Influence of ascorbic acid and 24-epibrassinolide on physiological characteristics of pot marigold under water-stress condition*

Water deficit is considered as a major limiting environmental factor for plant growth and yield. To ameliorate the adverse effects of water restriction, an experiment was conducted in the research field of Mohaghegh Ardabili University in two successive years (2014 and 2015). Foliar spraying of different concentration of epibrassinolide (EBL) (0, 10^?8, and 10^?7?M) and ascorbic acid (AsA) (0 and 10?mM) was carried out and water-stress trials included 50 and 100?mm evaporation from class A pan. Water stress significantly enhanced essential oil content, but reduced capitula yield and relative water content (RWC) of leaves. Water-stress damage ameliorated by foliar application of 10?mM AsA with 10^?7?M EBL and the essential oil yield and antioxidant enzymes activity improved significantly. Enhancing of malondialdehyde (MDA) content and electrolyte leakage indicates that water-deficit stress caused oxidative damage to the membrane by enhancing hydrogen peroxide (H₂O₂) level. Combined-application of regulators significantly declined the amounts of H₂O_2, MDA, and electrolyte leakage under water stress. Antioxidant enzymes activity and also proline and protein content were enhanced by drought stress as well as regulators. Also, the application of EBL and AsA induced tolerance to water deficit and reduced the reactive oxygen species by increasing antioxidant enzymes activity and osmotic adjustment.     

Physiological,biochemical and molecular evaluation of mungbean genotypes for agronomical yield under drought and salinity stresses in the presence of humic acid

Drought and salinity are potential threats in arid and semi arid regions. The current study was conducted with objective to optimize the production of different exotic genotypes of mungbean (NM-121-25, Chakwal M-6, DM-3 and PRI-Mung-2018) under drought and salinity stresses using humic acid in field experiments. One year tri-replicate field experiment was performed in RCBD using three factorial arrangement and effects of humic acid (60 kg ha^?1) were evaluated at physiological, biochemical, molecular and agronomical level under individual and integrated applications of drought (no irrigation till 15 days) and salinity (EC 6.4 dSM^?1). Data for physiological parameters (total chlorophyll, photosynthesis rate, stomatal conductance, transpiration rate and membrane damage), antioxidant enzymes (superoxide dismutase, catalase, peroxidase) and proline were collected on weekly basis since after the initiation of drought and salinity stresses. However data for agronomic characteristics (plant height, branches plant^?1, LAI, pods plant^?1, pod length and hundred seed weight) and grain carbohydrate content were collected after harvesting, while sampling for drought (VrDREB2A, VrbZIP17 and VrHsfA6a) and salinity (VrWRKY73, VrUBC1 and VrNHX1) related genes expression study was done after plants attained seedling stage. Under both individual and integrated applications of drought and salinity, all genotypes showed significant (p ≤ 0.05) increase in all traits excluding Cell membrane damage and proline during humic acid application. Likewise, genes expression revealed statistically distinct (p ≤ 0.05) up-regulation under humic acid treatment as compared to no humic acid treatment during both individual and integrated applications of drought and salinity. The genotype PRI-Mung-2018 recorded noteworthy performance during study. Moreover correlation and PCA analysis revealed that ultimate agronomical yield due to humic acid is an outcome of interconnection of physiological and biochemical parameters.     

Effect of water stress and NaCl triggered changes on yield,physiology, biochemistry of broad bean (Vicia faba) plants and on quality of harvested pods

Salinity and drought are the most important abiotic stresses affecting crop yield. Broad bean was chosen as model plant for assessing the impact of salt stress and its interaction with drought in the field experiments. The factors examined in the experiments were the two irrigation rates (normal watering — NW with 3 L plant^?1 and drought — D) and three salinity rates imposed by foliar application (0, 50, 100 mg L^?1 NaCl). Highest NaCl level with normal water irrigation caused maximum reduction in plant height and production, which it was due to photosynthetic disturbances. Salt injuries were alleviated by increasing water stress. The control plants exposed to NaCl lost their ability over water control. The increased malondialdehyde (MDA) and H₂O₂ indicate the prevalence of oxidative stress due to salinity. The levels of proline and carbohydrates were higher under salinity alone than under simultaneous exposure to drought and NaCl. The protein concentration of immature and mature broad bean pods was more inhibited more by NaCl supply than by drought alone. The combination of drought and NaCl resulted in a significant increase in proteins, glucose, fructose and sucrose content. Overall, the ameliorative effect of drought under NaCl supply was quantified.     

