Salinity in the First Phase of Salt Stress Alters Photo-physiology, Water Use Efficiency and Total Soluble Phenolics of Maize Genotypes -

Salinity is one of the most important abiotic stresses that adversely affect plant growth and development around the world. The growth and physiological responses of four maize genotypes namely indigenous yellow pure line, indigenous yellow, hybrid, and indigenous white were tested under first phase of salt stress in the present study. The experiment was laid out following completely randomized design with four replications and two treatments viz., control (without application of NaCl) and salinity (EC 12 dS m-1, by addition of NaCl) in the net house of Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh. Different growth parameters were measured from 28d old maize seedlings in both control and stress. Under first phase of salt stress, shoot height and stem diameter of maize plants were greatly reduced in almost all genotypes. Under salt stress, instantaneous water use efficiency was highly increased in indigenous yellow pure line (285.5%), in contrast it was decreased significantly in hybrid (16.99 %) genotype compared to their respective control. Photosynthesis rate, transpiration rate, and stomatal conductance were significantly reduced due to salinity in all the tested genotypes. In the younger shoot, total phenolics content increased significantly in the young shoots of hybrid (42.26%) and indigenous yellow pure line (40.03 %) genotypes under the first phase of salt stress. In contrast, there was no significant influenced of salinity on total phenolics content of older shoot fraction in any genotype tested. As the most traits studied were highly influenced by the salinity in the first phase of salt-stress among genotypes at vegetative stage, breeders can potentially use these traits further in breeding program for the development of maize genotypes tolerant to the salt-stress at the vegetative stage of growth.