Interactive Effects of Carbon Dioxide and Nitrogen Nutrition on Cotton Growth, Development, Yield, and Fiber Quality

The consequences of elevated carbon dioxide concentrations ([CO 2 ]) and N nutrition on cotton ( Gossypium hirsutum L.) growth, development, yield, and fiber quality were determined. Cotton cultivar NuCOTN 33B was grown in sunlit controlled environment chambers at three levels of [CO 2 ] (180, 360, and 720 μmol mol −1 ) and two levels of N [continuous N throughout the plant growth period (N+) and N withheld from flowering to harvest (N−)]. Leaf N concentration decreased with increasing [CO 2 ] under both N treatments. These low leaf N concentrations did not decrease the effect of elevated [CO 2 ] in producing higher lint yields at both N treatments, the response being highest for plants grown at elevated [CO 2 ] and N+ conditions. Fiber quality was not significantly affected by [CO 2 ], but the leaf N concentrations, which varied with [CO 2 ], had either a positive or a negative influence on most of the fiber quality parameters. Leaf N during boll maturation period had significant positive correlations with mean fiber length ( r 2 = 0.63), fine fiber fraction ( r 2 = 0.67), and immature fiber fraction ( r 2 = 0.65) and negative correlations with mean fiber diameter ( r 2 = 0.61), short fiber content ( r 2 = 0.50), fiber cross‐sectional area (r 2 = 0.76), average circularity ( r 2 = 0.74), and micronafis ( r 2 = 0.65). It is inferred that future elevated [CO 2 ] will not have any deleterious effects on fiber quality and yield if N is optimum. The developed algorithms, if incorporated into process‐level crop model, will be useful to optimize cotton production and fiber quality.