EFFECT OF POTASSIUM SULPHATE AND VINE LOAD ON THE GROWTH AND YIELD OF THOMPSON SEEDLESS GRAPEVINES WITH A SPECIAL REFERENCE TO THE OCCURRENCE OF CLUSTER TIP DESICCATION PROBLEM

This study was conducted during 2000 and 2001 seasons to examine the
effect of vine load (72, 96, or 108 buds I vine) and potassium sulphate ( 0.0, 100, 200
and 300 kgl fed) on growth, percentages of N, P, K and Mg, total and marketable
yield, cluster tip desiccation %, harvest date as well as some physical and chemical
characters of the berries and wood ripening of Thompson seedless grapevines.
Results showed that increasing vine load levels from 72 to 108 budsl vine was
followed by a gradual reduction in leaf area, main shoot length, percentages of N, P, K
and Mg , berry weight, total soluble solids % and wood ripening, meanwhile it was
responsible for increasing total yield slightly, cluster tip desiccation % and total acidity
%. Harvesting date was delayed in response to raising vine load levels. Increasing
potassium sulphate levels was accompanied by increasing the investigated characters
except percentages of P, K and Mg, cluster tip Desiccation % and total acidity % . In
most cases meaningless effect was detected in the studied characters between the
application of 200 and 300 kg potassium sulphate Ifed. The positive action of
increasing potassium sulphate and the negative influence of increasing vine load on
raising cluster tip desiccation % were ensured.
For checking cluster tip dryness % and improving yield and quality of
Thompson seedless grapes, it is recommended to leave 96 buds I vine and fertilize
the vines with 200 kg potassium sulphatel fed.