected.     

Effect of molybdenum stress on growth,yield and seed quality in black gram

Black gram (Vigna mungo L.) var. Shyam plants were raised in refined sand at four levels of molybdenum (Mo), i.e., low (0.002 µM) to excess (2 µM) for 70 days. The molybdenum deficiency symptoms appeared as interveinal chlorosis of young and middle leaves. Compared to control (0.2 µM Mo), total dry matter, seed yield and seed protein decreased at low and excess Mo. The concentration of Mo in leaves and seed as well as activity of nitrate reductase increased with an increase in Mo supply. Low and excess Mo deteriorated the quality of seeds by lowering the content of starch, sugars, protein, and nitrogen and increasing electrical conductivity of seed leachate. Molybdenum deficiency and excess both resulted in production of lightweight immature seeds, poor in vigor and germination potential. The values of sufficiency and threshold of toxicity in leaves were 0.078 and 2.15 µg Mo g^?1 dry matter of black gram.     

Critical comparison of the vanadomolybdate and the molybdenum blue methods for the analysis of phosphate in plant sap

Abstract

The performance of the vanodomolybdate and molybdenum blue methods for the routine determination of phosphate in plant sap were compared in order to assess their suitability for the detection of P deficiency at an early stage of plant growth. The molybdenum blue method was ca 10 times more sensitive than the vanadomolybdate one and required less sap to give a successful test. Recoveries of phosphate added to both sap and solution samples were close to 100% with both methods. The methods were in good agreement over a wide range of phosphate concentrations using sap samples from all leaves during the early stages of P deficiency, but increases in sap background colour caused the vanadomolybdate method to overestimate phosphate concentrations as the deficiency became more acute. Measurements on solutions of similar absorbance showed that the vanadomolybdate method was not significantly more variable than the molybdenum blue method but tended to overestimate phosphate concentration when very small volumes of sap were available. It was concluded that the molybdenum blue method was the most reliable for routine measurements of phosphate in plant sap.     

EFFECT OF PETUNIA STOCK PLANT NUTRITIONAL STATUS ON FERTILIZER RESPONSE DURING PROPAGATION

Fertilization strategies during stock plant and cutting production are linked in terms of cutting nutrient levels and quality. Objectives were to evaluate (1) the effect of stock plant nutrition on tissue nutrient concentration and growth during vegetative propagation and (2) response to fertilizer during propagation for cuttings with 4 different initial tissue nutrient concentrations. ‘Supertunia Royal Velvet’ petunia stock plants were grown under constant fertigation of 0, 50, 100 or 200 mg nitrogen (N)^.L^?1 for 21 days. The 200 mg N^.L^?1 solution contained 150 nitrate (NO₃-N), 50 ammonium (NH₄-N), 24 phosphorus (P), 166 potassium (K), 40 calcium (Ca), 20 magnesium (Mg), 0.7 sulfur (S), 1.0 iron (Fe), 0.5 manganese (Mn), 0.5 zinc (Zn), 0.24 copper (Cu), 0.24 boron (B), and 0.1 molybdenum (Mo). Providing a complete fertilizer during propagation of petunia, beginning immediately after sticking of cuttings, reduces the risk of nutrient deficiency. Particularly in situations where fertilizer is not applied early during propagation, stock plants should be managed to ensure unrooted cuttings have adequate nutrient reserves.     

Sulfur uptake by soybeans (Glycine max L.)

Abstract

Sulfur accumulation in young soybean plants tended to follow the pattern reported for P differing only in quantity. Soybean stems tended to have a more constant S concentration over time than did leaves or petioles.

The nutrient uptake pattern of a crop provides clues to more efficient management of plant nutrients. The recent reports of increased yields of soybeans due to foliar fertilization would seem to be a culmination of previous work done in Iowa on nutrient uptake patterns (1, 2, 3).

