بررسي تاثير تنش نيكل و همزيستي اندوفايت نيوتيفوديوم بر برخي شاخص هاي رشد و جذب نيكل در گياه Lolium perenne

Nickel stress and Neotyphodium endophyte symbiosis effects on growth parameters and nickel uptake in Lolium perenne

Lolium perenne has symbiosis relationships with an important group of endophytes; genus Neotyphodium. Agronomic traits of this plant and its resistance to biotic and abiotic stresses are affected by Neotyphodium spp., leading to changes in its physiology and morphology. Effect of nickel and endophyte symbiosis on growth parameters and nickel uptake in two different natural populations were investigated in this study. Each population consisted of two groups of plant (E+ and E-; with or without endophyte). Treatments consisted of 0, 30, 90 and 180 mg Ni kg 1- soil), and growth parameters including root and shoot wet, dry weight and length, tiller number, and nickel uptake in root and shoot were evaluated after 3 months from treatment. Significant decrease in root and shoot biomass of E+ and E- plants was observed in 180 mg.kg-1 nickel and endophyte infection led to decreases in the plant biomass. However, endophyte infection significantly improved the tillering ability of host ryegrass. Also, a significant increase in the Ni concentration of root and shoot was observed under Ni stress and the Ni concentration of E+ plants was 12.7% and 88.7% higher in root and shoot, respectively, than in E- plants. Root and shoot wet and dry weights were decreased when plants were grown under the 180 mg.kg-1 level of nickl tretment, while root length decreased with the 30 mg.kg-1 level of nickel in the soil. Greatest number of tillers was observed in population 1 in 30 mg.kg-1 treatments. Nickel uptake plant roots and shoots of both populations increased when soil Ni level increased from 0 to 180 mg.kg-1. Nickel uptake of root and shoot in two populations of L. perenne plants was decreased at the presence of endophytes (E+ plants) which is considered as an important factor towards decrease in negative effects of this element on plant attributes. The suitable population to be introduced for cultivation in stress conditions was population 1, as it produced more shoot tillers and had more nickel uptake under the stress conditions.