Effect of harvesting date on the quality and palatability of paddy rice cultivated by Aigamo duck farming system

摘要

The effect of harvesting date on the quality and protein content of paddy rice cultivated by using an Aigamo duck (crossbreed of wild and domestic ducks) farming system was examined. The proportion of perfect rice grain was increased with delay in harvesting, irrespective of the method and place of cultivation. The protein content of cv. Kinuhikari in the first year of Aigamo cultivation was 7.3/+-/0.1%, and that of cv. Koshibikari in the 5th year of Aigamo cultivation (the 7th year of organic cultivation) was 7.8/+-/0.4%. The protein content of Koshihikari under Aigamo cultivation was decreased 0.7% at most by a 10-day delay in harvesting after maturity. Yield was slightly increased by delay in harvesting. The proportion of green-grained rice wasclosely correlated with the protein content, and the protein content decreased with decreasing proportion of green-grained rice. In the evaluation by sensory test for palatability, the best was with early harvesting, followed by late harvesting and maturity harvesting. This tendency was notable particularly in the rice in the 5th year of Aigamo cultivation (the 7th year of organic cultivation). These results indicated that a 10-day delay in harvesting from the usual date decreased the proportion of green-grained rice, increased crop yield, and improved palatability by decreasing the protein content in brown (unprocessed) rice.