In the work reported to date there are no data which illustrate patterns of sulfur uptake by soybeans during the growing season. The work reported here was an attempt to determine the pattern of S uptake by soybeans during early growth stages.     

Corn forage yield and chemical composition as influenced by sulfur fertilization

Abstract

Soil sulfur (S) deficiency for plant growth has become an increasing problem in the United States. A field experiment was conducted to investigate effects of fertilization with 0 and 67 kg S/ha as a single or split application, in a Latin square design, on corn (Zea mays L.) forage yield and chemical composition. Sulfur fertilization by either method increased yield of whole plant and grain 7% and increased number of plants with two ears. Total S and sulfate‐S concentration in whole corn plants, leaf, stem, and grain were increased with S fertilization. The nitrogen (N):SO₄‐S ratio was a useful indicator of S deficiency.     

Nutrient deficiencies in lesser yam (Dioscorea esculenta) characterized using constant–water table sand culture

Nutritional deficiencies in Dioscorea esculenta (Lour.) Burk were studied using a novel culture system, applying a constant water table in acid‐washed sand, and a demand‐driven nutrient supply schedule. This system provided a stable growth environment and was highly efficient with respect to resources and labor. Yam plants (cv. Balbal) were propagated from 30 g tuber head setts and grown for 12 or 20 weeks, with nutrients supplied in the water reservoir to meet demand according to weekly leaf counts. Deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur were induced by reducing supply of the relevant nutrient to one tenth of normal. Deficiencies of iron, boron, manganese, zinc, copper, and molybdenum were induced by omitting the relevant nutrient from the culture medium. After 12 weeks, leaf blades of the main stem were sampled from four positions (immature, young expanded, mid, and old) weighed and analyzed for nutrient concentration, and dry weight of plant parts was recorded. Significant growth reduction was achieved for each deficiency except Fe, Zn, Cu, and Mo, which nonetheless developed some foliar symptoms. Effects on nutrient concentrations in leaves are reported, providing concentrations indicative of adequate and deficient status. Dioscorea esculenta was found to be particularly sensitive to Mn deficiency, although symptom presentation was atypical. Unusually low translocation of phloem‐mobile nutrients was also observed, paralleling reported observations on D. alata.     

The response of a high-yielding canola hybrid to sulfur fertilization in three contrasting Saskatchewan soils

Abstract

Canola (Brassica napus) is the primary oilseed crop in western Canada; however, it is often grown on sulfur (S)-deficient soils. Moreover, canola has a high S demand compared to cereals and, therefore, is particularly sensitive to S deficiency. This study examined the growth and nutrient uptake responses of a high-yielding canola hybrid cultivar to S fertilization when grown on three contrasting soils differing in S fertility, with and without the addition of fertilizer S. The soils were collected from three soil-climatic zones within Saskatchewan (Brown, Black, and Gray) and three different fertilizer S forms were used: ammonium sulfate (AS); ammonium thiosulfate (ATS); and a composite fertilizer containing nitrogen (N), phosphorus (P), and S (NPS; 50-50 blend of sulfate (SO₄) salt and elemental S). Sulfur fertilization increased the canola biomass, along with plant uptake of N, P, and S on all three soils. Fertilizer S use efficiency (i.e. recovery) ranged from 11-75%. For all three soils, the general trend among fertilizer S forms for biomass, nutrient uptake, and fertilizer use efficiency was AS?>?ATS?>?NPS. The greatest differences were observed with the Gray soil, which had the poorest S fertility. Residual soil SO₄ after harvest was greater for ATS and NPS; reflecting continued oxidation of thiosulfate and elemental S to SO₄. Principal component analysis demonstrated the importance of tissue N:S ratio as a key diagnostic measurement related to canola growth and nutrient uptake in S-deficient soils.     

