Phosphorus deficiency enhances root exudation of low-molecular weight organic acids and utilization of sparingly soluble inorganic phosphates by radish (Raphanus sativus L.) and rape (Brassica napus L.) plants.

摘要

Root exudates were collected from radishes and rape grown in P-sufficient and P-deficient nutrient solution. In radishes, tartaric, malic and succinic acids were the dominant organic acids which increased between 15-fold (succinic acid) and 60-fold(malic acid) under P-deficient conditions. In another experiment in quartz sand culture supplied with either Ca3(PO4)2 or AlPO4 radish utilized P from AlPO4 more effectively than from Ca3(PO4)2 whereas the opposite was true for rape. The results demonstrated the role of a particular organic acid in mobilizing sparingly soluble P and were in accordance with the preferential growth of the two crops on acid (radish) and calcareous (rape) soils in China.