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Accueil du site → Doctorat → États-Unis → 1981 → METHODS OF MEASUREMENT AND GENETICS OF HEAT AND DROUGHT RESPONSES IN SOLANUM SPECIES AND HYBRIDS

University of Nebraska – Lincoln (1981)

METHODS OF MEASUREMENT AND GENETICS OF HEAT AND DROUGHT RESPONSES IN SOLANUM SPECIES AND HYBRIDS

Elfigih, Ahmed

Titre : METHODS OF MEASUREMENT AND GENETICS OF HEAT AND DROUGHT RESPONSES IN SOLANUM SPECIES AND HYBRIDS

Auteur : Elfigih, Ahmed

Université de soutenance : University of Nebraska – Lincoln

Grade : Doctor of Philosophy (PhD) 1981

Résumé
The objectives of these studies were as follows : (1) Comparison of three methods for measuring heat and drought resistance in Solanum species and families. (2) Evaluation of these species and families for heat and drought resistance. (3) Evaluation of hybrids resulting from interspecific and intraspecific crosses of Solanum species for heat and drought resistance. The electrical conductivity method with leaf discs was correlated with whole plant resistance to heat using the heat machine method. The electrical conductivity method offers a rapid and simple technique to possibly screen large numbers of potato genotypes for heat tolerance. The chlorophyll stability index method does not seem to be useful as a screening tool for drought in potatoes. Significant differences between potato species and genotypes within the species were obtained for heat resistance and other plant characters related to heat resistance such as plant height, leaf area (index), wilting degree, regrowth index and weight of tubers per plant. Consequently selection for heat resistant genotypes in potatoes is feasible. The relationship between the degree of injury and the temperature at which that injury was induced was observed to be a sigmoidal response curve with respect to the treatment temperature. Fifty degree celsius was used as the standard heat treatment (critical temperature) for testing all the genotypes using the electrical conductivity method and the heat machine method. However physiological age and environmental conditions may influence the critical temperature. Heat resistance of potato leaves increased as the physiological age increased. Heat resistance of potato plants (using Heat machine method) was increased with decrease in plant height, wilting degree and % heat injury (electrical conductivity method). Large leaf area (index) and high yield (tuber weight) were associated with increases in resistance. The continuous distributions for resistance classes and % heat injury in potatoes suggest quantitative inheritance. Estimates of broad sense heritability indicated that resistance to heat injury, plant height, leaf index, wilting degree and tuber weight were highly heritable characters. Consequently selection for heat resistance should be effective. Expected gains from selection indicated that selection on family mean basis (most resistant families) is effective for predicting the improvement from selection in potatoes.

Présentation

Page publiée le 14 décembre 2018, mise à jour le 28 décembre 2018