The effects of delayed winter spur‐pruning on yield, yield components and fruit composition of Merlot vines was evaluated within a commercial vineyard in Marlborough, New Zealand. Vines were spur‐pruned, trained using vertical shoot positioning, trickle irrigated and grafted to Kober 5BB rootstock. Delaying pruning from July (usual winter pruning time in New Zealand) until up to October (when apical shoots on canes were 5 cm long) resulted in yield increases of up to 93%, 63%, and 82% over the three seasons of experimentation. These yield increases reflected higher average berry weight and in turn bunch weights. The increase in average berry weight was associated with a change in the relative abundance of different berry types. Later pruning increased the proportion of large seeded berries while the proportion of smaller seedless berries and live green ovaries (shot berries) decreased. The delayed pruning may have enhanced fertilisation of flowers and development of seeds by postponing flowering to a time when climatic conditions are more favourable; measurements of shoot lengths support this proposal. By delaying winter pruning until after budburst the development of basal nodes was inhibited, so that budburst on the resulting spurs was also delayed.

Background and Aims:  Variation in berry size is observed at harvest. Although the growth of seeded berries has been described, no such data are reported for seedless berries or live green ovaries that occur in wine cultivars. This study describes the growth of individual berries in relation to seed development. Methods and Results:  Regular measurements of berry diameter described the growth of Pinot Noir and Cabernet Sauvignon. Seeded berries had typical double sigmoid growth curves, whereas seedless berries, which developed more slowly from midway through Phase I, continued to grow in Phase III if a seed trace was present. Berries without a seed trace did not enlarge after Phase II. Live green ovaries failed to grow after a small initial expansion post‐cap fall. Conclusion:  Seeded berries had double sigmoid growth as a result of cell division and expansion, whereas the growth of seedless berries and live green ovaries was the result of cell expansion alone. Seed development is necessary for cell division within the mesocarp. Significance of the Study:  Seed development is essential for the full development of Pinot Noir and Cabernet Sauvignon berries. The data suggest that divergence of berry development from a characteristic growth curve may be linked to the extent of seed development.

Background and Aims:  Spring freeze events can result in substantial grapevine yield losses in many parts of the world. Understanding vine responses following early spring freeze events will aid in the development of decision support systems for vineyards damaged by freezing temperatures. Methods and Results:  The date of budburst of spur‐pruned Chardonnay vines was manipulated by pruning time and/or the application of sodium alginate gel. A spring freeze event occurred at bud swell/woolly bud, killing 33% of the developing shoots. Treatments that delayed bud development expressed a lower incidence of freeze damage (as low as 3%). Where primary shoots had been killed, secondary shoots developed in their place. The yield from secondary shoots was 32% of that from primary shoots, with the majority of fruiting secondary shoots bearing only one bunch. Average bunch weight, number of berries per bunch and average berry weight of secondary shoots were comparable with those from primary shoots. Conclusions:  The damage to primary shoots caused by early spring freeze events can be reduced by using treatments that delay bud development. Secondary shoots develop in response to death of the primary shoot, and although they have reduced fruitfulness, they can partially mitigate the potential yield losses associated with the death of primary shoots. Significance of the Study:  The number and fruitfulness of secondary shoots that develop after a spring freeze event determine the extent of mitigation of yield losses associated with the death of primary shoots.

Environmentally-responsive genes can affect fruit red colour via the activation of MYB transcription factors. The apple B-box (BBX) gene, BBX33/CONSTANS-like 11 (COL11) has been reported to influence apple red-skin colour in a light- and temperature-dependent manner. To further understand the role of apple BBX genes, other members of the BBX family were examined for effects on colour regulation. Expression of 23 BBX genes in apple skin was analysed during fruit development. We investigated the diurnal rhythm of expression of the BBX genes, the anthocyanin biosynthetic genes and a MYB activator, MYB10. Transactivation assays on the MYB10 promoter, showed that BBX proteins 1, 17, 15, 35, 51, and 54 were able to directly function as activators. Using truncated versions of the MYB10 promoter, a key region was identified for activation by BBX1. BBX1 enhanced the activation of MYB10 and MdbHLH3 on the promoter of the anthocyanin biosynthetic gene DFR. In transformed apple lines, over-expression of BBX1 reduced internal ethylene content and altered both cyanidin concentration and associated gene expression. We propose that, along with environmental signals, the control of MYB10 expression by BBXs in ‘Royal Gala’ fruit involves the integration of the expression of multiple BBXs to regulate fruit colour.