Effect of Artificial Leaf Cutting on the Growth and Yield of Rice Plants in Hokkaido

Abstract

The effect of artificial leaf cutting on the growth and yield rice plants to were analyzed under field conditions in Hokkaido, the northernmost area of rice culture. As in past surveys, suppression of plant height, retardation of growth and decrease in the numbers of culms and ears were observed. Our study also produced three sets of evidence; (1) Yield loss was considered to be caused mainly by the decrease in the number of ears among the yield components. (2) Compensatory responses in rice growth, such as increases in the percentages of productive tillers and ripening grains, and in the 1, 000-grain weight, were observed. However, such responses seemed to be minimal in cold years. (3) Loss of the entireties of the upper two leaves of each culm through insect injury was estimated to cause inevitable yield loss even in warm climate conditions. The loss of half the area of those leaves seemed to cause yield loss even in ordinary climate conditions.