Abstract:
Excessive irrigation and fertilization in the traditional planting of Panax notoginseng have often caused the direct waste of water and fertilizer resources, high incidence of diseases, the decline in quality and yield, even environmental pollution. These also limit the sustainable development of Panax notoginseng planting in modern agriculture. In this study, an optimal coupling scheme of water and fertilizer was therefore proposed to realize green production of Panax notoginseng using yield, quality, and use efficiency. Three irrigation levels (low water W1:0.5 of field capacity, medium water W2:0.7 of field capacity, high water W3:0.9 of field capacity) and four fertilization levels (Annual fertilizer application was 1 440 kg/hm2. According to the different fertilization ratios in each breeding period, set as F1 (the ratio of seedling period: flowering period: fruiting period: root weight gaining period is 25%: 25%: 25%: 25%), F2 (25%: 30%: 25%: 20%), F3 (30%: 30%: 25%: 15%) and F4 (40%: 20%: 30%: 10%) were set up with two-year-old Panax notoginseng as experiment materials in a field experiment. Each treatment was performed on two field blocks, each of which was about 15 m long and 2 m wide. The surface of the block was covered with 5mm thick pine needles, where the blocks were separated by plastic films buried underground to prevent the cross penetration of water and fertilizer. An analysis was made to clarify the effects of water and fertilizers, and their coupling effects on the yield, quality, and Water Use Efficiency (WUE) and Partial Factor Productivity of Fertilizer (PFP) of Panax notoginseng. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was also used to evaluate the comprehensive quality of saponins content. A scoring method was applied to evaluate the comprehensive performance in the growth and management model of each treatment. The results showed that the appropriate increases in the water stress and fertilizer during the seedling and fruit periods were beneficial to improve the yield, the content of notoginseng saponins, but reduce the incidence of disease. Nevertheless, the low-water treatment was not conducive to the yield, whereas, high-water treatment was not conducive to the quality of Panax notoginseng. More importantly, the greatest impact of irrigation presented on the WUE during the growth period, while the fertilization in different proportions performed the greatest impact on PFP. The effects of Panax notoginseng quality were ranked in the order of water and fertilizer coupling, moisture, as well as fertilizer. Additionally, the accumulation of notoginsenoside R1, ginsenoside Rg1, ginsenoside Re and ginsenoside Rd treated with W2F4 were significantly higher than others among the five saponins. Specifically, the content of notoginsenoside R1 treated with W2F4 was the highest, while the content of ginsenoside Rb1 treated with W1F4 was the highest. In comprehensive scoring, the W2F4 treatment presented the highest comprehensive score, where the incidence rate was 12.97 %, the yield was 2 976.42 kg/hm2, WUE was 1.65 kg/m3, and PFP was 1.09 kg/kg. The W2F4 treatment also scored the highest of 0.815 in the TOPSIS quality analysis. Consequently, the optimal mode of coupling between variable fertilization at different growth stages and irrigation was achieved, where the irrigation level of 0.5 FC, the fertilization ratio in the seedling, flowering, fruiting, and root gaining period of 40%: 20%: 30%: 10%. The finding can provide a strong theoretical basis and technical reference for the formulation of irrigation and fertilization system during Panax notoginseng planting.