Effect of Plantation Date, Plant Cultivars and Plant Density on Insects’ Populations and Yield of Sunflower Crop

Abstract

The effect of plantation date, plant density, and plant varieties on the population of insects that attack sunflower plants and their predators were examined. Two plantation dates, two sunflower varieties (Giza102 and Sahka53), and two distances between the planting pits were taken in account. Numbers of Aphis gossypii showed significant differences between the two plantation dates of Sakha53 and Giza102 varieties, whereas those of Empoasca lybica only showed significant differences between the two plantation dates of Giza102 variety. Only numbers of the green lacewing, Chrysoperla carnea exhibited significant differences between both dates of cultivation. In respect to March plantation, the distance of 25 cm had significantly higher numbers of Bemisia tabaci, Thrips tabaci, and E. lybica than 15cm for cultivation of Sakha 53 variety, whereas the distance did not affect the insects that harbored Giza 102 variety. In respect to June plantation, the distance of 15cm had significantly higher numbers of E. lybica than 25 cm for cultivation of Sakha 53 variety, whereas 25cm had higher numbers of A. gossypii and Icerya secyllarum than 15cm in Giza102 variety. In March plantation, Sakha53 variety harbored significant numbers of A. gossypii and T. tabaci compared with Giza 102, whereas in June plantation, it harbored significant numbers of E. lybica and I. secyllarum. In general, Sakha 53 variety seems to be a more sensitives sunflower host for insect infestation than Giza102, resulting in lower quantity of sunflower heads yielded by this variety. Chemical and morphological analyses support this finding.