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Submitted to: Annals of Botany
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/20/2001 Publication Date: 2/1/2002 Citation: Reddy, V., Pachepsky, Y.A. 2002. Temperature effects on node development rates in cotton. Annals Of Botany. 31:101-111. Interpretive Summary: Many management decisions are based on knowledge of effects of crop environment on crop development. Node appearance and internode elongation rates define the evolution of the architecture of cotton plants and their height, both properties being important for in-season treatments and harvesting. Both node development and internode elongation are affected by temperature. As weather patterns become more variable, more inter-annual variation can be expected in height development of cotton crops. Effect of temperature on main stem node development in cotton has been studied in controlled-environment experiments. Our hypothesis was that, as plants experience various stresses in the field, effect of temperature on the field main stem node development can be significantly different compared with the controlled environments. We have assembled a database of field studies done by the developers of the cotton crop simulation model GOSSYM in Mississippi and Texas. Twenty four datasets represented irrigated crops of nine cotton varieties. At temperatures above 25 degree C, the node appearance rate was up to 40 percent slower, internode elongation rate was 40 percent slower, and the duration of internode expansion was up to 23 percent longer in the field than in controlled-environments. To simulate field development of crops, we used controlled-environment data to determine the shapes of the dependencies of interest. These shapes were fitted to field data for individual cultivars. The parameter values for node appearance rates differed significantly between cultivars. Field studies provide a valuable resource to correct controlled environment data for decision support in crop management. Technical Abstract: Many management decisions are based on a knowledge of the effect of crop environment on crop development. Vegetative development of cotton is known to be affected by the temperature. The objective of this study was to develop simple models of effects of temperature on rates of main stem node appearance and internode elongation. A database was assembled from data of validation studies for the cotton crop model GOSSYM in Mississippi and Texas. Twenty four datasets represented nine cotton varieties. All the crops were irrigated. Observed mean daily temperatures were in the range from 17 to 30 degree C on 99 percent of the days in the growing seasons. Node number and plant height were measured typically on 20 replications. Controlled-environment data were used to determine the shapes of the dependencies of and node appearance and internode elongation rates on temperature. These shapes were fitted with equations that had few parameters, and the parameter values were estimated from field data for individual cultivars. The parameter values for node appearance rates differed significantly between cultivars. At temperatures above 25 degree C, the node appearance rate was up to 40 percent slower, internode elongation rate was 40 percent slower, and the duration of internode expansion was up to 23 percent longer, in the field than in controlled environments. The differences may be caused by stresses experienced by the plants in the field. To rely on the data from controlled-environment experiments, cotton crop models have to have a comprehensive description of stresses and their effects on crop phenology; otherwise a field data present a resource to develop empirical models like the one presented in this paper. |
