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The application of carbon-based nanomaterials (CBNMs) in plant science and agriculture is a very recent development. Many studies have been conducted to understand the interactions between CBNMs and plant responses, but how fullerol regulates wheat subjected to drought stress is still unclear. In this study, seeds of two wheat cultivars (CW131 and BM1) were pre-treated with different concentrations of fullerol to investigate seed germination and drought tolerance. Our results indicate that the application of fullerol at certain concentrations (25–200 mg L−1) significantly promoted seed germination in two wheat cultivars under drought stress; the most significant effective concentration was 50 mg L−1, which increased the final germination percentage by 13.7% and 9.7% compared to drought stress alone, respectively. Wheat plants exposed to drought stress induced a significant decrease in plant height and root growth, while reactive oxygen species (ROS) and malondialdehyde (MDA) contents increased significantly. Interestingly, wheat seedlings of both cultivars grown from 50 and 100 mg L−1 fullerol-treated seeds were promoted in seedling growth under water stress, which was associated with lower ROS and MDA contents, as well as higher antioxidant enzyme activities. In addition, modern cultivars (CW131) had better drought adaptation than old cultivars (BM1) did, while the effect of fullerol on wheat had no significant difference between the two cultivars. The study demonstrated the possibility of improving seed germination, seedling growth and antioxidant enzyme activities by using appropriate concentrations of fullerol under drought stress. The results are significant for understanding the application of fullerol in agriculture under stressful conditions. [ABSTRACT FROM AUTHOR]

The present investigation was designed to improve drought stress tolerance in eggplant (Solanum melongena L.) through the exogenous application of α-tocopherol (TOC). For exogenous application, two modes, i.e., foliar spray (FS) and pre-sowing seed treatment (PS), were used. Water deficiency treatment (50% field capacity (FC)) was applied on 32-day-old seedlings of two eggplant cultivars, i.e., Janak and Black Beauty. Five levels of TOC (0 mg/L, 50 mg/L PS, 100 mg/L PS, 50 mg/L FS, and 100 mg/L FS) were applied as PS and FS. Pre-sowing seed treatment was conducted before seed sowing, while FS treatment after 30 days of drought stress treatment. After 15 days of TOC as an FS application, it was observed that drought stress significantly reduced plant growth (5–15%) and chlorophyll contents (4–10%), while it increased proline (4–6%), glycine betaine (GB) (5–10%), malondialdehyde (MDA) (10.8%), hydrogen peroxide (15–16%), relative membrane permeability (RMP) (5–8%), and the activities of peroxidase (7–8%) and superoxide dismutase (12–15%) in both eggplant cultivars. The TOC application (FS and PS) exhibited a positive role in overcoming the adverse effect of water stress on eggplants. Plant growth increased (15–18%) as a result of the application of TOC, which could be linked with improved chlorophyll, ascorbic acid (AsA), GB, proline, total soluble proteins (TSP), and the activities of peroxidase (POD) and superoxide dismutase (SOD) activities. The reactive oxygen species H2O2 was also decreased by TOC application. Overall, TOC as a foliar spray was more effective in improving the accumulation of proline, GB, AsA, and activities of SOD and POD enzymes, while PS treatment was more effective in reducing RMP and improving the TSP of eggplant. Cv. Black Beauty was comparatively better in root dry weight, chlorophyll a and b, and MDA contents, while cv. Janak in RMP, AsA, TSP, and activity of the POD enzyme. It can be inferred that the application of TOC was useful in counteracting the harmful effects of drought stress on both cultivars of eggplants. [ABSTRACT FROM AUTHOR]

Trehalose regulates key physio-biochemical parameters, antioxidants, and the yield of plants exposed to a dry environment. A study was conducted to assess the regulatory roles of exogenously applied trehalose in drought-stressed sunflower plants. Two cultivars of sunflowers (Hysun 33 and FH 598) were subjected to drought stress (60% field capacity) and varying (0, 10, 20, and 30 mM) concentrations of trehalose. The data indicated that water stress significantly reduced the shoot length, root length, total soluble proteins, shoot Ca2+, root P, relative water content (RWC), and achene yield per plant. The foliar spray of trehalose was effective at improving plant growth, RWC, total soluble proteins, total soluble sugars, the activities of enzymatic antioxidants, Ca2+ (shoot and root), root K+, and the yield attributes. Exogenously supplemented trehalose considerably suppressed relative membrane permeability (RMP), but did not alter ascorbic acid, malondialdehyde, the total phenolics, shoot K+, or P (shoot and root) in both sunflower cultivars. The cv. Hysun 33 had better ascorbic acid, total soluble sugars, non-reducing sugars, shoot P, and root P than the other cultivar, whereas cv. FH 598 was relatively better at regulating RMP, malondialdehyde, peroxidase, and root Ca2+ concentration. Overall, exogenously supplemented trehalose, particularly at 10 mM, was effective at improving the physiochemical parameters and yield of sunflower plants under stress conditions. Therefore, a better performance of sunflower cv. Hysun 33 under drought stress can be suggested as a trehalose-induced enhancement of yield and oxidative defense potential. [ABSTRACT FROM AUTHOR]

