Seasonal Canopy Temperatures for Normal and Okra Leaf Cotton under Variable Irrigation in the Field

James Mahan,Paxton Payton,Haydee Laza

doi:10.3390/agriculture6040058

James Mahan, Paxton Payton + Show 1 more

Open Access

https://doi.org/10.3390/agriculture6040058

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Journal: Agriculture	Publication Date: Nov 4, 2016
Citations: 5	License type: CC BY 4.0

Affiliation: Cropping Systems Research Laboratory

Abstract

Temperature affects a number of physiological factors in plants and is related to water use, yield and quality in many crop species. Seasonal canopy temperature, measured with infrared thermometers, is often used in conjunction with environmental factors (e.g., air temperature, humidity, solar radiation) to assess crop stress and management actions in cotton. Normal and okra leaf shapes in cotton have been associated with differences in water use and canopy temperature. The okra leaf shape in cotton is generally expected to result in lower water use and lower canopy temperatures, relative to normal leaf, under water deficits. In this study canopy temperatures were monitored in okra and normal leaf varieties for a growing season at four irrigation levels. Differences in canopy temperature (<2 °C) were measured between the two leaf shapes. As irrigation levels increased, canopy temperature differences between the leaf shapes declined. At the lowest irrigation level, when differences in sensible energy exchanges due to the okra leaf shape would be enhanced, the canopy temperature of the okra leaf was warmer than the normal leaf. This suggests that varietal differences that are not related to leaf shape may have more than compensated for leaf shape differences in the canopy temperature.

Highlights

Temperature has a pervasive effect on the growth and development of plants and, since it is continuously variable, its influence can be difficult to understand on a mechanistic level, and even more difficult to manage in an agricultural context
It is possible that the normal leaf variety was more effective in extracting soil moisture than the okra leaf since such behavior would result in lower canopy temperatures in the normal leaf variety under the water-limited conditions
The hypothesis of the paper was that when transpirational leaf cooling was limited, the okra leaf shape would have greater sensible energy dissipation than the normal leaf

Summary

Introduction

Temperature has a pervasive effect on the growth and development of plants and, since it is continuously variable, its influence can be difficult to understand on a mechanistic level, and even more difficult to manage in an agricultural context. While the effects of these leaf shapes on cotton yield, quality, disease susceptibility, canopy temperature and water use have been the subject of numerous research efforts, the results have sometimes been contradictory and the value of okra-shaped leaves in production is not universally recognized [10,11,12,13]. Heitholt et al [12] summarized a number of possibly desirable characteristics of okra-leaf type cottons Included in their list are earlier maturity, yields similar to normal-leaf varieties, reduced boll rot, reduced leaf area index, higher single-leaf photosynthesis per unit leaf area, moderate pink bollworm resistance, and growth characteristics, such

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