Heat tolerance in spring wheat. I. Estimating cellular thermotolerance and its heritability |
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Authors: | M Fokar Henry T Nguyen A Blum |
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Institution: | (1) Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, 79409-2122;(2) Texas Agricultural Experiment Station, Texas A&M University Research Center, Lubbock, TX, 79401, U.S.A;(3) The Volcani Center, ARO, P.O. Box 6, Bet Dagan, Israel |
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Abstract: | High temperature is a major environmental stress factor limiting wheat (Triticum aestivum L.) productivity. Improvement of
heat tolerance in wheat is an important breeding objective. Genetic variation in cellular thermotolerance among 56 spring
wheat cultivars was evaluated at the seedling stage of growth by cell membrane thermostability (CMS) and triphenyl tetrazolium
chloride (TTC) assays. A subset of eight lines was also evaluated at the flowering stage using the same assays. With both
assays Average thermotolerance tended to decrease from the seedling to the flowering stages. However, thermotolerance was
well correlated between growth stages among the eight cultivars for both CMS (r = 0.92; p = 0.004) and TTC (r = 0.84; p =
0.050). The correlation between TTC and CMS among the eight cultivars tested at the seedling and the flowering growth stages
was significant (r = 0.74; p = 0.031 and r = 0.75; p = 0.029, respectively). The same correlation was less strong, though
still significant (r = 0.32; p = 0.014) across 56 cultivars at the seedling stage. In a study of the cross V747 (tolerant)/Barkaee
(susceptible), broad sense heritability was estimated at 89% for TTC. Most of the genetic variance was additive. CMS in seedlings
of 16 cultivars was positively and significantly (p ≤ 0.05) correlated with yields of these cultivars in each of four hot
environments in Mexico, Sudan, India, and Brazil. The same correlations for TTC were positive but nonsignificant.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | spring wheat heat tolerance heat stress |
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