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 GA3 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 GA3 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 GA3 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.

GA3- gibberellic acid, NAA-naphthalene acetic acid, ANOVA- analysis of variance