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Agronomy Journal Abstract -

Differential Response of Two Cotton Cultivars to Fertilizer and Soil Potassium


This article in AJ

  1. Vol. 81 No. 6, p. 870-876

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  1. K. G. Cassman,
  2. T. A. Kerby,
  3. B. A. Roberts,
  4. D. C. Bryant and
  5. S. M. Brouder
  1. Univ. of California Agric. Extension, Kings County,, Hanford, CA 93230.



Cotton (Gossypium hirsutum L.) cultivars have considerable yield differences on vermiculitic soils where late-season K deficiency occurs in California. A 2-yr field study was conducted to evaluate cultivar differences in K use efficiency (defined as higher yield with a limited K supply) in relation to K uptake, K partitioning, and critical internal and external K requirements. The experiment had a split plot design with fertilizer-K addition levels as mainplots, two cultivar subplots, and 10 blocked replications. Without K addition, yield was 29% (1986) and 35% (1987) greater in the K-use-efficient cultivar. Cultivar yield differences reflected greater boll retention at later fruiting positions, but was not related to differences in partitioning of K between vegetative and fruiting structures. When K supply was not limited, cultivar yields were similar. Yield of both cultivars was closely associated with leaf K concentration and soil K availability, but response curves indicated a lower leaf and soil K requirement for the K-use-efficient cultivar. The K-use-efficient cultivar had a higher K uptake rate during fruit development and greater total K accumulation, particularly at low soil K levels. Defining the physiological bases for such large genetic variation in K use efficiency will help to identify why the cotton plant is more sensitive to K limitation than other crops and will aid breeding efforts to develop germplasm more tolerant of a limited soil K supply.

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