The influence of zinc and selenium on some biochemical responses of Vigna unguiculata and Zea mays to water deficit condition and rehydration
The influence of zinc and selenium on some biochemical responses (lipid peroxidation, ascorbate, glutathione, growth rate, mineral content, catalase and glutathione peroxidase activities) of cowpea and maize seedlings to water deficit condition and rehydration were investigated. Plants seedlings were exposed to water deficit condition for 14 days. The relative water content in whole plant tissues was reduced from 78.6% (control) to 50.0% (water deficit) and 70.1% (control) to 37.3% (water deficit) for cowpea and maize samples respectively. Selenium-treated samples showed higher RWC values for both normal and water deficit samples. Under water deficit conditions, general increase in the levels of the biochemical parameters was recorded. Effects of water deficit were more pronounced on the maize samples than cowpea. At P<0.05, water deficit samples showed significant increase in MDA levels and antioxidant enzymes activities; the activity of selenium in reducing water deficit effects reached statistical significance and was also found remarkable due to its non-accumulation in the plant samples. In this present investigation, water deficit induced 7 times, 10 times and 12 times increases in the Fe, P and N contents respectively of water deficit cowpea samples. The water deficit maize samples also showed 6 times and 5 times levels of P and N respectively. Water deficit cowpea sample treated with selenium once weekly (WOS) returned back to full turgor after 6 days of rehydration with water. Rehydration caused significant reductions in MDA levels and antioxidant enzymes activities. The use of antioxidant chemicals particularly selenium is therefore recommended in this study to farmers that reside in the zone of short term drought.
KEYWORDS: selenium, zinc, growth rate, mineral