HCO3-对不同基因型水稻根生长及养分吸收分配的影响

采用营养液培养法,研究了缺Zn敏感(IR26)和耐性水稻品种(IR8192-31-2)根生长和养分吸收受HCO₃^-影响的差异.结果表明,HCO₃^-(20mmol·L^-1)严重抑制敏感品种根系生长,特别是在低Zn或缺Zn条件下,而对耐性品种影响很小,在低Zn水平下,对根系生长甚至有轻微的促进作用.HCO₃^-不仅抑制敏感品种对Zn的吸收和分配,而且也抑制对Cu、Mn和Fe的吸收,表明HCO₃^-对Zn的吸收无专性抑制作用,HCO₃^-抑制敏感品种根系生长可能是其诱发缺Zn的最初作用.NCO₃^-处理下,耐性品种上位叶和下位叶Zn浓度以及比率高于敏感品种,表明耐性品种将Zn从下位叶向上位叶转运的效率高,Zn在植物体内的转运能力可能是耐性品种适应石灰性土壤缺Zn的主要机制之一.

Effect of HCO3- on root growth and nutrient absorption of different rice genotypes

Solution culture experiments with Zn-inefficient cultivar(IR26)and the Zn-efficient cultivar(IR8192-31-2)were conducted to study the effect of HCO₃^- on the root growth and nutrient absorption of different rice cultivars.The results showed that HCO₃^- strongly inhibited the root growth of Zn-inefficient cultivar especially at low Zn concentration.In contrast,that of Zn-efficienct cultivar was slightly stimulated by HCO₃^- at low Zn concentration.HCO₃^- not only inhibited Zn absorption of Zn-inefficient cultivar,but also inhibited its absorption of Fe,Mn,Cu,implying that there was no specific inhibition of HCO₃^- on Zn absorption.These results demonstrated that the inhibition of root growth by HCO₃^- was likely to be the initial action of HCO₃^- in inducing Zn deficiency in lowland rice.With treatment of bicarbonate,Zn concentrations in upper and lower leaves of the Zn-efficient cultivar and their ratios were higher than those of the Zn-inefficient cultivar.The results showed that the Zn-efficient cultivar could transport more zinc from lower leaves to upper leaves,which might be one of mechanisms that the Zn-efficient cultivar adapted to zinc deficiency in calcareous soil.