Testing heat tolerance in the field
Global climate change and localised human impact, such as waste disposal or fertilizer use, has and will continue to have an effect on the world’s flora, both natural and agricultural. Predicting this effect can be difficult, but it is important. If land managers and farmers know which species will cope well with change, they will be better able to make a decision about the species which will struggle under certain conditions.
If a species is well-researched, it may be possible to look for QTL associated with resistance to heat, drought, flooding, or other abiotic stresses, but of course this does not predict real-world responses reliably and in any case is not an option in all cases. In the lab or greenhouse under controlled conditions, a simple observation experiment can tell you the effects of various conditions on a plant, but again this is not an indication of in situ viability.
Buchner et al. published a method of determining the heat tolerance of plants in the field in this month’s Plant Methods (vol. 9:7). Heat was the only imposed variable in their protocol, so any environmental factors are included in the experiment. The group, from Othmar Buchner’s group at Innsbruck, made their own Heat Tolerance Testing System (HTTS) from a number of pieces of technical equipment, including the customized exposure chambers seen in the image above (Figure 5B in the paper). They tested the system on alpine dwarf shrub species Vaccinium gaultherioides and Loiseleuria procumbens, showing that heat tolerance of both species was more than 10% lower in the field than in lab conditions. Interestingly, in situ heat tolerance was 3°C lower at night than in the daytime. Buchner et al. ascribed the increased heat tolerance in the field, and in the field during the day, to the protective effects of strong light radiation from the sun, which is not achievable in lab conditions.
They make no claims of the universal reliability of HTTS, but see no reason why it wouldn’t work on other species and present it as a means of testing heat tolerance of all plants in situ. It will be interesting to see if Buchner or anyone else uses this system in other research projects on other species. All the parts in the HTTS are clearly referenced in the paper for others to build it, but it is a serious piece of equipment to set up and a big waste of time if it doesn’t work on your favourite species. However if it is shown to be accurate for model species, food crops or ornamental plants, it will be a useful tool for land managers and scientists alike.
Highlighted article (and image source): Othmar Buchner, Matthias Karadar, Ines Bauer, Gilbert Neuner (2013) A novel system for in situ determination of heat tolerance of plants: first results on alpine dwarf shrubs. Plant Methods 2013, 9:7 doi:10.1186/1746-4811-9-7
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