مطالعه اثرات تراكم بوته بر عملكرد دانه و برخي از صفات مورفولوژيكي ارقام آفتابگردان

Effect of plant density on yield and some morphological characters of some sunflower {Helianthus annuus L.) cultivars

In order to study effect of plant density on yield and morphological characters of three sunflower varieties (Ghalami, Dorsafid and Pestie) an experiment carried out in Mahdashet - Karaj region (2003). Experiment design was split-plot based on RCBD with four replications. In this experiment, three varieties cultivated in two different density (50 and 120 plant/hec.). Analysis of variance indicated significant differences (1%) on yield, green area index and light absorption percent. Light extinction coefficients among varieties were significant at 5% probability level. Plant densities among varieties were significant at 1% probability level as well. Interaction between varieties and densities were not significant for all characters. With increasing of plant density, factors of yield and angle of petiole reduced, hence, light extinction coefficient was decreased and then more light penetrated to the canopy. Increasing of plant density caused reduction of leaf blade angle, consequently, leaves absorbed lower energy of sun-light. We conclude that reason of falling leaves, getting yellow and smaller green area index in the lower section of plants are because of larger leaves with larger area index in the middle section of plants.