Ecofisiologia e produção de fitomassa do mamoeiro cultivado sob irrigação com águas salinizadas e adubação orgânica.

Abstract

Papaya (Carica papaya L.) has great socioeconomic importance due to its potential use in the textile, pharmaceutical, food, cosmetics and medicine, being cultivated in almost every country in the world. It is a culture considered sensitive to salinity, and in view of the existence of problems related to the presence of salts in the soil, and saline waters in the areas of production, it is important to the adoption of technologies that enable its cultivation. An alternative to mitigate the negative impacts of salinity may be the addition of organic matter in the soil, aiming to improve the physical, chemical and biological, creating a favorable environment for the development of plants. Thus, the aim of this research was to evaluate the papaya tolerance to irrigation with salted water and the effect of organic fertilization, as reliever of the salts effect. The research was conducted on the premises of the Science and Technology Centre Agrifood - CCTA Federal University of Campina Grande - UFCG, Campus Pombal, Paraíba, which were studied two factors: 'Salinity' (0.6, 1.2, 1.8 , 2.4 and 3.0 dS m-1); and 'Organic Fertilization' (two levels - 10:20 liters of manure per plant). Combined factorial result in ten treatments, organized in a randomized block design with three replications, constituting 30 plots, each plot was composed of two papaya plants of Formosa group, grown in pots with a capacity of 150 liters. Growth variables were evaluated, physiology and soil characteristics. Data were evaluated by analysis of variance (F test up to 5% significance) and polynomial regression (linear and quadratic). For the qualitative factor, organic fertilizer, we used the mean comparison test (Tukey, p <0.05) in cases of significance for the 'F' test, using the SISVAR software 4.0. It was found that the increase in water salinity impaired growth papaya, especially in the number of leaves falling from 9 to 14, when the EC has increased from 0.6 to 3.0 dS m-1. As for biomass production, it was found that the increase of manure attenuates the degenerative effects of salinity, with the exception of biomass and leaf petiole, reducing 58 to 49%, indicating the sensitivity of these variables excess salts. Regarding the physiology, it could be concluded that the gas exchange of papaya are extremely altered by salinity, the most obvious negative effects with the increase in the stress period. On the other hand, the fluorescence parameters Chlorophyll a, Chlorophyll and carotenoid content, cell damage and relative water content were not influenced by the factors evaluated. It also concludes that the CE saturation extract of the soil increases linearly with increasing EC of irrigation water, increasing the PDT as to make the saline-sodic soil being necessary to adopt measures management and control, even in lower salinity (0.6 dS m-1).