Studies on pruning of grape <p>III. Fruit bud formation in Pusa Seedless grapes (<i>Vitis vinifera</i> L.) under Delhi conditions</p>

Abstract

Experiments conducted in 1965 and-1967 on the effect of pruning severity and certain fertilizer treatments on fruit bud initiation in Pusa Seedless under Delhi conditions showed that:

1. Fruit bud initiation commenced between the first and second week of April, and the time taken from pruning was 66 to 74 days, and from bud burst it was 45 to 53 days. At the time of fruit bud initiation, the shoots were carrying fully developed inflorescences, many of which were in full bloom. Thus both the development of the current season's crop as well as the inflorescence primordia for the next year occur simultaneously. The primordia showed full development by October though the differentiation of floral parts did not occur until after bud burst.
2. The severity of pruning past season's canes to 3 or 9 buds or 'no pruning' did not exert any influence on the time of fruit bud initiation. No difference was noticed between the basal and apical buds in the rate of development of primordia.
3. Dissection of buds prior to pruning and forecasting the fruiting potential was found to agree closely with the actual yields, the difference between the predicted and actual values being 11-19 percent.
4. Fruiting shoots of the current season were found capable of initiating fruit buds for the succeeding season also to the extent of 10 to 100 per cent. There were also instances of the fruitfulness in such shoots being reduced from zero to 10 percent. Non-bearing shoots of the current season were not necessarily fruitful in the following season.
5. Among 8 fertilizer treatments with two levels each of N, P and K, three combinations, viz., N₁P₀K₁  N₁P₁K₀ and N₁P₁K₁ showed significantly higher fruitfulness than N₀P₀K₀. Indications of earlier fruitfulness were also obtained in the treatment N₁P₁K₁.