ABSTRACT
Investigation was carried out at Samaru, Zaria, Nigeria, during the 1986 cropping season to study the effects of four plant populations (30,000; 60,000; 120,000 and 240,000 plants/ha), three sowing dates (July 2, 16 and 30) and two varieties (isaanka and Funtua) on growth characters, yield and yield components and seed quality of sunflower. Increasing the population density from 30,000 to 2l}.0,000 plants/ha, decreased stand establishment and survival rate from 53 to 35% and from 46 to 23%, respectively. Similarly, stem and head diameters, dry weight/head and weight of 1000 seeds decreased, but the number of seeds/head and seed yield/plant showed a significant decrease only at populations of 120,000 and 240,000 plants/ha There was no clear trend in oil content with increase in plant population. However, crude protein content, decreased with increase in population only from 30,000 to 120,000 plants/ha. Number of days to 50% flowering, days to maturity, lodging percentage, percent empty seeds and seed yield were not significantly affected by plant population. The July 16 sown sunflower with a mean seed yield of 1434.O kg/ha, out-yielded that sown on July 2 and July 30 by 18 and 24%, respectively. Delay in sowing date decreased dry weight/head, number of seeds/ head and seed yield/plant. The percent oil content of the seed increased from I44.1 to 47.2% when sowing was delayed from July 2 to July 16. Of the two varieties tested, Funtua excelled in almost all the parameters except in oil content and plant count. Significant treatment interactions were observed on yield parameters.