Agrobiological reaction of Centennial Seedless grape variety to changes in the numberof shoots and bunches on bushes

Abstract. Normalization of bushes is one of the ways to increase the productivity and quality of the grape yield. Primarily the yield is regulated by pruning shoots during the dormant period, as well as by breaking off at the beginning of the growing season. The article presents the results of studies of the effect of the load of bushes with shoots and bunches of the Centennial Seedless variety on productivity indicators in subzone № 4 of the Central agroecological zone of viticulture of the Krasnodar region. The climate is temperate continental, the soils are represented by low-humus, leached powerful chernozems. Over two years of research on the effect of the load of bushes with shoots and bunches of the Centennial Seedless variety, variant with a high load of shoots and bunches (I) was distinguished by the lowest proportion of dead buds (20.2 %), the largest proportion of fertile shoots (68.4 %), a high fruitfulness coefficient k1 (0.97); variant with the average load of shoots and high load of bunches (IV) was distinguished by a high proportion of fertile shoots (62.4 %) and fruitfulness coefficients k1 (0.92) and k2 (1.48); variant with the low load of shoots and high load of bunches (IX) was distinguished by a fairly low proportion of dead buds (22.1 %) and high fruitfulness coefficients k1 (0.82) and k2 (1.53). In 2022, according to the large bunch weight, variant with the average load of bushes with shoots and bunches was stood out (910 g), variant IV was distinguished according to the high productivity of the shoot (785.2 g/shoot). Yield capacity over 20 t/ha were observed in variant I (26.66 t/ha) and variant IV (22.58 t/ha). In 2023, the highest average bunch weight was observed in the variant VII – 590 g, as well as the highest shoot productivity – 331.9 g/shoot, and yield capacity – 6.6 t/ha. The analysis of the qualitative indicators of grape berries revealed stable and optimal values for a variant with a high load of bushes with shoots and bunches (I). Without taking into account biotic stress, in 2022, a variant with an average load of bushes with shoots and bunches (V) stood out. On average, over two years, the most productive variants are with a high load of bushes with bunches (I, IV and VII). Keywords: normalization of bushes, fruitfulness coefficient, yield capacity, bunch weight, shoot productivity