Growth and senescence of the grape berry*

Abstract

Benzothiazole-2-oxyacetic acid (BTOA) was applied to bunches of grapes (Vitis vinifera cv. Shiraz) at different times during their development and its effect on their subsequent growth was followed by measuring changes in berry weight, reducing sugars, malate, and tartrate. It lengthened the slow growth phase of berry development and this delayed ripening. It had no effect on the course of the first or second rapid growth stages. Greatest response to a single application was obtained when BTOA was applied at the end of the first growth stage or during the first week of the lag phase. Two and three applications made at 2-weekly intervals lengthened the lag phase more than a single application. During the prolonged lag phase malate continued to increase and reached a higher maximum than in untreated grapes. No consistent effect of BTOA on the tartrate content of grapes was apparent. The response of grapes to treatment with BTOA and other auxins is discussed in relation to growth and senescence of the grape berry. * This work was initiated at the Australian Wine Research Institute, Glen Osmond, S.A. 5064, Australia.