Morpho-physiological and phytochemical traits of (<Emphasis Type="Italic">Thymus daenensis</Emphasis> Celak.) in response to deficit irrigation and chitosan application

Thymus daenensis Celak. is an aromatic herb used as a popular medicine and its natural products in the form of extracts and essential oil have significant economic values in Iran. We hypothesized that spraying plants grown under deficit irrigation system with chitosan can be considered as an applicable method to enhance essential oil and antioxidant activity in thyme. Response of thyme to three irrigation regimes including well-watered, moderate stress, and severe stress along with three levels of chitosan application rates 0, 200, and 400 μL L^?1 was evaluated in a 2-year study in 2014 and 2015. Drought stress condition significantly shortened phenologic stages, more specifically in the first (establishment) year. All growth parameters were reduced dramatically as drought stress intensified. Imposing even moderate stress reduced leaf area as much as 59 and 44% in the first year and the second year, respectively. Biomass yield of plants grown under severe drought stress decreased substantially, whereas essential oil content and the share of thymol in thyme oil which possesses the greatest degree of biological activity improved. Maximum oil yield (1.50 g plant^?1) was obtained from plants under mild drought stress when sprayed with 400 μL L^?1 chitosan in the second year when plants were well-established. Foliar applications of chitosan reduced the adverse effect of water deficit on oil yield and improved thymol content of the essential oil. Chitosan also increased secondary metabolites including α-terpinene, p-cymene, γ-terpinene, thymol, carvacrol and β-caryophyllene. Leaf flavonoid reduced under deficit irrigation while more phenol was found in plants grown under deficit irrigation. The essential oil of thyme exhibited antioxidant property when the plants were sprayed with 400 μL L^?1 chitosan. The results of this study indicated that thyme can be grown successfully under moderate stress and that application of chitosan elicitor can to some degree compensate the negative impact of deficit irrigation on its biomass and essential oil yield.     

Elevated CO<Subscript>2</Subscript> Concentration and Drought Stress Exert Opposite Effects on Plant Biomass,Nitrogen, and Phosphorus Allocation in <Emphasis Type="Italic">Bothriochloa ischaemum</Emphasis>

Increased concentrations of atmospheric carbon dioxide (CO₂) and drought stress have greatly influenced plant growth, the status of nitrogen (N) and phosphorus (P), and N:P ratios. We identified the plant biomass, N and P distributional patterns, and N:P stoichiometry of a grass species on the Loess Plateau in China under elevated CO₂ concentration and drought stress conditions. Bothriochloa ischaemum, a C4 perennial herbaceous grass, was grown in pots at CO₂ concentrations of 400 (ambient) and 800 (elevated) μmol mol^?1 and at 60 ± 5 and 40 ± 5 % of field capacity. The elevated CO₂ concentration significantly increased plant total biomass, N concentration, N and P content, allocation of biomass to roots, and allocation of N to shoots, and increased the N:P ratios of whole plants and the shoots, especially under well-watered conditions. Drought stress significantly decreased plant biomass and plant N and P content, especially under elevated CO₂. Drought stress decreased the N:P ratios, but was only significant in the roots under ambient CO₂. Drought stress may attenuate the stimulation of plant growth and N and P acquisition by CO₂ enrichment, and projected elevated CO₂ concentrations may partially offset the negative effects of increased drought by increasing the assimilation of N and P.     

