Soil compaction reduces the yield potential of densely planted maize (Zea mays L.) by disrupting root and shoot growth coordination

AimsIncreasing planting density is a management option to improve maize (Zea mays L.) yield; however, soil compaction poses a challenge to this practice by adversely affecting maize growth. This study aimed to understand the physiological processes related to limitations in yield potential of densely planted maize from soil compaction.MethodsA two-year field experiment was conducted with two planting densities (low density-LD, high density-HD) and three soil compactions (no compaction-NC, 1.30 g cm-3, moderate compaction-MC, 1.45 g cm-3, and heavy compaction-HC, 1.60 g cm-3). Yield, root and shoot growth traits were measured during the maize growing season.ResultsCompared to LD, HD increased maize yield by 22.4-29.1%, 17.2-24.5%, and 10.6-12.3% under NC, MC, and HC condition, respectively. Yield benefits obtained from HD were diminished by compaction through inhibiting root and shoot growth. Compaction stress reduced root length, root surface area, and root dry weight, as well as root dehydrogenase activity and absorption capacity, and then negatively influenced photosynthetic parameters and dry matter accumulation, more severely in HD than in LD. Moreover, root growth indices declined more rapidly than shoot growth with increasing compaction, particularly under HD, leading to a reduced root/shoot ratio.ConclusionSoil compaction impacts maize root and shoot growth differently depending on planting density. Root growth was more sensitive to compaction stress than shoot growth under HD, which constrained yield potential of densely planted maize. Therefore, addressing soil compaction is essential for improving maize yields at high planting densities.