Plant Population Affects Zipper Ears in Corn.

Zipper ears in corn are characterized by missing entire or parts of kernel rows due to poor pollination and kernel abortion. Kernel abortion is usually associated with poor tip fill on corn ears (“tip die back”) but in recent years zipper ears have become common. Zipper ears are often curved because the absence of kernels on one side of the cob coupled with the continued development of kernels on the other side causes the cob to bend. Zipper ears are often observed when stress conditions occur during early grain fill. Little is known concerning effects of cultural practices such as hybrid selection and plant population on zipper ears. A study was conducted in 2011 at four Ohio locations, Hebron, South Charleston, Hoytville and Wooster, to determine plant population effects on zipper ears. A hybrid observed to exhibit ear zippering in past years was planted at seeding rates of 67,900, 95,100, and 122,200 seeds/ha.  Plots were visually rated for ear zippering at maturity using a 1 to 5 scale where 1=no zippering; 2=small number of missing kernels; 3=1 row affected (exhibiting missing and/or aborted kernels); 4=2 rows affected; 5=3 or more rows affected. In addition, 10 ears were sampled from randomly selected plants in each plot for evaluation of various ear yield components. Increasing seeding rates from 67,900 to 122,200 seeds/ ha increased ear zipper ratings from 1.7 to 4.4. Higher seeding rates were also associated with a significant reduction in kernel rows, kernels per row, kernels per ear, unfilled ear tip length, ear length, ear weight and kernel weight.