عنوان مقاله [English]
نویسندگان [English]چکیده [English]
To evaluate the effect of time and level of nitrogen application on quantity and quality of two carrot varieties, an experiment was carried out in the framework of a 4×3×2 factorial and based upon a randomized complete block design of three replications. The levels of 25, 50, 75 and 100 kg / ha of nitrogen fertilizer were investigated within 3 applied times, namely: simultaneous with bed preparation, 30 and 60 days following implantation and for two carrot varieties (‘Nantes’ and ‘Forto’). The results indicated that fresh weight of branch, fresh weight of root, dry weight of root, length of root, yield and carotenoid contents were highest in the treatments of 50 and 75 kg / ha of nitrogen fertilizer within 30 and 60 days following implantation for both two carrot varieties. Dry weight of branch and length of branch were highest in 75 and 100 kg / ha of nitrogen fertilizer treatment in 30 and 60 days following application in both varieties. Also phenolic compounds were affected by increase in the level of nitrogen fertilizer and applied times and as well by varieties. In ‘Forto’ variety, they were higher than in ‘Nantes’ in 50 and 75 kg / ha of nitrogen fertilizer application and in 30 and 60 days following implantation. Also, nitrate amount was affected by increase in level of nitrogen fertilizer, but was not affected by time of application and by variety. The highest nitrate was detected in the treatment of the highest level of nitrogen fertilizer application.