Maize yield in response to alternating low- and high-density rows of diverse hybrids

Production of rainfed summer crops like maize (Zea mays L.) must adapt to a changing climate and retain high productivity. Using diverse hybrids in the same stand is a simple way to adapt to unpredictable stresses during the growing season. However, some hybrids are available at a price premium and therefore their use needs to be cleverly incorporated in the system to balance cost and economic return. In a two-year study in Pennsylvania, we evaluated maize yield and economic return in response to combinations of two planting densities (4.6 and 8.9 plants m-2), two planting arrangements (rows with the same density or alternating rows of low and high density with medium overall density), and two hybrids (drought tolerant Aquamax and a non-drought tolerant Seedway hybrids), including mixtures of both density and hybrid. Both experimental years received adequate rainfall for production. Regression showed that increasing plant density by 1 plant m-2 increased biomass and grain yield by 2% in the density range tested. Using the Aquamax hybrid increased grain yield by 6% compared with Seedway in one of two years. However, economic analysis indicated lower returns when using the higher planting density. Using low density, or a medium density by alternating low and high-density rows, optimized economic output and yield. In 2019, mixing hybrids suppressed yield by reducing the number kernels per ear by 9% compared to pure hybrid stands, mostly for the Aquamax hybrid, which suggests that combining compatible hybrids is of primary importance in mixtures. In rotations highly dependent on maize yield, a combination of defensive agronomic tactics that keeps costs low and yield slightly below the attainable yield as proposed here may result in a resilient and profitable agricultural system adapted to a variable climate.