The efficiency of pre-treatment of maize seeds with plant growth regulators for resistance of maize seedlings to zinc ions

In this research, the effects of maize seed pre-treatment with synthetic (Thidiazuron, Cytodef, Kinetin and Epin-extra) and natural (Ribav-extra) plant growth regulators (PGRs) on axial growth of seedlings of maize (Zea maysL.) cultivar 'Tzaritza' exposed to zinc ions (Zn2+) were investigated. Also, the influence of applied PGRs on Zn2+ allocation in maize root tissues was studied. The seeds of maize were treated with various PGRs and grown for 7 days on 1 mu M, 10 mu M, 0.1 mM and 1 mM Zn2+ concentrations. After that the growth of shoot and root, and generation of catalase in maize leaves were recorded. In order to detect the effect of PGRs on Zn2+ allocation in maize root tissues, the seeds were treated with solutions containing different PGRs then 5-day old seedlings were treated with 1 mM Zn2+ for 3 days. The transverse root slices were stained with dithizone and observed under a microscope. It was found that pre-treatment of maize seeds with solutions containing different PGRs modified the allocation of Zn2+ in root tissues: Thidiazuron enhanced, while Epin-extra impaired the absorption of Zn2+ in root tissues. The effect of pre-sowing treatment of seeds with each PGR on seedling growth depended on the concentration of Zn2+ in the growth medium. Pre-sowing treatment of seeds with Epin-extra and Ribav-extra was the most effective under higher (0.1 and 1 mM) Zn2+ concentration by inducing both axial growth and the activity of catalase in maize, whereas pre-sowing treatment of seeds with Kinetin was effective for maize root growth under all applied Zn2+ concentrations. The research data suggests that the maize plants, whose seeds had been treated with PGRs, were more Zn2+-resistant than the untreated ones.

Automated summary

The research shows that using different plant growth regulators can modify the allocation of zinc ions in maize root tissues, and pre-treating maize seeds has the best growth effect under higher Zn2+ concentrations.