Effect of Exogenous Proline Application on Salinity Tolerance of Cordia myxa L. Seedlings. Effect on Vegetative and Physiological Characteristics.

Abstract

The study was conducted in the growing season of 2010 at a private orchard at Bab El Zubair area, Basra, Iraq, during the period from March, 1^st, 2010 to December, 1^st, 2010, to study the role of the amino acid (Proline) in salt tolerance of Lasura (Cordia myxa L.) seedlings (cv.Local). The experiment was designed according to Randomized Completely Block Design (R.C.B.D.) in a three factorial experiment of 27 treatments resulted from the interaction of :  Three levels for the first factor (the concentrations of  NaCl  ( 0, 6 and 12 Ds. m^-1),  three levels for the second factor (the concentrations of the amino acid proline   (0, 75 and 150 mg.L^-1) and three replicates for each experimental unit. The results showed a significant decrease in most studied vegetative characteristics with increasing the salt concentrations, but an opposite impact occurred with increasing the proline concentrations.  For physiological characteristics, the proline treatment (150 mg. L^-1) was of a significant superiority and possessed the highest content of chlorophyll, free proline quantity and acidity percentage. While for the interaction among the levels of NaCl and proline, the interaction treatment (12 Ds. m^-1 NaCl + 150 mg. L^-1 proline) showed the highest increment in the main stem height and diameter, length and diameter of secondary branch,  average of leaf area, total chlorophyll and true proline.

Keywords: Cordia myxa, proline, salinity tolerance.