Early generation selection for drought stress tolerance during vegetative stage in tomato

Abstract

Drought stress consists of a major productivity constraint in tomato. Two contrastant crosses were performed to estimate physiological and morphological traits involved in the response to drought stress during vegetative stage, aiming to identify superior genotypes for drought tolerance. Two varieties (GBT_2037 – drought sensitive and GBT_2016 – intermediate drought tolerant) were used as female parentals and a commercial hybrid (drought tolerant) was used as a pollen source in both crosses: C1 (GBT_2037 × Commercial hybrid) and C2 (GBT_2016 × Commercial hybrid). The populations of parentals (P), first generation of descendants (F₁) and second generation of self-polination (F₂) were exposed to drought stress during 20 days, when they were analysed: physiological traits (relative water content of leaves, proline and relative chlorophyll content) and morphological (plant height, stem diameter, number of leaves, fresh and dry matter of roots and shoot and a classification by wilt scale). The means of chlorophyll, root/shoot ratio and water content in leaves for the F₂ generation of C2 were higher than C1, indicating that C2 resulted in plants with greater capacity to maintain turgor under conditions of water stress and presented less damage on the photosynthetic structures, consequently showing greater tolerance to drought stress.