Intercropping of short and tall stature maize decreases lodging risk without yield penalty at high planting density

Jianhong Ren Wei Dejie Xinru Zhang Cai Wu Wenwen Han Lingxin Shi Zhiyi Tang Zhihua Wu Guangzhou Liu Yanhong Cui Xiong Du Zhen Gao ^*

• Hebei Agricultural University, Baoding, China

High planting density of maize usually results in higher grain yield but also raises the risk of lodging. Cultivar intercropping had been proved to improve yield and stress resistance. Thus, we aimed to coordinate grain yield and lodging resistance of maize under high planting density by intercropping short-stalked Zhengdan958 (ZD) with tall-stalked Xianyu335 (XY). SZD: sole Zhengdan 958 at normal density (7.5 plants m -2 ); SXY and SHXY: sole Xianyu 335 at normal and high density (9.0 plants m -2 ); IND and IHD: normal density ZD intercropped with normal and high density XY, respectively were set. Land equivalent ratio (LER) averaged to 0.99 and 0.96 in two years, indicating no land use advantage of maize variety intercropping compared to monocultures. The average relative yield (partial LER) of ZD was 0.36-0.42, but that of XY was 0.54-0.63, indicating dominance of tall XY in the intercropping. Averaged two experimental years, the yield of intercropped XY per meter row in IND and IHD was 12.0% and 18.8% higher than sole XY; however, yield of intercropped ZD in IND and IHD was 19.7% and 22.4% lower than sole ZD, respectively. Compared with normal density maize intercropping (IND), increasing density of tall-stalked XY in intercropping did not significantly enhance the population yield of IHD. The upper leaf area of intercropped XY was greater than sole stand, leading to increased interception of photosynthetically active radiation (PAR). However, the increased leaf area of intercropped XY resulted in reduced PAR for ZD, especially at the middle layer where assimilates are directly transported to the ear. Moreover, decreased superoxide dismutase (SOD) activity and SPAD, increased malondialdehyde content of ear leaf werewas observed for intercropped ZD, due to shading stress caused by tall XY. Lodging rate of sole XY under normal and high density was 4.3% and 22.0% in 2021, but lodging was absent for ZD and intercropped XY, which demonstrated that the lodging resistance of intercropped XY was significantly enhanced.This study presents a strategy to enhance maize lodging resistance without yield penalty or requiring additional inputs.