半干旱黄土丘陵区4种天然次生灌木光合生理和水分利用特征

Three-year old shrub species of Rosa xanthina, Caragana korshinskii, Prunus davidiana and Prunus sibirica in a semi-arid loess hilly region were selected as the experimental material for comparing physiological characteristics, such as photosynthesis, transpiration, water use efficiency, and etc. The results indicated that the non-rectangular hyperbola model could well simulate the photosynthesis-light response curves, with R~ 2 over 0.98. There were significant differences in the photosynthetic capacity, apparent quantum yield（AQY）, dark respiration rate（R_ d ）, light compensation point（LCP）, light saturation point（LSP）, transpiration rate（T_ r ） and water use efficiency（WUE） among four shrubs species. The four species displayed different photosynthetic performance in the same environment. The capacity of C. korshinskii was 1.7 times of that of R. xanthina, and 1.44 times of that of P. sibirica. C. korshinskii had the highest ability to use low light, and its AQY was 0.0765, and those of the other three species were among ordinary species. The consumption of photosynthetic products of C. korshinskii was the highest and its metabolism was the most active. R. xanthina. and P. davidiana had relatively higher shade-tolerance, though these four species were photophilous. The sequence of water consuming ability by transpiration was in an order of C. korshinskii>R. xanthina>P. sibirica.>P. davidiana. The water consuming ability of R. xanthina, P. sibirica, P. davidiana did not show significant correlation with meteorological factors. P. sibirica had the highest water use efficiency, and C. korshinskii and P. sibirica had little discrepancy in WUE, but both were obviously higher WUE than R. xanthina. In summary, P. davidiana and P. sibirica have higher development potential in the region, while C. korshinskii, which had higher photosynthetic ability, transpiration and water use efficiency, is the most suitable shrub species for afforestation. The photosynthetic ability and water use efficiency of R. xanthina were lower, and the species is not feasible for artificial plantation in large area.