Nitrogen and potassium synergism influences the yield and quality of Dioscorea cayennensis

Sinergismo de nitrogênio e potássio influencia na produtividade e qualidade de Dioscorea cayennensis

Abstract

This study aimed to evaluate yield, quality, nematode incidence, chlorophyll content, and primary foliar macronutrients of yam in response to nitrogen and potassium fertilization. A complete randomized block design was used in a factorial scheme (5 x 5), with five nitrogen (0; 60; 120; 180 and 240 kg ha^-1 of N) and five potassium doses (0; 60; 120; 180 and 240 kg ha^-1 of K₂O), with four replicates. The mass, total and commercial productivity of tubers, starch content, ash, leaf N, P, and K content, chlorophyll, and nematode incidence were evaluated. The average mass of tubers obtained was 1.935 kg with doses of 133 kg ha^-1 of N and 105 kg ha^-1 of K₂O. The dose of 178 kg ha^-1 of N promoted maximum total tuber productivity (22.56 t ha^-1). The doses of 132 kg ha^-1 of N and 118 kg ha^-1 of K₂O resulted in maximum productivity of commercial tubers with 20.35 t ha^-1. Leaf N and K, starch, and ash contents were within the standards for yam. The incidence of Meloidogyne, Scutellonema, and Pratylenchus reduced with the increasing simple effect doses of N and K₂O. The maximum chlorophyll content was obtained at the dose of 240 kg ha^-1 of N. The nitrogen and potassium interaction, despite the antagonistic effects on the accumulation of foliar P and starch, increased the productivity and average mass of commercial tubers, consequently ensuring the profitability of yam cultivation.

Keywords:
mineral nutrition; nematodes; tuber quality; yam