Soybean Yield in Different Sowing Dates and Seeding Rates in a Subtropical Environment

Abstract

The adjustment of sowing date and seeding rate of soybean can optimize plant development and yield. It is well known that the delay of the sowing date anticipates flowering and can reduce yields. In addition, the recommended seeding rate is usually fixed for all sowing dates and the interaction of these management practices is scarce in high yield subtropical environment. So, this study evaluated how soybean yield and its attributes are affected by the management of sowing dates and seeding rates in two growing seasons. Late sowing reduced yield due to reduced shoot biomass per area, leaf area index, final plant height, bottom pod height, pods per area, seeds per area, and seed mass. Increasing seeding rate increased yield, especially in late sowing, due to increased shoot biomass per area, leaf area index, final plant height, bottom pod height, pods per area, and seeds per area. However, higher seeding rates decreased the shoot biomass per plant, leaf area per plant, pods per plant, and seeds per plant. In early sowing, the lowest seeding rate, below the standard, yielded equivalent to the higher seeding rate. In late sowing, the increase in seeding rate increased yield. For growers who aim to increase soybean yields, it is important to consider using specific seeding rates for each sowing date.