Cowpea seeds lose their vigour during storage at high temperature and high relative humidity. Present study was conducted to invigorate the performance of high and low vigour seeds (exposed to 45 ± 2o C and 100% RH) by seed priming with different chemicals and concentrations (GA3 (100ppm); CaCl2 (10-3M); Ammonium Molybdate (10-3M); KBr (10-3M); Mg (NO3)2 (10-3M); ZnSO4 (10-3M); hydro primed and dry seed (control) at 15o C for 24 hours. Priming was effective in reducing the time for 50 % germination and mean germination time and increased the germination percentage in low vigour seeds, while energy of germination and final germination percentage in normal seeds displayed a minor increase. Priming of normal / low – vigour seeds improved the vigour of seedling in terms of seedling length and their dry weight and seedling vigour index. Seed priming of fresh and accelerated cowpea seeds increased the electrical conductivity of seed leachate, cell membrane stability, total protein content, a – amylase activity, peroxidase activity and dehydrogenase activity over control dry seeds. Esterase and peroxidase enzymes were completely lost as a result of accelerated ageing, which showed reappearance after priming. Priming showed little improvement in the banding pattern and intensity of enzyme in normal seeds.

Abiotic stress is a major threat to the farming community, biasing the crop productivity in arid and semi-arid regions of the world. The seed is an important component of agriculture, contributing significantly to the booming production of food and feed crops across the different agro-ecological regions of the world with constant challenges with reference to production, storage, and quality control. Germination, plant growth, and development via non-normal physiological processes are detrimentally affected by stress. Seed priming is an alternative, low cost, and feasible technique, which can improve various abiotic stress tolerances through enhanced and advanced seed production. Seed priming is a process that involves imbibing seed with a restricted amount of water to allow sufficient hydration and advancement of metabolic processes but preventing germination. The beneficial influence of priming on the germination performance of diverse species is attributed to the induction of biochemical mechanisms of cell repair: the resumption of metabolic activity that can re-impose cellular integrity, through the synthesis of nucleic acids (DNA and RNA) and proteins and the improvement of the antioxidant defense system metabolic damage incurred by dry seed and thus fortifying the metabolic machinery of the seed. With this background, this chapter highlights the morphological, physiological, biochemical, and molecular responses of seed priming and recent advances in priming methods as a tool to combat abiotic stress in crop plants.

A split plot design field study was conducted during summer month of 2012 and 2013 at the vegetable block of Indian Institute of Horticultural Research in Bangalore, India to evaluate if priming could improve grain yield and water use efficiency of cowpea under limited water supply condition through drip system. Seeds of cultivar Arka garima received the following priming treatments: they were soaked in GA 3 ,Calcium Chloride, Ammonium Molybdate, Potassium Bromide, Magnesium Nitrate, Zinc Sulphate solutions, and aerated distil water (hydropriming) for 24 hours at 15 o C. Crops were subjected to three irrigation intervals in which the irrigation was applied at 0.9, 0.7, 0.5 Epan Replenishment of evaporation. Seed priming treatments reduced the mean emergence time, promoted germination, early canopy development and flower initiation in comparison to the untreated control. Plant height, number of branches, total dry matter accumulation, number of pods per plant, number of seeds per pod, 1000 seed weight and grain and biological yield, harvest index and irrigation water use efficiency increased by different priming treatments. Seed priming increased the irrigation water use efficiency (IWUE) of all irrigation regimes. Grain yields linearly increased at 0.9 Epan Replenishment while maximum IWUE was achieved at 0.5 Epan Replenishment. Results suggest that the use of seed priming with either GA 3 (100ppm) or Ammonium Molybdate (10 -3 M) for 24 hours at low concentration can be helpful in cowpea under both optimum as well as limited water conditions.

A field study was conducted during summer season of 2012 and 2013 at Indian Institute of Horticultural Research in Bangalore, India to evaluate if priming could improve grain yield and water use efficiency of cowpea under limited water supply condition through drip system. Seed variety Arka Garima received the following priming treatments: they were soaked in GA 3 ,CaCl 2 , ammonium molybdate, KBr, MgNO 3 , ZnSO 4 solutions and water (hydropriming) for 24 hours at 15 o C. Crop was subjected to three irrigation intervals in which the irrigation was applied at 0.9, 0.7, 0.5 Epan Replenishment of evaporation. Plant height, number of trifoliate leaves, total dry matter accumulation, number of pods per plant, number of seeds per pod, 1000 seed weight and grain and biological yield were increased by different priming treatments compared to control. Seed priming increased the LAI, RGR, CGR and NAR at all irrigation regimes. Results suggest that the use of seed priming with either GA 3 (100ppm) or ammonium molybdate (10 -3 M) for 24 hours at low concentration can be helpful in cowpea under both optimum as well as limited water conditions.

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