Physiological analysis of yield gap between flooded and aerobic rice
2002
Visperas, R.M. | Peng, S. | Bouman, B. | Castaneda, A.R. (International Rice Research Inst., DAPO Box 7777, Metro Manila (Philippines). Crop, Soil and Water Sciences Div.)
Field experiments were conducted at the International Rice Research Institute during the dry season (DS) and wet season (WS) of 2001 using split-plot design with four replications to compare flooded and aerobic rice. The main plot was water management and the subplots were cultivars. The main plots were A-A (aerobic in both seasons), F-F (flooded in both seasons), and A-F aerobic in DS and flooded in WS). Aerobic rice was grown under -20 kPa to near field capacity, while 5-10cm of water was maintained in the flooded rice. The subplots were three cultivars, IR42, B6144F and IR55423-01, during the DS. B6144F was replaced with an indica hybrid (IR73868 H), during the WS. Three twenty-one-day-old wetbed seedlings were transplanted per hill at a spacing of 25 x 10 cm Plant samples from 0.5 sq m were taken at key growth stages. Grain yield was determined from two 5-sq m sampling area within each subplot. Grain yield of flooded plots was 31 percent higher during the DS and 28 percent higher during the WS than those of the aerobic plots. Flooded rice had 20 percent more panicles per sq m, 15 percent more spikelets per sq m, and 13 percent higher grain filling percentage. The number of spikelets per panicle and 1000-grain weight were not significantly different between water management treatments. Crop growth rate during ripening and total dry matter per sq m at physiological maturity was also higher in flooded rice than in aerobic rice in both seasons. Harvest index of flooded rice was higher than aerobic rice during the DS. The results suggest that yield gap between flooded and aerobic rice mainly resulted from differences in sink development before flowering and crop growth rate and grain filling during ripening.
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