Capsicum Genetic Preliminary Study On Heat-tolerance

Pepper （Capsicum annuum L.） originated in the Western Hemisphere’s tropical and subtropical regions, has become one of the important vegetable crops, cultivated all over the country. Most cultivars formed a thermophilic but not heat-resistant properties, high temperature often occur decreased fruit set rate and quality, output plummeted and so on. At present, the heat tolerance of pepper is increasing, and has bred a number of excellent comprehensive properties of heat-type pepper. But on the whole mechanism of chili heat still in the initial stage, the genetic mechanism is not entirely clear, heat-resistant material on the pro-choice and matching aspects of this study less. So to some extent limited the breeding of fine varieties of chili heat process. This study selected6different pepper heat tolerance were the parents, using Griffing’s diallel methods Ⅳ hybrid combinations, together with the parents, F1generation of selfing and backcross generations （P₁, P₂, F₁, F₂, B₁, B₂） as test materials, testing and identification of heat tolerance screening the best indicators of pepper, chilli heat of segregation in the F₂generation of the normal test, test the genetic model of chili heat to estimate heritability, of the selected parents and their combined with the ability for future pepper theoretical basis for heat tolerance.Key findings include:（1） to heat stress on seed germination of seed vigor, seedling leaf MDA content, proline accumulation, leaf cell plasma membrane injury index, thermal stability and heat to make the identification and analysis, the identification of indicators and heat correlational good heat tolerance can be identified as pepper reference. Thermal stability of plasma membrane was selected for the genetic analysis of pepper heat tolerance identification indicators.（2） separation of pepper heat tolerance groups F₂generation of normal test results show that the F₂generation of segregating populations pepper heat is to present a continuous change and meet the normal distribution. Pepper heat is the number of genetic control of multiple genes.（3） heat tolerance of pepper to analyze the genetic model, results showed that heat pepper found additive-dominance model of inheritance, and the additive effects, dominance effects small. Therefore, increased heat tolerance when pepper should pay more attention to the additive effects. Therefore, using conventional breeding methods, in the early generations of plant phenotype under selection, breeding is expected in the heat made good results.（4） Pepper narrow heritability of heat tolerance and broad heritability were higher, respectively,47.72%,48.1%and60.15%,59.04%. However, non-additive genetic effects also account for a certain weight, that are subject to certain heat-resistant pepper environmental impact, heat tolerance may be more susceptible to a variety of other environmental factors, so in the breeding process, should be in the same environmental conditions choice would be better.（5） combining ability of chili heat, all the parents of the combination of heat between the general combining ability and specific combining ability were highly significant level, but the variance of specific combining ability than the general combining ability, indicating The additive effect of heat tolerance dominant. Pepper heat tolerance to further estimate the general combining ability values, analysis of the genetic parents with the ability. The results show that co-JAC II the highest, followed by the green crown, is a very good heat tolerance parent. Suggested the use of distantly related group of parents with, the use of the additive effect of genes gradually accumulate heat at the same time maximize the use of genetic dominance effects. Conventional breeding methods will be used in pepper breeding and cultivation of resistant varieties, breeding is expected to heat a comprehensive new line of good character.