Effects of Leaf Spraying Biogas Slurry Fertilizer on Cotton Yield and Quality

【Objective】Biogas slurry fertilizer is a kind of high quality organic liquid fertilizer, and the application of organic fertilizer in cotton fields in Xinjiang is less or no. This study was conducted to explore the effects of foliar spraying biogas slurry fertilizer on the growth, yield and quality of cotton in oasis of Xinjiang.【Method】Four concentration gradients of biogas slurry fertilizer were set: Cotton foliar spraying experiment was carried out at 0 kg/hm2 (CK), 15 kg/hm2 (OM1), 30 kg/hm2 (OM2), 45 kg/hm2 (OM3). After spraying at bud stage and flowering stage, cotton plant height, leaf number and leaf width were investigated, and dry matter weight of each organ of cotton was weighed. The effects of biogas slurry fertilizer spraying on cotton growth, yield and quality were studied by measuring chlorophyll content of functional leaves and analyzing yield and quality indexes.【Result】(1) Application of biogas slurry fertilizer could promote the growth of cotton, significantly increase the plant height, leaf number and leaf width of cotton, and the growth indexes of cotton treated with OM2 (30 kg/hm2) were better. (2) The dry matter weight of stem, leaf, bud (boll) and root was significantly increased by applying biogas slurry fertilizer. The dry matter weight in various organs of cotton increased with the increase of spraying concentration at bud stage. After spraying at flowering stage, only the dry matter of leaves increased with the increase of spraying concentration. (3) Spraying biogas slurry fertilizer on leaves can increase the chlorophyll content of cotton leaves. From bud stage to flowering stage, the SPAD values of leaves in OM2 treatment was between 63.35 and 71.55, with the smallest change over time. (4) With the increase of biogas slurry fertilizer application rate, cotton yield first increased and then decreased, and OM2 treatment had the highest seed cotton yield (6 338 kg/hm2) which increased by 7.37% compared with the CK. The application of biogas slurry fertilizer showed that the overall quality of cotton fiber was improved, and the length, uniformity and Macronaire value of cotton fiber were improved. With the increase of biogas slurry fertilizer application amount, the length of cotton fiber showed a downward trend. The uniformity and Micronaire valu e of fiber increased first and then decreased. The breaking strength decreased first and then increased, and the lowest value was 31.78 cN/tex under OM2 treatment.【Conclusion】In the oasis cotton planting area of Xinjiang, spraying biogas slurry fertilizer on the leaf surface of cotton at bud stage and flowering stage promoted the growth of cotton, and was beneficial to maintain the chlorophyll content (SPAD values) of functional cotton leaves. Suitable for spraying biogas slurry fertilizer, can improve cotton yield and quality, but excessive spraying biogas slurry fertilizer (OM3: 45 kg/hm2) will reduce cotton yield.