HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Balota, M. Articles by Peters, T. R. PubMed Articles by Balota, M. Articles by Peters, T. R. Agricola Articles by Balota, M. Articles by Peters, T. R. Related Collections Crop Physiology & Metabolism Wheat

CROP PHYSIOLOGY & METABOLISM

Morphological and Physiological Traits Associated with Canopy Temperature Depression in Three Closely Related Wheat Lines

^a Texas AgriLife Research, Texas A&M University, 2301 Experiment Station Rd., Bushland, TX 79012
^b Virginia Tech, Tidewater AREC, 6321 Holland Road, Suffolk, VA 23437
^c Conservation and Production Research Laboratory, USDA-ARS, P.O. Drawer 10, Bushland, TX 79012
^d Irrigated Agriculture Research and Extension Center, Washington State University, 24106 N Bunn Rd. Prosser, WA 99350. The mention of trade names of commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the Texas A&M University System and the U. S. Department of Agriculture

^* Corresponding author (mbalota{at}vt.edu).

Wheat (Triticum aestivum L.) cultivars with high canopy temperature depression (CTD) tend to have higher grain yield under dry, hot conditions. Therefore, CTD has been used as a selection criterion to improve adaptation to drought and heat. The CTD is a result of the leaf's energy balance, which includes terms determined by environment and physiological traits. We hypothesized that one or more of several physiological traits contributed to consistent CTD differences among three closely-related winter wheat lines grown under dryland conditions. For three years we measured several leaf traits, including CTD, leaf dimension, gas exchange rates, and carbon-13 isotope discrimination (). Soil water content was also monitored. Data showed that daytime CTD was related to the leaf size in these wheat lines. The most drought-tolerant line, TX86A8072, had consistently smaller and narrower leaves than TX86A5606, the least drought tolerant. For TX86A8072, dryland and irrigated average noon CTD was –0.8°C, and average flag leaf area (LA) 11 cm², for TX86A5606, values were –1.7°C and 12.5 cm², respectively. However, TX86A8072 also had higher CTD (i.e., lower temperatures) than TX86A5606 at night, despite a theoretically greater sensible heat transfer coefficient, suggesting greater nighttime transpiration (T). Implications of these traits on nighttime leaf energy balance and possible adaptive roles of nighttime T are discussed.

Abbreviations: A, CO₂ assimilation rate • [CO₂]_i, intercellular CO₂ concentration • CTD, canopy temperature depression • , carbon-13 isotope discrimination • E, transpiration rate • g_lw, total leaf conductance to water vapor • IRT, infrared thermometer • LA, leaf area • RG, relative greenness • RH, relative humidity • RWL, rate of excised-leaf water loss • SLA, specific leaf area • T, transpiration • T_a, air temperature • T_c, canopy temperature • VPD, vapor pressure deficit