Effects of bicarbonate on growth and zinc nutrition of different wheat genotypes

Zinc deficiency of wheat plants in calcareous soil area is widespread throughout the world, and high bicarbonate concentration has been regarded as a major influencing factor. In this study, a soil pot experiment was conducted to investigate the influence of bicarbonate (HCO3-) on growth of wheat plants and zinc nutrition with three different wheat genotypes (Zhongyu6, S02-8, Yuanfeng998), which have different sensitivity to Zn deficiency. The results indicated that wheat growth (especially roots) and zinc uptake were inhibited under the condition of high concentrations of HCO3- solution, and the negative effect was more obvious under relatively low concentration HCO3- (15 mmol/L) than that of higher one (30 mmol/L). Under the conditions of high HCO3- concentration (30 mmol/L), the available Zn content in soil and the translocation ratio of Zn from root to shoot was decreased by 11.1% and 5.0%, respectively. The results suggest that the negative effects of HCO3- on Zn nutrition of wheat plants was caused by three reasons: firstly, bicarbonate caused the immobilization of Zn in soil; secondly, it inhibited root growth of wheat plants; thirdly, it decreased the translocation of Zn from root to shoot, and the first and second causes were probably major influencing factors. In conclusion, the effects of HCO3- on growth and zinc uptake of three genotypes of winter wheat plants tested was not as serious as expected, and this is perhaps because these wheat genotypes have high tolerance to high concentrations of bicarbonate.