Drought stress mediated consequences on morpho physiological and biochemical Characteristics of the Himalayan species Fagopyrum esculentum Moench Polygonaceae

Abstract

ABSTRACT newlineFagopyrum esculentum Moench is one of the vital unattended crops. Due to cultivation newlineconstraints the crop is at the verge of extinction, though it is of high medicinal and newlinenutritive value. The plant was studied to know the level of tolerance to drought stress. newlineThe effects of drought stress induced by polyethylene glycol (PEG 6000) on germination newline(%) and morphological parameters of seedling (shoot and root length; fresh and dry newlineweight) were studied. Seeds of F. esculentum were subjected to drought stress for fifteen newlinedays by using six different concentrations of PEG (15, 20, 25, 30, 35 and 40%) under newlinelaboratory conditions. Seeds of F. esculentum were also sown in nursery beds and with newlinethe appearance of first leaf; seedlings were transferred to ceramic pots filled with mixture newlineof soil and sand. Drought stress was imposed by watering while weighing method was newlineused to control water potential to meet the experimental requirements. Different water newlinepotentials (-0.01, -0.02, -0.03, -0.04, -0.05, -0.06 and -0.07 MPa) were achieved after 15 newlinedays of transplanting the seedlings to pots. Response of morpho-physiological and newlinebiochemical characteristics to drought stress was studied in leaves and roots of newlineF. esculentum at an interval of 30, 45, 60 and 75 days of plant growth. newlineThe study revealed that drought stress caused significant increase in seed germination and newlineroot length at lower drought stress level (15% PEG) but thereafter decreased with newlineincrease in drought stress intensity. Drought stress imposed by PEG significantly reduced newlinethe shoot length and seedling weight (fresh and dry) in a concentration-dependent newlinemanner. Plant height, number of leaves, leaf area, biomass (fresh and dry weight) and newlinerelative water content reduced with increase in the level and duration of stress. Increased newlineroot length at mild and moderate drought stress was an adaptive response. Membrane newlinestability index decreased with increase in the drought stress concentration. Increased level newlineof total carbohydrate, total protein, total free amino acids and proline content was an newlineadaptation of plant to overcome the drought stress conditions. F. esculentum has a newlineprotection mechanism against oxidative damage by maintaining higher activities of newlineenzymatic (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione newlineperoxidase and glutathione-s-transferase) and non-enzymatic (ascorbic acid, tocopherol, newlinephenol, flavonoid, rutin and malondialdehyde) antioxidants. Drought stress imposed to newlineix newlineF. esculentum significantly decreased leaf chlorophyll a , chlorophyll b and total newlinechlorophyll content in dependence with drought intensity and growth stages. Drought newlinestress increased the capacity of plant to scavenge DPPH and ABTS free radicals. It was newlineinteresting to note that the therapeutically active compound rutin was high in stressed newlineplants compared to control plants. newlineKeywords: Fagopyrum esculentum, drought stress, germination, rutin, antioxidants. newline