Influence of Simulated Mechanized Pruning and Hand Pruning on Yield and Berry Composition of Vitis rotudifolia Noble and Welder

Abstract

The influence of simulated mechanical pruning (SMP), hand pruning (HP) and SMP every year followed by HP every other year (SMP + HP) was assessed on yield and berry composition of muscadine grapevines (Vitis rotundifolia Michx.) Noble and Welder over a six-year period. Noble and Welder were statistically analyzed separately as randomized block designs, and data were subjected to a repeated measures analysis. Average yield varied from 16 to 19 t/ha for Noble and 13 to 15 t/ha for Welder. When data from all years were combined, pruning treatment did not influence yield or indices of berry composition with the exception of soluble solids (°Brix) of Noble (highest for the HP treatment). However, year effects for both cultivars were highly significant for all variables. Yield of Noble was influenced by pruning treatment during all years except 1994. Treatment effects were observed for °Brix and total °Brix/ha in three of six and four of six years, respectively. Differences in pH, titratable acidity (TA) and color of berry juice occurred in only one year. Yield and total °Brix/ha for SMP Noble vines decreased linearly with time, whereas a quadratic model described yield and total °Brix/ha for HP Noble with a maximum in 1991. Both Noble and Welder vines subjected to the SMP + HP treatment displayed a strong tendency to bear heavy and light crops in alternate years, with low yield recorded in the years that HP was employed. Although yield and total °Brix/ha of Welder were influenced by pruning treatment in certain years, lower order polynomial models did not adequately describe trends from 1989 to 1994.