Effect of cold hardening and GA₃ on growth and yield of ‘Boro’ rice

Four ‘boro’ rice cultivars viz., Topaboro, Jyotiprasad, Mahsuri and Joymoti were grown in field by transplanting of control (non-hardened), 4°C cold hardened and GA₃ pre-treated seedlings. Various morphological, physiological and biochemical parameters studied in the rice cultivars were significantly influenced by cold hardening and GA₃ treatments. Plant height, tiller number, leaf area, chlorophyll, leaf proline, total stem soluble sugar, relative leaf water content were found to be affected by the hardening treatments. Yield attributing parameters, such as panicle length, panicle number per plant, grain number per panicle, high density grain (%), thousand grain weight and yield were improved due to the treatments. Crop duration was significantly reduced by the hardening treatments. Among the varieties Joymoti recorded highest yield. GA₃ application at seedling stage was found to be more effective in improving the yield potential of ‘boro’ rice.