Abstract
Grape cuttings, Vitis labruscana Bailey, cv. Campbell Early, grown in a greenhouse were examined for following effects: a) defoliation and the leaf position with respect to inflorescence, b) SADH spray, on flowering, berry set and on subsequent berry development under natural sunlight conditions.
Development of floral organs at anthesis differed depending on leaf position; that is, proximal leaf contributed to better floral size than that distal to the inflorescence. The average percent of fruiting plants per treatment three weeks after full bloom in proximal lot and in distal lot was 40.0% and 25.0%, respectively. Poor fruit set in cuttings with expanding immature leaf above flower cluster is probably attributable to the diversion of reserve substances.
SADH (2500 and 5000ppm) treatment reduced the floral development in proximal lot, while it had no effect on percent of bearing plant per treatment. SADH treatment of proximal lot increased berry set, but the treatment did not inhibit vegetative growth, because all leaves were removed, one leaf being left. In completely defoliated treatment, percent of bearing plants three weeks after full bloom was high in all lots, and cuttings with SADH at 5000ppm gave the best result in berry set per cluster.
Berry maturity in distal lot was advanced more than in proximal lot. Leaf area of distal lot is larger than that of proximal lot as was the mean berry size. SADH treatment not only resulted in poorest berry size, maturation was also retarded.
