Synthesis-Analysis for US Maize Planting Date on High-Yielding Environments.

For maize (Zea mays L.) crop, planting date and yield relationships from field-research data are well documented in the scientific literature. Nonetheless, a review of high-yielding contest winner data and research studies on the effects of planting date and yield for maize is not yet available. Following this rationale, a synthesis-analysis was conducted from farmer annual maize contest-winner data (n = 16,198 data points; 2011-2016 period) cordially provided by the National Corn Growers Association (NCCA) and a literature dataset collected from publications since last three decades. The main objectives of this study were to: (i) identify spatial yield variability under the high yield environment; (ii) understand the impacts of planting date on yield variability; (iii) explore the effect of management practices on maize yield and planting date relationship, and (iv) utilize the maize and planting date collected via farmer contest-winner as a benchmarking data set to be compared to the compendium of scientific literature available for maize yield and planting date relationship for the primary US maize producing regions. Major findings of this study are: (i) a significant correlation between planting date and latitude was established, (ii) a significant difference between yield at different planting date categories at higher latitudes, (iii) medium-yielding (MY, 5-10 Mg ha^-1) group was associated with late planting, and iv) in overall, yield to planting date relationship fitted a bi-linear model for both yield contest and the literature data sets but with shorter duration of the plateau (yields remaining constant) and sharper yield reduction as the maximum yield was reduced.

Keywords:maize, high yield, latitude, planting date, synthesis-analysis