Effect of Increasing Concentration of Bicarbonate on Plant Growth and Nutrient Uptake by Maize Plants

摘要

Increasing concentration of HCO_3" ions in the nutrient medium progressively decreased the growth of maize plants as measured by decrease in shoots and root weight, these effects becoming more distinct with time, particularly at the two higher levelsof bicarbonate supply (10 and 20 mM). Various parameter of growth including plant height, root and shoot measurements, nutrient composition of shoots and roots and nutrient uptake were all affected in this manner as was also the appearance of iron chlorosis. In the cation-anion balance data of the roots and shoots, mineral cation totals exceeded anion totals for each HCO_3" treatment and in the same pattern was observed in the roots with high concentration levels, but it was more pronounced in the excess of Ca~(2+) in the roots. These high Ca~(2+) values suggest that the Ca~(2+) may not have been taken up but rather accumulated on the root surface. Therefore, the specific effect on roots and shoots growth as compared with control may be due to inhibited respiration caused by high levels of bicarbonate treatments.