The turning period of growth and of leaf appearance cycle in paddy rice (1)

Abstract

The authors obtained the following results from the observation on appear ance cycle of each leaf on the main stem in the rice plant, on the initiating date of flower-primordia-differentiation, and on the heading date, using six varieties transplanted at five different times from May 26 to June 23 with a week interval at Morioka in 1951. The difference between the earlier and later periods of leaf appearance cycle, b₂-b₁ in table 3, was smaller than that observed at Hukuoka and Suigen in whidh it was difficult to observe the turning period of appearance cycle dividing the earlier and later periods. The later the setting the shorter was the period from setting to heading and this shortened period was mainly due to the shorter period from setting to turning period of leaf appearance cycle, but with the period from turning to heading, there was found almost no correlation (Fig.1 and Table 4). The turning period of leaf appearance cycle and of growth from the vegetative to the reproductive stages seems to be about at forty days before heading almost constantly. Therefore, considered that they are, perhaps, closely correlated.