Improvement And Application Of SPAD Nondestructive Rapid Diagnostic Fertilization Technique In Cotton Growth Period

This experiment was conducted from April to October 2021 at the Xinjiang Cotton Field Non-point Source Pollution Prevention and Control Technology Demonstration Base of Baotou Hu Farm,Korla City,Xinjiang Academy of Agricultural Sciences,taking cotton as the research object,through the community experiment,the effect of different sample sizes measured at each growth period on the accuracy of SPAD values was studied,and the effects of different SPAD value determination sites on the recommended nitrogen application rates in cotton at each growth period were affected by different nitrogen fertilizer application rates,resulting in the effects of different nitrogen fertilizer application rates on cotton agronomic traits,dry matter,cotton buds and yields.There were four treatments in this test: no nitrogen treatment,two diagnostic nitrogen treatments(determination of 2 sites to diagnose nitrogen treatment;determination of 15 sites to diagnose nitrogen treatment),and local customary nitrogen treatment.The main findings are as follows:(1)When performing diagnostic fertilization during cotton growth,the number of samples with different SPAD values needs to be determined at different growth periods.The number of samples measured by THE SPAD value of cotton at different growth periods is the same as the standard deviation change trend,and the standard deviation shows a gradual decreasing trend with the increase of sample size in each period.Among them,the number of samples measured at the bud stage was the smallest,and the number of samples measured at the bell stage was the largest.(2)The agronomic traits such as plant height,stem thickness,and number of true leaves of the main stem showed significant differences in different treatments.During the same period,the plant height,stem thickness and number of leaves of the main stem were significantly lower than those of each nitrogen application treatment,and the overall performance of the two diagnostic nitrogen application treatments and the local customary nitrogen application treatment were not obvious,and the stem thickness and the number of leaves of the main stem were slightly higher than those of the local customary nitrogen application treatment.(3)The amount of dry matter accumulated in the upper part of the ground of different treatments of cotton showed significant differences.The differences were mainly manifested as: the accumulation of aboveground dry matter in the non-nitrogen treatment was significantly lower than that of the two diagnostic nitrogen application treatments and the local custom nitrogen application treatment at the budding stage and the flowering stage;the accumulation of aboveground dry matter in the local customary nitrogen application treatment was significantly higher than that in the no nitrogen application treatment,and significantly lower than that of the two diagnostic nitrogen application treatments,and the difference between the two diagnostic nitrogen application treatments was manifested in the accumulation of reproductive organs.(4)The budbell shedding in each period without nitrogen application was higher than that of the two diagnostic nitrogen application treatments and the local customary nitrogen application treatment,and the budbell shedding of the local custom nitrogen application treatment at the blooming stage and the flowering boll stage was higher than that of the two diagnostic nitrogen application treatments,and the lassel shedding rate of the two diagnostic nitrogen application treatments was higher than that of the local customary nitrogen application treatment.The number of three peaches without nitrogen application was significantly lower than that of the two diagnostic nitrogen treatments and the local customary nitrogen treatment,and the number of three peaches treated with two diagnostic nitrogen application treatments increased by 7.76% and 7.45% respectively compared with the local customary nitrogen treatment.(5)The two diagnostic nitrogen treatments and local customary nitrogen treatments increased the yield significantly compared with cotton without nitrogen application.The total nitrogen application rate of the two diagnostic nitrogen treatments decreased by 6.52% and 1.12% compared with the local customary nitrogen application treatment,respectively,while the yield increased by 6.15% and 7.06%,respectively,and the yield difference between the two diagnostic nitrogen application treatments was not significant.The two diagnostic nitrogen application treatments were more productive and more efficient in agronomic use than the local customary nitrogen application treatment.