monoculture of tobacco
The experiment included four treatments with different cropping system: (1) CKY, monoculture of tobacco (Nicotiana tabacum, K326); (2) BY, tobacco relay intercropping with cabbage (Brassica oleracea L.); (3) LY, tobacco relay intercropping with Chinese cabbage (Brassica campestris L.); (4) WY, tobacco relay intercropping with pea (Pisum sativum L.).Each experimental plot was 240 m2 (30 m× 8 m), and randomized blocks with three replications.