It's very easy to drive by a corn field without fully recognizing how amazing the plants are that we're seeing and all that's going on inside. (Even for agronomists!) I am amazed daily by the complexity and intricacy of the plants we get to work with.
One of my current favorite reads on corn development is a classic on tassel and ear development by O.T. Bonnett (1948). https://www.jstor.org/stable/pdf/2394693.pdf?seq=1
After we saw such stark differences in tiller development between our Goodland and Garden City tillering plot locations in 2019 (aka TASSEL EARS), I was intrigued as to how tassels developed and the timeline that enveloped this process.
Bonnett's paper is a particularly interesting read for me due to the amazing images included in the document. Anyone who knows me knows I LOVE pictures, and developing ears and tassels is no exception. This paper was a key source of inspiration for the additional study we are in the process of carrying out this season at the North Farm on the Kansas State University campus in Manhattan.
With the completion of early season measurements this week, I wanted to share a few of my favorite captured images here to depict the tassel development we've been tracking in this intensive phenology study. We have found three distinct categories of tiller apical inflorescences: normal staminate tassels, fully pistillate inflorescences, and mixed staminate and pistillate tassels ("tassel ears").
NOTE: These tillers were all taken from V12 corn plants and the tillers had at least 3-5 collared leaves. We are still working on determining if the tiller tassel initiation process occurs at the same main plant stage, tiller "stage", etc. (more to come on that!)
Normal Tassel Development in Tillers
"Normal" tassels are fully staminate, or male, with staminate branches. This is accomplished through a selective abortion process in the spikelets (identical but opposite to the process which occurs in pistillate, or female, ears) which begins in the center of the central spike, moving upward and downward, then subsequently outward to the spike branches. (This development pattern is key to remember as we move later to the more unique development of tassel ears.) For tillers that develop normal tassels, typical "lateral" ears from normal ear shoots are a possibility. This would be our desired result.
Pistillate Development in Tiller "Tassels"
Because tillers develop from axillary buds, just as ears do, they can also develop as fully female inflorescences with impressively long ear shanks. These images show typical ears developing in place of the tiller tassel. They may be exposed after flowering, or may remain concealed in a "husk" of tiller leaves. While these ears may successfully develop, concerns include differences in silking time with the main plant (preventing successful pollination), ear exposure if the tip is extended beyond the protection of the leaves, and loss of ears due to stalk/shank breakage.
True "Tassel Ears" in Tillers
As mentioned previously, the fully male and fully female inflorescences of corn come about through a selective abortion process. This process is not always perfect, however, resulting in some unique tassel properties with mixed pistillate AND staminate flowers. (This can also happen to ears!) It is important to remember the tassel development pattern I discussed before, as the midsection of the central spike of these tassels is consistently the problematic section. These were the first flowers to develop in the tassel. Tassel ears are undesirable for several reasons, but mostly because they will produce little or no harvestable grain, and the weight of the kernels will break the tassel as they develop. More importantly, we have observed that a tiller with a tassel ear generally will not bear productive typical ears.
So how can we predict the way tillers will develop? And if these outcomes will be good or bad for the plant as a whole? ... All great questions that we hope to find answers for!
For now, all that's left for us to do it wait! If you're curious how your tillers are developing, slice a few lengthwise and see what you find ... then don't forget to share pictures of what you see!