Growth response of wheat roots to phosphorus deficiency

Study on the plastic response of wheat (Triticum aestivum L.) root growth to P-deficiency has revealed. There were significant negative linear relationships between the length of root axis and internal or external P concentration of plant. The result of root-split experiment showed that the growth of root axis was regulated by internal rather than external P concentration of plant tissue. The internal P concentration of the plant changed after plant being treated for 1 day. However, significant difference in the length of noot axis in response to different levels of P supplement occurred on the eighth day after treatment. This suggested that the change in internal P concentration of plant may be the primary response to phosphorus deficiency. In concurrence zinc concentration in shoot and IAA concentration in the whole plant increased with the decrease of P supply. The increased IAA in root promoted the growth of root axes and the initiation of lateral roots, induced the expression of cyclin gene cyclAt and subsequently the division of meristematic cells with consequent speeding up the root extension.