Effect of stratification and gibberellic acid on seed germination and seedling growth of walnut under Kashmir valley conditions

Abstract

Off-season seed sowing in walnut in order to reduce sprouting period and extend propagation season under field conditions of Kashmir valley was undertaken during 2011 and 2012. Common walnut seeds at cold and ambient conditions treated with GA3 (50 and 100 ppm), ethrel (1000 and 1500 ppm), sulphuric acid (7.5 and 9.5%) and potassium nitrate (0.2 and 0.4%) were evaluated in split plot design (SPD) having 32 treatment combinations and three replications. GA3 100 and 50 ppm produced the maximum sprouting (58.24 and 54.23%). Ethrel 1500 and 1000 ppm showed low bud sprouting (38.07 & 35.58%, respectively), but was significantly higher than control (29.99%). Cold treated nuts showed significantly higher germination (46.51%) than ambient conditions (42.21%). Correlation between cold × unsoaked × GA3 was statistically significant. Unsoaked seeds × cold also produced sprouting rate (47.73%) higher than soaked with ambient storage (42.21%). Cold-30-day × 100 ppm GA3 interaction showed the maximum sprouting rate (63.29%). Interaction between unsoaked × 30-day-cold × GA3 100 ppm showed higher sprouting rate (65.33%) than soaked × 30-day-ambient storage × ethrel 1000 ppm (33.33%). Whereas, minimum sprouting (34.33%) was obtained in ambient-30-day × ethrel 1000 ppm. Vegetative growth viz., seedling height, number of days from germination leaf fall and stem diameter (mm) were the similarly influenced. Research findings indicate that off-season sowing in walnut and GA3 soaking could be economically viable method for enhancing seed germination. Refrigerated cold (30 days) and 100 ppm GA3 is feasible procedure for forcing seed germination and to extend the period of propagation in walnut.