Effects of 24‐epibrassinolide on plant growth,osmotic regulation and ion homeostasis of salt‐stressed canola

This study evaluated effects of foliar spraying 24‐epibrassinoide (24‐EBL) on the growth of salt‐stressed canola. Seedlings at the four‐leaf stage were treated with 150 mm NaCl and different concentrations of 24‐EBL (10^?6, 10^?8, 10^?10, 10^?12 m ) for 15 days. A concentration of 10^?10 m 24‐EBL was chosen as optimal and used in a subsequent experiment on plant biomass and leaf water potential parameters. The results showed that 24‐EBL mainly promoted shoot growth of salt‐stressed plants and also ameliorated leaf water status. Foliar spraying of salt‐stressed canola with 24‐EBL increased osmotic adjustment ability in all organs, especially in younger leaves and roots. This was mainly due to an increase of free amino acid content in upper leaves, soluble sugars in middle leaves, organic acids and proline in lower leaves, all of these compounds in roots, as well as essential inorganic ions. Na⁺ and Cl^? sharply increased in different organs under salt stress, and 24‐EBL reduced their accumulation. 24‐EBL improved the uptake of K⁺, Ca²⁺, Mg²⁺ and NO₃^? in roots, which were mainly transported to upper leaves, while NO₃^? was mainly transported to middle leaves. Thus, 24‐EBL improvements in ion homeostasis of K⁺/Na⁺, Ca²⁺/Na⁺, Mg²⁺/Na⁺ and NO₃^?/Cl^?, especially in younger leaves and roots, could be explained. As most important parts, younger leaves and roots were the main organs protected by 24‐EBL via improvement in osmotic adjustment ability and ion homeostasis. Further, physiological status of growth of salt‐stressed canola was ameliorated after 24‐EBL treatment.     

Grafting improves cucumber water stress tolerance in Saudi Arabia

Water scarcity is a major limiting factor for crop productivity in arid and semi-arid areas. Grafting elite commercial cultivars onto selected vigorous rootstocks is considered as a useful strategy to alleviate the impact of environmental stresses. This study aims to investigate the feasibility of using grafting to improve fruit yield and quality of cucumber under water stress conditions. Alosama F₁ cucumber cultivar (Cucumis sativus L.) was grafted onto Affyne (Cucumis sativus L.) and Shintoza A90 (Cucurbitamaxima × C. moschata) rootstocks. Non-grafted plants were used as control. All genotypes were grown under three surface drip irrigation regimes: 50%, 75% and 100% of the crop evapotranspiration (ETc), which represent high-water stress, moderate-water stress and non-water stress conditions, respectively. Yield and fruit quality traits were analyzed and assessed. In comparison to the non-grafted plants, the best grafting treatment under water stress was Alosama F₁ grafted onto Shintoza A90 rootstock. It had an overall improved yield and fruit quality under water stress owing to an increase in the total fruit yield by 27%, from 4.815 kg plant^?1 in non-grafted treatment to 6.149 kg plant^?1 in grafted treatment under moderate -water stress, total soluble solid contents (13%), titratable acidity (39%) and vitamin C (33%). The soil water contents were low in soil surface and increase gradually with soil depth, while salt distribution showed an adverse trend. The positive effects of grafting on plant growth, productivity, and water use efficiency support this strategy as an useful tool for improving water stress tolerance in greenhouse grown cucumber in Saudi Arabia.     

Dual Application of 24-Epibrassinolide and Spermine Confers Drought Stress Tolerance in Maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) by Modulating Polyamine and Protein Metabolism

