利用稳定碳同位素比技术与光合速率的测定 ,比较了高、中、低磷素利用效率共 8个小麦品种的水分利用效率 ( WUE)与光合作用特性。土壤干旱条件下 ,叶片宽度和单叶干重显著减少 ,δ13C值提高约 2‰ ,光合速率降低 16%～ 75% ,长期的水分利用效率增大 2 .3～ 3.0μmol/ mmol,因磷效不同而异。高磷效的小麦的δ13C和对 13C的分馏率Δ值较低 ,不论在正常的田间土壤水分或干旱下 ,其瞬时的水分利用效率或长期的水分利用效率皆高于磷效中等或低磷效的品种。正常条件下品种间的光合速率 ( Pn)差别不大 ,干旱下则高磷效品种可保持 68%～ 84 %的 Pn,而低磷效小麦的 Pn 只为其对照的2 5%～ 4 9%。小麦种子的 Δ值与单株籽粒重呈负相关性 ,r2 =- 0 .7184。高磷效的冀 87- 4 617是供试小麦中 Pn 和 WUE最高的品种。 Stable carbon isotope ratios and photosynthetic rate were used to compare the water use efficiency (WUE) and photosynthetic characteristics of 8 wheat cultivars with high, medium and low phosphorus utilization efficiency. Under soil drought conditions, leaf width and single leaf dry weight decreased significantly, δ13C value increased by about 2 ‰, photosynthetic rate decreased by 16% -75%, long-term water use efficiency increased by 2.3-3.0μmol / mmol, Different. The δ13C and 13F fractional Δ values ​​of wheat with high P efficiency were lower than those of P or M under normal field soil moisture or drought conditions, both of which had higher instantaneous water use efficiency or long-term water use efficiency Effective varieties. Under normal conditions, the photosynthetic rate (Pn) of the cultivars was not significantly different, while that of the P-efficient cultivars maintained 68% -84% of the Pn under drought conditions, while that of the P-deficient ones was only 25% -49% of the control %. The Δ value of wheat seed had a negative correlation with grain weight per plant, r2 = -0.7184. High phosphorus efficiency Ji 87- 4 617 is the highest tested Pn and WUE varieties.