Effects of calcium deficiency on nutrient concentration of xylem sap of excised tomato plants

The effects of calcium (Ca) deficiency on cation uptake and concentration of xylem sap from tomato roots after excision of the aerial parts, were studied. The measurements were made on tomato plants grown on nutrient solutions with +Ca or without‐Ca, over a period of 48 hours. Calcium deficiency entailed a significant increase of the flux of xylem sap between the 6th and 14th hour on the first day after excision. In spite of the lack of Ca in the nutrient solution, the Ca concentration in xylem sap was unaffected in regard to that of excised roots with +Ca. The maintenance of the Ca concentration in xylem sap of plants grown on a Ca deficient solution was related to a reuse of the Ca from the apoplastic root stores. So, this regulation indicates a possible translocation of the Ca available in the root supply and a mobility of this element out of the roots only during the early stages of exposure to a Ca deficiency. The presence of NH₄ ⁺ in xylem sap with both +Ca and‐Ca treatments confirms the nitrogenous reduction activity of tomato roots. The accumulation of free ammonium 24 h after excision in both xylem saps (+Ca and‐Ca) is likely to be evidence of an alteration process of protein synthesis which is related to the depletion of the root water soluble carbohydrate supply.     

INTERACTION OF MOLYBDENUM AND PHOSPHORUS SUPPLY ON UPTAKE AND TRANSLOCATION OF PHOSPHORUS AND MOLYBDENUM BY BRASSICA NAPUS

A hydroponic trial was conducted to assess interaction of molybdenum (Mo) and phosphorus (P) on uptake and translocation of P and Mo by Brassica napus. Molybdenum was applied at four rates (0, 0.01, 0.1 and 1 mg L^?1) and P at three rates (1, 30, and 90 mg L^?1) in nutrient solution. The results indicated that P increased shoot growth and 0.01 mg L^?1 Mo improved the growth of shoots and roots. Molybdenum increased shoot P uptake and root P concentration and uptake when higher P was provided, and had a stimulating effect on P translocation from shoots to roots. P increased shoot Mo concentration and uptake, decreased those in roots, and enhanced Mo transport from roots to shoots. These results implied that both Mo and P had beneficial effects on Mo and P absorption and translocation and co-application of them were necessary to promote growth and utilization of Mo and P for Brassica napus.     

Pattern of iron distribution in the soil‐plant system and its possible relation to iron‐chlorosis

Abstract

The frequent concentration‐ranges of various nutrient elements in soils and in plants are compared. Iron is different from almost all other nutrient elements in the fact that its optimal concentration range in plants is much lower than its frequent concentration range in soils. It is suggested that this observation is related to a chemical‐physiological mechanism of control on the uptake of iron by plants which in turn may explain the situations in which iron deficiency conditions in plants arise.     

Effect of sulfur deficiency and excess on yield and sulfur accumulation in tomato plants

Abstract

Tomato (Lycopersicon esculentum Mill. var. hybrid 6C‐204) plants were grown for 95 days after germination until each one bore 6 ripe clusters in a greenhouse using nutrient solutions with nine added sulfate levels ranging from 0 to 105 me/1.

Sulfur‐deficiency symptoms and characteristics of plants growing under hign SO₄‐S levels were observed and described. Fruit yields were negatively affected by both S‐deficiency and high SO₄‐S concentrations. Top growth was affected more than root growth by changes in the amount of SO₄‐S supplied. The critical SO₄‐S concentration in the growth media ranged from 2 a 22.5 me/1.

Leaf sulfate‐S increased gradually in leaves and roots as SO₄‐S supply in the nutrient solution increased while organic‐S remained relatively constant. Leaf sulfate‐S critical value was growth stage dependent. Maximum yields at flowering were associated with leaf concentrations of 0.48–1.2% SO₄‐S and 0.25–0.35% organic‐S.     

