Interaction of potassium with the form and amount of nitrogen nutrition on growth and nitrogen uptake of maize

Abstract

Although a mixture of NO₃‐N and NH₄‐N improves the growth of maize plants over that with NO₃‐N or NH₄‐N alone, the ratio required for maximum growth remains unclear. Maize hybrid B73 × MoI7 was grown in vermiculite at 25°C in a controlled climate room with a 16‐h photoperiod at 280 μE/sec/m² to evaluate effects of the form and amount of N, and the N/K ratio on the growth of seedlings. The proportion of NH₄‐N in the mixture required for maximum growth varied according to the total amount of N in the medium. Under low N conditions, seedlings grew faster with a higher proportion of N in the NH₄ form while a greater proportion of NO₃‐N was advantageous at high N conditions. When seedlings were grown under NH₄‐N as the sole N source, high K levels promoted root growth, and dry matter and N accumulation in the shoot.