Effects of plant population on growth, development and oil yield of safflower (Carthamus tinctorious L.)

Abstract

Two field trials were done in the winter of 2010 and summer of 2010/2011 to evaluate the effects of plant density. on the growth, development and yield of safflower. The results showed that plant density and season of growth had significant (P < 0.05) effects on growth, development, yield. components, seed yield and seed oil content of safflower. Increasing safflower plant density from 100,000 to 250,000 plants/ha significantly (P < 0.05) reduced plant height (13.2- 21.3%, branch number/plant (37-54.7%), leaf number/plant (39-39.2%), leaf area (19.5-51%), plant spread (39.6-54.4%), root length (28.1-54.4%), plant biomass (17-50%), capitula size (12- 12.7%, capitula number/plant (39.5-50.570), seed number/capitula (39-4570), capitula weight (3.3-3.6%), seed yield (67.9 -69.8%) and seed oil content (14.7-20.8%) depending on season of growth. The reduction in vegetative growth, yield components, seed yield and seed oil content of safflower due to increased plant density was attributed to mutual competition (inter and intra plant competition) for light, nutrients and water necessary for growth and development. Winter prolonged the maturation period of safflower by 22 days compared summer. Winter grown safflower was better in quality in all the variables measured than summer grown safflower. The differences between winter and summer grown safflower was attributed to DIF and the average daily temperature which weree optimum for safflower growth in winter. Based on the results of the study it was concluded that plant density and season have a significant effect on the growth, development, yield components, yield and seed oil content of safflower. Under Botswana conditions, safflower should be planted at 50 cm x 20 cm or wider in order to maximize yield and oil content and allow the plants to express their maximum genetic potential.