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A New Method for Measuring Relative Maturity Differences

Tom Speed, David W. Albers, Ken E. Lege, Kevin Howard, and Tom A. Kerby

ABSTRACT

Many different cotton maturity rating methods have been used by breeders and agronomists since cotton maturity ratings have been taken. Most of these methods incorporate a visual rating method, due to the numerous plots that need to be rated. Delta and Pine Land Company’s Technical Services department has developed a rating scale that estimates the number of additional heat units (DD 60’s) required to open all the harvestable first position bolls. This estimation is made by counting the nodes or branches between the node of the upper most first position open or cracked boll (NUCB) and the node of the upper most harvestable boll (NUHB). The numerical difference between the NUHB and the NUCB is multiplied by 50 to estimate the number of additional heat units required to open all first position, harvestable bolls. Relative maturity ratings can be determined among varieties in field trials when this method is used. This new method has been very helpful in developing the relative maturity rating for new germplasm releases. Knowing a cotton variety’s relative maturity is key in the introduction process a new variety. This new method also offers the opportunity to more objectively quantify a variety’s relative maturity.





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Document last modified 04/27/04