Effects of different amounts of stover mulching on improving photosynthetic characteristics and yield of maize in Mollisol of Northeast China under long-term no-tillage

Objectives This study investigated maize yield and photosynthetic characteristics under the influence of stover mulching and long-term no-tillage in the mollisol of Northeast China. We aim to propose a suitable no-tillage and stover mulching technology system in the study region.

Methods The conservation tillage field experiment started in 2007 with a single maize cropping system. The treatments included conventional tillage (CT) and no-tillage combined with stover mulching at 0%, 33%, 67%, and 100% of the harvested maize stovers, denoted as NT-0, NT-33%, NT-67%, and NT-100%, respectively. We measured the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), chlorophyll content, and leaf area at the maize seedling, jointing, and tasselling stages in 2021. Maize yield and yield components were measured at the maturity stage.

Results Compared with CT, the four no-tillage treatments improved the Pn of seedling stage, Pn, Gs, and Tr at the jointing stage and tasseling stage. NT-67%, NT-33% and NT-100% (P<0.05) decreased intercellular CO₂ concentration at the jointing or tasselling stages, while NT-67% and NT-100% maintained higher chlorophyll content at the tasselling stage. NT-100% recorded the highest photosynthetic efficiency at the jointing and tasselling stages, followed by NT-67%, with (P<0.05) higher values than CT, NT-0, and NT-33%. All the NT with stover mulching treatments (NT-33%, NT-67%, NT-100%) increased the kernel number per row, 100-kernel-weight, and grain yield, and there was no significant difference (P>0.05) in yield between NT-0 and CT. The Pn values were significantly (P<0.01) correlated with maize yield.

Conclusions No-tillage combined with stover mulching is effective in increasing chlorophyll content, Pn, Gs, Tr, and the capacity of utilize intercellular CO₂ at the tasselling stage, which enhances maize yield. No-tillage combined with 67%−100% of the harvested maize stover showed a good potential for maize net photosynthetic efficiency, making it a promising approach under the no-tillage condition in the Mollisol of Northeast China.