Indicadores de tolerância à salinidade da água em limeira ácida 'Tahiti' sob 13 porta-enxertos

Abstract

The citrus yield is limited by biotic and abiotic stresses, however, the response it be variable between rootstocks, being it possible by identifying tolerant materials, in order to guarantee sustainability in the production system. Thus, the aimed it was to study the salt content in the soil and the productive and physiological aspects of 13 citrus rootstocks combinations with ‘Tahiti’ acid lime under saline water during the first two years of cultivation, in order to identify salinity tolerance indicators. The rootstocks were studied, corresponding to the ‘Rangpur Santa Cruz’ lime, the ‘Indio’, ‘Riverside’ and ‘San Diego’ citrandarins, the ‘Sunki Tropical’ mandarin, and eight citrus hybrids, generated by the Genetic Improvement Program of Citrus from Embrapa Cassava and Fruits. The irrigation water consisted of three salinity levels: 0.14; 2.40 and 4.80 dS m-1. The experimental design was randomized block design adopting the split-plot scheme, with the rootstocks composing the plots and the types of water in the subplots, with four replications. During the period from August 2019, when the plants were 300 days after being transplanting in pots adapted as lysimeters, until February 2021, fruit harvests were carried out, and agronomic aspects were measured. At the end of each productive year, soil samples were analysed in order to assess soil cations and salinity. Concomitantly of the soil sampling, analyses of gas exchange and chlorophyll a fluorescence were realized. It was possible to conclude that salinity reduces the production of citrus plants, but the ‘Riverside’ citrandarin, ‘Sunki Tropical’ mandarin, and the trifoliate hybrid HTR - 069 have good production stability. It was found that: (1) the effect of salinity on citrus plants was osmotic, reducing the gas exchange of plants; (2) salinity did not significantly damaged the photosynthetic apparatus until the second year of production; (3) the cultivation of ‘Tahiti’ acid lime under irrigation with water of 2.4 dS m-1 is possible when using more stable tolerant rootstocks.