Responses of root morphology and architecture to phosphorus deficiency at seedling stage of tobacco (Nicotiana tabacum) growth

Plant root has various responses under a low phosphorus (P) status, but knowledge on enhancing root development in tobacco is limited. The aim of this study was to investigate responses of root morphology and architecture of tobacco to different P application levels (0, 0.002, 0.02, 0.2, 2 m mol L-1, at early seedling stage; 0.05, 0.1, 0.2, 1.0, 10 m mol L -1 at later seedling stage). Two varieties, XiangYan No.4 and K326, were used in water culture with complete nutrient solution (Hoagland’s solution). Results indicated that P deficiency can enhance the lateral root development of tobacco, and thus may be useful in breeding developed tobacco with stronger root system. At early growth stage (within 30 days), 5-fold diluted Hoagland nutrient solution was selected as culture solution. P deficiency of 0.02 m mol L can enhance the development of tobacco root hairs, while P deficiency can cause decline in taproot elongation. At later seedling stage (31 days 75 days), P deficiency concentration with 0.1 m mol L was more likely to improve root growth under normal Hoagland nutrient solution condition, mainly by enhancement of lateral root development. In brief, compared with normal P concentration treatment (1 m mol L), P deficient concentrations with 0.02 m mol L and 0.1 m mol L can effectively promote development of tobacco roots at early and later seedling stages, respectively.