Analyzing the stable yield mechanism of maize-soybean intercropping based on the perspective of assimilation product distribution, leaf photosynthetic physiology and leaf anatomical structure

Relay intercropping maize yields are comparable to sole cropping maize yields, but mechanism explanations and studies based on plant morphology, source-sink relationships and leaf photosynthesis physiological perspectives are unclear.

The experiments was conducted in a two-factor randomized block design, including two different maize varieties (A1: RongYu 1210 (RY1210), A2: ZhongWangYu 18(ZWY18)) and two plant pattern (B1: Relay intercropping (RI), B2: sole cropping (SC)).

The net photosynthetic rate (Pn) of A1B1 wide row (WR) was increased by 6.95% and 10.78% compared to A1B2, respectively. Chlb and Chl(a + b) of A1B1 WR were no significant difference from A1B2. Average dry matter accumulation in ear of A1B1 was significantly lower than that of A1B2 by 9.77%. When ¹³CO₂ labeling the WR of ear leaves, the abundance of ¹³CO₂ in the ear of A1B1 WR was significantly increased by 0.75% and 150% compared to A2B1 WR in the ear and ear leaves, respectively. Silking stage, the thickness of upper and lower epidermis and leaf thickness of A1B1 significantly increased by 10.70%, 5.82% and 1.77% compared to A2B1. The average yield of A1B1 was 8344.13 kg ha⁻¹, which was no significant difference compared to A1B2.

It was attributed mainly to increase the Pn of WR maize, which increased the ¹³CO₂ abundance of WR ear leaves, leaf epidermal thickness and photosynthetic leaf area, and facilitated the transfer of photosynthetic assimilated products to the seeds, which guaranteed stable yields of A1B1.