Cereal grafting in rice and pearl millet preserves photosynthetic performance and stomatal dynamics, establishing a platform for root-shoot communication studies

Cereal grafting using embryonic tissues has recently become technically feasible; however, the physiological consequences of cereal grafting remain uncharacterized.

We systematically evaluate photosynthetic performance and stomatal dynamics across different graft combinations in two photosynthetically distinct species, rice (C ₃ ) and pearl millet (C ₄ ). We first assessed steady-state photosynthetic performance and dynamic stomatal responses in five-week-old rice and pearl millet grafts grown under a saturated water regime, to establish whether cereal grafting alters physiology at early stages. Next, we assessed same traits at the onset of optimal water regime, and after five days to determine whether any graft-induced effects on photosynthesis or growth persisted over time.

We observed that across contrasting water regimes and at different plant developmental stages, cereal grafting did not alter growth, photosynthesis or stomatal kinetics in either species, while revealing modest early stage C ₄ -specific adjustments in stomatal dynamics without affecting photosynthetic capacity or biochemical parameters.

We demonstrate that cereal grafting does not alter core physiological traits in rice or pearl millet and can be deployed without long-term impact on photosynthesis. These findings establish cereal grafting as a tractable platform for mechanistic dissection of root-shoot signaling and trait combination across different C ₃ and C ₄ cereals.