Lepekhov S B
Federal Altai Scientific Centre of Agro-BioTechnologies, Barnaul, Russia.
Vavilovskii Zhurnal Genet Selektsii. 2022 Mar;26(2):196-201. doi: 10.18699/VJGB-22-24.
An infrared thermometer was first used to assess drought and heat tolerance in plant breeding more than 40 years ago. Soon afterward, this method became widely used throughout the world. However, Russia has not yet applied the described method for evaluating stress tolerance. This paper presents an overview of using infrared thermometry in plant breeding. Taking wheat as an example, it shows major advantages and disadvantages of canopy temperature depression (CTD) values measured by the infrared thermometer. The paper also demonstrates that genotypes with higher CTD values, and therefore with a lower canopy temperature, use more available soil moisture under drought stress to cool the canopy by transpiration. It refers to CTD as an integrative trait that reflects an overall plant water status. Its coefficient of variation lies in the interval of 10 to 43 %. A large number of publications illustrate a close relation between CTD values and yield and indicate a high heritability of the former. Meanwhile, the same works show that yield has a higher heritability. Moreover, some researchers doubt that CTD should be used in applied wheat breeding as there are many factors that influence it. CTD has a high correlation with other traits that reflect plant water status or their adaptation to drought or heat stress. Quantitative trait loci (QTLs) associated with CTD are localized in all chromosomes, except for 3D. These QTLs often explain a small part of phenotypic variance (10-20 %, more likely less than 10 %), which complicates the pyramiding of canopy temperature genes through marker-assisted selection. The paper concludes that the evaluation of CTD appears to be a reliable, relatively simple, labor-saving, objective, and non-invasive method that sets it apart from other methods as well as shows the best results under terminal drought and heat stress conditions.
40多年前，红外温度计首次被用于评估植物育种中的耐旱性和耐热性。此后不久，这种方法在全世界得到广泛应用。然而，俄罗斯尚未应用上述评估胁迫耐受性的方法。本文概述了红外测温法在植物育种中的应用。以小麦为例，展示了用红外温度计测量冠层温度降低（CTD）值的主要优缺点。本文还表明，CTD值较高、冠层温度较低的基因型在干旱胁迫下利用更多的土壤有效水分通过蒸腾作用冷却冠层。它将CTD称为反映植物整体水分状况的综合性状。其变异系数在10%至43%之间。大量出版物表明CTD值与产量之间存在密切关系，并表明前者具有较高的遗传力。与此同时，同样的研究表明产量具有更高的遗传力。此外，一些研究人员怀疑CTD是否应用于小麦应用育种，因为有许多因素会影响它。CTD与其他反映植物水分状况或其对干旱或热胁迫适应性的性状高度相关。与CTD相关的数量性状位点（QTL）定位在除3D以外的所有染色体上。这些QTL通常只能解释一小部分表型变异（10%-20%，更可能小于10%），这使得通过标记辅助选择将冠层温度基因聚合变得复杂。本文得出结论，CTD评估似乎是一种可靠、相对简单、省力、客观且非侵入性的方法，使其有别于其他方法，并且在终末期干旱和热胁迫条件下显示出最佳结果。
