B. K. Garg

Influence of Water Stress on Water Relations, Photosynthetic Parameters and Nitrogen Metabolism of Moth Bean Genotypes

Effects of water stress at pre-flowering stage were studied in three genotypes (RMO-40, Maru moth and CZM-32 E) of moth bean [Vigna aconitifolia (Jacq.) Marechal]. Increasing water stress progressively decreased plant water potential, leaf area, net photosynthetic rate, starch and soluble protein contents and nitrate reductase activity while contents of reducing sugars, total soluble sugar, free amino acids and free proline progressively increased. Significant genotypic differences were observed and genotype CZM-32-E displayed a better drought tolerance than other genotypes.

Salinity‐fertility interaction on growth, mineral composition and nitrogen metabolism of Indian mustard

Abstract Indian mustard (Brassica juncea L.) was grown under low fertility (LF) and improved fertility (IF) [60, 40, and 20 kg/ha N, P2O5, and K2O, respectively] and irrigation with saline waters of different concentrations (0, 50, 100, and 150 meq/L) of the same composition as local ground waters. Although a progressive decline with increasing salinity was observed on all observed parameters, growth and seed yield was consistently and significantly greater for the IF as compared to LF plants. The magnitude of the detrimental effects at increasing salinity was also less in the IF as compared to the LF plants. These results suggest that an improvement in the concentration and uptake of NPK, particularly N, and an increase in K:Na ratio under IF, stimulated nitrate reductase (NR) activity as well as the ammonia assimilating enzymes, such as GS, GOGAT, and GDH, despite the high salinity. This led to higher levels of free amino acids and soluble protein in the plants. Starch tissue content also showed a marke...

Interactive effects of thiourea and phosphorus on clusterbean under water stress

Effects of phosphorus and thiourea application (either alone or in combination) were studied on clusterbean (Cyamopsis tetragonoloba Taub.) plants subjected to water stress by withholding irrigation at pre- and post-flowering stages in pot culture trial. Water stress significantly decreased shoot water potential, relative water content of leaves, net photosynthetic rate, contents of total chlorophyll, starch and soluble proteins as well as nitrate reductase activity at both the growth stages. Application of phosphorus and thiourea or combined application increased most of these parameters. Results revealed synergistic effects of P and thiourea in enhancing net photosynthesis, leaf area, chlorophyll content and nitrogen metabolism leading to significant improvement in plant growth and seed yield under water stress condition.

Influence of nitrogen on Indian mustard grown underdifferent levels of stored soil moisture

Abstract Responses of Indian mustard to different levels of stored soil moisture (100, 90, 75 and 60% of field capacity) and nitrogen doses (0, 30 and 60 kg ha−1) were studied. Decreasing moisture levels caused a general decline in all observed parameters. Nitrogen fertilization enhanced the soil moisture extraction (especially below 40 cm depth) and increased the water use through larger leaf area, particularly during the vegetative period without affecting the water use during the reproductive phase. An increase in nitrogen dose increased dry matter production, seed yield, water use efficiency, nitrogen and phosphorus uptake coupled with increased levels of total chlorophyll, starch, reducing sugars, soluble protein and free amino acids, despite a consistent decline in plant water potential and percentage relative turgidity at all levels of stored moisture. Notwithstanding the decline in the activities of nitrate reductase and glutamine synthetase under low soil moisture, the increase in glutamate dehydrogenase activity on one hand and nitrogen mediated increases in all these enzymes irrespective of soil moisture status, on the other, possibly helped the fertilized plants to maintain ammonia assimilation.

Effect of Phosphorus Application on Clusterbean under Different Intensities of Water Stress

ABSTRACT Response of clusterbean [Cyamopsis tetragonoloba (L.) Taub.] to phosphorus (P) application (0 and 40 kg ha−1) under different intensities of water stress at the critical pre-flowering stage was studied in a pot trial by withholding irrigation for 0, 3, 6, and 9 days. Increasing stress intensity progressively decreased plant water potential (Ψplant), relative water content, levels of different leaf metabolites, photosynthetic rate, and nitrate reductase activity under both phosphorus (P) treatments. However, P-fertilized plants displayed higher photosynthetic efficiency, leaf metabolism, and enzyme activity than unfertilized plants, though decrease in plant water status was more in P-fertilized plants. Recovery upon rewatering was also more in P-fertilized than unfertilized plants with respect to all the parameters studied. Consequently, P application significantly enhanced dry matter and seed yields at all stress intensities. The results indicate the possibility of alleviation of water stress effects by P nutrition in clusterbean, at least up to moderate stress level.

