Effect of growth stimulators on yield and yield components of rice (Oryza sativa L.) ratoon

A field study was designed to evaluate the effect of growth stimulators application on rice ratoon performance in north of Iran conditions during 2009. Accordingly a randomized complete block design in a factorial arrangement with three replicates was used. Treatments were two factors of gibberellic acid and Ecormon at three levels (0.5, 1 and 2 times of the recommended dose rate). Results indicated that using growth stimulators had a significant effect on all studied parameters such as plant height, flag leaf, tiller number, grain number, 1000 grain weight and paddy yield. Both GA 3 and Ecormon markedly increased tiller number in ratoon. The grain yield of the ratoon crop was ranged between 1192.1 to 1753 kg ha -1 and remarkably increased when GA 3 was applied to the ratoon crop before flowering. Orthogonal comparisons indicated that the Ecormon treated plants had nearly 7% greater grain yield than the GA3 treated plants. Application of both GA 3 and Ecormon, however, markedly increased grain yield and grain number per panicle (up to 32 and 40 %, respectively) as compared to untreated plants. There were a positive and significant correlations between flag leaf length (r=0.91**), flag leaf area (r=0.76**), grain number (r=0.79**), panicle length (r=0.96**) and 1000 grain weight (r=0.79*) with paddy yield.