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Effects of simulated karst soil habitat stresses on photosynthetic characteristics and dry matter allocation of Robinia pseudoacaciaseedlings.

HANG Hong-tao1,2, WU Yan-you2*, ZHANG Kai-yan1,2, TAN Dai-jun1, LU Na-na1, MIN Xiao-ying1, GUO Tao1, CHEN Lei1   

  1. (1State Engineering Technology Institute for Karst Desertification Control, School of Karst Science, Guizhou Normal University, Guiyang 550001, China; 2State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China).
  • Online:2019-09-10 Published:2019-09-10

Abstract:

To explore the adaptability of Robinia pseudoacacia to different karst environments and its configuration in ecosystem construction, four kinds of karst soil habitat stresses, including drought, highcarbonate, lownutrient, and phosphorusdeficiency, were artificially simulated under indoor hydroponic experiment. We measured the photosynthetic characteristics, carbonic anhydrase activity, δ13C value and dry matter allocation of seedlings under different karst habitat stresses. The results showed that under  drought environment, the seedlings of R. pseudoacacia were the most sensitive and inhibited in the short term (10 days). Although the rootshoot ratio and water use efficiency were increased, the seedlings could survive in a longer term (20 days). Under the high bicarbonate environment, R. pseudoacacia seedlings increased the utilization of HCO3- by increasing the activity of carbonic anhydrase due to the decrease of stomatal conductance, thereby improving dry matter allocation to stems and leaves and maintaining normal growth for a longer term. Under low nutrient environment, stomatal factor was the main limitation for the growth of R. pseudoacacia in a short term (10 days). R. pseudoacacia increased the utilization of HCO3- in the solution by increasing the activity of carbonic anhydrase in the longer term (20 days), and increased dry matter allocation to roots. However, the growth was still limited by the concentration of inorganic elements in the solution. Under phosphorusdeficient environment, the R. pseudoacacia seedlings increased the utilization of HCO3- in the solution by up-regulating the activity of carbonic anhydrase, increased dry matter allocation to roots, and maintained the high growth capacity. The adaptation strateiges of R. pseudoacacia seedlings differed under different karst environments. The results of comprehensive evaluation showed that the adaptation of R. pseudoacacia to four simulated karst soil stresses was in the order of high carbonate, phosphorus deficiency, low nutrition, and drought.