THE CHANGES OF COTTON SEED-LINT YIELD IN PARTS OF FURROW LENGTH UNDER DIFFERENT IRRIGATION SCHEDULING

The paper indicates the results of furrow irrigation technology along parts of furrow and its impact on seed-lint yield and boll weight of upland cotton varieties (Gossypium hirsutum L.) Sultan, UzPITI-103, C-8295 and Kelajak. The research was conducted in the condition of old irrigated typical sierozem soils with mechanical composition of silt loam in Tashkent province, at the Central Experimental Station of Uzbekistan’s Cotton Breeding, Seed Production and Agrotechnologies Research Institute in 2015 to 2019. In research, cutoff flow furrow irrigation was applied where irrigating with inflow rate of 0.40 to 0.42 l s-1 in the beginning of irrigation in three in four part of furrow, then decreasing it till 0.20 to 0.22 l s-1, the inflow rate decreased twice 0.12 to 0.15 l s -1 by reaching water the end of furrow which ensured wetting the root zone layer of soil smoothly along the furrow length. Irrigation scheduling 70-75-65% Fc was optimal for cotton varieties of Sultan and C-8295, where the irrigation scheduling 70-70-60% Fc for UzPITI-103 variety and irrigation scheduling 65-65-60% Fc for Kelajak variety was optimal. In all abovementioned varieties the highest seed-lint yield and boll weight were obtained in the furrow length of 30 to 70 m. The highest seed-lint yield of cotton (4.71 t ha-1 Sultan variety, 4.48 t ha-1 UzPITI-103 variety, 4.27 t ha-1 C-8295 variety, 3.93 t ha-1 Kelajak variety) was obtained in the part of furrow length 30 to 70 m in comparison with the furrow length 0 to 30 m and 70 to 100 m the seed-lint yield was decreased by 0.17 t ha-1 and 0.39 t ha-1 in Sultan, 0.13 t ha-1 and 0.16 t ha-1 in UzPITI-103, 0.10 t ha-1 and 0.16 t ha-1 in C-8295, 0.14 t ha-1 and 0.21 t ha-1 in Kelajak varieties. According to research results, the furrow length must not exceed 70 m.