圃場における水稲の光合成のエネルギー転換効率の測定

抄録

Using the variety 'Hoyoku' cultured on a fertile soil in the field with nearly an optimum supply of water and fertilizer in an early planting or a normal season, the efficiency for photosynthetic light energy conversion of a rice population was measured under natural conditions for each 3-week period of the whole growth duration. The absobed PAR was obtained from the observed data of short wave solar radiation by the experimental formula of Kishida (1973), and gross chemical energy fixed by the population was obtained from adding the net production to the net production to the dark respiration. Th efficiency for light energy conversion thus determined was found to be fairly uniform during most of the growth period except for the last phase of the grain filling period. ranging from 7.7% to 4.6%. The average and the highest values for the carly planting culture were 6.2% and 7.7%, respectively, and those for the normal season culture were 6.4% and 7.0%, respectively. The ratio of net production to gross production was found to be 72% to 55% in the carly planting culture 77% to 60% in the normal season culture, both with an average value of 67%, indicating that one third of the gross production was lost by respiration