Investigation of Cotton Growth: Temperature and Carbohydrate Dynamics

Abstract

Research involving NAWF monitoring determined the last effective boll population for ultra-narrow row cotton (UNRC) compared to conventional cotton (CONC) grown in the northern rain-fed production region. The UNRC produced the majority of seedcotton plant-1 on the upper portion of the plant, NAWF 3-5, while CONC produced the most seedcotton plant-1 at NAWF 3-7. Boll numbers showed a similar pattern. The UNRC produced more seedcotton on an area basis at NAWF 2, 3, 4, and 6.

Research on heat unit accumulation revealed that single variable models were somewhat related to boll fill period in terms of regression fits, with degree-days 30/13°C providing the best adjusted R2 of 0.9399; the degree day 15.5°C model had an adjusted R2 of 0.9268. Modifying the DD15.5 model by adding either minimum air temperature or maximum and average air temperature increased the adjusted R2 to 0.9632 and 0.9934, respectively, while also reducing mean square error and coefficient of variation.

The root and stem carbohydrates study revealed cultivar differences for starch concentration at both sample times, but starch content was only significant at first bloom in 2002. These differences, though, did not show a strong relationship with year of cultivar release, indicating that a century of breeding efforts has not altered stem and root starch dynamics.