Effects of irrigation regime on growth and seed yield of sunflower (Helianthus annuus L.)

Field experiments were conducted at national agricultural research center islamabad pakistan to study the response of sunflower hybrids to irrigation levels. four irrigation levels (control,heading stage,heading + flowering stages,and heading + flowering + grain filling stages) were applied to two sunflower hybrids (parsun-1 and sf-187). randomized complete block design in split plot arrangement having 5 replications were used. irrigation levels were kept in the main plots while hybrid in the sub plots. plant height,number of leaves plant-1 and head diameter was significantly (p≤ 0.05) affected by irrigation,hybrids and year. the effect of irrigation was non significant on 100 seed weight,seed yield ha-1 and oil content (%) due to rainfall at the experimental site during both growing seasons. the effect of the year was significant on 100 seed weight,seed yield (kg ha-1),and oil content. taller plants,bigger heads,maximum 100 seed weight and high seed yield was produced during 2002 when sunflower crop received three irrigations at heading stage,heading + flowering stages,and heading + flowering + grain filling stages compared with other treatments.