Zhang Shan, Zhang Xiaolong, Jia Zechen, Liu Kaichang, Guo Zhongxiao, Lv Yanjie, Wang Yongjun
College of Agronomy, Jilin Agricultural University, Changchun 130118, China.
Institute of Agricultural Resources and Environment, Jilin Academy of Agricultural Sciences, Changchun 130033, China.
Plants (Basel). 2025 Aug 9;14(16):2470. doi: 10.3390/plants14162470.
Soil degradation limits maize grain yield, but the mechanisms by which leaf functions respond to topsoil depth and their contributions to yield are unclear. We quantified the response mechanisms of leaf functions to topsoil depth with topsoil depths of 10 cm (S), 20 cm (S), 30 cm (S), 40 cm (S), and 50 cm (S) and planting densities of 15,000 plants ha (D, the plant spacing was 111.1 cm and there was no mutual influence between individuals) and 75,000 plants ha (D). The grain yield in S was significantly lower than that in S, S, S, and S, and the maximum reductions in yield were 39.7% in D and 39.1% in D. The coefficients of variation for yield in S and S were significantly higher than those in S, S, and S at both densities and in both years. The net assimilation rate and production efficiency of leaf area, as well as leaf nitrogen and carbon accumulation, all decreased with decreasing topsoil depth. The decreasing topsoil depth significantly reduced the maize leaf net photosynthetic rate, activities of key nitrogen metabolism enzymes, and photosynthesis. Therefore, eliminating intraspecific competition did not reduce the yield loss caused by a reduction in topsoil because leaf nitrogen metabolism and photosynthetic processes were severely limited by the decrease in topsoil depth.
土壤退化限制了玉米籽粒产量，但叶片功能对表土深度的响应机制及其对产量的贡献尚不清楚。我们通过设置10厘米（S）、20厘米（S）、30厘米（S）、40厘米（S）和50厘米（S）的表土深度以及15000株/公顷（D，株距为111.1厘米，个体间无相互影响）和75000株/公顷（D）的种植密度，量化了叶片功能对表土深度的响应机制。S处理下的籽粒产量显著低于S、S、S和S处理，在D密度下产量最大降幅为39.7%，在D密度下为39.1%。在两种密度和两年中，S和S处理下产量的变异系数均显著高于S、S和S处理。随着表土深度的降低，叶片的净同化率、叶面积生产效率以及叶片氮和碳的积累均下降。表土深度降低显著降低了玉米叶片的净光合速率、关键氮代谢酶活性和光合作用。因此，消除种内竞争并不能减少因表土减少导致的产量损失，因为叶片氮代谢和光合过程受到表土深度降低的严重限制。
