Maize plant population and row spacing data

To collate peer-reviewed articles, a literature search was conducted using the Institute for Scientific Information Web of Science Database (http://apps.webofknowledge.com). The “Web of Science Core Collection” option was used. No timeframe limitation was set and the last online search was conducted on 5 September 2017. The keywords used included combinations of “corn yield”, “maize yield”, “plant population”, “planting density”, “sowing rate”, “planting rate”, “corn population”, and “maize population”. When articles were unavailable online or from local libraries, a request was made directly to author(s) of the particular article to provide a reprint. Articles were read in full text and examined on the basis of the following eligibility criteria: (i) plant population was evaluated as a treatment to investigate the effects thereof on maize grain yield, (ii) data reported were generated by field experiments with sound statistical designs, and (iii) field trials received no irrigation prior to planting or during the growing season. Any article that was not in English or did not meet the abovementioned eligibility criteria was excluded. Field trial data generated for modelling purposes were included. To overcome publication bias challenges, studies selected for analysis were not geographically limited. This ensured the inclusion of field trial data from various climatic conditions, combined with different agronomic management systems.