万寿菊-烤烟间作密度对根结线虫防治及烟叶品质的影响OA

To elucidate the regulatory mechanism of intercropping density on the allelopathic effects and ecological func-tions of marigold,and to establish an optimized model for'disease control,quality improvement,and efficiency enhance-ment',Nicotiana tabacum cultivar Yunyan87 was used as the material.Five intercropping density ratios of marigold to flue-cured tobacco(4∶1,5∶1,6∶1,7∶1,8∶1)were set as treatments BW1,BW2,BW3,BW4,and BW5,respectively,with no marigold intercropping as the control(ck).Agronomic traits,enzyme activities,economic indicators,and nematode control efficacy were measured,combined with root exudate analysis,soil microbiome sequencing,and canopy spectral imaging.The results showed that in the BW3 treatment,the secretion of root α-terthienyl increased by 152％,actinobacterial abun-dance increased by 698％,and the incidence of nematode disease was synergistically reduced by 78.9％.Canopy photosyn-thetic active radiation utilization efficiency increased by 18.6％,and the proportion of deep roots of tobacco plants in-creased by 32％.The land equivalent ratio reached 1.28,the carbon footprint was reduced by 0.38 tCO2e,and the output value was 100 591 yuan/hm2.Therefore,a density-dependent mechanism of'allelochemical activation,microbial prolifera-tion,and resource complementarity' is proposed,with a 6∶1 intercropping density ratio of marigold to flue-cured tobacco identified as the optimal solution.