The interactive effects of temperature and light intensity on Vitis vinifera cv. 'Semillon' grapevines. II. Berry ripening and susceptibility to sunburn at harvest.

摘要

High light intensities and high temperatures occurring during the development of grapes are known to have persistent effects on their growth and ripening processes and also induce sunburn and, therefore, reduce berry quality. Vitis vinifera cv. "Semillon" grapevines were grown in controlled environments, exposed at three stages of berry development to short-term temperature and light treatments and, at the time of harvest, assessed for impacts on berry ripening and susceptibility to sunburn. Despite treatments being imposed during development, there were highly significant interactions between temperature and light intensity and the growth stage on berry size and sugar content when measured at harvest. Berries treated at the conditions at the early stage of development (pea size) were largely unaffected and there was no carryover at harvest. By contrast, when treated at the mid (veraison) and late stages, the treatment effects were very persistent, especially the highest temperature and light intensity which caused continued marked reductions in berry size and sugar content compared to when the treatments were applied. Although, rates of ripening for berries treated early in development in all conditions actually increased at harvest, whereas mostly the ripening rates declined for those berries treated at 30 and 38 degrees C and at the mid and late stages. There were similar interactive effects of temperature and light intensity on the susceptibility of the berries to sunburn, with nearly 100% of berries affected when exposed to the highest temperature and the highest light intensity of 660 1/4 mol m2 s1. Again, stage of development had a marked influence with no sunburn occurring with vines treated early and most susceptible when treated late in development. These results suggest growers need to protect bunches in the late stages of development from exposure to high light intensities by maintaining an adequate canopy cover over bunches, especially when temperatures approach heat conditions.