Produção de mudas de cultivares de melancia sob estresse salino e espécies de Trichoderma spp.

Abstract

Abiotic stress factors are responsible for the loss of agricultural production worldwide, especially in semi-arid regions, where salinity of water and soil negatively affect growth, development and production of olive groves. The use of salinity-tolerant watermelon cultivars is relevant for agriculture. This is due to the use of antagonistic fungi of the genus Trichoderma spp, which has been shown to act as growth promoters and contribute to a better development of the plant root system. The objective was to evaluate cultivars, soil inoculation with Trichoderma spp and saline levels during the production of watermelon seedlings. The experiment was conducted in a greenhouse at the Federal University of Campina Grande at the Agro-Food Science and Technology Center, Pombal-PB municipality. Selection of four cultivars of saline was tested, with four watermelon cultivars (Fair Fax, Crimson Sweet, Crimson Select Plus and Charleston Gray) being tested during seedling production, five saline concentrations (0.3, 1.3, 2 , 3; 3.3 and 4.3 dS m-1) and two types of Trichoderma (harzianum, longibrachiatum) with 4 replicates. The sowing was carried out in 350 mL polypropylene containers with substrate composed of soil and commercial substrate mixture in a 2: 1 ratio, with a 30-day period after sowing. The variables were: seedling height, leaf diameter, number of leaves, leaf area, chlorophyll a and b, caratenoids, fresh and dry shoot mass, fresh and dry root mass, total fresh and dry mass and salinity tolerance index. The experimental design was a randomized block and the treatments were distributed in a factorial scheme 4x5x2, whose factors correspond to cultivars, salt concentrations and Trichoderma spp, respectively. The data referring to the variables measured were submitted to the F test at 0.05% significance by means of analysis of variance and the mean values of the significant variables were submitted to the mean comparison tests for the cultivars and species of Trichoderma spp and Polynomial Regression for saline levels. The saline stress provided a reduction in the phenological development of the watermelon seedlings despite the inoculation with Trichoderma spp. However, Trichoderma longibrachiatum provided an attenuating effect to salt stress when compared to T. harzianum, the watermelon cultivar most adapted to the conditions imposed was the Fair Fax and the most sensitive was Crimson Select Plus.