Salinity tolerance of tomato fertigated with different K⁺/Ca²⁺ proportions in protected environment¹

Tolerância do tomateiro à salinidade quando fertigado com diferentes proporções de K⁺/Ca²⁺ em ambiente protegido

HIGHLIGHTS:

Cultivation of tomato in coconut fiber promotes greater tolerance to salinity.

Higher doses of potassium and calcium increase salt stress in tomato fertigated with saline nutrient solutions.

Adequate nutritional management with Ca²⁺ and K⁺ allows the use of saline water in tomatoes grown in coconut fiber.

ABSTRACT

Adequate potassium and calcium nutrition is a strategy to reduce salt stress on tomatoes, as it reduces nutritional imbalance in plants. With the objective of evaluating tomato production using irrigation with saline waters and fertigation with different potassium-calcium proportions, an experiment was carried out in a protected environment in Mossoró, RN, Brazil. The experimental design used was randomized blocks, in a 5 x 4 factorial scheme, with four replicates. The treatments consisted of the combination of four electrical conductivity of nutrient solution (ECns) (1.75; 3.25; 4.75; and 6.25 dS m^-1) combined with five ionic proportions (m/m) of potassium and calcium (F1 = 2.43:1; F2 = 2.03:1; F3 = 1.62:1; F4 = 1.30:1 and F5 = 1.08:1). The response variables were: number of fruits, mean fruit weight, fruit production per plant and relative yield. It was possible to identify satisfactory results of production when higher salinity was used. Fertigation with low K⁺/Ca²⁺ proportions intensifies the effect of salinity on tomato crop.

Key words:
Lycopersicon esculentum Mill; nutrition; potassium; calcium; salt stress