IRON CHLOROSIS DEVELOPMENT AND GROWTH-RESPONSE OF PEACH ROOTSTOCKS TO BICARBONATE

For dicots, bicarbonate (HCO3-) is regarded as a main factor in the induction of iron (Fe) chlorosis in calcareous soils, and sand and solution culture. In sand culture experiments, peach [Prunus persica (Batsch) L.] rootstock developed chlorosis only when HCO3- levels were equal to or higher than 6 mM. Above this level, chlorosis increaeed as HCO3- level was increased. In spite of the lack of chlorosis at to or below 6 mM of HCO3-, large growth reductions (40-60% reduction in fresh shoot weight) were seen in all rootstocks, although the tolerant rootstock had less reduction than the more susceptible rootstocks. Shoot growth was affected by HCO3- more than was root growth.