ABSTRACT
Objective: The moisture content in the soil directly affects the yield and quality of Panax notoginseng, especially at the age of three years old. However, the suitable moisture for the growth of P. notoginseng is unknown. In this study, the effects of different soil moisture on the growth of P. notoginseng were studied. Methods: Four different water treatments (0.45 field capacity (FC), 0.60 FC, 0.70 FC, and 0.85 FC) were set up in Shilin County, Yunnan Province, China. The water consumption and daily dynamic of water consumption were determined daily (from April 21 to October 18, 2012), and the daily dynamic of water consumption under different weather conditions (sunny and rainy) was determined. The transpiration coefficient and water use efficiency were calculated through dry matter accumulation and total water consumption. Accumulation of saponins of roots of P. notoginseng were analyzed by HPLC after treated, and the soil moisture content suitable for the growth of P. notoginseng was estimated by regression fitting of the active ingredient accumulation and the soil moisture content. Results: The water consumption of 0.85 FC, 0.70 FC, 0.60 FC and 0.45 FC were 2.89, 3.68, 3.37 and 2.73 kg/plant per day, respectively. The water consumption of P. notoginseng from June to August was greater than other months. The daily dynamic of water consumption on sunny days and sunny days after rain showed a “double peak” feature, and it showed a “single peak” feature on rainy days. The water uses efficiency (WUE) of 0.85 FC, 0.70 FC, 0.60 FC and 0.45 FC were 2.51, 3.32, 4.59, 3.39 gDW/kg H
ABSTRACT
In this study, Andrographis paniculata seedlings were used as experimental materials to study the effects of salicylic acid(SA) on the growth and effective component accumulation of A. paniculata under NaCl stress. The results showed that with the increase of NaCl concentration, the growth of A. paniculata seedlings was significantly inhibited, and the content of carotene and carotenoid decreased. The activity of antioxidant enzyme was enhanced. At the same time, the contents of proline, proline and soluble protein were on the rise. The contents of andrographolide, new andrographolide and deoxyandrographolide showed an upward trend, while deoxyandrographolide showed a downward trend. Treatment with 100 mmol·L~(-1) NaCl+5 mg·L~(-1) SA showed a significant increase in antioxidant enzyme activity in A. paniculata leaves. Treatment with 100 mmol·L~(-1) NaCl+10 mg·L~(-1) SA showed significant changes in soluble protein and proline content in A. paniculata leaves, while MDA content in A. paniculata leaves significantly decreased. 10 mg·L~(-1) SA had the best effect on the growth of A. paniculata seedlings under salt stress. Under the treatment of 50 mmol·L~(-1) NaCl+10 mg·L~(-1) SA, fresh weight, dry weight and leaf dry weight of A. paniculata seedlings reached the highest level, which were 1.02, 1.09 and 1.11 times of those in the control group, respectively. The concentrations of NaCl and 10 mg·L~(-1) SA were significantly higher than those of the control group. Four key enzyme genes of A. paniculata diterpene lactone synthesis pathway were selected to explore the molecular mechanism of salicylic acid to alleviate salt stress. With the increase of salt stress, the relative expressions of HMGR, GGPS and ApCPS were up-regulated, indicating that salt stress may enhance the synthesis of A. paniculata diterpene lactone through MVA pathway. SA can effectively promote the growth and development of A. paniculata under salt stress, improve its osmotic regulation and antioxidant capacity, improve its salt tolerance, and alleviate the effects of salt stress on A. paniculata.