Alleviation of sodium chloride induced inhibition of growth and nitrogen metabolism of clusterbean by calcium

Increasing NaCl concentration (0, 50, 100 and 150 mM) progressively decreased growth and seed yield of clusterbean (Cyamopsis tetragonoloba Taub.) which was associated with decreased concentrations of potassium and calcium and increased concentration of sodium in the shoots. Supplemental calcium (2.5 and 5.0 mM) significantly ameliorated the adverse effects of NaCl due to enhanced Ca and K uptake and reduced Na uptake. Calcium also alleviated the negative effects of NaCl on activities of nitrogen metabolism enzymes as well as on contents of soluble protein and free amino acids.

Genotypic differences to soil salinity in clusterbean

This study relates the changes in performance (dry matter, seed yield, and leaf area), mineral composition (N, P, K, Na, and Cl), concentrations of leaf metabolites (chlorophyll, starch, reducing sugars, soluble protein, free proline, and free amino acids), and activities of nitrate reductase and glutamine synthetase at soil salinity of 10 dS m‐1in 10 genotypes of clusterbean (Cyamopsis tetragonoloba Taub.). Based on the extent of reduction in seed yield, genotypes were initially categorized as tolerant (Malosen and HFG‐182), moderately tolerant (AG‐111, Kutch‐8, KVS‐2, DP Safed, and B‐22–11–55), and sensitive (Durgajai, FS‐277, and B‐31–1‐55) to increased salinity. The responses between the tolerant and sensitive genotypes to salinity were different in all the parameters considered here. The responses of the moderately tolerant genotypes to salinity were variable and inconsistent. The sensitive genotypes had higher concentrations of Na and Cl in the shoot tissue and also a lower K:Na ratio under stress a...

Water management of transplanted seedlings of Azadirachta indica in arid areas

Abstract Large mortality and general growth restriction of transplanted tree seedlings in the Indian arid zone prompted this study on the effects of different levels (1/4, 1/2, 3/4 and full field capacity (FC)) and intervals (1, 2, 4 and 6 weeks) of irrigation, during the first dry period (September to July), following transplantation. Results are expressed as increases in height and stem diameter over time in relation to soil moisture regime and plant water status under different treatments. Final measurements 450 days after starting irrigation treatments indicated that watering at FC at 1- and 2-week intervals brought about the maximum increase in height and stem diameter, which declined progressively with increasing intervals and decreasing level. Despite the similarity in trend, final biomass production and crown area were highest under watering at FC at a 2-week interval due to larger increase in stem and foliage weight. Limited data on root growth along a single vertical plane suggested that branching of root laterals was mostly confined to the 10–50-cm depth irrespective of irrigation treatments, while depth of rooting tended to increase at longer intervals of watering. Under the prevailing conditions, average application of 46 1 (FC) per plant at 2-week intervals led to maximum growth and biomass production with no mortality, while under the low-threshold average irrigation of 121 (1/4 FC) per plant at 2-week intervals could eliminate mortality although the biomass production was reduced by about 91%.

Effect of saline waters on drought affected cluster bean

The influences of saline water irrigation of different concentrations (0, 40, 80 and 120 me l-1) were compared in droughted and undroughted plants of cluster bean (cv. FS-277) at its critical pre-flowering stage. Observations recorded on plant water status, diffusive resistance, nodulation behaviour and on different metabolic parameters (free proline, reducing sugars, starch and activities of N2-ase and nitrate reductase) after one and seven days of saline water irrigation revealed that the adverse effects were far greater in droughted plants revived with saline water, as compared to those which suffered only salt stress. These resulted in significant declines in growth and yield in the former as compared to the latter case, at all salt concentrations. The seed yield obtained in undroughted plants even under 120 me l-1, significantly exceeded the level of droughted plants revived with non-saline tap water. Since drought and salt stresses appeared to have cumulative adverse effects, it is proposed that irrigation with saline water at the critical stage, in the beginning of a dry spell, may be more rewarding than irrigation with saline waters at a belated stage when the plants have already suffered water stress. Salinity build-up in soil under this condition was not high.

Influence of repeated water stress on wheat

Fertility-induced performance alterations in wheat (cv Kalyansona) have been evaluated under two cycles of droughts at various developmental stages and also repeated droughts. The significant alleviation of growth and yield, despite the higher stress experienced by plants under improved soil fertility, seems to be related to larger root growth and greater post-drought nutrient uptake and not to favourable tissue water modulations. Limited wet-period interludes, under repeated stress, reduced these advantages. Stress-mediated increases in proline and free aminoacids and decline in chlorophyll content in leaves followed established trends. Their levels, however, were relatively higher under better soil fertility. The proline accumulation was reduced in the second cycle of drought, as compared to the first, indicating an absence of hardening effect.