No information is available concerning the influence of dual application of 24-epibrassinolide (EBL) and spermine (Spm) on the nitrogen metabolism in plants subjected to drought conditions. As a first report, this investigation assesses the role of EBL, Spm, and their dual application on polyamine and protein pools in water-stressed plants. It explores the ameliorative effects of these foliar applications under water deficiency. Two maize hybrids (Giza 10 and Giza 129) were treated with or without EBL and/or Spm foliar applications under well-irrigated and drought-stressed conditions (75 and 50 % of field capacity). Dual application (25 mg l^?1 Spm + 0.1 mg l^?1 EBL) significantly relieved the drought-induced inhibition on the activities of ribulose-1,5-bisphosphate carboxylase and nitrate reductase and the contents of relative water, nitrate, and protein, particularly in hybrid Giza 129. Changes in the content of free polyamines and in the activity of polyamine biosynthetic and catabolic enzymes were detected when water-stressed plants were treated with EBL and/or Spm. Putrescine content and arginine decarboxylase activity were significantly increased in stressed hybrid Giza 10 plants treated by the dual application. However, spermidine and Spm levels as well as ornithine decarboxylase and S-adenosylmethionine decarboxylase activities were significantly increased in stressed hybrid Giza 129 plants treated with the dual application. Diamine oxidase, polyamine oxidase, protease activity, carbonyl content, and ethylene formation were increased in response to water stress and significantly decreased when stressed plants were treated by the dual application. Total free amino acids, phenols, and flavonoids concentration were increased with the increasing water stress level; moreover, they further increased in stressed plants treated with the dual application. Overall, the combined utilization of EBL and Spm serves as complementary tools to confer plant drought tolerance by altering polyamine, ethylene, and protein levels.     

Silicon Alleviates Drought Stress of Rice Plants by Improving Plant Water Status,Photosynthesis and Mineral Nutrient Absorption

Drought is a major constraint for rice production in the rainfed lowlands in China. Silicon (Si) has been verified to play an important role in enhancing plant resistance to environmental stress. Two near-isogenic lines of rice (Oryza sativa L.), w-14 (drought susceptible) and w-20 (drought resistant), were selected to study the effects of exogenous Si application on the physiological traits and nutritional status of rice under drought stress. In wet conditions, Si supply had no effects on growth and physiological parameters of rice plants. Drought stress was found to reduce dry weight, root traits, water potential, photosynthetic parameters, basal quantum yield (F _v/F ₀), and maximum quantum efficiency of PSII photochemistry (F _v/F _m) in rice plants, while Si application significantly increased photosynthetic rate (Pr), transpiration rate (Tr), F _v/F ₀, and F _v/F _m of rice plants under drought stress. In addition, water stress increased K, Na, Ca, Mg, Fe content of rice plants, but Si treatment significantly reduced these nutrient level. These results suggested that silicon application was useful to increase drought resistance of rice through the enhancement of photochemical efficiency and adjustment of the mineral nutrient absorption in rice plants.     

Cumulative effect of nitrogen and sulphur on <Emphasis Type="Italic">Brassica juncea</Emphasis> L. genotypes under NaCl stress

In the present study, N and S assimilation, antioxidant enzymes activity, and yield were studied in N and S-treated plants of Brassica juncea (L.) Czern. & Coss. (cvs. Chuutki and Radha) under salt stress. The treatments were given as follows: (1) NaCl₉₀ mM+N₀S₀ mg kg^-1 sand (control), (2) NaCl₉₀ mM+N₆₀S₀ mg kg^-1 sand, (3) NaCl₉₀ mM+N₆₀S₂₀ mg kg^-1 sand, (4) NaCl₉₀ mM+N₆₀S₄₀ mg kg^-1 sand, and (5) NaCl₉₀ mM+N₆₀S₆₀ mg kg^-1 sand. The combined application of N (60 mg kg⁻¹ sand) and S (40 mg kg⁻¹ sand) proved beneficial in alleviating the adverse effect of salt stress on growth attributes (shoot length plant⁻¹, fresh weight plant⁻¹, dry weight plant⁻¹, and area leaf⁻¹), physio-biochemical parameters (carbonic anhydrase activity, total chlorophyll, adenosine triphosphate-sulphurylase activity, leaf N, K and Na content, K/Na ratio, activity of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, catalase, superoxide dismutase, ascorbate peroxidase and glutathione reductase, and content of glutathione and ascorbate), and yield attributes (pods plant⁻¹, seeds pod⁻¹, and seed yield plant⁻¹). Therefore, it is concluded that combined application of N and S induced the physiological and biochemical mechanisms of Brassica. The stimulation of antioxidant enzymes activity and its synergy with N and S assimilation may be one of the important mechanisms that help the plants to tolerate the salinity stress and resulted in an improved yield.     

