Role of Diode Laser Radiation Pretreatments in Growth of Pisum sativum L. Plant Seedlings and Callus under Salinity Stress

Abstract

The research included a study of the effect of the red diode laser radiation at wave length 650 nm and power 50 mw/cm2 for different periods of time 2,4,6,8 and 10 minutes in the growth and development of seedlings and callus of Pisum sativum L. plant under salt stress at 200mM. The results showed that seeds exposed to laser radiation for different periods of time caused a clear increased in all studied growth indicators compared with the control treatment. Seeds treated with laser radiation for 10 minutes showed superiority on the other treatments in stimulation of germination speed, rate of the radical and coleoptile lengths and their fresh and dry weights with an increase in the rate of fresh and dry weight of plant. The results showed also that exposing callus segments to the laser radiation for different periods of time caused an increase in the rate of their fresh and dry weights after 21 days of growth on MS medium supplement with 1.0 mg/l of BA and NAA for each one. The present study proved possibility of treating the negative effects of sodium chloride at the concentration 200mM on the growth indicators of seedlings and callus of Pisum sativum by treatment seeds and callus with laser radiation for 10 minutes before salinity treatment at 200 Mm. This led to increase in the speed of seeds germination, the activity of α-amylase enzyme during different germination stages and increasing in plant growth rates (the lengths rate of each of the radical and coleoptile and their fresh and dry weights, plant height, root length, number of stem and root branches, fresh and dry weights of plant with an increase in the leaves content of chlorophyll. Also the results indicated a positive effect of laser radiation for10 min. in the increasing the fresh and dry weights of callus and return its viability after 21 days of growth and reduce the damage of cellular membranes with an increase in the amount of total soluble carbohydrates, level of proline and protein content in the tissues of seedling leaves and callus according to salinity treatment only.