Assessment the Effect of Water Stress and Calcium Silicate on Rice (Oryza sativa L.) Yield in North of Iran

In order to consider the effect of irrigation cut off and calcium silicate on seed yield and its components of rice (Local cultivar, Tarom Hashemi), a research was carried out as split plot experiment based on randomized complete block design in three replications in 2014 in Sari, Mazandaran, Iran. Irrigation cut off arranged 15 days in 4 growth stages (At beginning, middle and last of tillering stage and 50% of flowering stage) as main factor and calcium silicate in three amounts (0, 500 and 1000 kg.ha-1) as sub-factor applied 15 days before transplanting. Results of analysis of variance showed that effect of irrigation cutoff on all measured traits (except percentage of filled spikelet per panicle) was significant. Effect of calcium silicon and interaction effect of treatment on all measured traits were no significant. According to mean comparison cut off of irrigation at beginning of tillering stage showed significantly decrease in panicle length, number of panicle per m2, number of spikelet per panicle and drastically reduce in seed yield. Cut off of irrigation at middle of tillering stage caused to decrease in 1000-seed weight. Maximum number of panicle per m2 and grain yield (405.78 gr.m-2) was found in cut off of irrigation at 50% of flowering stage. Correlation between traits showed number of spikelet per panicle (0.58*), number of panicle per m2 (0.56*), 1000-seed weight (0.59*) and percentage of filled spikelet per panicle (0.51*) have a significant and positive correlation with seed yield at 5% probability level. In general, it can be concluded that beginning of tillering stage was too sensitive to cut off irrigation because it caused to reduce of yield and yield contributing.