Responses of in vitro-cultured <Emphasis Type="Italic">Allium hirtifolium</Emphasis> to exogenous sodium nitroprusside under PEG-imposed drought stress

Drought stress is a major threat to plant production in semi-arid and arid areas of the world. This research was laid out to asses the effects of sodium nitroprusside (SNP) as a nitric oxide donor on growth, physiological and biochemical changes of in vitro-cultured Allium hirtifolium under polyethylene glycol (PEG) induced drought stress. Basal plate explants of A. hirtifolium were cultured on MS medium containing different levels of PEG (0, 2, 4, 8 and 16 mM) and SNP (0, 10, 40 and 70 µM). After prolonged drought, growth responses, oxidative stress indicators, and phytochemical variations of regenerated plantlets with or without PEG and/or SNP treatments were recorded. Water limitation reduced regeneration potential of explants and consequently number of shoots per explant. Relative water content, total chlorophyll and carotenoid contents of regenerated A. hirtifolium plantlets decreased, but accumulation of malondialdehyde, H₂O₂ and proline and the activities of superoxide dismutase, ascorbate peroxidase, catalase and peroxidase enzymes increased with decreasing water availability. Total phenol and allicin contents were also increased in response to drought stress. Exogenous SNP in 10 and particularly in 40 µM was effective in enhancing regeneration rate and relative water content as well as protecting photosynthetic pigments under different levels of water availability. SNP also inhibited the hydrogen peroxide (H₂O₂) accumulation and lipid peroxidation in cell membranes via increasing the activities of superoxide dismutase and ascorbate peroxidase enzymes and accumulating proline and allicin. In general, these results suggest that exogenous SNP at 40 µM not only could somewhat protect A. hirtifolium from drought stress, but also can help to improve the propagation and allicin production of that plant under in vitro condition.     

Exogenous Glutathione Modulates Salinity Tolerance of Soybean [<Emphasis Type="Italic">Glycine max</Emphasis> (L.) Merrill] at Reproductive Stage

In this study, we evaluated salt stress responses of 11 soybean genotypes and explored the protective roles of exogenous glutathione (GSH) against salt toxicity by assessing various biochemical and yield-attributing parameters. Exposure of the soybean genotypes to salt stress at the reproductive (R1) stage significantly decreased their yields by down-regulating the yield-contributing parameters as compared with unstressed controls. The highest decrease was found in number of seeds plant^?1, yield plant^?1, and number of pods plant^?1, whereas the lowest decrease was recorded in number of seeds pod^?1. Exogenous GSH was found to be effective in improving salinity tolerance, and the highest positive effects of GSH were recorded in terms of yield plant^?1, number of seeds plant^?1 and number of pods plant^?1, whereas its lowest effect was observed with respect to the 100-seed weight. Cluster analysis of the genotypes based on yield-contributing and yield data revealed different levels of salt tolerance. Notably, BINA-01 and -02, and BINA-04 were recognized as the highest and lowest salt-tolerant genotypes, respectively. Furthermore, exogenous GSH alleviated oxidative stress in the representative contrasting genotypes at the vegetative (V3) stage by decreasing salt-induced accumulation of malondialdehyde and hydrogen peroxide. Taken together, our findings revealed that exogenous GSH application can minimize oxidative stress and contribute to the improvement of yield-contributing parameters, leading to improved yield in soybean genotypes under salt stress. Further investigations on molecular aspects will enable us to gain an in-depth understanding of how exogenous GSH can improve salinity tolerance in soybean, particularly at reproductive stage, to discover relevant pathways for biotechnological manipulation.     

