Estratégias de manejo de irrigação com águas salinizadas para produção da limeira-ácida 8tahiti9 em diferentes porta-enxertos

Abstract

Brazilian citrus farming holds a significant position in global agribusiness, particularly for its production and export of juices. However, irregular rainfall limits production, especially in the Northeast region, where productivity is the lowest, thus necessitating irrigation. In this region, however, water availability is limited in both quantity and quality, prompting the need to adopt water management practices to address the high salt concentration problem. This study aimed to evaluate the use of different saline water irrigation strategies on the growth, physiological aspects, and production of combinations of the 'Tahiti' acid lime tree grafted onto different citrus rootstocks during the first year of production. The experiment was conducted in an open-air area at the Center for Agro-food Sciences and Technology (CCTA/UFCG), Pombal Campus, using 150 L drainage lysimeters. The experimental design was in randomized blocks with four replications in a 5 x 4 factorial scheme, for 'Tahiti' acid lime plants grafted onto five citrus genotypes. The grafted plants were subjected to four irrigation strategies (E) with water of electrical conductivity (ECa) levels of 0.3 dS m-1 and 3.0 dS m-1, as follows: E1 = irrigation with water of 0.3 dS m-1, from sowing until the end of the first year of plant production; E2 = irrigation with water of 3.0 dS m-1, starting 120 days after grafting and continuing until the end of the first year of production; E3 = alternating irrigation with water of 0.3 dS m-1 for two months and 3.0 dS m-1 for another two months, beginning 120 days after grafting until the end of the first production year; E4 = alternating irrigation with water of 0.3 dS m-1 for four months, followed by 3.0 dS m-1 for another four months, starting 120 days after grafting until the end of the first production year. The 8Tahiti9/citrus rootstock combinations were evaluated for growth, physiology, production, and water productivity. The 8Tahiti9/TSKC x CTARG-019 combination, despite showing the highest photosynthesis rate, exhibited the poorest growth and production, regardless of the irrigation strategy used. Salinity in irrigation water reduced growth in 'Tahiti'/citrus genotype combinations, especially under the electrical conductivity of 3.0 dS m-1, from grafting until the end of the first production year (E2). The 'Tahiti' citrus genotype combinations under irrigation strategies with alternating saline water (E3 and E4) showed superior growth compared to those under E2 irrigation management. The increase in photosynthesis did not translate into production gains for citrus genotypes. Photochemical efficiency, photosynthetic pigment content, and electrolyte leakage were not affected by saline water irrigation strategies. The 8Tahiti9/8Cravo Santa Cruz9 lemon tree combination was the most productive in terms of fruit count per plant across all irrigation management strategies and in total fruit production per plant in the E1 and E3 irrigation strategies. The 8Tahiti9/8Cravo Santa Cruz9 lemon tree combination, under the E2 irrigation management strategy, produced fruits with higher soluble solids content. The 8Tahiti9/8Cravo Santa Cruz9 lemon tree combination and the TSKC x (LCR x TR) – 059 (BRS 'Bravo') were efficient in water productivity under E3 and E4 irrigation strategies, respectively.