Resistência ao deficit hídrico em famílias de tomateiro derivados de Solanum pennellii

Abstract

Environmental stress, such as drought stress, constantly cause production loss. Breeding programs search for genotypes which may overcome climate adversities, producing in ideal as well as in stressful environments. For tomato plant, some advances were obtained through crossing the wild species Solanum pennellii with micro-tomatoes, obtaining the genotype WELL (Water Economy Lycopersicum Locus). In this case, an introgression of a wild species locus in the micro-tomato was done, this locus being responsible for increasing water use efficiency. However, the WELL is not yet at commercial level, being necessary further studies for verifying its utility in breeding programs. Based on this, the first experiment aimed to study the morphological characteristics of tomato lines TOM-684 and M-82 when submitted to different levels of water deficit. With the increase of water deficit occurred reduction in the number of leaves, plant height, leaf, stem and root system fresh mass, transpiration, stomatal conductance and increase in leaf temperature. All these factors may have influenced, directly or indirectly, the reduction of photosynthetic rate and, consequently, the reduction of fruit production. In the second experiment, morphological parameters related to tolerance to drought stress were used for selecting plants in 20 families F3RC1, originated from the crossing with the WELL genotype. Five families were highlighted according to fruit production (T4, T5, T6, T15, T17) and, among the nine families evaluated in both cultivation environments, the T6 was the most productive, indicating good production stability. T5 and T9 families were highlighted for the low incidence of blossom-end rot and higher relative water content in the leaf, these parameters were directly related to water deficit plant tolerance . For selecting plants tolerant to water deficit, the following parameters should be taken into consideration: fruit production, plant height, number of leaves, relative water content in the leaves and the incidence of blossom-end rot. Among the 20 evaluated families, T5 and T6 presented the best results when submitted to water deficit and should be used in breeding programs