Screening Chinese Wheat Germplasm for Phosphorus Efficiency in Calcareous Soils

Abstract

Twenty commonly used winter wheat genotypes collected throughout China were used in field screening for phosphorus (P)-efficient germplasm in a calcareous soil with and without fertilizer P application; the same genotypes were also evaluated for high and low P inputs in a greenhouse experiment. The overall criterion for P efficiency was the capacity to produce a relatively high yield with low P availability. Significant differences in grain yield production occurred between efficient and inefficient genotypes. Four parameters were calculated to determine which was the most useful for describing P efficiency: (1) percentage of relative yield with no applied P; (2) total P uptake; (3) P-harvest index (PHI: grain P/total P uptake); and (4) P-utilization efficiency (PUE: grain yield produced per unit of P taken up). A simple but satisfactory criterion in screening P-efficient wheat genotypes, 85% of relative grain yield at low P/high P, was recommended and proved to be more effective than the other three parameters. With this criterion, 12 out of 20 genotypes were classified as P-efficient (≤ 15% yield reduction with no P applied) from both field and pot experiments. Phosphorus efficiency may have resulted from either P uptake or P-utilization efficiency. Three parameters, namely relative yield without applied P, PHI and PUE, were found to be useful, together with P uptake, in determining overall P efficiency. Successful selection for P efficiency was found to be possible at the shooting stage (but not at tillering) by comparing P uptake and P-utilization efficiency of plants at this growth stage with those of plants at maturity.

Keywords:

• P uptake
• P harvest index
• P utilization efficiency
• relative yield

ACKNOWLEDGMENTS

This work was funded by the National Natural Science Foundation of China (Project No. 39790100). We thank numerous colleagues in the Research Center for Eco-Environmental Sciences and the Institute of Genetics, Chinese Academy of Sciences, for technical assistance.

Notes

^aGrain P uptake + straw P uptake, mg pot^{− 1}.

^bGrain DM yield/(grain P uptake + straw P uptake), g DM g^{− 1} P.

^cRatio of grain P uptake/(grain P uptake + straw P uptake).

^aGrain P uptake + straw P uptake, mg pot^{− 1}.

^bGrain DM yield/(grain P uptake + straw P uptake), g DM g^{− 1} P.

^cRatio of grain P uptake/(grain P uptake + straw P uptake).

*Significant at P < 0.05

**Significant at P < 0.01 (n = 20).

r_yxi = correlation coefficient between Yi and Xi.

Sy = standard deviations for Xi and Yi, respectively.

The proportion of the sum of squares for Y attributable to Xi is ∑ X_iY/∑ Y² = (r_yxi) Sxi/Sy.

*Significant at P < 0.05

**Significant at P < 0.01.

P-utilization efficiency at shooting stage represents DM produced by per g of P taken up.

*Significant at P < 0.05

**Significant at P < 0.01 (n = 60).