Effects of cutting height of main plant on the ratooning traits of different varieties in rice (Oryza sativa L.)

In order to evaluate cutting height of the main plant on the ratooning traits of different varieties in rice, an experiment was carried out in 2006. The experimental design was a split plot based on a randomized complete block with four replications. Main plots were four varieties and lines including Sang Tarom, Tarom Hashemi, Tarom Dylamani cultivars and Irton line and sub-plots were three cutting height of ground cutting, standing (cutting at 40 cm height) and lodging stubble (cutting at 40 cm height). Results showed that the highest plant height, panicle length, number of tiller per hill and grain yield of ratoon were obtained for the Sang Tarom. The reason of highest grain yield in this variety was the increasing panicle length and increased number of tillers per hill. The greatest number of spikelets per panicle was obtained on Tarom Hashemi. The highest plant height and number of tiller per hill was observed at standing method. The lodging stubble method had the highest panicl length, percentage of filled spikelet and 1000 grains weight. The greatest flag leaf length, number of panicle per m2, number of spikelets per panicle and ratoon grain yield were observed in the ground cutting method. The number of spikelets per panicle had positive correlation with grain yield and the grain yield had negative correlation with tiller number at α=%1 level of probability. The results showed that the highest of ratoon grain yield was obtained in Sang Tarom varietiy through lodging stubble method.