Nutritional status, Na⁺ and Cl^- concentrations, and yield of sugarcane irrigated with brackish waters¹

Estado nutricional, concentrações de Na⁺ e Cl^- e produtividade em cana-de-açúcar irrigada com águas salobras

HIGHLIGHTS:

Salinity above 0.5 dS m^-1 reduced the foliar concentrations of N, P, K⁺, Mg²⁺, S, Fe²⁺, Mn²⁺, Cu²⁺, and Zn²⁺ in plant-cane.

Salinity of 8 dS m^-1 without leaching fraction decreases yield by 43 and 47% in plant-cane and first ratoon, respectively.

With leaching fraction of 0.17 the yield is 26 and 28% higher in plant-cane and first ratoon, respec-tively.

ABSTRACT

Salinization reduces the osmotic potential of soil solutions and promotes the accumulation of toxic ions (Na⁺ and Cl^-) in plants, causing nutritional imbalance and yield reductions. Thus, the objective of the present study was to evaluate foliar concentrations of nutrients and Na⁺ and stalk yields in sugarcane RB92579 under different electrical conductivities of irrigation water and leaching fractions (LF). The experiment was conducted in drainage lysimeters in a 5 × 2 factorial scheme with five electrical conductivities of irrigation water - ECw (0.5, 2.0, 4.0, 6.0, and 8.0 dS m^-1) without (LF1 = 0) or with a leaching fraction (LF2 = 0.17), and four replicates. Increased ECw decreased the concentrations of N, P, K, Mg, S, Fe, Mn, Cu, and Zn and increased those of Ca, Cl, and Na, reducing the biomass production in two cycles (plant-cane and first ratoon). The use of a leaching fraction of 0.17 mitigated the deleterious effects of salinity on nutrient concentration and yield.

Key words:
Saccharum spp.; salt stress; mineral nutrition; yield; leaching fraction