中文摘要：

为了揭示自然条件下不同种源油松光合特性的差异，为优良种源选择提供依据，在黄土高原种源实验地，对5个油松种源（陕西洛南LN，陕西黄陵HL，山西吕梁山LL，山西灵空山LK，辽宁千山QM）幼苗的光合生理特征及其与环境因子的关系进行了研究。结果表明：5个油松种源的净光合速率（Pn）呈双峰型，蒸腾速率（Tr）、气孔导度（G8）亦基本呈双峰型，第1峰值均出现在上午8：00，有明显的光合午休现象。种源QM的水分利用效率（WUE）日变化呈单峰性，峰值出现在10：00，而种源LN、LL、LK和HL呈双峰型，第一峰值出现在8：00，第二峰值出现在12：00～16：00。种源LN、LL、LK和QM午间净光合速率的下降主要由气孔因素引起的，而种源HL则主要由叶肉细胞同化能力的降低引起的。种源LK的日均Pn、Tr和WUE均高于其他种源，是高光合、高蒸腾和高水分利用效率的种源，而种源HL属于低光合、低蒸腾和低水分利用效率的种源。Ta是影响各种源的Pn的首要因子，其次是VPD；RH是影响种源LN、LL和LK的r，r的首要因子；而L和VPD是影响种源HL和QM的r的主要因子。

英文摘要：

In order to reveal the photosynthetic characteristic variations of different provenances and provide the theoretical basis for the work of provenance selection, the seedlings of Chinese pine （Pinus tabulaeformis Carr. ） from five provenances, including provenances Luonan （LN） and Huangling （HL） from Shaanxi, Lvliang Moun- tain （LL） and Lingkong Mountain （LK） from Shanxi and Qian Mountain （QM） from Liaoning were planted in Loess Plateau. The photosynthetic parameters and their correlations to environmental factors were studied with Li- 6400 portable photosynthesis system under natural condition in order to reveal the mechanism of adaptation of dif- ferent provenances. The results indicted that the diurnal dynamics of net photosynthetic rate （Pn）, transpiration rate （Tr） and stomatal conductance （Gs ） for five provenances were double-peak curves with obviously midday depression in Pn The water use efficiency （WUE） of porvenance QM had only one peak, while those of prove- nances LN, LL, LK and HL had two peaks. The first peaks for all provenances occurred at 8：00 or 10：00, and the second peaks of provenances LN, LL, LK and HL occurred between 12：00 and 16：00. Based on the tenden- cy of changes in Pn, Gs, intercellular CO2 concentration （ Ci ） and stomatal limitation （Ls ）, we speculate that the midday depressions of provenance HL was not controlled by stomatal factors, while those of the other four provenances were. The daily mean values of Pn, Tr and WUE for provenance LK was the highest and those for provenance HL was lower than the other provenances. The correlation analyses showed that the main factors af-fecting Pn were air temperature （ Ta） and vapour pressure deficit （VPD）. The main factor affecting Tr was rela- tive humidity （RH） for provenances LN, LL and LK, while for provenances HL and QM, the main factors were Ta and VPD.