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Partitioning Variety and Environment Contribution to Variation in Yield, Plant Growth, and Fiber Quality

Tom Kerby, Janet Burgess, Marc Bates, Dave Albers and Ken Lege


 
ABSTRACT

Yield response of a variety in a variety trial is the result of the genetic capacity of the variety and the environment where the trial is grown. Cotton breeders seek to develop genetic materials that will exceed the performance of current varieties. Agronomist, soil scientists, entomologists, pathologists, and physiologists, conduct studies to identify the environment that optimizes cotton production. Many areas of the U.S. cotton belt have experienced environments that are believed to be significant departures from expected norms during recent years. Questions have been raised regarding varietal performance and what percentage of variation in yield, fiber quality, and growth can be accounted for as due to factors associated with varieties or with environments. Delta and Pine Land Company Technical Services conducts wide scale testing of varieties at many locations over multiple years. Nine early picker varieties were compared at nine locations each in 1997 and 1998 from North Carolina to Texas. Yield variation as assessed in large grower strip plot trials or mean values of University Official Variety Trials (OVT's) was conducted for 12 varieties using a total of 785 locations over the period 1996 through 1998. Summary results indicate about 90 % of the total sum of squares could be accounted for by location. Location (environment) accounted for the following percentages of total variation in other variables: fiber length (85 %); micronaire 69 %; fiber strength (48 %); final plant height (90 %), final number of nodes (85 %); cutout node (80 %), and percent retention on the bottom five first position fruiting branches (78 %).



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pp. 528 - 532
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000