Physiological responses of wheat seedlings to drought and UV-B radiation. Effect of exogenous sodium nitroprusside application

Physiological and biochemical responses of wheat seedlings to drought, UV-B radiation, and combined stress were investigated. Drought, UV-B, and combined stresses retarded seedling growth by 26.5, 29.1, and 55.9%, respectively. One reason for growth retardation may be the oxidative damage indicated by an increase in the H₂O₂ content and lipid peroxidation degree. Furthermore, there was negative correlation between shoot fresh weight and H₂O₂ content, fresh weight and the content of thiobarbituric acid-reacting substances (TBARS), and the positive correlation between H₂O₂ content and TBARS (R ² = 0.9251, 0.9005, and 0.9007, respectively). The activities of superoxide dismutase, guaiacol peroxidase, and ascorbate peroxidase increased under drought, UV-B, and the combination of stresses, while catalase activity decreased under the combined stress as compared to the control. The combination of drought and UV-B caused more severe damage to wheat seedlings than stress factors applied separately. Thus, the combined application of drought and UV-B had more strong adverse effects on wheat seedlings. The addition of 0.2 mM sodium nitroprusside (SNP) enhanced wheat seedling growth under drought, UV-B, and combined stress, likely, due to decreasing the accumulation of H₂O₂ and lipid peroxidation as well as activating the antioxidant enzymes. However, SNP treatment decreased the proline content. Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 5, pp. 763–769. The text was submitted by the authors in English.     

Improving growth and productivity of faba bean (Vicia faba L.) using chitosan,tryptophan, and potassium silicate anti-transpirants under different irrigation regimes

This work aims to study the effect of foliar spraying of three anti-transpirants i.e., A­₁: tryptophan (Tri), A₂: potassium silicate (KS), A₃: chitosan (Chi) as well as A₀: control (Tap water) under three irrigation regimes, I₁: 2400, I₂: 3600, and I₃: 4800 m³ha^?1 on the quality and production of faba bean crop and its nutrient contents. The study was carried out during two successive winter seasons of 2018/2019 and 2019/2020. Drought stress affected the average performance of all studied traits as it reduced seed yield and traits, as a result of the decrease in chlorophyll related to photosynthesis, protein, carbohydrates, total phenols, amino acids, macronutrients (N, P, and K), micronutrient contents (Fe, Mn, and Zn) and their absorption. The single foliar spraying of faba bean with tryptophan 75 ppm, potassium silicate at 100 ppm, or chitosan at 750 ppm significantly increased all studied traits and reduced the drought stress compared to control under different irrigation systems. We recommended using a foliar spray of chitosan (750 ppm) on faba bean plants under an irrigation level of 4800 m³ led to an improvement in the physiological properties of the plant, i.e., plant height, the number of branches/plants, and the number of plants, pods plant^?1, the number of seed pods^?1, the weight of 100 seeds and seed yield ha^?1 increased with relative increase about 42.29, 89.47, 28.85, 75.91, 24.43, and 306.48% compared to control. The quality properties also improved, as the total chlorophyll, protein, carbohydrates, total phenols, and amino acids were higher than the control with a relative increase of 63.83, 29.58, 27.72, 37.54, and 64.19%. Additionally, an increase in the contents and uptake of macronutrients (N, P, and K), and micronutrients (Fe, Mn, Zn) and their absorption. The increase was estimated with 29.41, 75.00, 16.56, 431.17, 630.48, 72.68%, 22.37, 35.69, 42.33, 397.63, 452.58, and 485.94% about the control. This was followed by potassium silicate (100 ppm), then tryptophan (75 ppm) compared to the control, which recorded the minimum values ??in plant traits.     

Photosynthetic responses of wheat (Triticum aestivum L.) to combined effects of drought and exogenous methyl jasmonate

