Relationship between air temperature and characteristics of developing fig syconia at different nodal positions

Abstract

The relationship between air temperature and characteristics of developing syconia at different nodal positions of 'Houraishi', a common fig (Ficus carica L. var. hortensis Shinn), was investigated from 1996 to 1998. 1. The fruit development period from budbreak to harvest of the second cop figs, borne on the 3rd, 8th, and 13th nodes, was 80 to 89 days. The cumulative temperature during this period was approximately 2,100 degree-days (°C), independent of years and nodal positions. The diameter and weight of fruit on the 3rd node were largest and decreased at higher nodal positions. Peel color developed largely in the fruit at high nodal positions. 2. Air temperature increased from budbreak to harvest for the fruit on the 3rd node, while it rapidly fell in the latter half of the developmental period for fruits on the 13th node. Changes in air temperature after budbreak on the 8th node were intermediate between those on the 3rd and 13th. The minimum air temperature during fruit development in all nodal positions was above 15 °C except for a decrease to 13 °C during the development of the fruit on 13th node in 1996. These fruits did not ripen even after autumnal leaf fall. 3. Fruit diameter and weight correlated negatively with air temperatures for the first 30 days after budbreak; they correlated positively with air temperatures for 5 to 15 days before harvest, especially when the minimum air temperatures persisted for 5 days before harvest. In contrast, peel coloration correlated negatively with air temperatures 5 to 15 days before harvest.