POSSIBILITY OF IMPROVING GROWTH, YIELD AND BUNCH QUALITY OF BLACK MONUKKA AND RED GLOBE GRAPEVINES THROUGH THE APPLICATION OF SOME SUMMER PRUNING PRACTICES

This study was carried out for two successive seasons (2007 & 2008) in a private vineyards located at El-Khatatba, Menoufiya governorate; to study on the possibility of improving vegetative growth, yield and bunch quality through the application of some summer pruning practices on Black Monukka and Red Globe grapevines. The chosen vines were ten-year-old, grown in a sandy loam soil, spaced at 2 X 3 meters apart, irrigated by the drip irrigation system, cane-pruned and trellised by the double "Y" shape system. Eight treatments were applied as follows; pinching the main shoots before the beginning of bloom and removing laterals, pinching the main shoots before the beginning of bloom and topping laterals to 4-5 leaves, pinching the main shoots before the beginning of bloom and maintaining laterals, defoliation (removal of leaves beneath the clusters at veraison stage), pinching the main shoots and removing laterals + defoliation, pinching the main shoots and topping laterals to 4-5 leaves + defoliation as well as pinching the main shoots and maintaining laterals + defoliation, in addition to control (untreated vines).
The results showed that all treatments, except for defoliation treatment was effective in increasing number of bunches/vine, average bunch weight and yield. All pinching treatments alone or combined with defoliation treatment improved the physical characteristics of bunches, physical and chemical properties of berries, morphological characteristics of vegetative growth, leaf content of total chlorophyll and cane content of total carbohydrates as compared with control. Vines treated with pinching the main shoots, maintaining laterals accompanied with defoliation resulted in a great stimulation of all the studied parameters. On the other hand, control was found to record the minimum values of these characters.
The economical study indicated that vines treated with pinching the main shoots, maintaining laterals accompanied with defoliation of Black Monukka and Red Globe grapevines gave the highest net income as compared to the control.