Drought stress limits wheat growth and productivity. The response of wheat (Triticum aestivum L.) to different water supply conditions (well-watered and drought-stressed) and exogenous methyl jasmonate (MeJA; 0 and 0.25 μM) was studied. The application of MeJA enhanced wheat adaptability to drought stress by physiological and metabolic adjustments. Drought stress reduced net photosynthetic rate (P _N), stomatal conductance (g _s), transpiration rate (E), and water-use efficiency (WUE) in wheat. The application of exogenous MeJA decreased also g _s and E, but stimulated WUE. Meanwhile, MeJA mitigated the decline of P _N, g _s, and WUE induced by drought stress and midday depression by 6–183%. Both drought stress and exogenous MeJA induced stomatal closure, which improved water status and delayed plant senescence. MeJA enhanced the activities of superoxide dismutase, peroxidase, catalase, and reduced malondialdehyde content. P _N-PAR response curves showed that MeJA mitigated the decline of maximum P _N, apparent quantum yield, and saturation irradiance, and the increase of compensation irradiance. Drought stress and exogenous MeJA increased dark respiration rate and showed an additive effect. These results indicated that 0.25 μM MeJA enhanced the photosynthesis under drought stress mainly by improving the water status and antioxidant capacity of wheat.     

Physiological and biochemical adaptations in lentil genotypes under drought stress

Drought is a major restrictive factor for declining grain yield in lentil globally. Present investigation was conducted by taking microsperma (HUL-57) and macrosperma (IPL-406) genotypes of lentil (Lens culinaris Medik.) as information regarding physiological and biochemical basis of differences in drought resistance in macrosperma (bold-seeded) and microsperma (small-seeded) are not well understood. Pot grown plants were exposed to drought stress at specific phenophase viz. mid-vegetative, flower initiation and pod formation stage by withholding irrigation till the plants experienced one cycle of permanent wilting (PWP). Genotypes exhibited substantial differences for most of the measured traits under drought irrespective of the phenophase of stress imposed. Under drought HUL-57 had lower CMI, higher CSI, lower values of Δ¹³C, maintained higher SLN, accumulated more N and efficiently remobilized accumulated N to developing seeds. Higher chlorophyll content, increased accumulation of osmotically active solutes viz. soluble sugars and proline under drought stress was evident in HUL-57. Drought induced H₂O₂ accumulation and lipid peroxidation in both genotypes, but increments were of lesser magnitudes in HUL-57. Drought stress of pod formation stage followed by flower initiation stage was most damaging than the stress imposed at mid-vegetative stage in both genotypes. HUL-57 showed a better drought resistance capacity than IPL-406. Drought indices viz. DSI, STI and MP are proposed as criterion to identify and breed lentil genotypes for drought conditions.     

Differences in the responses of stem diameter and pod thickness to drought stress during the grain filling stage in soybean plants

This study investigated the factor of the physiological characteristics causing the reduction of yield of soybean plants (Glycine max (L.) Merr.) by drought stress, by monitoring changes in stem diameter and pod thickness, and photosynthetic activity, partitioning of ¹³C-labeled photosynthate. Drought stress reduced the whole plant dry weight due to the decrease in leaf and pod dry matter accumulation; however, this stress did not have a significant effect on stem growth. Leaf photosynthesis was also severely decreased by drought stress in the early stage of stress treatment as leaf water potential decreased. Imposition of stress decreased pod thickness, but stem diameter increased. The adverse effect of drought stress on pod thickness was more evident at night than during the day. The stem diameter also shrank during the day and expanded at night, but the nocturnal increase in stem diameter during drought stress treatment was greater for stressed plants compared with well-watered controls. Drought stress significantly promoted ¹³C partitioning from the fed leaf to other parts of the plant; the stem was the largest beneficiary. Soluble carbohydrates accumulated in various plant parts under the influence of the stress, but starch concentration declined in all organs except the stem. These results indicated that stem growth was promoted by drought stress compared to pod growth at the early grain-filling stage.     

