Growth and gas changes of melon seedlings submitted to water salinity

ABSTRACT The melon is an outstanding fruit crop in Brazil, mainly in the Northeast region due to favorable conditions for cultivation. Water salinity affects the growth and production of several species, but there is tolerance among cultivars of the same species. The objective of this study was to evaluate the growth and gas exchange in melon seedlings subjected to water salinity. Experiment was carried out in a greenhouse belonging to the Center of Sciences and Agri-Food Technology, Federal University of Campina Grande, Pombal, PB, Brazil, from September to October 2016. The experimental design was a randomized complete block design in a 6 x 5 factorial scheme, with four replicates, for six cultivars of melon (Natal, Solares, Goldex, Iracema, Mandacaru and Amarelo Ouro) and five irrigation water salinity levels with the following electrical conductivities: 0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1. Each experimental unit consisted of a polypropylene container with a volume capacity of 0.350 dm3, which contained soil + Basaplant® commercial substrate at a ratio of 2:1. At 25 days after sowing, the plants were evaluated for growth, gas exchange and dry mass accumulation. Increased salinity of irrigation water inhibits the growth, dry mass accumulation and physiological processes of melon cultivars. The cultivar Natal showed to be more tolerant, while the cultivars Solares, Goldex, Iracema and Mandacaru were moderately sensitive and the cultivar Amarelo Ouro was more sensitive to the salinity of irrigation water.