Response of intercropped maize "source-sink" characteristics to elevated CO₂ concentration and phospho-rus application in maize intercropping with peanut system.

This study aimed to clarify the impacts of elevating CO₂ concentration (e[CO₂]) on maize "source-sink" characteristics in maize intercropping with peanut system. We investigated the impacts of e[CO₂] on leaf "source" quantity, gas exchange parameters, population "source" productivity, "sink" capacity, grain to leaf ratio, yield and intercropping advantage of maize under 0 (P₀) and 180 kg P₂O₅·hm^-2(P₁₈₀). The results showed that compared with ambient CO₂ concentration (a[CO₂]), e[CO₂] augmented leaf "source" quantity and "source" activity of intercropping maize, and significantly increased productivity of population "source". The silk maximum number, actual seed number and effective "sink" capacity were increased by 8.0%-9.3%, 10.0%-13.4%, and 10.4%-20.8%, respectively. Concurrently, the average dry matter accumulation rate of grains was significantly increased by 10.7%-50.4%. The grain to leaf ratio and harvest index were increased by 3.3%-7.4% and 2.4%-7.9%, respectively. The yield and intercropping advantage were increased by 10.8%-48.7% and 20.4%-102.7%, respectively. Under e[CO₂], phosphorus application could further improve the "source-sink" relationship and maize yield, and increase the intercropping advantage. In summary, e[CO₂] enhanced the "source" performance and "sink" capacity of intercropping maize, promoted grain filling, regulated the "source-sink" relationship, enhanced yield, and thus increased the intercropping advantage.