EFFICACY OF GYPSUM AND MAGNESIUM SULFATE AS SOURCES OF SULFUR TO RAPESEED IN LATERITIC SOILS

A field experiment conducted on rapeseed (Brassica juncea L.) during 2005–2006 in a typical lateritic soil (Alfisol) of West Bengal, India revealed that sources of sulfur viz. gypsum and magnesium sulfate and levels of sulfur (0, 20, 40, 60 kg S ha^?1) have significant influence on grain yield, total biological yield, sulfur concentration in grain and stover, total sulfur uptake, oil content and oil yield and chlorophyll content. The maximum grain yield (18.28 q ha^?1) and oil yield (8.59 q ha^?1) was obtained with magnesium sulfate followed by gypsum yielded the grain yield of 17.99 q ha^?1 and oil yield of 8.22 q ha^?1 at 40 kg S ha^?1. Overall, the best performance was recorded when sulfur was applied at 40 kg S ha^?1 either as magnesium sulfate or gypsum. Results revealed that magnesium sulfate may be considered as the better source of sulfur than gypsum to raise the mustard crop in sulfur deficient acidic red and lateritic soils of West Bengal and if farmers apply either magnesium sulfate or gypsum to soils, the possible deficiency of sulfur and magnesium/calcium in soils and plants can be avoided.     

Influence of Silicon on Sunflower Cultivars under Drought Stress,II: Essential and Nonessential Element Uptake determined by Polarized Energy Dispersive X‐ray Fluorescence

Abstract: There is no information regarding genotypic variation in essential and nonessential nutrient accumulation of sunflower grown under drought stress with the presence or absence of supplemental silicon (Si) despite the role of this element in improving growth of some cultivars under drought conditions. Accumulation of elements in sunflower cultivars might be important for the genetic improvement of the crop's response to drought. An experiment under controlled conditions was carried out to study the genotypic response of 12 sunflower (Helianthus annuus L.) cultivars to drought and Si and the relationship to the uptake of elements [phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), copper (Cu), zinc (Zn), manganese (Mn), chloride (Cl), molybdenum (Mo), Si, sodium (Na), vanadium (V), aluminum (Al), strontium (Sr), rubidium (Rb), titanium (Ti), chromium (Cr), nickel (Ni), bromine (Br), and barium (Ba)]. This was determined by polarized energy‐dispersive X‐ray fluorescence (PEDXRF). It was observed that uptake of nutrient and nonessential elements by sunflower cultivars were differentiated in response to applied Si and drought stress. Drought stress decreased mineral uptake of all the cultivars, and generally, application of Si under drought stress significantly improved Si, K, S, Mg, Fe, Cu, Mn, Na, Cl, V, Al, Sr, Rb, Ti, Cr, and Ba uptake whereas Zn, Mo, Ni, and Br uptake were not affected.     

Effect of leaching events on the fate of polyhalite nutrient minerals used for crop fertilization

Abstract

Polyhalite is a natural mineral containing potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S) and is proposed as a fertilizer source for these essential nutrients. Application of polyhalite is expected to be most relevant in soils where the availability of these nutrients is low: in sandy soils, in highly leached soils, or in areas where crops are irrigated by water with low content of these nutrients or are rain-fed. A controlled lysimeter experiment investigated the efficacy of surface applied polyhalite as a fertilizer supplying K, Ca, Mg and S compared to soluble sulfate salts in two soils (sandy and loamy) with or without simulated rain leaching events through two cycles of cropping. In the first cycle, carrot response and nutrient uptake, transport, and loss through leaching were studied, while in the second cycle the residual effect of the fertilizer was considered on maize without additional fertilizer application or leaching. Polyhalite plus rain led to increased carrot yield due to augmented Ca uptake in sandy soil. In both soils, polyhalite behaved as a prolonged availability fertilizer with more nutrients retained in the top soil layer and not leached below the root zone. The treatments did not affect maize growth or nutrient uptake except for lower K and S uptake in soils where rain had been simulated for the previous crop. We conclude that polyhalite shows potential as a commercial fertilizer to supply K, Ca, Mg, and S nutrients under conditions of dryland agriculture where occasionally leaching by rainfall occurs.