EMERGENCE, GROWTH AND PRODUCTION OF SESAME UNDER SALT STRESS AND PROPORTIONS OF NITRATE AND AMMONIUM¹

EMERGÊNCIA, CRESCIMENTO E PRODUÇÃO DE GERGELIM SOB ESTRESSE SALINO E PROPORÇÕES DE NITRATO E AMÔNIO

ABSTRACT

In arid and semi-arid regions, the quality of irrigation water varies in geographic terms and during the year, and the occurrence of water with high concentrations of salts is common. In this context, this study aimed to evaluate the emergence, growth and production of sesame, cultivar CNPA G3, irrigated with saline water and fertilized with N of different carrier proportions by the ratio of nitrate and ammonium ( NO --N and NH +-N) in an experiment conducted in lysimeters arranged in a greenhouse in the municipality of Campina Grande-PB, Brazil. The treatments were distributed into randomized blocks using a 5 × 5 factorial scheme relative to levels of irrigation water salinity (ECw; 0.6, 1.2, 1.8, 2.4 and 3.0 dS m-1) and five proportions of NO3 -N/NH4 -N (200/0; 150/50; 100/100; 50/150 and 0/200 mg of N kg-1), with three replicates. The increase in ECw compromised the emergence, growth and production of sesame, cultivar CNPA G3, and the production components were the most sensitive variables. The highest growth in diameter was obtained with the proportion of 200/0 mg kg -1 of NO3 -N/NH4 -N. An ECw level of 3.0 dS m and fertilization with 0/200 mg kg of NO3 -N/NH4 -N promoted deleterious effects on the total mass of sesame fruits and mass of seeds. The interaction between water salinity levels and NO3-/NH4 proportions significantly affected the number of leaves (at 50 and 70 days after sowing), the total mass of fruits and the mass of seeds.

Keywords:
Sesamum indicum L.; Water quality; Nitrogen.