Growth responses of Stylosanthes guianensis ‘Reyan No. 2’ to root exudates from different relatives

Plants communicate with each other and cooperate or compete with their relatives through identity recognition. The aim of this study was to clarify the identification differences of Stylosanthes guianensis ‘Reyan No. 2’ on root exudates of different plant relatives. In this study, the effects of root exudates from S. guianensis ‘Reyan No. 2’ itself and its close and distant relatives on seedling growth of this taxa were studied. This was undertaken by culturing them in seven nutrient solutions containing root exudates of different relatives of Stylosanthes. Results showed that the average values of lateral root number, total biomass, stem leaf biomass, and root biomass (fresh weight) in the close relative treatment group were significantly higher than those in the self root exudate treatment group (P < 0.05). For the self-treatment group, the average values of lateral root number and root biomass increased by 250.00% and 41.85%, respectively. Meanwhile, the average values of plant height, root length, and root-shoot ratio were not significantly different (P > 0.05). Compared with the self-treatment group, the average values of root length, lateral root number, root biomass, and root-shoot ratio in the distant treatment group significantly increased (P < 0.05). In this group, plant height significantly decreased by 10.52% (P < 0.05). There were differences in the specific response results for each species/variety in the close relative and distant relative treatment groups. Grey correlation analysis showed that the response of S. guianensis ‘Reyan No. 2’ to the root exudates of seven Stylosanthes species was ranked as follows: S. hamata > S. guianensis ‘Reyan No. 24’ > S. gracilis > S. scabra ‘Seca’ > S. grandifolia > S. guianensis ‘Reyan No. 5’ > S. guianensis ‘Reyan No. 21’. It is suggested that kin recognition is an important mechanism for the competition and interaction between Stylosanthes and neighboring plants. In production, it is possible to develop new technologies for forage mixed sowing and increase forage yield per unit area by mixing Stylosanthes species with close relatives, such as mixed planting S. guianensis ‘Reyan No. 2’, S. guianensis ‘Reyan No. 5’, and S. guianensis ‘Reyan No. 21’.