The Influence of High pH on Maize Growth and Utilization of Micronutrients under Various Concentrations of Bicarbonates

摘要

Increasing concentration of bicarbonate ions in the nutrient medium markedly decreased dry weight of shoots and roots of maize plant. These effects becoming more distinct with time, particularly at the two higher levels of bicarbonate supply (10 and 20 mM). Micronutrients composition of Fe, Cu and Zn in shoots and roots of maize plants were all affected in this manner as was also the appearance of iron chlorosis. Maximum reduction of the concentration of these elements (Fe,Cu and Zn) in shoots was recorded at (20 mM) HCO3 - treatments by 45.9%, 78.4% and 80.8% respectively as compared with control. FeIII - reduction activity was decreased sharply on root intact plants by increasing HCO3 level of treatments. This inhibition was obtained - as soon as day 2 and by day 8, the inhibitory effect was more pronounced with bicarbonate treatments. In contrast, the enzyme of phosphoenolpyruvate carboxylase (PEPC) - activity was highly increased on roots after 2 and 8 days of all HCO3 treatments supply. At day 8 the activity of PEPC in the roots of HCO3 treatments - - (10 and 20 mM) was more than double that of the control.