Abstract

Sunflower has become an important crop for both farmers and consumers in Sudan. It is a crop that fits well in the local cropping system and is considered one of the most important oil crops of the country. Regular irrigation intervals could be reduced in order to increase total yield and maximize water productivity. In contrast prolonged irrigation intervals during sensitive growth stages may result in reduction in total yield. The application of water below the evapotranspiration requirements is termed deficit irrigation (DI). The experiments were conducted at Gezira Research Station, WadMedani, Sudan, in a randomized complete block design with three replications. In this study irrigation intervals every week (W) during the whole growing period, 10 days interval (F1), 15 days interval (F2) and 20 days interval (F3) after flowering stage and 10 days interval (S1), 15 days interval (S2) and 20 days interval (S3) after seed filling stage were applied to study the effect of full and deficit irrigation on yield and yield components of sunflower crop during the two growing periods 2011/12 and 2012/13. Results showed that water stress decreased the number of filled seeds per head, weight of full seed and seed yield. The highest seed yield of (3130 and 3140 kg/ha) was obtained from full irrigation (W) and the lowest seed yield of (2082 and 2130 kg/ha) from irrigation every 20 days after flowering stage in the first and second season respectively. Results indicated that there were no-significant differences on head diameter, plant height and stem diameter when water deficit occurred after the flowering stages. Lower WP of 0.21 to 0.26 and 0.21 to 0.27 kg/m3 were obtained when sunflower irrigated every 20 days after flowering and seed filling stages in the first and second season respectively. Results revealed that water productivity was low under Gezira conditions.

Key words: Water productivity, deficit irrigation, sunflower, seed yield.