Abstract
Strawberry plants of 'Morioka 16' were grown in growth environments in which the daytime and nighttime temperatures were such that the mean temperatures were : 15° (A), 20° (B) and 25 °C (C). The diurnal subset temperatures for sets (A), (B), and (C) were : 15°/15 °C, 20°/10 °C, and 25°/5 °C ; 20°/20 °C, 25°/15 °C, and 30 °C/10 °C ; 25°/25 °C, 30°/20 °C, and 35°/15 °C, respectively. The photoperiod for all chambers were : day (12 hr) and night (12 hr).
1. Fruits from (A) required the most days from anthesis of the primary flower to harvest; but they were largest, had the highest Brix values, and Brix/acidity ratio, compared to fruits from sets (B) and (C). Within a set in which the mean diurnal temperature was constant, fruits on plants exposed to warmest daytime temperatures were the first to ripe even though the night temperatures were the lowest. In sets (B) and (C), the time required from anthesis to harvest became shorter, but the daytime temperatures had less influence on fruit size.
2. Comparisons among plants in sets (A) 15°/15 °C, (B) 20°/20 °C, and (C) 25°/25 °C revealed that the whole plant, terminal inflorescence, and roots in (A) accumulated the most dry matter; those from (B) were intermediate; whereas the plant and its parts from set (C) accumulated the least assimilates.
3. Within any set, the position of the flowers on the terminal inflorescence had a significant effect on the final size of the fruit and the number of days from anthesis to harvest. Among the subset, the day- and nighttime temperatures had the greatest effect. Fruits, resulting from the primary flowers, especially those exposed to the coolest daytime temperature, were always the largest and required the most days from anthesis to harvest.
