Components of genetic variance for plant survival and vigor of apple trees

Abstract

The additive and non-additive variance components were estimated from progenies derived from two samples of parents (representing a northern continental type climate) for five factors relating to plant survival and two composites of the factors. It was found that additive variance made up 90 and 100%, 91 and 100%, 91 and 100%, 100 and 100%, 82 and 59%, 91 and 100%, and 90 and 100% of the total genetic variance for leafing-out date, leafingout percent, tip injury, stem damage, root damage, a shoot composite, and a shoot-root composite for the two samples respectively. A third sample had 100% additive variance for plant height while, in contrast, a sample of rootstocks, differing from each other in their ability to dwarf grafted scions, had approximately 50-70% additive variance for plant height. It was shown that breeding progress for both winter survival and plant height could be achieved by exploiting the additive variance, the total genetic variance, or (where progenies were the selection unit rather than individuals) by progeny selection. By exploiting the additive variance, it should be possible to improve plant survival and change plant height in each of several successive generations. It is predicted that (with the exception of selection for vigor in a population having a range of dwarfing abilities) potential parents could be efficiently screened phenotypically and so obviate the need for genotypic evaluation. A total of 9180 progeny trees were involved in the analyses considered in this paper.

Combining Ability and Correlations of Winter Survival, Electrical Impedance and Morphology in Juvenile Apple Trees

“…Combining ability and correlations of winter survival, electrical impedance and morphology in juvenile apple trees. In apple rootstocks and scion diallel crosses, general combining ability (GCA) was high for winter survival, juvenile tree morphology and electrical impedance (except in late spring, due to desiccation) and specific effects (SCA) were higher than reported by Watkins and Spangelo (1970 For personal use only. …”

“…In apple rootstocks and scion diallel crosses, general combining ability (GCA) was high for winter survival, juvenile tree morphology and electrical impedance (except in late spring, due to desiccation) and specific effects (SCA) were higher than reported by Watkins and Spangelo (1970). Correlations showed that electrical impedance is reliable for indicating presence of winter damage but not for predicting it.…”

“…Leur aptitude sp6cifique )r la combinaison (SCA) a 6galement 6t6 plus 6lev6e que celle signal6e par Watkins et Spangelo (1970). Par corr6lation, on a constat6 que I'imp6dance est un moyen str de d6celer les d6gits commis par l'hiver, mais qu'elle ne permet pas de les pr6voir.…”

“…Watkins and Spangelo (1970) Griffing (1956) to give 15 progenies. Seed was reported on components foi plint survivai sown in January 1966, stratified For personal use only.…”

The Models for Estimation of a Combining Ability of Varieties and Rootstocks to Forecast Yielding in Apple Trees

“…Despite that, these experiments are conducted to study the structure of genotypic dispersions (18)(19)(20) and to estimate general and specific combining ability of crossed components (21)(22)(23). But the scientists who studied the inheritance of variability of polygenic traits in fruit crops did not try to use the principle and models of biometrical genetics when examined the effect of varieties and rootstocks on yields and other properties of grafted plants.…”