不同磷营养水平对烟草叶片光合作用和光呼吸的影响(英文)

研究了不同磷营养水平(0,1/4,1/2,1,2 P)对烟草(Nicotiana rustica L.)叶片光合、光呼吸、乙醇酸合成和乙醇酸氧化酶活性的影响,结果如下; 光合强度在0～1P范围内随磷水平的提高而增高,但在2P水平中略为下降。光呼吸强度在1/4～2P范围内与光合强度有相同的变化趋势,但在磷水平为零时最高;光呼吸/光合比值亦在磷水平为零时最高,并随磷营养的增加而下降。 HPMS抑制乙醇酸氧化酶活性,乙醇酸的积累量随磷水平的变化与光呼吸有一致的趋势。 在加入FMN时,不同磷营养水平的烟草叶片中乙醇酸氧化酶的活性随磷水平的提高而下降;加入FMN对酶活性的促进作用亦随磷水平的提高而下降。 叶片无机磷、有机磷及总磷含量均随磷营养水平的提高而增加。 用不同浓度的磷酸盐溶液真空渗入在1P培养的烟草叶圆片,并在0.25,0.5,10mmol/LNaHCO_3溶液中测定光合和光呼吸,结果表明在0.25和 0.5mmol/L NaHCO_3中,光呼吸随磷浓度的增加而下降;在 10mmol/L中光呼吸完全受抑制。光合作用与磷浓度关系呈单峰曲线,随着NaHCO_3浓度的提高,其高峰位置向右移,即光合最适磷浓度增大。 根据试验结果及从化学计量学推算,认为磷营养有抑制光呼吸的作用,而光呼吸的运转则有补充叶绿体内进行光合作用所需的无机磷的功能。

Effects of Phosphorus Nutrition on Photosynthesis and Photorespiration in Tobacco Leaves

Tobacco plants were grown in vermiculitein pots with Hoagland's solutions containingfive levels (0, 1/4, 1/2, 1, 2) of phosphate nutri-tion. Photosynthesis was ehhanced when phos-phate level was raised from 0 to 1 P level, butdecreased slightly at 2 P level. Photorespirationchanged in parallel to photosynthesis in the ran-ge of 1/4-2 P levels, but had its highest ratioat 0 phosphate level. The ratio of photores-piration/photosynthesis decreased with an inc-rease of phosphate nutrition. Glycolate formation in tobacco leaves res-ponded to phosphate nutrition as photorespira-tion did. Glycolate oxidase activity was lowerin leaves at 0 level of phosphate nutrition, roseat 1/4 P level and decreased at higher phosphatelevels. The addition of FMN to the assay me-dium greatly enhanced glycolate oxidase acti-vity in phosphate deficient leaves. Infiltrating phosphate solutions of differentconcentrations into tobacco leaf disks showedthat photorespiration was reduced with an inc-rease of phosphate concentration. Basing on the experimental evidences ahypothesis is advanced that photorespirationhas the important function of supplementingphosphate for photosynthesis in the chloroplasts.