Corn kernel: a fruit and a seed

​The dual function of a corn kernel, from human’s perspective, adds to the difficulties of improving grain production with this crop. In most ‘wild’ plants the fruit functions in protection and distribution of the seed. Fruits originate from the ovary of the female plant and have evolved specific structures for distribution by wind or animals.  Grass species have reduced ovary contribution of the fruit as it functions as protection of the single seed within it.  The seed endosperm, originating from genetic contribution of both male and female parents, is the bulk of the grass fruit.  Human’s effort to increase grain production has led to increase the endosperm production of a corn plant while maintaining its function of plant reproduction.
 
Most growers prefer high grain production per area of land- bushels per acre of corn at kernel moisture adequate for storage.  It is not only the size of the kernel but also the female plant characteristics that allow rapid drying of the grain after completion of expansion of the endosperm but also maximum number of plants per acre or hector. Successful hybrids have DNA contributions from both parents that lead to structures favoring high production, efficient movement and storage of carbohydrates in grain and fruit structures that protect the grain from pathogens while allowing loss of moisture. It is not surprising that it takes DNA contributions of two parents to accomplish improvement of corn grain production.
 
Both hybrid parents contribute genetics leading to plant structures such as plant size, and structure growth rate, disease resistance, flowering time, root growth and mineral uptake. Diversity of origin of the two parents adds to the probability of favorable genes being found and combined in a desirable hybrid.
 
The female parent has the additional ‘responsibility’ of contributing to the germination efficiency of the seed.  Mitochondria DNA of the hybrid seed is solely inherited from the female parent.  The fruit outer wall, the pericarp, is a structure of the female parent of a corn seed. Successful gemination and uniform emergence, two major contributors to grain production per acre, is mostly dependent upon the female parent of the hybrid seed.