Sunflower Growth Performance under Tillage or No Tillage Practice, Irrigation Intervals and Nitrogen Fertilization Rates

Abstract

Growth expressions of sunflower, supplied with 30, 45, and 60 kg N/ fad, were examined under the treatment of two tillage practices (conventional tillage and no tillage applications) and three irrigation intervals (12, 18 and 24 days, between each two successive irrigations) during 2017 and 2018 summer seasons at the Experimental Farm of the Itay-EL-Baroud Agricultural Research Station. Responses of plant height, leaf area index, flowering date, stem diameter, head diameter, 1000-seed weight, seed yield/ fad., harvest index and seed oil content in addition to oil yield/ fad. were significant having the maximum records for sunflower with 12 days interval of irrigation. Also, the highest values of plant height, leaf area index, harvest index, seed yield/ plant, during the two seasons, and seed yield /fad, oil yield (in 2017) and 1000-seed weight (in 2018) were achieved with conventional tillage compared to no tillage. Meanwhile, no significant effects were obtained for flowering date, stem diameter and head diameter during the two seasons of study, and 1000-seed weight (in 2017), seed yield and oil yield/ fad (in 2018) based on tillage practice. Increasing the level of nitrogen fertilization up to 60 kg/ fad, significantly increased all studied characters except nitrogen use efficiency (NUE) and oil percent which decreased with increasing nitrogen levels during the two seasons. The interaction of irrigation intervals and tillage practice significantly affected plant height over the two seasons. This trait had maximum values with the shortest irrigation interval (every 12 days) and 60 kg N/ fad. The obtained data indicated that 1000-seed weight, seed yield/plant, leaf area index and harvest index were significantly affected by the irrigation interval and nitrogen levels interaction. Meanwhile, high seed and oil yields were achieved with short interval (every 12 days) under conventional tillage and nitrogen levels of 40 and 60 kg N/ fad. It is recommended to grow sunflower under conventional tillage practice, with applying irrigation every 12 to 18 days and nitrogen fertilizer at the rate of 45 to 60 kg N/ fad, to obtain highest seed and oil yields.