Twenty Cycles of Biparental Mass Selection for Prolificacy in the Open‐Pollinated Maize Population Golden Glow

Selection for increased ears per plant may be an effective method for increasing grain yield in maize (Zea maysL.). Since 1970, biparental mass selection for prolificacy has been carried out in the open‐pollinated maize population Golden Glow. The objectives of this study were to (i) evaluate the direct and correlated responses to 20 cycles of mass selection for prolificacy in Golden Glow, and (ii) relate changes prolificacy to the population's performance at different plant population densities. Yield trials were conducted in 1993 at Madison and Arlington, WI, and in 1994 at Madison, Arlington, and Hancock, WI. In each location and year, the trials were grown at four plant population densities: 28 889 plants ha−1; 44 444 plants ha−1; 57 778 plants ha−1; and 73 333 plants ha−1. Ears per plant increased by 3.3% per cycle, from an average of 0.98 ears plant−1for C0 to 1.63 ears plant−1for C20. Grain yield per plant and grain yield per hectare both increased by 1% per cycle, from 126.5 g plant−1and 5.91 Mg ha−1for C0 to 151.9 g plant−1and 7.16 Mg ha−1for C20. Days to midpollen, days to midsilk, silk delay, and grain moisture decreased across cycles of selection. Root lodging decreased while stalk lodging did not change. Number of ears per plant was significantly and positively correlated with both grain yield per plant (r= 0.71) and grain yield per hectare (r= 0.76). The later, more prolific cycles yielded more than the initial population at high plant population density. The principal benefit of prolificacy for Golden Glow is that it may contribute to the population's ability to produce grain under competitive stress.