Study On Genetic And Physiological And Biochemicalcharacteristics Of The Hybrid Cotton CCRI63

In this study, 9 upland cotton cultivars(lines) were selected as parents, including CCRI63’s parents, and the 16 F1 and 16 F2 were produced according to an incomplete diallel design(NCII). All plant materials were planted in four different ecological environments, and eleven agronomic traits and five fiber traits were analyzed by the genetic model of additive-dominance-additive×additive epistasis with environment interaction(ADAA model), and SAS and EXCEL softwares. What’s more, the genetic mechanism of heterosis in hybrid CCRI63 was the key point of analysis in this study. In addition, the heterosis of CCRI63 was analysed in the physiological and biochemical aspects, based on the investigation of content of chlorophyll, MDA, CAT, SOD, PRO, soluble sugar, soluble protein, IAA, CTK, GA, ETH and ABA of CCRI63 and its parents in seedling stage, squaring stage, peak flowering stage and boll-setting stage. The main results were as follows:The important agronomic and fiber traits mainly controlled by genetic main effects and its interactions with the environment. Growth period, flower and boll stage, plant height, fruit branch number, seed index and lint index were mainly controlled by dominance andenvironment effects. Lint percent was controlled by both additive and dominance effects, which can be genetically improved by conventional breeding or heterosis utilization. Boll weight and lint yield were mainly controlled by dominance effects and its interaction with the environment. Fiber upper half mean length, uniformity index, elongation and strength were mainly controlled by dominance by environment effect.Phenotypic and genetic correlation coefficients between lint yield with plant height, fruit branch number, boll number, boll weight, lint percent, lint index, seed cotton yield and micronaire were positively significant or highly significant, and addtive correlation and dominance by environment correlation were important genetic correlation components. The rD and rDE between lint yield with boll weight and lint percent were 64.52%, 34.20%, 87.00% and 61.10%, the rD and rDE between fiber upper half mean length with strength were 82.20% and 65.70%. So they were easily achieved simultaneous improvement.In the research, seed cotton yield and lint yield of F1 and F2 performed heterosis, and both of population heterosis over parent better and population heterosis over mid-parent were detected. The generation of lint yield heterosis over parent better, which was more than 5%, for P5 × P7 was 5.519, for P3 × P8 and P5 × P9 were greater than 4, and for P2 × P7 and P4 × P6 were greater than 3. The heterosis of these hybrid crosses could be utillize to F3 to F5 generation, so these hybrid crosses should be further investigated.The CCRI63’ parents were the P3(9053) and the P8(s GK9078) lines. The P3 could significantly increase the lint percent, lint index, UHML and STRG of filial generations. Also, the P3 could significantly reduce the MIC of filial generations. The P8 could significantly shorten the flower and boll stage and reduce the MIC. Also, the P8 could significant increase the seed cotton yield, UHML and STRG of filial generations. So the CCRI63 not only showed a significant advantage in lint yield, but also has significant positive in STRG by dominant effect.The chlorophyll content of CCRI63 was significantly higher than its parents in the flowering stage, which was contributed to the accumulation of photosynthate and would provide material foundation for developing more flowers. The CCRI63 had resistance and strong production capacity, low degree of lipid membrane peroxidation, high photosynthetic capacity, and efficient accumulation of photosynthetic product in the whole period, which might be the physiological and biochemical basis of the formation of the heterosis.