Growth Traits of Torreya grandis ‘Merrillii’ and Polygonatum cyrtonema under Different Canopy Density

In 2009, Torreya grandis ‘Merrillii’ grafted seedling were planted in Songyang, Zhejiang province. In October 2018, intercropping of Polygonatum cyrtonema under T. grandis ‘Merrillii’ stand was carried out with canopy density of 0.5, 0.7 and 0.9. In August and October 2019, determinations were implemented on growth traits of T. grandis ‘Merrillii’ and P. multiflorum, and on soil traits. The results showed that under 0.7 canopy density, growth of shoot, ground diameter, tree height, crown width and yield of T. grandis interplanted with P. multiflorum were 18.97%, 14.18%, 24.55%, 20.79% and 40.00% higher than CK (no interplanting), and P. multiflorum had the best growth under this canopy density, as well as the comprehensive benefit of interplanting stand. The soil pH, contents of organic matter, total nitrogen, alkali hydrolyzable nitrogen, total phosphorus and available potassium in interplanting stand increased by 12.73%, 52.86%, 77.30%, 96.90%, 88.24% and 27.57% than that in the control, while the contents of soil available phosphorus and total potassium decreased by 18.50% and 24.57%. The experiment demonstrated that interplanting could improve soil nutrient content and pH of the stand.