The root strategy of the C4 grasses tends to be 'do-it-yourself'

Root resource acquisition strategies play a crucial role in understanding plant water uptake and drought adaptation. However, the interrelationships among mycorrhizal associations, root hair development, and fine root strategies, as well as the disparities between C-3 and C-4 grasses, remain largely unknown. A pot experiment was conducted to determine leaf gas exchange, root morphology, root hair, mycorrhizal fungi, and biomass allocation of three C-4 grasses and four C-3 grasses, common species of grasslands in Northeast China, under the control and drought conditions. Compared to the C-3 grasses, the C-4 grasses increased specific surface area by decreasing tissue density, yet exhibited root hair factor at only 21 % of the C-3 grasses. Under the drought conditions, the C(4 )grasses exhibited more intense and extensive adjustments in root traits, characterized by shifts toward a more conservative morphology with increased root diameter and tissue density, as well as reduced mycorrhizal colonization rates. These adaptations led to a decrease in root absorptive function, which was compensated in the C-4 grasses by greater root biomass partitioning and root hair factor. Variances in root strategies between plants functional groups were closely related to leaf photosynthetic rate, water and nitrogen use efficiency. We observed that the C-4 4 grasses prefer direct acquisition of soil resources through the fine root pathway over the root hair or mycorrhizal pathway, suggesting a 'do-it-yourself' approach. These findings provide valuable insights into how plant communities of different photosynthetic types might respond to future climate change.