Variation in root characteristics relative leaf water content and dry matter yield of eggplant accessions grown under drought and well-watered conditions

Longer drought periods due to climate change are projected to have a severe impact on agricultural productivity. Although drought tolerant varieties are being developed, this is not the case for eggplant which is perceived to be a hardy crop. However, published reports show that eggplant yields decrease significantly under drought. This study was conducted to characterize the drought response of twenty eggplant genotypes in order to provide baseline data for identifying genotypes that can be used in a drought breeding program. The experiment was conducted under greenhouse conditions with drought and well-watered control, and eggplant accessions as treatments. Seedlings were transplanted and established in 16 liter-plastic pails. Six weeks after transplanting, drought was imposed by stopping irrigation of the drought treatment. After 14 days, the experiment was terminated when the plants were wilted and the soil moisture content has dropped from 53% to 10%. The genotypes differed in plant height, root volume, dry matter yield, root-shoot ratio and relative leaf water content. Adverse effects due to drought were observed in overall growth. Plant height differences between well-watered and drought-stressed plants were obvious at 7 days after stopping irrigation. Significant genotype-water regime interaction was observed in root volume wherein narrower variation among entries was observed under drought compared to wider varietal differences in the control. Root volume positively correlated with plant height and dry matter yield. The root-shoot ratio of six entries increased by 4%-36% under drought conditions, implicating that increased biomass allocation to the roots under drought. Although most entries were already wilted at 13 days after drought imposition, the leaf relative water content was still more than 50% for majority of the entries. This observed variability in the genotypes response could lead to the identification of traits that are important in selection and breeding for drought tolerance.