Close mixed planting with pearl millet improves drought tolerance in rice by the increased access to deep water

Rice is often cultivated in drought-prone regions causing growth inhibition. Therefore, we investigated whether close mixed planting of rice with pearl millet would mitigate these effects. We used pot and lysimeter to evaluate whether close mixed planting with pearl millet is more effective than single-stand planting in suppressing the growth inhibition of rice (NERICA4) under drought. Close mixed planting only slightly alleviated the growth inhibition of rice under drought in the pot experiment and the first year lysimeter experiment, but mitigated this in the second year lysimeter experiment due to the lower levels of competition. Deuterated water applied from the bottom of the pot and lysimeter was present at a higher concentration in the xylem sap of rice under close mixed planting than under single-stand planting, and this tendency was enhanced by drought. Partitioning of the available water between the two crops was also observed under close mixed planting, with the rice and pearl millet depending on water from the soil surface and deep soil, respectively. Close mixed planting with pearl millet effectively mitigates the growth inhibition of rice under drought due to the increased access to deep water and the partitioning of available water between the two crops.