Effects of honeybee and other bee pollination and nanocomposite fertilizers on improvement of vegetative and reproductive characteristics of different cultivars of sunflower (Helianthus annuus) in Karbala City, Iraq

A field experiment was conducted during spring 2017 to determine the effect of honeybee(Apis mellifera L.) pollination and four concentrations (0, 1, 1.5, and 2 ml/L) of the protic-carbon nanocomposite on vegetative (plant height and plant leaf area) and reproductive (number of seeds per head) characteristics of 6 cultivars of sunflower (Helianthus annuus L.). For this purpose, a plot of land (420 mm2) was selected and 6 cultivars (French E5g12, Argentine A4g13, American F13g4, Turkish C13s4, Iraqi G14s, and Iraqi Q5g14) were individually planted in 6 replicates. For non-pollination treatment, the plants were covered with muslin cloth (40 Mesh), while in pollination treatment; plants were uncovered so that, honeybees and other pollinators could easily pollinate the sunflowers. Nine honeybee hives were located nearby the field. Data were analyzed using a two-way analysis of variance to investigate the effects of insect pollination and different concentrations of nanocomposite, or the effects of insect pollination and different cultivars of sunflower. The results revealed that occurrence of pollination and increasing concentration of nanocomposite significantly influenced vegetative and reproductive characteristics of all cultivars. Moreover, unlike vegetative characteristics, in which there were no interactions between pollination and cultivar type, reproductive characteristics were influenced by the interaction of these two variables, and in most treatments, vegetative and reproductive characteristics were significantly higher in the plant treated by insect pollination than non-pollinated plants. Our results confirmed the previous findings regarding higher vegetative characteristics and production of seeds in sunflowers as a result of introduction of honeybee colonies in culture.