Background
The authors write that "the development of heat-tolerant varieties is a feasible and cost-effective way to reduce the impacts of climate change on cotton production," but they state that "the development of heat-tolerant plant material through breeding requires the presence of genetic variation for heat tolerance within the species." Hence, they explored this potential with respect to cotton (Gossypium hirsutum L.).

What was done
The five researchers screened 51 different cotton accessions for growth and development characteristics under heat-stressed (about 10°C higher than optimum) and non-stressed conditions in both a glasshouse and in the field, measuring relative cell injury percentage (RCI %), which is a measure of cell membrane thermostability (CMT), along with cotton yield and fiber quality.

What was learned
Azhar et al. determined, first of all, that RCI % was strongly and negatively associated with the plant traits they measured, and, therefore, that CMT was "a useful technique for identification of heat-tolerant cotton." Second, they determined that the heat-tolerant accessions "produced high seed cotton yield with good quality fiber whist susceptible varieties ... were lower yielding with inferior fiber characteristics."

What it means
The work of the Pakistani and Australian scientists clearly demonstrates "the presence of genetic variation for heat tolerance within the species," and that purposeful breeding for heat tolerance in cotton would indeed be both "feasible and cost-effective." In addition, they note "there is ample information in the literature on variation for heat tolerance in [other] crop species, including wheat (Ibrahim and Quick, 2001a,b), rice (Yoshida et al., 1981), cowpea (El-kholy et al., 1997), tomato (Abdul-Baki and Stommel, 1995), mung bean (Collins et al., 1995) and [again] cotton (Rahman et al., 2004)," suggesting that breeding for heat tolerance in these crops -- and, very likely, many others -- could also be successfully accomplished.

In this regard, it is also important to recall that there is great genetic variability within most species with respect to their response to atmospheric CO2 enrichment -- see Biodiversity (Among Genotypes) in our Subject Index -- which information could also be used as a guide to successful breeding for plant adaptability to earth's future aerial environment. These realizations lead to the conclusion that mankind possesses both the knowledge and the skills required to successfully develop crop varieties that will actually welcome the changed characteristics of the "brave new world" that awaits us. We need to get on with this important work.

References
Abdul-Baki, A.A. and Stommel, J.R. 1995. Pollen viability and fruit set of tomato genotypes under optimum and high-temperature regimes. HortScience 30: 115-117.

Collins, G.G., Nie, X.L. and Saltveit, M.E. 1995. Heat shock proteins and chilling sensitivity of mung bean hypocotyls. Journal of Experimental Botany 46: 795-802.

El-kholy, A.S., Hall, A.E. and Mohsen, A.A. 1997. Heat and chilling tolerance during germination and heat tolerance during flowering are not associated in cowpea. Crop Science 37: 456-463.

Ibrahim, A.M.H. and Quick, J.S. 2001a. Heritability of heat tolerance in winter and spring wheat. Crop Science 41: 1401-1405.

Ibrahim, A.M.H. and Quick, J.S. 2001b. Genetic control of high temperature tolerance in wheat as measured by membrane thermal stability. Crop Science 41: 1405-1407.

Rahman, H., Malik, S.A. and Saleem, M. 2004. Heat tolerance of upland cotton during the fruiting stage evaluated using cellular membrane thermostability. Field Crop Research 85: 149-158.

Yoshida, S. Satake, T. and Mackill, D.J. 1981. High-Temperature Stress in Rice. IRRI Research Paper Series 67. International Rice Research Institute, Manila, Philippines.