|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1993 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1992 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Photosynthesis rate was lower in tropical fruit trees than subtropical and temperate ones. Especially the efficiency to acquire light energy was very low in neo-tropical fruit trees such as mangosteen. However, Sugar apple had high photosynthetic ability under high temperature and strong irradiance. The photosynthetic response seems to be different among species.
Photosynthetic rate of subtropical fruit trees, which was comparative with that of temperate ones, was affected by temperature. In cherimoya and passionfruit, the rate increased with increase in irradiance level under cool condition. However, the rate was lower at high light intensity at high temperature. Subtropical fruit trees should be grown under cool condition to utilize the light energy most efficiently. On the contrary, high temperature was favorable for the efficiency of photosynthesis in tropical fruit trees like mango and sugar apple.
From fall to winter during which air temperature decreased, photosynthetic rate of tropical and subtropical fruit trees drastically decreased. In apple, the rate decreased when the anthocyanin pigments were produced in the leaf and the leaves falled soon. In guava, however, the rate was still rather high even when the leaves truned to be red. Tropical fruit trees may obtain much light energy by keeping the leaves on the tree during early winter.
The conductance for CO_2 greatly affected the photosynthesis of subtropical and tropical fruit trees. The decrease of photosynthetic rate was reduced by increasing to CO_2 conductance under shade condition in cherimoya. In mango and passionfruit, the increase in CO_2 conductance increasede the photosynthesis under unfavorable conditions Such phenomenon was not found in temperate fruit trees.