Effect of rice planting date and optimal planting window for Southwest Louisiana

Rice (Oryza sativa L.) yield and grain quality are highly influenced by the planting date; thus, it is crucial to determine the optimal planting window for an area of cultivation. In this study, date of planting experiments conducted at the Louisiana State University (LSU) AgCenter Rice Research Station from 2011 to 2018 were analyzed to quantify the effect of planting date, genotype, and year on key agronomic traits. Planting date was strongly associated with yield across every year, explaining 55.6% of the overall phenotypic variation. A clear relationship was observed between later plantings and reduced yields; and the highest yields were observed during plantings between 11 and 31 March. Rice planted after the optimal planting window displays a yield reduction following a cubic regression trend. Planting date was associated with milling yield, explaining 28.6% of the phenotypic variation, however the effect size varied year to year. Milling yields were highest with the early and late planting dates, while reduced milling yields were observed in plantings between mid‐April and early June. Days to heading and days to seedling emergence were strongly associated with planting date; with planting date explaining, on average, 86 and 96% of the variation, respectively. Plant height was less influenced by planting date, with genotype being the largest source of variation. The results from this study highlight the importance of choosing the optimal planting date and identifies an optimal planting window to maximize grain and milling yield for Southwest Louisiana.