Selection of tomato plant families using characters related to water deficit resistance

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. The present work aimed at to evaluate parameters related to water deficit in 20 F 3 RC 1 families of tomato plants derived from the crossing with a (WELL) genotype, originated from a drought resistant species, as well as select plants using characters related to water deficit resistance. The delineation was in randomized blocks design with three replications. Two experiments were carried out, the first in Lavras, Minas Gerais state, Brazil, that consisted in evaluating nine F 3 RC 1 families derived from two self-fertilizations of the following crosses: {TOM-684 x (WELL x M-82)}. The second experiment was carried out in Ijaci, in the same state, and evaluated the same nine families from the previous experiment and another eleven families obtained from the same crossing. The plants were submitted to water deficit by means of the suspension of irrigation at 35 days after transplanting the seedlings to the field. The families T4, T5, T6, T15, T17 were highlighted regarding fruit production and, among the nine families evaluated in both cultivation environments, the T6 was the most productive, indicating good productive stability. Families T5 and T9 were highlighted for presenting low incidence of blossom-end rot and higher relative water content in leaves. The blossom-end rot incidence and relative water content are good parameter to be indirect selection of plants more resistant to drought.

Seleção de genótipos de tomateiro submetidos ao estresse hídrico em função da expressão de características fisiológicas

“…De forma que, é pelos estômatos que ocorre a perda de água, juntamente com absorção de CO 2 , resultando na redução da fotossíntese. O fechamento dos estômatos priva as folhas de assimilação de CO 2 e de realizar fotossíntese, em favor da fotorrespiração (Morales et al, 2015). A planta tende a fechar os estômatos quando os níveis de luz estão abaixo da radiação fotossinteticamente ativa, ou para evitar o estresse hídrico (Cochard et al, 2002).…”

Gas exchanges and water use efficiency in the selection of tomato genotypes tolerant to water stress

“…UFU-222 is a pre-commercial line that has small fruits (>18 g), 9° Brix and is susceptible to water stress. The wild genotype also presents small fruits (15 g) but is tolerant to water deficit (Morales et al, 2015b;Rocha et al, 2016).…”

“…The South American country is among the top 10 tomato producers (AGRIANUAL, 2016), evidencing the relevance of the crop. The tomato [Solanum lycopersicum (L.)] adapts to different climatic conditions (Neves et al, 2013), and despite this, the abiotic stress occurrence, like water stress, is one of the biggest problems that the crop presents (Morales et al, 2015b).…”

Déficit hídrico induzido por manitol para seleção de genótipos de tomateiro

“…Diante disso, aprimorar novas metodologias de seleção no melhoramento genético do tomateiro para tolerância à seca é de fundamental importância. Há relatos de métodos eficientes de seleção direta (Nahar & Ullah, 2006;Shamim et al, 2014;Rocha et al, 2016;Borba et al, 2017) e indireta em tomateiro (Aazami et al, 2010;Morales et al, 2015) visando avaliar a tolerância ao déficit hídrico, no entanto, tais procedimentos demandam maior período de tempo, custos elevados e exigem mais mão de obra para execução.…”

“…O substrato (Germitest) foi previamente umedecido na proporção equivalente a 2,5 vezes o peso do substrato seco, com água destilada (controle) e 11 soluções de manitol (Tabela 1). As diferentes condições de déficit hídrico foram calculadas pela fórmula de Van't Hoff (Morales et al, 2015), ou seja (Equação 1):…”