This article was written by UMN Extension educator Angie Peltier.
Little brings more contentment than walking through a corn field in the early summer, particularly if it is a nice, sunny day, with a gentle breeze. When walking through a neighborhood corn field over the last week, I had a couple of observations: the plants had a nice, green color, appeared to be evenly sized, spaced and healthy overall and many had tillers, or small stalks growing from the base of the plant (Figure).
Various research programs over the years have looked at the relationship between tiller production and the availability of essential resources, like sunlight.
During two years in the mid-1980’s researchers in Florida planted corn at different population densities to investigate the relationship between density and tillering (Tetio-Kagho and Gardner, 1988). They found that the number of tillers decreased as plant population density increased.
Using molecular genetic tools, other researchers looking at how individual genes influence plant architecture revealed that both genes and inter-plant competition appear to influence tillering (Whipple et al. 2011). By mutating a single gene they were able to create plants that looked much more like their many-tillered distant teosinte ancestors. These scientists were also able to show that plants were able to sense to how much light in both the red and far-red wavelengths they were exposed. When plants are shaded, the red to far-red ratio decreases and triggers a series of genes to get turned on resulting in axillary buds remaining dormant. However, when plants are not shaded, the red to far-red ratio increases resulting in active axillary buds and the formation of tiller (Whipple et al. 2011). This is why when corn is grown at modern-day population densities, the shading they are exposed to by their neighbors often ensures that they do not send out tillers.
As there were an average of 7,250 tiller per acre in the neighborhood corn field, the population density was 32,500/acre and the plants and growing point appeared to be in good health, the hybrid must simply be one prone to tillering.
Whether and to which plant parts nutrients were translocated was primarily determined by whether tillers or main stalks had ears they were trying to fill out. As far as carbohydrate accumulation is concerned, the best-case scenario is when the tiller is barren and the main stalk has an ear. In this case the sugars produced by the tiller’s leaves end up in the main stalk’s ear (Alofe and Schrade, 1975). While accounting for little of a plant’s dry weight, 24% of the phosphorus that accumulated in the main plant originated in tillers (Russelle et al. 1984). So this source-sink relationship between tillers (partial source) and developing ears (sink) may be at least partly responsible for tillers not being a drag on yield, provided that the tillers themselves are barren.
Little brings more contentment than walking through a corn field in the early summer, particularly if it is a nice, sunny day, with a gentle breeze. When walking through a neighborhood corn field over the last week, I had a couple of observations: the plants had a nice, green color, appeared to be evenly sized, spaced and healthy overall and many had tillers, or small stalks growing from the base of the plant (Figure).
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| Figure. Note the two tillers, one on either side of the main stalk (photo: Angie Peltier). |
What is an axillary bud?
Axillary buds are easy to see in soybean plants – these are the little buds that sit in leaf axils or where the petiole (the leaf stem) meets the main stem. Axillary buds are sitting ready to send out a lateral branch should environmental conditions warrant and are one of the reasons why soybeans have such a tremendous ability to compensate for small gaps in the canopy. Corn plants also have axillary buds. When corn’s axillary buds break dormancy, those lower in the plant will send out additional stalks, while those higher up will send out ear shoots.Various research programs over the years have looked at the relationship between tiller production and the availability of essential resources, like sunlight.
Plants sensing plants.
From corn’s ancient ancestor teosinte to our modern-day corn hybrids, humans have been selecting plants with characteristics that better fit human needs. Over time these cycles of selection have taken teosinte, a grass with many tillers supporting small ‘ears’ with few kernels, and ended up with modern-day corn hybrids, in which the norm is one ear (or two) with many kernels typically produced on a single dominant stalk.During two years in the mid-1980’s researchers in Florida planted corn at different population densities to investigate the relationship between density and tillering (Tetio-Kagho and Gardner, 1988). They found that the number of tillers decreased as plant population density increased.