• Nitric oxide regulates oxidative defense system, key metabolites and growth of broccoli (Brassica oleracea L.) plants. • Foliar applied NO was more effective in enhancing the drought tolerance in broccoli plants. • Application of NO helpful in enhancing the water stress tolerance of broccoli plants. Nitric oxide (NO) is a diffusible gaseous molecule and has been under wide consideration because of its ability to mitigate adverse effects of several abiotic stresses on plants. In the current study, it was determined whether or not exogenous application (presowing seed treatment and foliar application) of sodium nitroprusside (SNP), donor of nitric oxide (NO), could alleviate the drastic effects of drought stress on broccoli plants. The broccoli seeds were soaked in 0.02 mM NO solution or distilled water for pre-sowing and control treatments, respectively. Two levels of water stress (control, 100% field capacity (FC) and 60% FC) were applied to 4 week-old broccoli (Brassica oleracea L.) plants. Foliar treatment of NO (0.02 mM) was applied to broccoli plants after 3 weeks of initiation of drought stress. After 12 days of foliar application, leaf samples were collected to determine photosynthetic and antioxidant activities as well as other biochemical parameters. The results showed that water deficit conditions decreased the shoot fresh and dry weights and shoot length, glycine betaine, and chlorophyll contents, while it enhanced ascorbic acid (AsA), hydrogen peroxide and activities of CAT and SOD enzymes. However, exogenously applied NO as a presowing seed treatment or foliar spray enhanced the fresh and dry biomass of shoot, shoot length, chlorophyll contents, GB, total phenolics, total soluble proteins and activities of SOD and POD enzymes in broccoli plants under water deficiency. It was also observed that foliar application of NO was more effective in enhancing the drought tolerance in broccoli plants as compared to pre-sowing application of NO. Therefore, foliar as well as pre-sowing application of NO could be helpful in up-regulating the oxidative defense system of broccoli plants under water deficit conditions. [ABSTRACT FROM AUTHOR]

It is known that trehalose has the ability to mitigate the adverse effects of abiotic stresses on plants. Thus, the role of exogenously-applied trehalose was examined on water stress-induced changes in the enzymatic and non-enzymatic antioxidative defense system within roots (edible part) of Raphanus sativus L. (radish) plants. Two radish cvs. (Manu and 40-day) were grown under normal and water-deficit conditions. Trehalose was applied through two different modes, i.e., presowing seed treatment and foliar spray using its two levels, 25 and 50 mmol/l. It was observed that water deficiency significantly reduced the root fresh weight, while increased the accumulation of carotenoids, ascorbic acid (AsA), malondialdehyde (MDA), glycinebetaine (GB), and total soluble proteins (TSP) contents coupled with an increase in the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) enzymes in the roots of radish. Both modes of exogenous application of trehalose were effective in reducing MDA contents, while improving root fresh weight, and contents of AsA, total phenolics, GB, total tocopherols and TSP as well as the activities of SOD, CAT and POD. It was observed that cv. Manu was better in MDA, total phenolics, GB, TSP contents and activities of CAT and POD, while cv. 40-day was better in root fresh weight, carotenoids, AsA and total phenolics. Overall, of both modes of exogenous application of trehalose, foliar application was most effective in improving the enzymatic and non-enzymatic antioxidant defense system in edible part of radish. [ABSTRACT FROM AUTHOR]

The influence of seed priming with varying levels (50 and 100 mg L−1) of alpha-tocopherol (Toc) was investigated in carrot plants under water-deficit conditions. For this purpose, two cultivars of carrot, DC4 and DC90, were selected and subjected to well-watered (100% field capacity (FC)) and water-deficit stress (50% FC). After 21 days of water-deficit conditions, a significant suppression was observed in shoot and root fresh and dry weights, their lengths, chlorophyll a, b and total contents, and total soluble proteins (TSP). However, an up-regulatory effect of water stress was observed on the concentrations of glycinebetaine (GB), hydrogen peroxide (H2O2), malondialdehyde (MDA), ascorbic acid (AsA), total phenolics as well as the activities of catalase (CAT) and peroxidase (POD) enzymes. Exogenous application of alpha-tocopherol was effective in reducing the accumulation of H2O2 and MDA contents and improving all growth attributes, contents of chlorophyll, proline, GB, AsA, total phenolics, TSP, and the activities of CAT and POD enzymes. Of both carrot cultivars, cv. DC4 had better performance in terms of growth attributes, whereas the response of the two cultivars was similar in all other attributes varying water regimes. Overall, it is suggested that seed priming with 100 mg L−1 Toc was effective in improving plant growth attributes, osmoprotectants and the oxidative defense system of carrot plants under water-deficit conditions. [ABSTRACT FROM AUTHOR]