Study On Inheritance Of Earliness And It's Relative Traits Of Short-season Cotton And QTLs Mapping

Genetic effect and it's environment interaction were studied for short season cotton of Upland cotton (Gossypium hirsutum L.) by Mixed linear model approaches using an 9x9 incomplete dialell crosses in three ecological environments. The results reviewed that the hereditability in narrow sense(h2]sj) for earliness traits were low, only 16.1%, and it's environment interaction was significant, about 17.5%, especially first fruiting branch node and squaring with the lowest hereditability and the highest environment interaction, but growth date, plant height and flowering with higher hereditability and lower environment interaction when same experiment materials planted in different test places were affected. The h2N for yield traits were 20.1%, and it's environment interaction was low, about 7.4%, Lint percent, boll weight and seed index are three most important traits in short season cotton yield breeding because of their relative higher h2N and lower environment interaction. Interaction between genetic effect and environment for five fiber qualities were significant or mighty significant. The h2N of fiber qualities were 28.6%, and it's environment interaction was about 6.9%. The average h2n for earliness of short season cotton in Anyang, Yuncheng and Shihezi were 46.0%, 10.9%, 12.3% respectively. Average h2N of cotton plant properties including earliness, yield and fiber quality: Anyang>Yuncheng > Shihezi. The results explained and developed the different views of the former about the hereditability of the first fruiting branch node and squaring.Primary contradiction among earliness, yield and fiber quality were found by the canonical correlation analysis for three main short season cotton breeding environments, respectively. In order to solve the main problem of breeding and realize the objective to earliness, high yield and fine fiber quality, corresponding breeding strategies were brought forward. For Anyang, the key was that the period from sowing to squaring should be prolonged properly and concentrative boll opening should be selected so that pre-frost lint yield would be increased. At the same time, fiber strength and micronaire would be improved with paying attention to the selection of high lint index. For Yuncheng, the key was to make the period from sowing to flowering long properly for improving the fiber length of short season cotton. But bolls growth must be rapidly during the period of flowering to boll opening. In addition, breeding materials with high lint percent should be selected in order to keep fine fiber strength and micronaire. For Shihezi, the key was to shorten the period from sowing to flowering properly to increase fiber micronaire and maturity. At the same time, the selection of lines with short stage from flowering to boll opening should be intensified for high pre-frost lint yield. But the increase of fiber micronaire went against fiber length and strength. This problem could be solved by high seed index selection. The results mentioned above were expected to offering scientific evidence to adjust the current selection strategies of short season cotton in three main areas.The genetic analysis of short season cotton earliness and it's relative traits by mixed major gene and poly gene model showed that earliness and it's relative traits were not onlycontrolled by major gene generally, but also modified by minor effect polygene. There was one major gene at least expressing at different growth and development stages. Major genes controlling cotton plant traits were different in number, effect, direction and hereditability. Except of the days from sowing to squaring and plant height, genetic effect and hereditability of major gene, 30.23%~66.79%, was higher than that of polygene, 2.83%~35.07%. Plant traits were categorized to three classes: the first class traits were dominated by major gene with little genetic effect of polygene, including days from sowing to flowering, days from sowing to boll opening, lint percent, days from squaring to flowering, days from flowering to boll openi...