The Optimum Seeding and Harvesting Dates of Sorghum-Sudangrass Hybrid (Sorghum bicolor L.) via Optimum Moving Response Surface Methodology

This study aimed to detect the optimum seeding and harvesting dates, and to verify the variation of dry matter yield (DMY) for sorghum-sudangrass hybrid (SSH) via optimum moving RSM proposed to optimize the RSM in metadata. For detecting the optimum point, a response surface methodology (RSM) has been known well in agricultural science. The SSH metadata (n = 856) consists of individual experiments that could be performed to check the optimum seeding and harvesting dates by classic RSM. However, the SSH metadata failed to produce an effective single equation which can be detected the optimum seeding and harvesting dates due to different characteristics of the experimental design. Therefore, RSM were optimized by moving to an optimum point, it was called the optimum moving RSM in this study. As a result, the optimum seeding and harvesting dates were obvious based on a single quadratic function. The maximum DMY at the optimum seeding and harvesting dates (4th of May and 23th of September, respectively) were 25,404.50 kg/ha and 23,697.01 kg/ha, respectively. The SSH yield was rapidly decreased after 10 days from the optimum date, and the seeding and harvesting should be performed within 5 days to ensure a stable yield. Furthermore, the optimum moving RSM was expected to be useful to detect the optimum point in the metadata. About 11 hours grazing time was suggested focused on milk fatty acid and yield (27 kg/d) for Holstein cows as the optimum through eco-pastoral system. This study will be helpful to select a time of grazing in alpine grassland for farmers who want to produce good quality milk. This paper was published in the journal, Grassland Science (Wiley), in March (Kim et al, 2020).