Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2008
Publication Date: 3/23/2009
Citation: Bauer, P.J., Foulk, J.A., Gamble, G.R., Sadler, E.J. 2009. A comparison of two cotton cultivars differing in maturity for within-canopy fiber property variation. Crop Science. 49:651-657.
Interpretive Summary: Each cotton plant in a high-yielding field has a number of bolls, and these bolls mature at different times during the season. The quality of the fiber of the bolls can vary due to differences in the weather that occurs during the development of the boll. Since textile processors want uniform cotton fiber, we conducted this study to determine how the rainfall patterns affect the distribution of fiber properties within the canopy of an early maturing cultivar and a late maturing cultivar. We found that when there is adequate rainfall, there are relatively small differences within the plant for fiber properties. On the other hand, within-plant differences for fiber properties can be quite large when a short-term rain-free period occurs. Bolls that developed during the rain-free period had shorter fibers that were thicker than bolls that developed when there was adequate soil water. We also found that a rain-free period can increase the concentration of sugars and salts on the cotton fibers, which affect the strength of the yarn and the efficiency of processing. The two cultivars exhibited similar responses to the rain-free period for fiber length and sugar and salt concentration. For fiber thickness, the early season cultivar was more influenced by the rain-free period than the late season cultivar. These results are important because they will be used by cotton breeders to develop cotton cultivars with improved fiber quality.
Technical Abstract: Within-bale variability for cotton (Gossypium hirsutum L.) fiber properties reduces overall fiber processing performance. Our objectives were to compare two cultivars differing in relative maturity for within-canopy variability of fiber physical properties and fiber surface chemical constituents. Two commercial cultivars [DPL 555 (mid-full maturity) and PM 1218 (early maturity)] were grown in plots on a Goldsboro loamy sand in 2004 and 2005. Whole crop yield and fiber properties were determined after machine harvest. Fiber physical properties and extractable glucose and salts were determined on all first (FP1) and second (FP2) reproductive branch position bolls in a 1-m section of row in each plot. There was no difference between the two cultivars for whole crop yield (two year mean of 1040 kg/ha) in either year. Averaged over all mainstem node positions, DPL 555 had fibers that were longer and finer than fiber of PM 1218 in both years. PM 1218 had higher fiber glucose and fiber extract conductivity than DPL 555 among FP1 bolls both years. Timely precipitations during reproductive growth in 2004 resulted in little difference among mainstem nodes for fiber physical properties. In 2005, a prolonged rain-free period occurred during the growing season. First branch position bolls that developed early during this rain-free period had shorter fibers that were coarser than bolls that began developing near the end of the rain-free period. Similarly, fiber glucose and fiber extract conductivity differences among nodes were substantially greater in 2004 than in 2005. The data suggest water-deficit stress conditions during boll development affects fiber length of these two cultivars similarly, but the effect of water-deficit stress on fiber secondary wall characteristics (fiber fineness and maturity) are genotype dependent.