Changes of Available Phosphorus and phosphatase activity in the rhizosphere of some field and vegetation crops in the fast growth stage

Abstract

A large proportion of P is found in organic forms. Phosphatase, plays an essential role in the mineralization of organic phosphorus. Agronomy species can affect phosphatase activity in rhizosphere. The aim of our study was to determine the effects of some agronomy species (Gramineae, Leguminose, Solanaceae, Labiatae, Cruciferae, Umbellifera, Alliaceae) on phosphatase activity in their rhizosphere. The agronomy species were planted in a semiarid soil in the pots under greenhouse condition. Phosphatase activity in the rhizosphere of any species was studied at middle of their growth. Phosphatase activity was greatly enhanced in the rhizosphere of all species. Alkaline phosphatase activity increased 102-325% and acid phosphatase activity increased 205-455% in the rhizosphere soil compared to the non-rhizosphere soil. This suggests that agronomy species actively promote rhizosphere phosphatase activity either directly by secretion or indirectly by stimulation of microbial activity and/or by depletion of Pi. There were significant differences between phosphatase activities in rhizosphere of plant species. The highest and lowest means of alkaline phosphatase activity were found in rhizosphere of Trifolium repens and Ocimum basilicum respectively. The highest and lowest means of acid phosphatase activity were found in rhizosphere of Triticum aestium and Cicer arietinum respectively.