Effects of Calcium Peroxide on Root Morphology and Yield Formation of Summer Maize in Waterlogging Farmland

In the context of global climate change, frequent extreme rainfall has exacerbated farmland waterlogging, which severely restricts high and stable yields of maize. This study aimed to elucidate the regulatory mechanisms of calcium peroxide (CaO₂) application on root morphology and yield formation in summer maize under waterlogged field conditions, for providing the theoretical support for stress-resistant and stable-yield cultivation of maize under waterlogging stress.

The experiment was conducted at the Huang-Huai-Hai Regional Maize Technology Innovation Center, Shandong Agricultural University during the 2023-2024 summer maize growing season. Using the maize variety Denghai 605(DH605) and a randomized complete block design, treatments consisted of CaO₂ application and a non-amended control (CK). At the V3 stage of summer maize, artificial waterlogging was simulated. The effects of CaO₂ application were systematically investigated on: (1) soil oxygen concentration in the 0-40 cm profile; (2) maize root morphology parameters (total root length, total root surface area, total root volume, root dry weight); (3) leaf area index (LAI), SPAD value, photosynthetic parameters (net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), transpiration rate (T_r)) and aboveground dry matter accumulation; and (4) grain filling characteristics, yield formation.

Under waterlogging stress, two-year results indicate that CaO₂ application significantly improved the soil oxygen environment. During a total of 10 measurements from the start of the treatment to 10 days after the end of the treatment, the average oxygen content in the 0-20 cm and 20-40 cm soil layers increased by 7.38% and 7.44%, respectively, compared with the control (CK), averaged over two years. Root morphology was markedly altered: at the flowering stage, total root length, total root surface area, total root volume, and root dry weight increased by 51.63%, 44.10%, 39.81% and 51.98% versus CK, respectively; canopy photosynthetic performance was significantly enhanced: maximum LAI and SPAD value at the flowering stage increased by 11.28% and 11.61%, respectively. At the flowering stage, the P_n, G_s, and T_r of the ear leaf increased by 23.84%, 30.63%, and 85.99%, respectively, while dry matter accumulation at maturity increased by 31.51%. Grain filling parameters improved: maximum grain filling rate, mean grain filling rate, grain weight at maximum filling rate, and grain weight at maturity increased by 7.29%, 7.29%, 5.81%, and 6.24%, respectively, compared with CK. CaO₂ synergistically increased kernel number per ear and 1000-grain weight, with average two-year increases of 39.98% and 5.00%, respectively, ultimately increasing grain yield by 50.77% under CK.

Calcium peroxide application mitigated waterlogging stress and enhanced grain yield in summer maize by optimizing soil oxygen environment, remodeling root morphology, improving canopy photosynthetic efficiency and increasing dry matter accumulation, thereby increasing the grain-filling rate. This measure significantly increased grain yield by simultaneously increasing kernel number per ear and 1000-grain weight. This study provided a novel agronomic approach for stabilizing and increasing maize yield under waterlogging stress at the seedling stage.