Using molecular genetic tools, other researchers looking at how individual genes influence plant architecture revealed that both genes and inter-plant competition appear to influence tillering (Whipple et al. 2011). By mutating a single gene they were able to create plants that looked much more like their many-tillered distant teosinte ancestors. These scientists were also able to show that plants were able to sense to how much light in both the red and far-red wavelengths they were exposed. When plants are shaded, the red to far-red ratio decreases and triggers a series of genes to get turned on resulting in axillary buds remaining dormant. However, when plants are not shaded, the red to far-red ratio increases resulting in active axillary buds and the formation of tiller (Whipple et al. 2011). This is why when corn is grown at modern-day population densities, the shading they are exposed to by their neighbors often ensures that they do not send out tillers.
But how do tillers affect yield?
According to two well-respected Extension corn agronomists, Bob Nielsen (2003) at Purdue University and Peter Thomison (2017) at the Ohio State University, as long as there are no problems with stand establishment, diseases such as crazy top or Stewart’s wilt or there has been injury to the apical growing point on the main stalk, tillers are no cause for concern in regards to yield. Just because a hybrid is more prone to tillering than others does not necessarily mean that one should steer clear of it, provided that it has good yield potential and is adapted to your region.As there were an average of 7,250 tiller per acre in the neighborhood corn field, the population density was 32,500/acre and the plants and growing point appeared to be in good health, the hybrid must simply be one prone to tillering.
Why no negative yield penalty with tillers?
Other scientists have investigated whether tillers drew the products of photosynthesis (sugars) or macro-nutrients such as phosphorus away from the main stalk or vice-versa and whether tillers had any affect on yield. To quantify how much of foliar applied phosphorus or carbon dioxide taken up by either leaves of the main stalk or tillers was translocated throughout the plant, scientists used radioactively-labeled CO2 (Alofe and Schrader, 1975) and P (Russelle et al. 1984).Whether and to which plant parts nutrients were translocated was primarily determined by whether tillers or main stalks had ears they were trying to fill out. As far as carbohydrate accumulation is concerned, the best-case scenario is when the tiller is barren and the main stalk has an ear. In this case the sugars produced by the tiller’s leaves end up in the main stalk’s ear (Alofe and Schrade, 1975). While accounting for little of a plant’s dry weight, 24% of the phosphorus that accumulated in the main plant originated in tillers (Russelle et al. 1984). So this source-sink relationship between tillers (partial source) and developing ears (sink) may be at least partly responsible for tillers not being a drag on yield, provided that the tillers themselves are barren.
References
- Alofe, C.O. and Schrader, L.E. 1975. Photosynthate translocation in tillered Zea mays following 14CO2 assimilation. Canadian Journal of Plant Science. 55:407-414.
- Nielsen, R.L. 2003. Tiller or “suckers” in corn: Good or bad? Corny News Network, Purdue Univ. online at: https://www.agry.purdue.edu/ext/corn/news/articles.03/Tillers-0623.html {accessed June 26, 2020}.
- Russelle, M.P., Schlid, J.A. and Olson, R.A. 1984. Phosphorus translocation between small, non-reproductive tillers and the main plant of maize. Agronomy Journal. 76(1):1-4.
- Tetio-Kagho, F. and Gardner, F.P. 1988. Responses of maize to plant population density. I. Canopy development, light relationships and vegetative growth. Agronomy Journal. 80:930-935.
- Thomison, P. 2017. Does tillering impact corn yield? Ohio State Univ. online at: https://agcrops.osu.edu/newsletter/corn-newsletter/2017-24/does-tillering-impact-corn-yield {accessed on June 26, 2020}.
- Whipple, C.J., Kebrom, T.H., Weber, A.L., Yang, F., Hall, D., Meeley, R., Schmidt, R., Doebley, J., Brutnell, T.P., Jackson, D.P. 2011. grassy tillers1 promotes apical dominance in maize and responds to shade signals in the grasses. PNAS. 108(33):13375-13376.