DORMANCY DYNAMICS OF GRAPE AND KIWIFRUIT BUDS IN A REGION OF LOW CHILL OCCURRENCE
The objective of this work was to observe the dormancy dynamics of Niagara Branca grape and Bruno kiwifruit buds in a region of low chill occurrence. Stems were collected weekly during autumn-winter 2009. Extra sets of stems were collected during the last week of winter and maintained at 4-7°C for 672 and 1440 h, for grape and kiwifruit, respectively. The evaluation of dormancy was performed inside a growth room, at 25°C, and 16-h photoperiod, by using the single-node cutting biological test. Chilling hours (CH) and chilling units (CU) of the region were estimated for both species individually. A completely randomized experimental design with 15 treatments for grape and 19 treatments for kiwifruit, four replica¬tions, and ten cuttings per plot was used. Grape cuttings were monitored for 40 days, and kiwifruit cuttings for 50 days. Endodormancy in Bruno buds got stronger at the end of May, when average bud break time (ABT) was longer than 40 days and the velocity of bud break (VB) was lower than 0.2 buds day-1. The endodormancy gradually decreased during autumn and winter but there was not enough chilling for a good budburst. Buds that received additional chilling presented shorter ABT (2.7 days) and higher VB (4.04 buds day-1). Niagara Branca buds reached deeper endodormancy at the end of May, until the end of June. Endodormancy was released spontaneously in mid-August; however, both ABT (4.6 days) and VB (2.38 buds day-1) were better with additional chilling.
Biasi , L.A., Zanette , F. and Carvalho , R.I.N. (2012). DORMANCY DYNAMICS OF GRAPE AND KIWIFRUIT BUDS IN A REGION OF LOW CHILL OCCURRENCE. Acta Hortic. 932, 507-512
Vitis labrusca, Actinidia deliciosa, budburst, endodormancy, chilling hours