3 MIN READ
Chilling Injury and Planting Decisions in Cotton
February 28, 2022
Chilling Injury in Cotton
Planting is a critical time for cotton production and many factors should be considered to help establish a healthy, uniform cotton stand.
Soil temperature is the most important factor in determining when to plant cotton. If soils are too cold or if the crop is planted too early it increases the chance of a cold snap, and chilling injury to the cotton seedling can occur.
Key Planting Considerations to Avoid Cotton Chilling Injury
Plant quality seed as determined by germination tests.
Plant when a five-day warming period is forecasted.
Plant into soils with a minimum soil temperature of 65 °F.
After a seed is planted, water is absorbed (imbibed) to begin the germination process. This is a critical time for a young cotton seedling, and cool temperatures can disrupt the correct growth and function of developing cells within the seed. Cotton seeds are most sensitive to temperatures during imbibition. If the water imbibed is cold (<50 °F) chilling injury can result and seedling death can occur at 41 °F due to the radical or the taproot not forming properly.2 Seedlings may survive exposure to cold temperatures if very warm conditions (88 °F) occur prior to exposure.3 However, seeds or seedlings that survive chilling injury are more prone to delayed emergence and may be negatively impacted throughout the growing season including reduced yield potential.
Under ideal situations, seedbeds should be moist and warm. Good seed-to-soil contact is essential for initial water uptake. Once the seed is planted, 80 to 100 heat units are required for emergence. In most regions, emergence occurs after 7 to 10 days under favorable temperatures. The following simple guidelines can help to increase the probability of a successful cotton crop.
Considerations When Planting Cotton
Seed Quality. Prior to planting cotton seed, review the seed viability information on the bag from the standard germination test. This test estimates the percentage of seeds likely to emerge under ideal, warm growing conditions. The percentage should be at least 80%. For germination testing under less-than-ideal conditions, results from the cool germination test provide an estimate for the percent of germination when planting into cooler soils (near 65 °F). To obtain Cool Germination Testing information, check with your seed supplier or send seed samples in for university or private testing. The percentage should be at least 50 to 60%. To obtain the standard (warm) and cool germination data for Deltapine® brand cotton varieties, contact your dealer.
Cotton Product Selection. Select cotton varieties with proven high yield potential and desired agronomic qualities within the geography in which it will planted. The use of multiple cotton varieties with different maturities can help create a larger harvest window so the crop will not mature at the same time. Staggering the planting dates of a single variety can also help with harvest planning. Including a seed treatment product can help improve emergence and seedling health. Remember, early-planted cotton is more prone to seedling diseases due to cool temperatures, making additional disease prevention efforts valuable.
Soil Temperature. Soil must warm before cotton is planted to help assist in a quality stand. For optimum cotton germination, the soil temperature in the seed zone (1.5 to 2 inches deep depending on geography, soil type, and water availability) should be at least 65 °F. Cotton is a crop of semi-tropical origins, so the embryo is very sensitive to cool temperatures. Cotton seed germination can be sporadic at soil temperatures less than 58 °F. It is best to plant cotton according to soil temperature as opposed to calendar date.
Favorable Weather Outlook. Monitor weather forecasts and plant when there is a favorable five-day weather forecast. Delayed emergence can result when the first 5 days are below 58 °F. Cotton planted in unfavorable conditions for the first five days can have delayed emergence, reduced stands, yield loss, and an increased risk of seedling diseases. Rainfall levels of 1 inch or more can drop soil temperatures as much as 5 °F. After the cotton seed is planted, imbibition occurs within 24 to 48 hours. Hydration of the seed is critical; however, if the seed is exposed to cooler temperatures due to irrigation or rain, imbibitional chilling injury can occur. To avoid injury, plant into moist soils with temperatures above 65 °F. Avoid planting when air temperatures in the forecast are below 50 °F for anytime during the first five days.
Tillage. Reduced tillage or no-till systems help conserve soil moisture and reduce soil erosion, but tend to result in cooler soil temperatures in the spring. As a result, fields that are managed with these tillage systems may need to be planted later. Additionally, if no-till is used and a good stand is not achieved, replanting in a no-till system can impact weed control options.
Sources
1 Waddle, B.A. 1984. Crop growing practices. pp. 233-263. IN. Cotton. American Soc. Agron., Madison WI.
2 Hake, K., McCarty, W., Hopper, N., and Jividen, G. 1990. Seed quality and germination. National Cotton Council. Physiology Today. https://www.cotton.org/.
3 Hake, S.J., Kerby, T.A., and Hake, K.D. Cotton Production Manual. University of California Division of Agriculture and Natural Resources. Pub. 3352. pg. 24.
4 Marsh, B. 2008. Chilling injury. University of California Cooperative Extension.
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