Expert Insight

March 24, 2020 - Variety selection and planting seed quality

Cotton planting season is fast approaching. Getting off to a good start is essential for stand establishment and high yields.

VARIETY SELECTION. The biggest decision that happens each spring prior to planting cotton is choosing what variety is going to be planted. Many variables go into making a variety selection, such as yield potential, yield stability, fiber quality, native resistance traits, herbicide resistance traits, and Bt traits all factor into the decision that ultimately determines production success. There are many sources of data that can aid making variety selection decisions. On-farm performance and trialing along University and company trial testing should all factor into the decision. However, choosing the most popular or highest yielding variety from locations that are not like your farm can lead to reduced profits.

Identify yield limiting factors that you have on each farm. These factors range from irrigated versus dryland acres, low fertility soils, root-knot and/or reniform nematodes, persistence of diseases like bacterial blight or verticillium wilt and the presence troublesome-resistant weeds. Once you identify each farm’s need, choose the best performing variety from multiple years of data with the traits or growth habits that you needed. Spread risk over multiple varieties. A good general recommendation is the 60-30-10 rule. Plant 60% of your acres to a proven, reliable variety that you are comfortable managing. Next, plant 30% of your acres to varieties that you trialed last year and appear to have a fit on your farm where your primary variety may not have performed the best. Finally, plant the remaining 10% of acres to new varieties that show promise in variety trials or have a trait that may benefit your farming operation.

SEED QUALITY. Cottonseed for planting must have a minimum warm germination rating of 80% to be sold. Consider that at this minimum standard 20% of the seed purchased will not become a plant therefore the seeding rate must be increased to obtain an adequate stand for high yields increasing seed costs. Choosing a variety that has excellent warm-cool vigor can get your crop off to a strong start and prevent replants. However, we must remember that cottonseed in a bag is a living organism waiting for appropriate conditions to germinate and will likely never have a 100% germination rate.

There are three parameters that measure cottonseed quality.

  1. Warm Germination Test. Seed are provided water to germinate and placed in a growth chamber set to cycle with 16 hours at 68 degrees F and 8 hours at 86 degrees F. Germination percentage is calculated after 7 days by counting seeds that have an emerged normally.
  2. Cool Germination Test. A similar test to the warm germination test, but seed are held at a constant temperature of 64 degrees F and germination percentage is calculated after 7 days by counting seeds that have an emerged normally. This is sometimes referred to the Texas Cool Test.
  3. Warm-Cool Vigor Index. This index utilizes data from both the warm and cool germination tests. Add the warm germination test percentage with the cool germination test percentage and compare to the established guidelines.
  • Excellent 160 or above
  • Good 140 – 159
  • Fair 120 – 139
  • Poor less than 120

An additional piece of cottonseed information that can be beneficial as we approach planting is seed size. Seed size can impact planter setup and what planting plates we choose. Seed size can be found printed on bags and boxes of seed. Warm and cool germination test results can be obtained by contacting your seed retailer or PhytoGen Cottonseed territory manager.  

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