Effect of harvest time on IR 44 ratoon grain yield [Philippines]
1985
Chauhan, J.S. | Lopez, F.S.S. | Vergara, B.S. (International Rice Research Inst., Los Banos, Laguna (Philippines))
Main crop yield was 516 g/m2. Ratoon crop harvest time significantly affected spikelet fertility, fully filled grains, and ratoon grain yield. Ratoon grain yield varied from 126 g/m2 for 75 DAH to 168 g for 85 DAH. Number of regenerated hills among treatments varied from 86% for 75 DAH to 75% for 90 DAH. Ratoon grain yield was calculated based on maximum recorded regeneration (92%) to eliminate the differences due to number of regenerated hills, which caused large variation in ratoon grain yield and partially concealed the effect of time of harvest. The lowest grain yield (136 g) was at 75 DAH and the highest at 85 DAH; however, they were not significantly different from those at 80 and 90 DAH. Spikelet fertility did not differ significantly between 85 and 90 DAH. Spikelet fertility at 75 DAH was at par with that at 80 and 85 DAH. The differences in spikelet fertility did not explain the differences in grain yield. The proportion of fully filled grains was the lowest at 75 DAH. The differences in fully filled and total spikelets/panicle can explain the differences in grain yield among the treatments. Late tillers with low spikelet number/panicle contributed to low yields in 90 DAH treatment. Shattering of overripe grains also reduced yield. The optimum time of IR 44 ratoon crop harvest is 80-85 days after main crop cutting, which is still too long for most situations
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