| For studying the feasibility of non-pruning and non-topping in cotton region in Yangtze River basin, and the combined effect on cotton with mepiquat chloride (DPC), the field experiment was conducted in2011and2012at the Lukou farmland in Ezhou, Hubei province. To study the effects of DPC and pruning with topping on cotton agronomic characters, boll setting of fruit branches, dry matter accumulation, cotton seed index, seed cotton yield and lint yield, yield components and fiber quality. The experimental material was hybrid cotton H318variety; The experiment was double-facter split-block experimental design, and the two facters were DPC and plant pruning with topping. The DPC used was commercially available, plant pruning with topping included removing leafy branch and tipping the growing point from the top of the cotton plant. The field experiment results showed that:1. Spraying DPC could restrain the vegetative growth of cotton, while different patterns of pruning had not a big effect on agronomic characters. The plant height and internode-length of fruit branch reduced after spraying DPC, it didn’t have a big effect on stem diameter, the height of the first fruit branch and the first node of fruit branch. Pruning with topping could affect palnt height and the first node of fruit branch, but there was no effect on the other agronomic characters. The dynamic change figure of SPAD value showed that its value raised markedly after spraying DPC, the leaf was greener, but DPC didn’t affect the number of green leaves on cotton stem while topping did, there was more green leaves which the plant was not topped.2. Spraying DPC and non-pruning with non-topping inhibited the reproductive growth of cotton, they were bad for bolls setting of fruit branches. There were different numbers of bolls of fruit branches by spraying DPC in different growing stages, while the bolls of temporal distribution didn’t have a big change; Retaining nutrition branches with non-topping could have an effect on the growth and development of fruit branches and the treatment had fewer bolls. the treatment of pruning with topping had fewer bolls from July16to Auguest15, and had more bolls from Auguest16to Auguest31, it showed that pruning and topping could improve the formation of the bolls between Auguest15to September15, and so that the ratio of the bolls of temporal distribution changed.3. The dry matter accumulation and the percentage of the stem, leaf with petiole and reproductive organs didn’t had a big change by spraying DPC and pruning with topping in this field experiment. 4. Spraying DPC or not didn’t have a significant effect on cotton yield, and non-pruning with non-topping could sometimes increase yield. The result showed that spraying DPC didn’t have a significant effect on seed cotton yield and lint yield in the two years, but it improved the boll weight, and sometimes it could reduce the lint percentage. The vegetative branches could produce some economic yield and retaining nutrition branches with non-topping had a trend of improving the cotton yield, so that non-pruning and non-topping didn’t have a bad effect on cotton yield. The seed cotton yield and lint yield of the treatment of retaining nutrition branches with non-topping had a significant difference with the treatment of pruning and topping in2012year, its seed cotton yield and lint yield increased14.2%and15.2%, respectively. Retaining nutrition branches had more bolls per plant while it didn’t have a significant effect on boll weight and lint percentage.5. Spraying DPC and pruning with topping both could improve the seed index of the lower-level, middle-level, upper-level and the whole cotton plant. In2011the seed index of the upper-level, lower-level, and the average of three levels all had a significant difference compares with the control, it increased1.41g,0.44g,0.67g, respectively. In2012the seed index of the treatment of non-pruning and non-topping was lighter than the treatment of pruning and topping. Compared to the former, The latter’s seed index of the upper-level, middle-level, lower-level, and the whole cotton plant increased0.27g,0.32g,0.12g,0.23g, respectively.6. The two facters didn’t affect fiber length, specific breaking strength and elongation rate. Pruning with topping could improve uniformity index, Micronaire changed after spraying DPC. Spraying DPC didn’t have a significant effect on fiber length, specific breaking strength and elongation rate, but it could affect micronaire which the rank hadn’t changed; Pruning with topping didn’t have a significant effect on fiber length, micronaire and elongation rate, but it had a significant effect on uniformity index, retaining nutrition branch with non-topping reduced the uniformity index.7. The interaction effect of the two facters of pruning with topping and DPC was small. The two facters of pruning with topping and DPC had a significant interaction on boll numbers of fruit branches, the rate of boll shedding, the number of bolls per plant, boll weight, specific breaking strength and uniformity index, but they all appeared just once, the two facters didn’t have a significant interaction on the other measurement indexes in the field experiment in the two years, it showed that the interaction of the two facters had a small effect on cotton. So, we can draw a conclusion that in my field trial the non-pruning and non-topping is good for cotton yield and sometimes it can improve the yield significantly, and so that it could be viable in the cotton practical production; we should spraying DPC according to the cotton growth, weather, soil fertile and moisture and so on, and we can get a better chemical control of cotton. |
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