Diurnal dynamics of photosynthesis and light response pattern at different growth stages of rice cultivars

摘要

Monitoring of diurnal canopy photosynthesis in four rice cultivars indicated that the photosynthetic rate increased linearly after sunrise, reached a peak between 10 h to 11 h (time of the day) followed by a marked decrease until about noon (12 h), then increased again and reached a second but lower peak between 14 h to 15 h. Thereafter it steadily declined until 16 h. Under simulated condition, the curve relating photosynthesis to irradiance (photosynthesis-light response curve) picked up a linear increase from threshold base irradiance of 400 muE m~(-2) s~(-1) until saturation intensity at 1200-1400 muE m~(-2) s~(-1) followed by a plateau. In this study, the range of variation in canopy photosynthesis was suggestive of exploitation of potential toenable produce more biomass per unit land area under well managed conditions.