The Effect Of Level Of Heterozygosity On The Performance Of Hybrids Between Isogenic Lines Of Barley

Author : Garry Austin Smith
Publisher :
ISBN 13 :
Total Pages : 176 pages
Book Rating : 4.:/5 (487 download)

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Download or read book The Effect of Heterozygosity on Phenotypic Stability in Spring Barley written by Garry Austin Smith and published by . This book was released on 1968 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of heterozygosity on the phenotypic stabilities of six morphological plant characteristics was studied in hybrid crosses of two self-pollinated barley species Hordeum vulgare L., emend Lam. and Hordeum distichum L., emend Lam. Experimental material consisting of parents and their F1 diallel progeny were grown at two field locations and one greenhouse location in the spring of 1967. The phenotypic stability for plant height, kernels per spike, kernel weight, grain yield per plant and awn length was determined by the use of two statistics, the standard deviation, and the coefficient of variation. These statistics were computed on each individual plot based on measurements taken from three plants per plot. The mean coefficient of variation and standard deviation values representing the phenotypic stability of each of the entries were compared at each of three locations and across the three locations. Analyses of variance facilitated the comparison of four groups. Two of the four groups were composed of homozygous genotypes (parental groups) and two of the groups were composed of highly heterozygous genotypes (6 X 6 and 2 X 2 crosses). The associations between the phenotypic stabilities of all characteristics measured were studied by the use of linear correlations. Further, associations between the mean values of each characteristic measured and its phenotypic stability were determined. In addition, the association between the two statistics coefficient of variation and standard deviation utilized in this study as a basis of measuring phenotypic stability was determined by correlation studies. The results of this research indicated that the phenotypic stability of heterozygotes as a group was neither greater nor less than the homozygotes for any morphological characteristic when compared across the three locations. This would suggest that heterozygosity per se does not influence phenotypic stability over rather diverse environments. On the other hand heterozygosity did increase the phenotypic variation of kernel weight and plant height at the Klamath Falls field location. And, the phenotypic variation of tiller number was increased at the Corvallis field location. The phenotypic stability of heterozygotes and homozygotes was greatest for all characteristics measured under the minimal environmental stress at the greenhouse location. The phenotypic stability of kernel weight, plant height, kernels per spike and awn length were associated. Evidence also indicated associations between the phenotypic stability of plant height and the phenotypic stabilities of kernels per spike and awn length. Additional evidence indicated that the phenotypic stabilities of kernels per spike and awn length were associated. This association among the phenotypic stability of several plant characteristics may suggest a common control mechanism for phenotypic stability within the plant. If as the evidence indicated, the phenotypic stability of several plant characteristics are associated, the selection for levels of phenotypic stability of one plant characteristic could lead to increased stability for certain other plant characteristics. It was found that the parents used in a hybrid barley cross can influence the phenotypic stability of the hybrid. These results suggest the possibility of selecting parents which when crossed would result in hybrids which exhibit high phenotypic stability for particular morphological characteristics. The coefficient of variation and standard deviation were highly associated when used to measure phenotypic stability. The coefficient of variation was the most reliable of the two statistics because it was not influenced by the size of the mean as was the standard deviation.