Document Type : Research Paper
Department of Plant and Soil Sciences, 117 Dorman Hall, Box 9555, Mississippi State University, Mississippi State, MS 39762
Department of Plant and Soil Sciences, 117 Dorman Hall, Box 9555, Mississippi State University, Mississippi State, MS 39762.
Nutrient (N) stress affects cotton growth, primary physiological processes and
fiber properties. This study utilized two sunlit growth chambers to compare cotton
(cv. TM-1) responses to two levels of N nutrition imposed at the onset of flowering
stage of development, 100 and 0% of optimum N, in plants grown under otherwise
optimal temperature and soil moisture conditions. Flowers and bolls were tagged
daily to estimate boll maturation period (BMP). Leaf N concentration was
determined every four days from flowering to maturity. Plant height and main stem
nodes were determined every four days from emergence to 25 days after treatment
(DAT) and photosynthetic measurements were recorded weekly from 0 to 56 DAT.
Plant and boll-component dry weights were recorded at end of the experiment.
Fiber quality was determined in samples of lint that were grouped based on average
leaf N concentration during the BMP. Total plant biomass was reduced 23% by N
deficient treatment and these plants produced 14 bolls per plant as compared with
21 bolls in N sufficient plants. Stress-induced decrease in leaf N was associated
with linear decreases in leaf photosynthesis (r2=0.92) and stomatal conductance
(r2=0.86). Fiber length and strength increased linearly with increase in lean N
concentration, while fiber micronaire and uniformity declined linearly with
increase in leaf N concentration. Among the measured fiber properties, fiber
micronaire was the most sensitive to changes in leaf N followed by strength, length
and uniformity. Knowledge of the functional relationship between leaf N
concentration and a fiber property can be used to develop a fiber quality submodel
for cotton under optimal temperature and water conditions.