Effect of Temperature on the Size of Strawberry Fruit.

Abstract

Strawberry, Fragaria × ananassa Duch. cv. Toyonoka, plants were grown from October onward in two glasshouses where the air temperature was controlled at either 15°or 19 °C night and day. Several days after pollination, the diameter of all the fruits in the first inflorescence (truss) was measured at approximately two-day intervals, and fully red ripe fruits were sampled. The growth of the fruits showed a double sigmoidal curve in all ranks of the inflorescence at both temperatures. The growth was faster in the higher rank fruits that developed earlier and at 19 °C than in the lower rank fruits and at 15 °C. Fresh and dry weight per fruit was larger in the higher rank fruits and at 15 °C (mean of all fruits; 0.879 g DW) than in the lower rank fruits and at 19 °C (mean of all fruits; 0.774 g DW). The total numbers of ripe fruits per inflorescence (plant) were slightly smaller at 19 °C. The values of the total fruit fresh and dry weight per inflorescence (plant) were much lower at 19 °C. The bearing fruit period from the flowering of the first flower to the ripening of the last fruit in the inflorescence was 88 days at 15 °C and 69 days at 19 °C, respectively. The daily dry weight increments of total fruit in the inflorescence (per plant) were 0.170 g at 15 °C and 0.151 g at 19 °C. It was considered that the small size of the fruits at a high temperature like 19 °C was not caused by the increase in the number of fruits. but by the low rate of dry matter accumulation in fruit.