Resumen de Effect of short‐term temperature and shading on fruit‐set, seed and berry development in model vines of V. vinifera, cvs Chardonnay and Shiraz
A. Ebadi, Peter May, Bryan G. Coombe
Small Chardonnay and Shiraz vines were grown under controlled environment conditions at 25/20°C and 400 μE/(m2.s) radiant energy. These conditions were interrupted for some plants for one week, at two periods near flowering, by imposing reduced temperatures (17°/14°C or 12°/9°C) and shading (8, 40 or 72% light reduction), in factorial combinations. Fruit‐set was reduced by exposure to the lower temperature regime in both cultivars (confirming the results of a previous experiment) and tended also to decrease with increasing intensity of shading. Seed characteristics were examined only in Chardonnay where total number of seeds per berry was not affected by any of the treatments. However, pre‐flowering exposure to 12°/9°C resulted in fewer berries with one or two sinker seeds and more berries with floater seeds and, overall, in a greater proportions of seeds being floaters. Shading had little effect on seed development. Berries on vines exposed to 12°/9°C, at both stages of development, had lower pericarp and seed weights compared with those treated with 17°/14°C or 25°/20°C. At harvest, pericarp weight and seed weight per berry were positively correlated; the linear regression for berries exposed to the higher temperature regimes had a significantly steeper slope than that for berries exposed to the lowest temperature regime. It is concluded that differences in pericarp weight were due to differing cell numbers. These differences may have developed firstly in the ovary due to a direct effect of exposure to varying temperature regimes, and secondly in the developing berry after fruit‐set because of variation in the stimulatory activity of the seeds, caused by residual effects of pre‐flowering temperature conditions on ovule and seed development.
