Effects Of Regulated Deficit Irrigation On Photosynthetic And Boll Development In Island Cotton At Budding Stage

Water shortage is the main limiting factor for the sustainable development of agricultural production in Xinjiang, developing water-saving irrigation is the surest way to boost yield. Effects of regulated deficit irrigation on cotton yield is signif icant, clearing effects of regulated deficit irrigation on cotton yield and quality and its relationship with cotton boll growth and development at budding stage has important theoretical and practical significance. The experiment was performed with two materials(Xinhai24 and Xinhai35) and three drip irrigation quotas : 0 m3/ha(severe deficit), 900 m3/ha(mild deficit) and 1800 m3/ha(abundant irrigation) to study the variation characteristics of yield, quality and water utilization efficiency in is land cotton under regulated deficit irrigation at budding stage, discuss effects of regulated deficit irrigation on photosynthetic gas exchange parameters and chlorophyll fluorescence parameters in island cotton and clear relationship between cotton boll growth and development and regulated deficit irrigation, providing a theoretical basis on accurate moisture management for arid areas under drip irrigation at budding stage. The main results were as follows:1. Effects of regulated deficit irrigation on yield, quality and water utilization in island cotton at budding stage Among drip irrigation quotas, water utilization efficiency was 1800 m3/ha< 0 m3/ha < 900 m3/ha, lint yield of 900 m3/ha was highest(2372.9 kg/ha), fiber length was greater, fiber specific breaking strength was larger, micronaire value was the most appropriate(3.7-4.2), it improved yield and fiber quality. Water utilization efficiency of 0 m3/ha was higher(0.6 kg/m3), but the lint yields the lowest(1675.2 kg/ha), fiber length was shorter, fiber specific breaking strength was larger, micronaire value was higher. Therefore, it was not conducive to the formation of yield and quality.2. Effects of regulated deficit irrigation on photosynthetic characteristics in island cotton at budding stage Among drip irr igation quotas, changes of leaf area index(LAI) of 900 m3/ha and 1800 m3/ha was converge, LAI of 0 m3/ha was the lowest level during whole growth period. At full boll stage, net photosynthetic rate(Pn), transpiration rate(Tr), stomata conductance(Gs), maximum photochemical efficiency(Fv/Fm), photochemical quenching coefficient(q P), non-photochemical quenching coefficient(q N) and photochemical quantum yield(Yield) of 900 m3/ha and 1800 m3/ha had no significant difference, but they had significant difference with 0 m3/ha.3. Effects of regulated deficit irrigation on boll development in island cotton at budding stage Among drip irrigation quotas, the rapidly expanding stage of cotton boll diameter was within 10 d after flowering, rapid expansion stage of cotton boll volume was within 20 d after flowering and boll weight increased faster within 30 d after flowering, but cotton boll diameter and cotton boll volume after 30 d of flowering and boll weight at 50 to 60 d after flowering were all decreased of 0 m3/ha. The cotton boll diameter, cotton boll volume and boll weight of 900 m3/ha has no obvious difference with 1800 m3/ha. Boll shell and seed dry matter was 1800 m3/ha> 900 m3/ha> 0 m3/ha, fiber dry matter was 0 m3/ha>900 m3/ha> 1800 m3/ha.