Influence of Nitrogen, Narrow Rows, and Plant Population on Cotton Yield and Growth1
- Stephen E. Koli and
- L. G. Morrill2
Narrow row planting of cotton (Gossypium hirsutum L.) has the potential for improving yield and production efficiency. Fertilizer needs and other production technology for narrow row cotton have received little attention, especially the nitrogen (N) requirement. The objective of this study was to ascertain if N fertilizer, narrow row, and high population, has any effect on growth and yield of dryland cotton. The relationship between petiole NO−3-N at various stages of development and yields was also investigated. Row spacinq (25, 51, and 76-cm), plant populations (123,550 and 173,000 plants/ha), and N rate (0, 45, and 90 kg/ha) variables were placed in a factorial arrangement of a randomized, complete block design with four replications. Low N treatments (45 kg/ha) produced no significant change in yield, but higher N rates reduced yield significantly. The 25 and 51-cm row spacings produced significantly higher yield than 76-cm rows. The range of plant populations used did not materially affect yield, but there was a significant N-population interaction. Narrow rows reduced plant height. NO−3-N levels in petioles increased with increased N rate, being highest at the square stage of plant growth and decreasing sharply at the flower and boll stages. There was no significant correlation between petiole NO−3-N and yield. Narrow row cotton can result in higher yield and is especially of interest where the length of growing season is not optimum.
Sugarcane was grown in solution cultures and in potted soil material which provided several concentrations and ratios of NO3 and SO4 in solution. External S and N requirements were estimated from plots of yield vs. SO4 or NO3 concentrations in solution cultures and in artificial soil solutions. The external S requirement at age 35 days was about 9 ppm. After 70 days the requirement was about 5 ppm when N was adequately supplied. The external NO3 requirement was about 50 ppm N. The internal S requirement for early growth was 0.36% S in the whole plant and 0.24% for leaf blades 3 through 6. When plants were 70 days old, 0.10% S in leaf blades or 0.08%, S in leaf sheaths was sufficient. Sulfur-deficient, field-grown sugarcane 18 months old contained 0.075% S in leaves 3 through 6 and 0.072% S in the corresponding leaf sheaths. Sulfur fertilized sugar cane contained 0.138% and 0.232% for the same tissues. Ratios N:S differed for various tissues of the same plant. Distribution of S in the plant may be a valuable tool for assessing the S status of sugarcane. When S is deficient, old leaf blades contain more S than corresponding leaf sheaths, and blades and sheaths of leaves 3 to 6 contain about equal concentrations of S. Good S nutrition was associated with an elevated concentration of S in leaf sheaths as compared with leaf blades.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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