Submitted to: European Journal of Agronomy
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/24/2005
Publication Date: 2/1/2006
Citation: Read, J.J., Reddy, K.R., Jenkins, J.N. 2006. Yield and fiber quality of upland cotton as influenced by nitrogen and potassium nutrition. European Journal of Agronomy. 24:282-290. Interpretive Summary: Management of soil nitrogen (N) and potassium (K) has a role in satisfying an increased demand for high quality cotton by textile mills that require longer, stronger fibers for current spinning machines. This study determined the independent effects of N and K deficiency in cotton on fruit (boll) development, lint yield and fiber quality. Plants were grown in pots outdoors under favorable water and nutrient conditions until some plants received a restricted supply of either N or K at different growth stages. Withholding N or K from first square (floral bud) stage onward led to deficient levels in leaves, earlier crop maturity, and decreased lint yield. Under N stress, the fibers produced in late-season bolls were shorter, weaker, and lower in micronaire (a measure of fineness and maturity) than plants under favorable N conditions. Potassium stress decreased micronaire of plants under favorable N and water conditions. Results indicate adverse effects from early-season N or K stress on fiber strength and micronaire. Results should guide further research in N and K nutrition in cotton, and may also provide information on boll development that is important for the proper diagnosis of a nutrient deficiency in the field. Cotton production is more profitable with improved nutrient management practices.
Technical Abstract: Insufficient nitrogen (N) or potassium (K) nutrition limits cotton (Gossypium hirsutum L.) yield, and may adversely affect fiber quality. A 2-yr study was conducted to determine the effects of N and K deficiency on fiber yield and quality in five fruiting zones. Plants were grown outdoors in pots at five N treatments: control N throughout; 20% of control N from first square (floral bud) onward; 0% and 20% N from first flower onward; and 0% N from boll-filling stage onward. A separate group was grown at three K treatments: control K throughout; 20% of control K; and 0% K commenced at first flower in 1999 and first square in 2000. Mature bolls were harvested from sympodial (fruiting) branches only and grouped according to week of anthesis across a 35-d flowering period. In 1999, N deficiency decreased fiber strength and micronaire in late-season bolls, and lower weighted-sum average strength in the crop. Potassium deficiency decreased micronaire to about 3.6 or less in flowering groups Two and Four in 2000, and to 3.2 or less in flowering groups Three and Five in 1999. Stress did not consistently alter length, suggesting early stages of fiber development are buffered by plant nutrient reserves. Results support evidence of the indirect effects of nutrient stress on cotton yield and fiber development, and the strong negative impacts of early-season N or K stress on fiber strength and micronaire.