Battle for the Belt: Season 2, Episode 19- Corn Development and Water Use

Episode 19 of Battle for the Belt is now available: https://www.youtube.com/watch?v=SzrbsXIK-Mg

In Episode 19, we are with Dr. Osler Ortez at the Wooster Campus speaking on Corn Development and Water Use.

Wooster Location Crop Development

Dr. Osler Ortez takes us through the stage of each planting date of corn at the Wooster location for Battle for the Belt. The first planting date (April 22) is consistently at the R4 or dough stage, with the 115-day hybrid being relatively behind, closer to the R3 growth stage. The second planting date (May 3) is at the R3 growth stage or milk stage. An observation for the last two seasons that will be evaluated is that, with the corn, as planting date is later, the taller the corn has been. Plant and ear heights are measured toward the end of the season, in the previous year, the tallest corn was generally planting date three. The third planting date (May 21) is at the silking stage across the different relative maturities. The fourth planting date (June 4) does not have any tassels or silk yet, the average stage is V13. The fifth planting date (June 20) is at V8. To continuously be able to stage throughout the season, paint is used to track the stage of the plant and the total leaves produced on the plant. The first leaves will fall off and become very difficult to identify, so the fifth and tenth leaves are painted for tracking stages during the vegetative phase.

Physiological Function by Stage

Planting date has a direct effect on crop development throughout the season. At the Wooster location, there was about a 60-day planting window and a range of growth stages from V8 (8 collared leaves) to R4 (dough). Through corn development there are several important milestones that the plant goes through, requiring adequate conditions for optimal yield potential (e.g., water, weather, nutrients). For example, after the crop germinates and emerges and we get a good stand, the plant begins ear shoot initiation between V4-V6 stage. The shoots will eventually become harvestable ears. Along with the shoots, the plant is also developing the tassel. The tassel and shoots cannot be seen with the naked eye but can be seen with careful dissection and a microscope. So, yield is beginning to be determined very early in the season. During the mid to late vegetative stages the potential ear size is being developed and influencing the potential number of kernels that will be set. The number of kernels is not determined until we achieve pollination. Each silk is attached to an ovule that will become a kernel if pollination is successful. Then grain fill will begin after pollination. Kernel abortion can occur between R1 and R2. At the end of the season, timing of stress can be determined by the ear because these critical times of development affect ear size and kernel potential. Different diagnostics can be made to determine the timing and the stressor.

Water Requirements of Corn

Water is one of the primary resources that a plant needs to survive and reproduce, for example, in order to produce about 200 bushels of corn, we need about 20 inches of water in that growing season. The crop use of water is broken down into two components, water loss from soil or evaporation and water loss from the crop or transpiration. Therefore these 20 inches of water will be divided into these two uses of water and are necessary over the growing season.

The amount of water that the crop needs is influenced by the stage of the crop (Table 1). The silking stage is the most critical for water availability, crops at this stage are taking up to 0.30 inches of water per day. This means we need about 2 inches per week either from rain or from water stored in the soil. If the soil reserves are low and there has not been precipitation, we can begin to see stress responses from the corn with leaf rolling. This was reported around the state early last week and was seen at the Northwest location for Battle for the Belt, hopefully the weekend rains hit the areas that needed it the most. The water requirements for the crop are less at the very beginning of the season (prior to 12-leaf stage) and towards the end of the season (R5 or Dent). Therefore, it is most imperative that during the beginning of the reproductive stages there is adequate moisture since the crop is more resilient to this stress in early stages and at the very end of grain fill.

Table 1. Water use rates for corn at different growth and developmental stages using the leaf collar method.

What planting date will be best this year?

We are entering into yield estimating season with the beginning of August. When yield estimating corn, it is recommended to evaluate corn that is at least at the milk stage. Before milk stage a yield estimate is more subjective since kernels at still at early stages and abortion can still occur. Yield estimates on later planted corn around the state may need to wait until later into August to reach more kernel development and the R3 stage (Figure 2).

Table 2 has an updated summary of planting dates, last week’s weather, and stages for corn and soybean at the three research stations with Battle for the Belt.

Figure 1. Planting date one, two, three, and four with 100-day, 107-day, 111-day, and 115-day in order from left to right at the Western Agricultural Research Station on 7-29-24.

Table 2. Weekly weather conditions for each planting date at the Western Agricultural Research Station, Northwest Agricultural Research Station, and Wooster Campus, with day of planting, soil, air temperature averages, and Growing Degree Days (GDDs) from July 29^th to August 4^th. Information from CFAES Weather System (https://weather.cfaes.osu.edu/).

References

Licht, M., and Archontoulis, S. 2017. Corn Water Use and Evapotranspiration. Integrated Crop Management News, Iowa State University Extension and Outreach. https://crops.extension.iastate.edu/cropnews/2017/06/corn-water-use-and-evapotranspiration