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| Photosynthetic characteristics of Amorpha fruticosa L. and environmental factors on the artificial slope of highway |
| Zhao Bin1,2, Wang Yingyu1, Song Guilong2 |
| 1. Beijing Shoufa Tianren Ecological Landscape Co. , Ltd. , 102600, Beijing, China; 2. Institute of Turfgrass Science of Beijing
Forestry University, 100083, Beijing, China |
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Abstract The diurnal variations of Pn or Tr of Amorpha fruticosa L. on different aspects of artificial slope were studied under natural conditions by Li -6400 photosynthesis analyzer. The result showed that the
mainly factors affecting the growth of A. fruticosa at highway artificial slope were PAR, atmospheric CO2 concentration, relative atmospheric humidity on sunny days of July, and PAR was the primary factor that affected photosynthesis on different slope aspects, the highest solar radiation and the daily average solar radiation in shady slopes were both lower on shady slopes than on sunny slopes. The diurnal variation in different slope directions varied, with the range of variation larger on sunny slopes. The varying time of environmental factors on the shady slopes was two hours later than on the sunny slopes. The lowest point of relative atmospheric humidity appeared two hours later on shady slopes. The atmospheric CO2 concentration on shady slopes on shady slopes was higher than that on sunny slopes all day long. The stomatal conductance of A. fruticosa in different slope directions had the same trend of variation, showing bimodal curves, but without obvious midday depression. The water utilization in different slope directions varied: the water utilization on shady slopes was higher in the morning, while on the sunny slope it was higher in the afternoon. This indicated that, in practice, irrigation on highway artificial slopes should take into account the different aspects of site conditions, which plays an important role in water utilization and water loss reduction. In this study, the photosynthesis characteristics of A. fruticosa in different slope directions were different, and there were no obvious higher growth and water consumption on sunny slope (photosynthetic rate 6.57 μmol·m-2·s-1, and transpiration rate 3.3 mmol·m-2·s-1 ). Different correlations could be found between photosynthetic rate and environmental factors in different slope directions. The stomatal conductance, light intensity and net photosynthetic rate on sunny slopes showed a significantly positive correlation, while there existed a significantly negative correlation between the relative atmospheric humidity and net photosynthetic rate. Stomatal conductance plays a major role among the environmental factors on the highway artificial slopes. Shady slope had a highly significant, positive
correlation with the light intensity, and a significantly positive correlation with vapor pressure deficit, and light intensity was the main reason that affected photosynthetic rate on shady slopes. The relation between Pn of A. fruticosa and environmental factors in the artificial slope was constructed as YsunnyPn = -0.428 +45.913XGs + 0.003XPAR (R2 = 0.965, P<0.05), YshadyPn = 0.761 + 0.005XPAR (R2 = 0.852, P <0.05). Our research also showed that photosynthetic rate of the plants had different correlations with the environmental factors under the unique conditions on the highway artificial slope. The relationship between growth of plants in vegetation restoration and the unique environmental factors of highway artificial slopes still need further research.
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Received: 22 August 2014
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