Improving grain yield in rainfed rice production
2013
Hayashi, K. | Agbisit, R. | Llorca, L.
Fertilizer application is imperative to close the yield gap in rice production. However, it is difficult to achieve higher nutrient use efficiency under the rainfed environment because of various stresses that hamper yield increase. Field experiments were conducted using three varieties, PSB Rc14, PSB Rc68, and NSIC Rc12 to understand the existing constraints to nutrient use efficiency in rainfed rice production. The first experiment was done during the 2011 wet season to test the yield performance of these varieties using 0, 45, and 90 kg urea/ha. Another experiment was done during the 2012 wet season using the same set of varieties to test the effect of planting time on grain yield. All experiments were conducted at the research station of IRRI, Los Baños and all fertilizer applications commonly practiced in IRRI were followed. Results showed that grain yield increased as fertilizer dosage increased. However, there was yield stagnation at higher fertilizer dosage, which could indicate inefficient nutrient use. This is shown by the decrease in percentage of filled spikelets and physiological efficiency as nitrogen fertilizer dosage increased. These results indicated that application of nitrogen fertilizer contributed to the increase in capacity of grain production, but full potential was not realized at the higher dosage as indicated by yield stagnation. Results from the second experiment showed that 1 week and 2 weeks of delay in transplanting resulted in significant yield loss due to significant reduction in total number of spikelets per m2 and percent filled grain. These imply that appropriate timing for transplanting is key to efficient nutrient use and increased grain yield in rainfed rice production.
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