Abstract

Potassium fertilization is one of the main techniques that has been studied to mitigateeffects of salt stress in plants, probably because potassium reduces the toxic effect of sodium by competitive inhibition and provides greater tolerance to genotypes of plants to salinity. Hence, this study aimed to evaluate the effect of different salinities of irrigation water in the formation of phytomass and quality of rootstocks of guava cv. Paluma, fertilized with increasing doses of potassium, in an experiment conducted using eutrophic Fluvic Neosol with sandy loam texture under greenhouse conditions, in the municipality of Pombal-PB, Brazil. The experimental design was randomized blocks in 5 × 4 factorial scheme, and the treatments resulted from the combination of five levels of irrigation water electrical conductivity (ECw = 0.3; 1.1; 1.9; 2.7 and 3.5 dS m^-1) and four K doses (70, 100, 130 and 160% of K), in which the dose of 100% K corresponded to 726 mg of K dm^-3 of substrate, with four replicates and two plants evaluated in each plot. Irrigation with water salinity from 0.3 dS m^-1 compromises the total dry matter accumulation and the Dickson quality index of guava rootstocks cv. Paluma at 225 days after emergence (DAE), independent of potassium fertilization. Fertilization with different potassium doses did not promote differences in phytomasses and quality of rootstocks. There was no significant effect of interaction (salt × doses of K) on the studied variables.

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