SOURCE AND SINK CAPACITY IN RELATION TO YIELD OF SOME EGYPTIAN COTTON VARIETIES 1- EFFECT OF PLANT DISTRIBUTION DENSITY AND VARIETIES

Two field trials were established in 2003 and 2005 seasons to study the response of source (photosynthetic organs) and sink (reproductive organs) of Giza 70, Giza 85, Giza 88 and Giza 89 cotton cultivars to six plant distribution densities (60 X 15), (60 X 20), (60 X 25), (80 Xl5), (80 X 20) and (80 X 25) cm. The experimental design used was split- plot with four replications. Results revealed that dense distribution exhibited taller plants, lower number of leaves, vegetative branch number, dry weight of leaves and also leaves area per cotton plant. Leaf area index (LAI) of dense distribution was greater than that of thin distribution while specific leaf weight (SLW) followed opposite trend. Giza 89 variety ranked first with regard to plant length, no. of leaves, vegetative branch, dry weight of leaves, leaves areal plant, LAI and also SLW values. Number of open bolls and dry weight of bolls per plant of (80 X 25) cm distribution showed greater values than other densities. Moreover, diifferent parts of cotton boll, i.e. seed, lint and loculi of thin planting were heavier than dense ones. However, seed cotton yield of (80 X 15) cm distribution density was greater than other treatments. Cotton varieties can be arranged in descending order with regard to their yield as Giza 89, Giza 85, Giza 88 and Giza 70.