Studies on the sultana vine. I. Fruit bud distribution and bud burst with reference to forecasting potential crop.

Abstract

Fruit bud distribution and bud burst on sultana canes were studied by microscopical examination of bud samples in autumn and direct observation of vines in spring. The percentage of fruitful buds found by niicroscopical examination, and the percentage bud burst and percentage of fruitful shoots found in spring all showed highly significant differences between bud positions in all seasons. In all cases polynomial regressions could be fitted from which the bud position means did not differ significantly. Fruitfulness was always low at the base of the cane, rose to a maximum at about bud position 9, and then fell away. Bud burst also rose rapidly over the first few bud positions but did not show the same pronounced falling off after bud position 9. The percentage of fruitful buds and percentage of fruitful shoots also showed highly significant differences between seasons and between individual vineyards, and highly significant interactions between seasons and vineyards. The major sultana growing districts did not differ greatly in any respect, nor did the separate settlements within the Sunraysia district. The percentage of fruitful buds agreed with the percentage of fruitful shoots except in seasons of low fruitfulness. The examination of 20 canes from each of 10 Sunraysia vineyards gives a satisfactory estimate of the percentage of fruitful buds in May, and this gives a useful forecast of potential crop.