بررسي تأثير سطوح مختلف كود نيتروژن و فسفر بر تجمع نيترات و خصوصيات زراعي كاهو

Effect of different levels of nitrogen and phosphorous fertilizers on nitrate accumulation and agronomic characteristics in lettuce

A field experiment was conducted to investigate the effect different levels of nitrogen and phosphorus fertilizers on nitrate accumulation in lettuce (Lactuca sativa L.) at research site of Varamin Agricultural Research Center, Varamin, Iran. The experimental was comprised of five nitrogen fertilizer levels 0, 150, 200, 250, 300 kg N ha1 and five phosphorus fertilizer levels 0, 37.5, 50, 62.5, 75 kg P205 ha-1. Layout design was a randomized complete block design (RCBD). With split plot arrangement with three replications. Head fresh weight and leafy nitrate were determined at crop harvest. Based on the statistical results, nitrate level of all treatments was in accordance with European standards. Moreover, there was a significant positive correlation between nitrogen fertilizer content and nitrate accumulation. But there was no correlation between phosphorus fertilizer content and nitrate accumulation. The statistical results of the study also indicated that in order to predict nitrate accumulation based on nitrogen fertilizer content the regression model Y=0.0312x2-4.0931x+85.138 with R2=0.98 can be recommended.