|07-108 Project Manager: D. C. Jones|
DEVELOPMENT OF COTTON BREEDING TECHNIQUES AND GERMPLASM TO ENHANCE COTTON YIELD AND QUALITY
Freddie M. Bourland, Derrick M. Oosterhuis and Androniki Bibi, University of Arkansas
Improving the effectiveness and efficiency of selection requires continued development and refinement of breeding techniques. Modifications made to, and germplasm releases from, the University of Arkansas Cotton Breeding Program were summarized in a paper presented at the 2013 Beltwide Cotton Conference. These modifications include a better understanding and utilization of methods to increase yield efficiency and to improve fiber quality. Yield efficiency has been enhanced by altering yield components and basic plant conformation (how lines achieve yield), and by improving resistance/tolerance to insects, diseases, and stress (how lines protect yield). Fiber quality has been improved by the development and use of Q-score as a selection index and by evaluation and reduction of marginal bract trichomes. In this project our 2012 work focused on further study of basic yield components by studying the relationships associated with marginal bract trichomes (hairs) and evaluation of the visible true leaf at emergence (VTLE) trait.
Within the UA Cotton Breeding Program, high yielding lines that rely more heavily on increased lint index (lint per seed) rather more seed per acre have been preferred. Dissertation work by Frank Groves (former Cotton Incorporated Fellow) helped to confirm these relationships and refined a method for estimating fiber density (number of fiber per unit area of seed coat). This refinement should assist with improving yield components.
Cotton breeders have long given high priority to reduced trichomes (hairs) on leaves and subsequently have developed many "smooth leaf" varieties. Cooperative studies with the USDA Gin Laboratory in 2011 and 2012 indicated that both high leaf pubescence and high marginal bract trichome density contribute to high trash in ginned lint. Surveys of cotton breeding lines and varieties indicate that marginal bract trichome density tends to be lower on smooth leaf genotypes but may vary significantly among genotypes having the same leaf pubescence density. Some hairy leaf lines have been found to have relatively low bract trichome density and may combine the positive attributes associated with the smooth leaf (lower trash) and hairy (better agronomics) leaf traits.
Another objective of this project was to develop a rapid method of screening cotton germplasm for heat tolerance. A variety of techniques were tested to determine and quantify thermotolerance in cotton genotypes. The techniques ranged from controlled environment measurements of fluorescence and membrane leakage to measurement of glutathione reductase and fluorescence-temperature response curves using a leaf thermoelectric cooler heater. The second objective was to compare genotypes for thermo-tolerance. Fluorescence and membrane leakage were determined as the most suitable and practical techniques for determining plant response to elevated temperature. Subsequently, we added a thermoelectric control to the fluorometer to be able to measure plant response to a range of temperatures from 20 to 45C. The fluorometer with thermoelectric control assembly for measuring plant response to a range of temperatures from 20-45C consists of the thermoelectric cooler/heater to rapidly adjust leaf temperature, a digital thermometer with a type K fine wire thermocouple to monitor temperature, and a portable fluorometer to measure actual quantum yield. The fluorescence equipment with the thermoelectric cooler/heater instrumentation was tested for rapid screening of cotton cultivars for heat tolerance under growth chamber and field conditions.
|Project Year: 2012|
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