RT - Journal Article T1 - Effects of Water Stress, Nitrogen Levels and Application Times on Yield and Yield Components of Sunflower at Different Growth Stages JF - JSTNAR YR - 2011 JO - JSTNAR VO - 15 IS - 55 UR - http://jstnar.iut.ac.ir/article-1-1556-en.html SP - 199 EP - 207 K1 - Water stress K1 - 1000-seed weight K1 - Seed yield K1 - Oil yield. AB - The optimum levels of soil moisture and nitrogen are important to obtain higher yields. To investigate the effects of water stress, nitrogen levels and application times on yield and yield components of sunflower (Helianthus annuus L.), the cultivar Euroflor at different growth stages, a two year study (2006-007) was conducted at Research Fields of College of Agriculture, Shiraz University (Badjgah) using a split factorial design with four replications. Treatments were water stress at three levels, (non-stress and stress at flowering and seed formation) as main plot and three N levels (0, 70, 140 kg ha-1) and N application times (split application at planting and stem elongation, planting and heading, and stem elongation and heading) as subplot. Number of seed per head, 1000-seed weight, seed yield, Oil yield and HI were measured. Results showed that the effects of water stress and N rates on yield and yield components were significant, but the effects of N application times and interaction between water stress, nitrogen rates and application times were insignificant. Overall, the crop showed more sensitivity to drought stress at flowering time, and 70 kg N ha-1 is recommended for the region. LA eng UL http://jstnar.iut.ac.ir/article-1-1556-en.html M3 ER -