Srivastava, Prof. J.P.Priyadarsini, payal2018-09-192018-09-192017osmotic stresshttp://krishikosh.egranth.ac.in/handle/1/5810073767Effect of ionic stress created by NaNO3 and NaCl and osmotic stress created by polyethylene glycol-6000 in isosmotic concentrations i.e. nearly -0.42 MPa was observed on water uptake, seed germination parameters, early seedling growth and morpho-physiological attributes of maize (Zea mays L.) variety Bio-9542. Experiments were carried out in Petri plates, germination papers and on sand culture. Normal treatment consisted of normal Hoagland solution. As compared to normal Hoagland, water uptake by seeds, strong seed index, Plumule, radical and mean of coleoptile + radical lengths decreased significantly by ionic and osmotic stresses and the reduction was the maximum in PEG-Hoagland solution, followed by Na-Hoagland and NaCl-Hoagland. Seed germination per cent, mean number of roots decreased significantly in PEG-Hoagland treated seeds. Plants treated with Na-Hoagland did not survive when experiment was conducted on sand culture. It is observed that total chlorophyll, chlorophyll a, chlorophyll b contents, ratio of chlorophyll a:b and carotenoid content reduced significantly in plants treated with NaCl-Hoagland. Free amino acid and proline content in shoot and Na+, N and crude protein in root, shoot and plant increased significantly, while P content increased marginally in NaCl-Hoagland and PEG-Hoagland treated plants. K+ content is reduced in plant and plant parts under such condition. On the basis of present investigation it is inferred that mild ionic and osmotic stresses in almost equal osmotic potential range (-0.42 MPa) has no significant effect on imbibition of the seed, but osmotic stress has significant effect on root number. At later phase of seed germination, osmotic stress is more deleterious than the ionic stresses on seedling growth parameters and among ionic stresses salinity caused by Na+ is more lethal than that caused by NaCl. Chlorophyll and carotenoid pigments are also decreased under ionic and osmotic stresses and ionic stress is more deleterious than osmotic stress to this parameter. Similar trend has also seen on soluble sugar, free amino acid and proline contents. Major effect of salinity stress is observed to be through increased sodium content in plant tissues while, deficiencies of K+ under ionic and osmotic stress.ennullThesis