RAO Sen1,2，WU Yanyou1
(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract: The objective of this paper is to study the effect of slope location on the differentiation of water regulation, photosynthetic capacity and morphology in Platycarya longipes grown in karst habitat. Soil characteristics, physiological and biochemical indexes, and morphological traits were investigated. Results showed that: (1) soil water content and soil organic matter of the middle slope were 94.73% and 81.96%, respectively, which were higher than those in the upper slope. The content of available phosphorus in the middle slope was higher than that in the upper slope. No significant difference was observed in the content of total nitrogen and total potassium between two slope locations. (2) Net photosynthetic rate (Pn) of Platycarya longipes in the middle slope was higher than that in the upper slope at the time period of 9:00 to 11:00 and 13:00 to 16:00. The Pn was down-regulated at the noon in both slopes. The highest Pn was found at 10 O’clock with 7.53μmol·m-2·s-1 in the middle slope while 7.03 μmol·m-2·s-1 was measured at 11 O’clock in the upper slope. Transpiration rate (Tr) of Platycarya longipes in the middle slope was higher than that in the upper slope at the time period of 9:00 to 12:00 but lower than that in the upper slope between 12:00 and 15:00. (3) Contents of chlorophyll a (chl a)、chlorophyll b (chl b) and the total chlorophyll of Platycarya longipes in the middle slope were 74.35%、80.89% and 76.57%, respectively, which were higher than those in the upper slope. However, the content of malondialdehyde (MDA) in leaves of Platycarya longipes in the middle slope was lower than that in the upper slope. (4) Leaf length, width and area of Platycarya longipes in the middle slope were higher than that in the upper slope, respectively, but the specific leaf area (SLA) was lower than the latter. Further, the diameter of cone of Platycarya longipes in the middle slope was 2.65±0.16cm, which was 31.48% higher than that in the upper slope. There were 27 more seeds in average in the middle slope than that in the upper slope. In conclusion, soil nutrition in the upper slope was much poorer than that in the middle slope, which meant that soil in the upper slope couldn’t provide enough nutrition for the growth of plants. Moreover, water input and output were well regulated in the middle slope than that in the upper slope. According to the diurnal variation of photosynthesis between two slopes, the middle slope could accumulate much more photosynthetic products.
Key words: slope location; Platycarya longipes; water; photosynthesis; morphology.
EARTH AND ENVIRONMENT Vol.45, No.1 Tot No.315, 2017, Page 10-17
