Evaluation of nitrogen fertilizer and row spacing effect on yield and physiological characteristics of maize (Zea mays L.) under irrigated and rainfed conditions

This research aims to investigate the yield and physiological traits of Hybrid 704 Single Cross maize under rainfed (without any irrigation) and irrigation based on plant needs as a split-plot experiment in a randomized complete block design with three replications during 2017-2018. It was carried out in Langrud, Gilan province, Iran. The total amount of precipitation during the plant growth period was 580.4 and 463.4 mm in 2017 and 2018 respectively, which happened to improper distribution during the plant growth. In experimental treatments, the first factor includes irrigation and rainfed in the main plots and the second factor is the combination of urea fertilizer levels (control, applying 100, 200, and 300 kg per hectare) with row spacing (10, 20, and 30 cm distance) were in sub-plots. The results showed that the effect of nitrogen source and row spacing under rainfed and irrigation conditions was significant on all investigated traits in this experiment. In the conditions of rainfed, the maximum grain yield was 11394.6 kg.h-1 for applying 300 kg of nitrogen fertilizer per hectare and 20 cm row spacing. In irrigation conditions, the highest grain yield was assigned to 200 and 300 kg of nitrogen fertilizer per hectare and of 20 cm row spacing, with an average of 14050.5 and 14993 kg per hectare, respectively. In addition, an increase in physiological traits, including relative water content, proline, antioxidant activity, and improvement of electrolyte leakage under rainfed conditions was observed by applying nitrogen fertilizer and increasing the row spacing. As a result, in rainfed conditions, using 200 to 300 kg of nitrogen fertilizer and increasing the row spacing should be used to obtain the highest maize yield in the experimental area.