Desempenho agronômico e reação de genótipos quanto a viroses do meloeiro

Abstract

In Brazil, the viruses are among the main phytosanitary problems affecting species of this family, causing reduction in fruit quality and significant loss in production. The aim of this study was to obtain and evaluate melon genotypes regarding their resistance to virus, but with emphasis on the Melon Yellowing (MYaV), their production capacity and their fruit quality. In the second half of 2014, two experiments were conducted in Bebedouro (Embrapa Semiárido’s experimental field located in the city of Petrolina – PE, Brazil), in the design of randomized blocks, constituted as follows: Experiment I, three replications and 24 treatments; Experiment II, six replications and seven treatments. In 2015, the Experiment III was conducted with three replications and 21 treatments. It was adopted the spacing 2.0 m x 0.5 m (Experiment I and II) and 2.0 m x 0.3 m (Experiment III). The sow was in polystyrene trays containing commercial substrate, which was kept in a greenhouse until the appearance of the first leaf stage, following what the transplanting was conducted. The incidence and severity of Melon Yellowing (MYaV) was evaluated with a rating scale of 0 to 4 (where 0 = no visual symptoms; 4 = severe yellowing in 75 up to 100% of the leaf area. In Experiment III (2015), was also made the estimation of total chlorophyll on the leaves and serological identification of the virus: Melon yellowing associated virus (MYaV) was by DAS-Elisa, Papaya ringspot virus - type watermelon (PRSV-W), Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV) and Cucumber mosaic virus (CMV ) by dot – Elisa. After harvest, the fruits were evaluated regarding fruit mass (FM); fruit length (FL); fruit diameter (FD); aspect ratio (AR); pulp thickness (PT) and soluble solids. The lowest average for melon yellowing severity was shown by the Line 5 genotype (T4), the derivatives of Lineage 1 (Experiment I), BGMEL 160 (Experiment II) and BGMEL 109 (Experiment II and III). Among the genotypes, there are differences in the reaction to MYaV, ranging from highly resistant to highly susceptible. It's possible to select resistant genotypes to MYaV in BGMEL 109, GoldF2 Lineage, BGMEL 001, Lineage 8 and Lineage 1. Most of the genotypes analyzed came from the inodorus group, the yellow type, with yellow skin, but the skin color intensity ranged from medium to dark.The virus more often found was the MYaV, which justifies the concern of the productive sector with this virus. The severity of the Melon Yellowing is negatively correlated with the total chlorophyll on the leaves. For the breeding program, the note scale used in this study based on symptoms, associated with total chlorophyll measurements and serologic evaluation, are efficient tools for discriminating resistant and susceptible genotypes, making it possible to advance the breeding program for resistance to MYaV.