Studies on the dynamic model of plant adaptation of quantitive characters

Abstract

A full set of diallel cross of nine genetic lines of Arabidopsis thaliana was made and used to analyze the mechanism of inheritance of the three types of stability of fresh weight in dynamic model. A dynamic model combining features of Griffing's method with the linear regression was established to assess the combining abilities of combiners and examine the fluctuation of heterosis under different environmental conditions for different growth periods. Analysis of combining ability revealed that inheritance of the three types of stability was controlled predominantly by dominance deviations whereas both additive and dominance effects were equally important. Reciprocal crosses showed lower yield and higher stability than their single crosses. Lack of association between the general combining ability of stability and the phenotypic mean of parents suggested that a desirable parent did not necessarily transmit the high potential yield and low linear response to its progeny. It was also difficult to select a desirable hybrid having above average specific combining effect (SCA) for phenotypic mean and remarkably low SCA for stability. Heterosis with high phenotypic mean and low stability was pronounced under favourable environment at the final stages of growth. Both growth and environment stabilities were heritable and possessed the same genetic constitution by means of Jinks-Hayman's diallel analysis. They were controlled mostly by the dominance effect, but the heritabilities were very samll. Low stability was dominant over high stability and overdominance was obvious. Maternal effects in reciprocal crosses were found. The dominant and recessive alleles in the parents were nearly equal in frequency and number. There seemed to be at least four gene groups affecting stability.