Abstract: P distribution and use efficiency in two wheat cultivars, e.g. large-spike cultivar CA9325 and multi-spike cultivar JM2, as affected by P omitting started at jointing and flagging stage were investigated under the controlled conditions, in order to obtain and provide scientific basis for the respective regulatory techniques and get higher yields according to the genetic characters of different wheat cultivars. The results showed that with the prolonged plant growth, the increase of P contents in main shoot, valid tillers and whole plants grown under P-sufficient conditions shown a typical "S" pattern, the peak of the P contents appeared at grain filling stage. In all of the treated plants, P percentage in main shoot to whole plant of both cultivars showed a steady increase. However, it decreased gradually in the invalid tillers and roots, and also in the valid tillers of P-deficient plants in both cultivars; The P content and percentage of P in grains of main shoot in the P-sufficient CA9325 were higher than those in valid tillers; but it was contrary in JM2, because they belonged to different spike types of wheat. P contents in all vegetative organs and glumes in the P-deficient plants were lower than those in the P-sufficient plants. As a result, the percentage of P in grains of main shoot and valid tillers of the P-deficient plants were higher than those of the control plants; At harvest, the grain yields of the P-deficient plants of both cultivars were lower than those of the control plants. In comparison, P uptake efficiency of the P-sufficient CA9325 and P harvest indexes of all treated CA9325 plants were higher than those in JM2. However, P use efficiency of CA9325 was lower than that of JM2. The differences in P use efficiency in plants between the two cultivars were discussed.

Key words: P deficiency, Wheat, P distribution