Comprehensive evaluation of reduced obstacles of continuous cropping of Panax notoginseng using TOPSIS-RSR analysis

Panax notoginseng, a species of Araliaceae family and panax genus, is a perennial crop cultivated under no-tillage and shaded conditions in warm and damp environments. Because of years of large-scale monoculture of this crop, the ecological environment of P. notoginseng rhizosphere soil has deteriorated due to severe continuous cropping obstacles. Previous studies noted that autotoxins adsorption, soil sterilization, balanced fertilization, soil amendments and other technical measures or the combination of these measures had the potential to improve soil micro-ecological environment to varying degrees which promoted growth or yield of P. notoginseng. However, relevant studies on how to scientifically evaluate the effects of these measures, comprehensively compare the differences among different measures and screen out the most effective mitigation measures were still highly limited. The improved TOPSIS method combined with RSR method was used in this study to screen out the most effective mitigation measures. An experiment was conducted to screen effective technical measures for reducing the obstacles of continuous cropping of P. notoginseng. The eight indicators — including emergence rates (reflecting emergence conditions), survival rates (reflecting survival conditions), and above-ground and belowground fresh weight, dry weight and total dry weight (reflecting growth conditions) of P. notoginseng in 67 treatments — were used in TOPSIS and RSR analyses to comprehensively evaluate the reducing effects of soil amendments, organic compounds, beneficial microorganisms and other technical measures and combinations of these on the obstacles of continuous cropping of P. notoginseng. The evaluation results showed that treatments such as soil disinfectant + beneficial microorganisms + organic fertilizer (WY) and soil disinfectant + soil amendments + beneficial microorganisms (WX) and other measures increased emergence and survival rates of continuously cropped P. notoginseng, and promoted growth of P. notoginseng, increased dry matter accumulation and effectively reduced the effects of the continuous cropping obstacles of P. notoginseng. TOPSIS and RSR analyse results were strongly consistent and therefore suitable for evaluating the reducing effects of on the obstacles of continuous cropping of P. notoginseng. The effective measures reducing the obstacles of continuous cropping of P. notoginseng included WY7 (4 500 kg·hm^-2 lime + 22 500 kg·hm^-2 pig manure), WX9 (4 500 kg·hm^-2 lime + 675 kg·hm^-2 bio-fertilizer + 4 500 kg·hm^-2 carbon powder), etc. The orders of effects of other treatments were also consistent with the pot experiment, suggesting that TOPSIS analysis combined with RSR analysis increased the accuracy of evaluation and was therefore suitable for screening effective measures reducing the obstacles of continuous cropping of P. notoginseng.