Ecofisiologia da aceroleira irrigada com água salina sob doses de nitrogênio e fósforo.

Abstract

The west indian cherry plant tree exerts socioeconomic importance in Brazil, due to the high ascorbic acid content of the fruit, which justifies being cultivated nationally, mainly in the Northeast region, where water salinity problems are frequent. Thus, the adoption of management techniques of nitrogen fertilization with nitrogen and phosphorus can mitigate the deleterious effects of saline stress on the plantation. The objective of this study was to evaluate the effects of the interaction between the salinity of irrigation water and the proportions of phosphorus and nitrogen in growth vegetative, physiological, nutritional and productive west indian cherry cv. BRS 366 Jaburu grafted in the Criola variety. The experiment was carried out in a protected environment, in lysimeters with Neosol Regolítico; the design was randomized blocks with the treatments arranged in a 5 x 4 factorial scheme, referring to the levels of electrical conductivity of the irrigation water - CEa (0.6, 1.4, 2.2, 3.0 and 3, 8 dS m-1) and four percent proportions of phosphorus and nitrogen P/N (100:100, 140:100, 100:140 and 140:140% P/N), with three replicates. The west indian cherry plants were evaluated for growth, physiology, leaf composition of macronutrients and sodium and production components. The salinity and fertilization interaction during the first 45 days after irrigation with increasing salinity waters was influenced by the salinity, growth and gas exchange conditions in west indian cherry. The proportion was 100: 140% P/N, which provided the best results. At the age of the plants, there was stabilization of the vegetative phase growth (reduction of the growth rates), physiological components and even of the production, not responding to the fertilization, and with compromise of the stomatal conductance and CO2 assimilation rate of the plants irrigated with water salinity greater than 2,2 dS m-1. The chlorophyll a decreased, chlorophyll b and carotenoids increased among the plants that received fertilization increments until the salinity of 3.0 dS m-1. However, the harmful effects of saline stress on chlorophyll a fluorescence were mitigated by a 40% increase in the recommended P and N fertilization for plants irrigated with water up to 3.0 dS m-1, mainly due to the increase. xviii With the increase of water salinity and sodium content in leaf tissues, a reduction in the phosphorus content was observed only in the plants that received 100% of the fertilization recommendation of P and N. The increase of the salinity of the water from 0.6 dS m-1 reduced the cherry production of the plants that received only the P and N fertilization recommendation. The 40% increase in phosphorus fertilization on nitrogen (140:100% P/N) stimulated the emission of fruits plants. Fertilization with the highest values of the P/N proportion promoted the highest production even by the plants irrigated with the salinity water of 3.0 dS m-1.