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Genetic studies on sorghum seedling tolerance to heat and development of a rapid screening technique
Abstract
Failure of seedling establishment is a major factor limiting crop production of Sorghum (Sorghum bicolor L. Moench) in the semi and tropics where soil surface day temperatures can exceed 50°C. Improvement of seedling heat tolerant genotypes would reduce crop losses due to insufficient plant populations. The objectives of this study were to develop a simple, repeatable and effective screening procedure to consistently estimate seedling heat tolerance and to gather information on the expression of heterosis for seedling heat stress, determining the individual parental contribution and to estimate additive, dominance and epistatic effects for seedling heat tolerance by utilizing generation means analyses of populations developed from a specific set of parents. Two experiments were conducted, one to develop screening procedures to determine heat recovery indices (HRI) of seven genotypes by subjecting seedlings grown in a in dark growth chamber at 30°C to direct heat shock in a controlled temperature water bath at 50°C for 0, 10, 20 and 30 minutes returning them to them 30°C growth chamber then measuring recovery at successive intervals. The second experiment estimated genetic parameters of MU in hybrids of four lines of varying MU crossed with three tester lines, and, evaluating the derived F1, F2, F3, BC1 and BC2 families for generation means analysis. Exposure at 10 minutes and 30 minutes gave the best separation between genotypes for MU. The technique of using 10 minutes exposure at 50°C, and measuring coleoptile length after 32 hours of recovery is an effective method to determine seedling heat tolerance that can be used to screen a large number of genotypes. Generation means analyses showed additive and dominance effects contributed to coleoptile elongation under normal conditions, but only additive effects were significant in recovery growth. Epistatic effects were present in both conditions. General combining ability (GCA) effects for HRI were highly significant under all conditions but specific combining ability effects were negligible. These results offer an opportunity for improving plant population of sorghum in tropical areas with high seedling mortality.
Subject Area
Agronomy
Recommended Citation
Setimela, Peter Sekwena, "Genetic studies on sorghum seedling tolerance to heat and development of a rapid screening technique" (1999). ETD collection for University of Nebraska-Lincoln. AAI9951306.
https://digitalcommons.unl.edu/dissertations/AAI9951306