Abstract:

According to the characteristics of 'Summer Black' grape, the key technical measures for the management of flowers and fruits were studied. 5 flower thinning lengths of 0(CK), 5, 6, 7, 8 cm were set during the peak fruiting period and two dipping treatments with different concentrations of gibberellin and chlorpyramide were performed. We measured the length of the fruit during the peak flowering period, evaluated the appearance quality by measuring 8 indicators, including ear length, ear width, stem length, stem thickness, grain longitudinal and transverse longitude, fruit shape index, and peel color during the mature stage. Two indicators of ear weight and grain weight were measured to estimate yield, and three indicators of soluble solids, soluble reducing sugars, and titratable acids in fruits were measured to evaluate fruit quality. The results showed that the length, width, and weight of the fruit increased during the peak flowering and mature periods with the increase of the length of the treated panicles, but the weight of the fruit grain and time for flower trimming and dipping were decreased; the content of soluble solids, soluble reducing sugars, and titratable acids in mature fruit increased with the increase of length of the flower spikes. Compared with CK, the ear serial and appearance of the flower ear trimming treatment generally performed better. Based on fruit quality, 7 cm was considered as optimal flower thinning length. The 7 cm flower thinning treatment combining with 25 mg/kg gibberellin, 50 mg/kg gibberellin, and 5 mg/kg chlorpyramide dipping treatments had the best performance on fruit spike and grains, increased fruit quality and appearance, soluble solids content, soluble sugars, and decreased titratable acids. The labor cost of flower trimming can be ignored compared to the benefits brought by the early marketing and quality and yield improvement of ‘Summer Black’ grape.

Key words: ‘Summer Black’ grape, spike length, growth regulator, gibberellin, clopidogrel, ear dipping treatment, fruit quality