Sodicity is a major soil constraint in many arid and semi-arid regions worldwide, including Australia, which adversely affects the ability of crops to take up water and nutrients from the soil, reducing yield. Reliable methods and tools are required for appropriate selection of traits, may provide a better understanding of crop responses to multiple stresses, especially in sodic soil. A novel strategy was developed using unmanned aerial vehicle (UAV)-thermal imaging and agglomerative hierarchical clustering-based techniques to evaluate and rank the physiological performance of 18 contrasting wheat genotypes grown on a moderately sodic and a highly sodic soil in north-eastern Australia. We obtained UAV-thermal imaging data at different times of the day (9:30, 12:00, and 15:00 hrs) close to flowering stage. Crop biophysical parameters (Leaf potassium concentration, normalized difference vegetation index, crop water uptake, stomatal conductance, plant moisture content, and aboveground biomass) were measured at close to flowering by destructive plant sampling and ground-based proximal sensing and yield was machine harvested at maturity. Canopy temperatures derived from thermal imagery between 28.9 and 35.4 °C were observed at the moderately sodic site, and between 36.2 and 41.0 °C at the highly sodic site from 9:30 to 15:00 hrs. Canopy temperature was consistently higher than corresponding ambient air temperatures indicating plant water stress at both sites. While the air temperature was not significantly different (p > 0.05) between the two sites, canopy temperature was significantly higher (p < 0.01) on highly sodic soil compared to moderately sodic soil, indicating greater water stress at the highly sodic site. This difference was most likely due to the adverse impacts of sodic soil constraints and not primarily due to environmental variations. Hence, our study revealed that sodic soil constraints can intensify plant water stress. Statistical analysis between canopy temperature (9:30, 12:00, and 15:00 hrs) and crop biophysical parameters showed close negative correlations at both moderately sodic (R² = 0.54 to 0.83) and highly sodic (R² = 0.30 to 0.89) sites. A closer correlation was observed at 15:00 hrs for both sites. Thus, high-resolution UAV-thermal imaging has potential to detect water-stressed plants on sodic soil. Agglomerative hierarchical clustering was used as an unsupervised machine learning tool for ranking of physiological performance of wheat genotypes. Results suggest that UAV-thermal imaging and AHC techniques can discriminate cultivars tolerant to sodicity. The study improves our understanding of crop physiological behaviour and can assist farmers in selection of water stress tolerant genotypes to sustain food security in sodic soil under water-limited environments.

在包括澳大利亚在内的世界许多干旱和半干旱地区，钠肥是主要的土壤限制因素，对作物吸收土壤中水分和养分的能力产生不利影响，从而降低了产量。所需要的性状适当选择可靠的方法和工具，可以提供更好地了解作物应对多重压力，尤其是在盐碱土。利用无人机（UAV）-热成像和聚类的层次聚类技术，开发了一种新的策略，以评估和排名在澳大利亚东北部中等苏打和高苏打土壤上生长的18种不同小麦基因型的生理性能。我们在接近开花期的一天的不同时间（9：30、12：00和15:00）获得了无人机热成像数据。在作物接近开花期，通过破坏性植物取样法测量作物生物物理参数（叶钾浓度，归一化差异植被指数，作物水分吸收，气孔导度，植物水分含量和地上生物量），并通过地面近端感测，并在到期。在9:30到15:00时，在中度苏打点观测到的热成像冠层温度在28.9和35.4°C之间，在高苏打点观测到的冠层温度在36.2和41.0°C之间。冠层温度始终高于相应的周围空气温度，表明两个地点的植物水分胁迫。虽然气温没有显着差异（和地上生物量）在接近开花时通过破坏性植物采样和地面近端感测进行测量，并在成熟时通过机器收获产量。在9:30到15:00时，在中度苏打点观测到的热成像冠层温度在28.9和35.4°C之间，在高苏打点观测到的冠层温度在36.2和41.0°C之间。冠层温度始终高于相应的周围空气温度，表明两个地点的植物水分胁迫。虽然气温没有显着差异（和地上生物量）在接近开花时通过破坏性植物采样和地面近端感测进行测量，并在成熟时通过机器收获产量。在9:30到15:00时，在中度苏打点观测到的热成像冠层温度在28.9和35.4°C之间，在高苏打点观测到的冠层温度在36.2和41.0°C之间。冠层温度始终高于相应的周围空气温度，表明两个地点的植物水分胁迫。虽然气温没有显着差异（9:30至15:00小时在高碱度的地方为0°C。冠层温度始终高于相应的周围空气温度，表明两个地点的植物水分胁迫。虽然气温没有显着差异（9:30至15:00小时在高碱度的地方为0°C。冠层温度始终高于相应的周围空气温度，表明两个地点的植物水分胁迫。虽然气温没有显着差异（p  > 0.05）在两个位置之间 ，高碱度土壤的冠层温度显着高于中碱度土壤（p <0.01），表明高碱度土壤的水分胁迫更大。这种差异很可能是由于钠盐土壤限制的不利影响，而不是主要由于环境变化。因此，我们的研究表明，钠盐土壤的约束会加剧植物的水分胁迫。冠层温度（9：30、12：00和15:00小时）与作物生物物理参数之间的统计分析表明，中度苏打（R ²  = 0.54至0.83）和高苏打（R ² = 0.30至0.89）网站。两个站点在15:00时观察到更紧密的相关性。因此，高分辨率的无人机热成像技术有潜力检测苏打土壤上的水分胁迫植物。聚集层次聚类被用作无监督的机器学习工具，用于对小麦基因型的生理表现进行排名。结果表明，无人机热成像和AHC技术可以区分耐盐碱度的品种。该研究提高了我们对作物生理行为的理解，并可以帮助农民选择耐水胁迫的基因型，以在缺水的环境下维持苏打土壤中的粮食安全。