Coupling Effects of Optimized Planting Density and Variety Selection in Improving the Yield, Nutrient Accumulation, and Remobilization of Sweet Maize in Southeast China

Abstract

Low planting density and lack of density-tolerant varieties are the critical factors limiting the yield of sweet maize in Southeast China. However, there is relatively limited information about the interaction effects of plant density and variety on sweet maize in Southeast China. A two-year (2021–2022) field experiment was conducted with two sweet maize varieties (MT6855 and XMT10) and three plant densities (D1: 45,000 plants ha−1, D2: 60,000 plants ha−1, and D3: 75,000 plants ha−1). The results showed that plant density and variety had significant interaction effects on sweet maize yield and most traits. Increasing plant density significantly increased the fresh ear yield of MT6855, while it did not affect the XMT10 variety. The increase in fresh ear yield for MT6855 under D2 treatment was 14.9% and 14.0% higher than that under D1 treatment in 2021 and 2022, respectively. Meanwhile, increasing plant density significantly increased the bare plant rate and decreased the number of grains per ear of XMT10, while no sustainable changes were observed in MT6855. Moreover, we observed significantly increased pre-silking dry matter, N, P, and K accumulation across different densities in both varieties. In contrast, during the post-silking stage, the increasing plant density significantly improved the accumulation of dry matter, N, P, and K, only in MT6855 but not in XMT10. Meanwhile, harvest index, dry matter remobilization, and leaf N, P, and K remobilization of MT6855 were significantly higher than those of XMT10. Increasing plant density significantly increased N, P, and K partial factor productivity of MT6855 but did not remarkably affect those of XMT10. In addition, fresh ear yield of sweet maize was significantly and positively correlated with pre-silking, post-silking, and total N and P accumulation but had no significant relationship with leaf K remobilization across the two varieties. These results suggest that MT6855 is a density-tolerant variety of sweet maize, and optimizing planting density with a density-tolerant variety can improve the accumulation and remobilization of dry matter and nutrients, thereby improving the fresh ear yield and nutrient use efficiency of sweet maize.

Optimal Plant Density Improves Sweet Maize Fresh Ear Yield without Compromising Grain Carbohydrate Concentration

“…These results indicate that maintaining higher ears ha −1 resulting from lower bare plant rate, with a smaller decrease in the 100-grain weight and grains per ear, is the major contribution to MT6855 and WT2015 (sweet maize compact-type variety) increased fresh ear yield with the increasing planting density. Furthermore, compact-type varieties of maize have smaller leaf angles and a greater leaf orientation value above the ear and have an ideal canopy structure, resulting in more light interception within the canopy, and they also have more dry weight accumulation and nutrient uptake, as well as having a stronger ability to distribute dry matter and nutrients to ears [27,36]. Consequently, coordinating the relationship among the ears ha −1 , grains per ear, and grain weight through selecting compact-type varieties is essential to enhancing the sweet maize fresh ear yield under a high plant density.…”