Growth and Some Physiological Activities of Pepper ( Capsicum annuum L.) in Response to Cadmium Stress and Mycorrhizal Symbiosis

Abstract

A greenhouse experiment was conducted to investigat e the effects of mycorrhial fungus ( Glomus mosseae ) on cadmium (Cd) toxicity in pepper ( Capsicum annuum L. cv. Zhongjiao 105) plants. Half of plants were inoculat ed with arbuscular mycorrhizal fungi (AMF). Cd was supplied in the form of cadmium chlor ide at 0.0, 0.1 and 0.5 mM through irrigation water in the soil. Mycorrhizal colonizat ion was higher in the control than in cadmium - treated soil. Dry weights of root and shoot of myco rrhizal (M) plants were higher than non mycorrhizal (NM) ones in both contr ol and cadmium treatments. Measurements of Cd concentration indicated that M p lants immobilized more Cd in the root and partitioned less Cd to the shoots. Cd decr eased the leaf chlorophyll content, total sugar and total protein contents, and the concentra tions of phosphorous and magnesium. M plants had greater contents of chlorophyll, total sugar, total protein and P and Mg concentrations than NM plants. Moreover, increasing the Cd concentration caused an increase in malondialdehyde (MDA) content in leaves of pepper plants; however, M plants showed a lower MDA content than NM plants. C d decreased the activity of superoxide dismutase (SOD) in leaves of NM and M pl ants, on the other hand, it increased the activity of peroxidase (POD) and asco rbate peroxidase (APX) in leaves of NM and M plants. APX was stimulated more than POD i n M plants versus NM plants, suggesting that APX is a major player in H 2 O 2 -scavenging in M plants. The study suggests that mycorrhization with G. mosseae can be a suitable way to induce Cd-stress resistan ce in pepper plants. Keywords: Ascorbate peroxidase, Chlorophyll, Glomus mosseae , Heavy metals, Root colonization.