Middle-Season Drought Tolerance in a RIL Population of Cultivated Peanut
Type of DegreeMaster's Thesis
Agronomy and Soils
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Grown extensively in Asia, Africa, and the Americas, cultivated groundnut or peanut (Arachis hypogaea L.) is one of the world’s most important food and oilseed crops. However, a vast majority of peanut crops are grown in nonirrigated conditions and are vulnerable to the effects of seasonal droughts. Methods of efficiently evaluating drought tolerance and understanding the inherent principles of traits related to drought tolerance are critical for the success of peanut breeding programs that aim to improve it. Therefore, the objectives of this research were to examine the consistency of traits related to drought tolerance, to examine their relationships with yield after drought stress, and to estimate their heritabilites. A RIL population of 149 runner peanut genotypes, resulting from the cross of ‘Tifrunner’ × ‘C76-16’ was examined for middle-season drought tolerance over two different growing seasons, using an augmented experimental design. Plants were grown in environmentally-controlled rainout shelters and phenotyped using specific leaf area (SLA), visual ratings, and infrared photography. SLA measurements were taken before drought, after drought, and after recovery. Results indicate that SLA measurements taken after recovery demonstrate the strongest correlation with yield for this population (r = -0.23, p = 0.0027) and that neither visual ratings nor infrared photography were statistically correlated with yield. Broad-sense heritability estimations were calculated for all traits studied and yield per se was calculated to be the most heritable. Top and bottom bulks from the population were identified for the highest and lowest yielding genotypes across both years and treatments. These lines are also valuable materials for identifying the genes responsible for drought tolerance in peanut through the candidate gene expression approach.