Nitrogen nutrition of garlic ( Allium sativum L.) under irrigation. Components of yield and indices of crop nitrogen status

Abstract

The effects of nitrogen levels from 0 to 240 kg N ha −1 on the yields of field-grown garlic, planted at two different times, were assessed. Total plant and bulb yields responded linearly to the logarithm of the nitrogen rate, but reductions in bulb quality at high levels of nitrogen suggested that 120 kg ha −1 was the optimum nitrogen rate in the conditions of this experiment. Measurements of crop growth and nitrogen concentrations at about 500 growing degree days from emergence were assessed as indices of the crop nitrogen status. Nitratenitrogen concentrations of the youngest mature leaf and soil mineral nitrogen concentrations varied closely with final bulb yields. However, the relationships between these indices and final bulb yields differed markedly for the two crops.