Potassium-Induced Regulation of Cellular Antioxidant Defense and Improvement of Physiological Processes in Wheat under Water Deficit Condition

Drought is the most common form of abiotic stress that reduces plant growth and productivity.It causes plant injuries through elevated production of reactive oxygen species(ROS).Potassium(K)is a vital plant nutrient that notably ameliorates the detrimental effect of drought stress in the plant.A pot experiment was conducted at the Laboratory of Plant Stress Responses,Faculty of Agriculture,Kagawa University,Japan,under controlled environment of green house to explore the role of K in mitigating drought severity in wheat(Triticum asevitum L.)seedlings.Three days after germination,seedlings were exposed to three water regimes viz.,100,50,and 20%field capacity(FC)for 21 days.Potassium was adjusted in Hoagland nutrient solution at 0,6 and 12 mM concentration and applied to pot instead of normal water.Results show that,water deficit stress notably reduced plant growth,biomass accumulation,leaf relative water content(RWC)along with reduced photosynthetic pigments.Increased amount of biochemical stress markers viz.,malondialdehyde(MDA),hydrogen peroxide(H_(2)O_(2)),methylglyoxal(MG),proline(Pro)as well as an impaired antioxidant defense system were observed in drought affected wheat plants.On the contrary,K supplementation resulted in improvement of biochemical and physiological parameters that worked behind in improving growth and development of the wheat plants.In addition,enzymes of ascorbateglutathione(AsA-GSH)cycle were also enhanced by supplemented K that accelerated the ROS detoxification process in plant.Although glyoxalse system did not performed well till MG was detoxified might following another short stepped pathways.Our results revealed that drought stressed plants showed better performances in terms of biochemical and physiological attributes,antioxidant defense and glyoxalase system,as well as ROS detoxification due to K supplementation with better performance at 12 mM K added in 50%FC growing condition.

Organic Amendments Improve Plant Morpho-Physiology and Antioxidant Metabolism in Mitigating Drought Stress in Bread Wheat(Triticum aestivum L.)

Due to the unpredictable climate change,drought stress is being considered as one of the major threats to crop production.Wheat(Triticum aestivum L.cv.BARI Gom-26)being a dry season crop frequently faces scarcity of water and results in a lower yield.Therefore,this experiment aims to explore the role of different organic amendments(OAs)in mitigating drought stress-induced damage.The pot experiment consisted of different organic amendments viz.compost,vermicompost and poultry manure@0.09 kg m^(−2)soil,biochar@2.5%w/w soil and chitosan@1%w/w soil which was imposed on the plants grown under both well-watered and drought conditions.Results showed that drought stress reduced plant height(15%),SPAD value(16%),relative water content(13%),number of spikelet spike^(−1)(17%),number of grains spike^(−1)(12%),and 100-grain weight(18%).Organic amendments act as a protectant and reduce drought stress-induced damages by enhancing the morpho-physiological and yield attributes.Vermicompost enhanced SPAD value by 18%,number of spikelets spike^(−1)by 20%,number of grains spike^(−1)by 17%,whereas poultry manure increased plant height by 16%under drought condition compared to control plant.Unlike other OAs applied,vermicompost was proved to be capable of reducing the higher lipid peroxidation and proline content raised by drought condition.Drought stress-induced increment of catalase,ascorbate peroxidase and glutathione reductase activities were also efficiently modulated by the organic amendment application.The present study concluded that OAs play significant roles in alleviating drought stressinduced damages by improving the morpho-physiological attributes and among the different types of OAs used vermicompost performed better which in addition ceased the production of reactive oxygen species.