Changes of vegetative growth indices and yield of garlic (Allium sativum L.) in different sources and levels of nitrogen fertilizer

ABSTRACT: Nitrogen is necessary for increasing yield and quality of vegetables including garlic. Nitrogen has got effect on morphological characteristic of garlic, therefore for the determination of the optimal source and level of fertilizer, different levels (100, 150, 200, 250 and 300 kg N/ha) of nitrogen fertilizer as urea and ammonium sulphate were evaluated on the number and length of leaves during vegetative growth and on the yield and its components after harvesting. Results showed that the highest leaf length and number were observed in 300 kg N/ha, while the lowest was related to 100 kg N/ha. The highest leaf number, 221 days after planting and the highest leaf length 235 days after planting were observed. Nitrogen source had got significant effect on weight of bulb per plant, cloves number per bulb, length and diameter of bulbs and single clove and clove weight, while had not significant effect on yield and leaf length and number. Fertilizer level less than 200 kg N/ha increased mean clove number, bulb weight per plant, clove and bulb length and diameter and clove weight, while in higher levels, all mentioned factors decreased. Positive and significant (p ? 0.01) correlation between yield and leaf length and number, clove and bulb length and diameter and clove weight were observed. According to the results, 200 kg N/ha ammonium sulphate is recommended.