Growth responses and essential oil profile of Salvia officinalis L. Influenced by water deficit and various nutrient sources in the greenhouse

Salvia officinalis L. is a medicinal plant extensively used in foods, traditional medicine, and the pharmacological industry. In the current study, the effects of different irrigation regimes [irrigation after 70 ± 5 (regular), 105 ± 5 (moderate drought stress), and 140 ± 5 (severe drought stress) mm evaporation] and nutrient sources (control, NPK, farmyard manure, foliar fertilizer, and hydrogel) were investigated on the growth parameters and essential oil (EO) components of S. officinalis in the greenhouse. The plants were harvested two times. The regular irrigation treatment had the most significant effect on plant height (51 cm), fresh and dry herb weight (51.5 and 18.1 g plant⁻¹), and fresh and dry leaf weight (40.1 and 13.1 g plant⁻¹). The highest amount of EO was observed after moderate drought stress (1.48%). The NPK treatment had the greatest effect on plant height (40 cm), branch number (19 per plant), fresh and dry herb weight (53.4 and 18.9 g plant⁻¹), fresh and dry leaf weight (41.2 and 13.6 g plant⁻¹), and EO content (1.67%). The 1^st cutting was superior in EO amount, while the 2^nd cutting had a high agronomic yield. α-Thujone (from 21.6 to 34.2%) was identified as the predominant compound. Additionally, the content of α-thujone in the 2^nd cutting was higher after moderate drought stress, NPK, and hydrogel treatments. Moreover, 1,8-cineole, β-thujone, camphene, α-pinene, α-humulene, viridiflorol, borneol, and bornyl acetate were the other main compounds. As a general result, regular irrigation and NPK treatments improved the agronomic yield of S. officinalis. The plants under drought stress produced high amounts of EO. The farmyard manure also improved plant yield by providing a part of the plant's nutritional needs. Therefore, it could be concluded that it is crucial to determine the effects of limited water availability and various nutrient sources on yield and chemical compositions for medicinal and aromatic plant growth.     

Interactive effect of nitric oxide and brassinosteroids on photosynthesis and the antioxidant system of <Emphasis Type="Italic">Lycopersicon esculentum</Emphasis>

An interactive effect of nitric oxide and 24-epibrassinolide (EBL) or 28-homobrassinolide (HBL) was investigated in Lycopersicon esculentum Mill. cv. K-21. Seeds prior to sowing were exposed to sodium nitroprusside (SNP) (0, 10⁻⁵ M or 1 M), a nitric oxide donor, for 8 h, and the resulting seedlings were subsequently sprayed with 10⁻⁸ M EBL or HBL at 30-day stage. The analysis of plant samples after 24 h of the EBL or HBL spray showed that the lower SNP concentration (10⁻⁵ M) favored the growth, pigment content, photosynthetic and enzymatic activities, and also improved the antioxidant system. However, 1 M SNP had inhibitory impact on most of the indices, except the antioxidant system. Brassinosteroids (EBL or HBL), on the other hand, had a stimulatory impact on the aforementioned indices. The inhibitory effect of SNP (1 M) was neutralized by the application of BRs, where EBL was more effective than HBL.     

24-Epibrassinolide alleviates salt-induced inhibition of productivity by increasing nutrients and compatible solutes accumulation and enhancing antioxidant system in wheat (Triticum aestivum L.)

Two wheat (Triticum aestivum L.) cultivars, Sids 1 and Giza 168, were grown under non-saline or saline conditions (4.7 and 9.4 dS m^?1) and were sprayed with 0.00, 0.05 and 0.10 mg l^?1 24-epibrassinolide (EBL). Salt stress markedly decreased plant productivity and N, P, and K uptake, particularly in Giza 168. A follow-up treatment with 0.1 mg l^?1 EBL detoxified the stress generated by salinity and considerably improved the above parameters, especially in Sids 1. Organic solutes (soluble sugars, free amino acids, proline and glycinebetaine), antioxidative enzymes (superoxide dismutase, peroxidase, catalase and glutathione reductase), antioxidant molecules (glutathione and ascorbate) and Ca and Mg levels were increased under saline condition, and these increases proved to be more significant in salt-stressed plants sprayed with EBL, particularly at 0.1 mg l^?1 EBL with Sids 1. Sodium concentration, lipid peroxidation, hydrogen peroxide content and electrolyte leakage were increased under salt stress and significantly decreased when 0.1 mg l^?1 EBL was sprayed. Clearly, EBL alleviates salt-induced inhibition of productivity by altering the physiological and biochemical properties of the plant.