الفهرس | Only 14 pages are availabe for public view |
Abstract The P-salinity interaction on growth and mineral uptake by hydroponically-grown hybrids 163 and 310 of maize was investigated. The low P supply (0.05 mM) was adequate and resolved the vague genotypic difference in maize growth, in favor of hybrid 310, which was more salt-sensitive than hybrid 162. Root growth was robust to salinity stress; it benefited from 50-100 m NaCl. Salinity mildly led to the production of longer and narrower blades. The salt-tolerant hybrid 162 had higher content and greater salinity-induced increase in Chl a compared with hybrid 310. Salinity induced mild increase in soluble sugars of leaves with non-consistent effect on starch content. The ion content was higher in the shoot than the root. The salt resistance of maize is associated with high K+, low Na+ content in the shoot. The salinity-induced increase in shoot Na+ was progressive while that in the root was saturable. Ca2+ was preferentially accumulated in the shoot with salinity-induced reduction, but P was accumulated in the roots, with salinity-induced increase. The effect of P supply on mineral composition of maize was mild and dependent on the hybrid × salinity interaction. Salt shock imposed primarily osmotic stress. Maize has high external P use efficiency. The genotypic difference in leaf growth, in favor of hybrid 310, was evident under the combined stress of salt shock and HP. The salinity-induced increase in soluble sugars was found only in the salt-tolerant hybrid under the combined stress of HP and salt shock. Starch content of leaves not soluble sugars is a reliable measure of the genotypic and environmental factors on maize performance. An additional effect of salt shock, over gradual salinization, in reducing K+ content of maize tissues was evident only in the root under LP; but the increase in Na+ content was more evident in hybrid 162 and in the root than the shoot. Whereas the salinity-induced reduction in K+ concentration was more severe in root than shoot the reverse was true for the salinity-induced increase in Na+ concentration. The salinity-induced reduction in Ca2+ concentration was evident only in roots of hybrid 310 with almost no effect in the shoot in general and root of hybrid 162. The effect of salt shock on Ca2+ concentration of plant tissue was comparable or even mild relative to the effect of gradual salinization. Salinity increased P concentration of the shoot, particularly in the HP-hybrid 310 and the LP-hybrid 162, with comparable effect of gradual salinization and salt shock. Under HP, gradual salinization increased root P whereas salt shock might decrease it; but under LP, salinity consistently reduced in root P. |