Effects of Aluminum and Phosphorus on peroxidase activity, lignin content and certain physiological parameters of lisianthus (Eustoma grandiflora L.)

Aluminum (Al) is one of the main factors limiting the growth and developments of the plants in acid soils. There is a relationship between aluminum toxicity and phosphorous (P) shortage in acidic soil and it is likely that sufficient P supply enable plants to withstand more against Al toxicity. In the present studythe effect of P and Al on the activity of peroxidase, lignification and some physiological parameters of Lisianthus (Eustoma grandiflora L.) were investigated. The young plants were grown in hydroponic culture with a modified 1/4 strength Hoagland nutrient solution for 10 days. After depletion of elements which were remained from the soil and adaptation of the plants to the new media, they were treated with or without 300 µM Aluminum (AlCl3), 3 mM phosphorus (NaH2PO4), and a combination of both. The pH was adjusted to 4.5.The treatments were continued for 10 days, and the solutions were renewal every 4 days. The results showed that in the roots, Al treatment caused significant decrease in the activity of peroxidase (soluble, ionically- and covalently- wall bound PO; SPO, IPO, and CPO, respectively), compared to the control group. In root of P-treated plants, a significant increase was observed in the activity of SPO and CPO. Treatment with Al significantly decreased the activity of IPO and SPO. Decrease of lignin content in this treatment can explain positive effects of Al in lowering the toxicity risk of excess P and promotion of the growth of Lisianthus.