Effects of Arbuscular Mycorrhizal Fungi on Spores Density and Root Colonization of Four Hybrids of Sunflower (Helianthus annuus L.) at Different Rock Phosphate Levels

The present experiment was carried out in a net house at the University of Peshawar, Pakistan. Themain purpose of this research was to find out the effects of arbuscular mycorrhizal fungal (AMF) inoculation (with and without Mycorrhiza) along with application of various levels (0%, 25%, 50% and 100%) of rock phosphate (RP) fertilizer on spores density and percent root colonization of selected sunflower (Helianthus annuus L.) hybrids in P-deficient soil. It was observed that spore density and AMF root colonization was higher in the soil of control (RP0) plants, which decreases progressively with increasing fertility level. Less number of spores and percent root colonization was found at high RP level (RP100) in all hybrids. Higher P doses declined the sporulation and colonization. There was total seven AMF species that were observed and recorded. The dominant genus was Acaulospora which was followed by Glomus, Sclerocystis and Gigaspora. The average AMF spore density ranged from 56-260 spores/100g soil while root colonization ranged from 32-100%. Mycorrhizal enhancement regarding AMF spores density and root colonization ranked as- RP0 RP1 RP2 RP3 in all hybrids i.e 0% 25% 50% 100%.