作物生理の動態解析に関する研究

In order to realeze a high-efficient growth control for higher yielding, it is important to clarify the relationships between the physiolofical dynamics and the growth of a particular crop. Therefore, an assimilation chamber for simultaneous measurement of photosynthesis, shoot and root respiration,transpiration and ion uptake of a whole plant was developed. The relationship between plant growth and constructive respiration coefficient which was calculated by using McCree's equation, was investigated. The coefficient increased with the ratio of the assimilation of nitrogen and carbohydrate(⊿N/⊿C) during measurement. The higher ratio of ⊿N/⊿C is closely related to an increase in dry-matter partitioning of the leaf blade.In this measurement,light intensity was daily lowered to estimate the constructive respiration coefficient and plant gowth might be influenced under these conditions. Then measurements at condtant daylight intensity were done under different humidity and nutrient conditions, using several varieties. Consequently,shoot respiration rate was estimated by relative shoot growth rate and leaf blade/sheath ratio of dry matter increase.Respiratory enegy costs for organogenesis differed among the plant parts, and that of the leaf blade was higher than that of the leaf sheath. Root respiration rate was explained by the combination of relative root growth rate and nitrogen uptake rate. The respiratory energy cost for nitrogn uptake did not change with the transpiration rate, the nitrogen concentration in the culture solution nor with other varieties. Dry matter partitioning rate to shoot was found to have two main componets,i.e.initial nitrogen content of shoot and ratio of assimilated nitrogen and carbon in the first day. Dry-matter increase and dry matter partitioning of intact plants could be discovered by measuring CO2 exchange, nitrogen uptake and shoot nitrogen content.