基于三温模型和热红外遥感的不同大豆品种蒸腾特征研究

蒸腾耗水是水循环中重要的水分存在形式之一,是准确量化水分利用效率的关键参数,对研究碳水循环关系及节水农业有重要意义。本研究以大豆品种‘晋21’(J21)和‘Union’(C08)为研究对象,设置两种水分处理当地经验灌水定额的75%(A0)和37.5%(A1)],基于三温模型(3TModel)和热红外遥感,定量研究不同品种和不同水分胁迫下的大豆蒸腾速率,揭示其时空特征差异,从而为抗旱节水大豆品种筛选提供参考。研究结果表明:1)不同处理下大豆的蒸腾速率日变化趋势与气温、太阳净辐射和冠层温度的基本一致,呈先增加后减小的单峰曲线,且于午间达到峰值,峰值为1.2～2.5mm·h~(-1);各处理的大豆冠层温度和蒸腾速率均呈现出明显的空间异质性。2)J21与C08大豆的冠层温度A0处理分别低于A1处理6.55K和5.91K,蒸腾速率A0处理高于A1处理0.28 mm·h~(-1)和0.29 mm·h~(-1);大豆蒸腾速率与灌水量呈正相关、与冠层温度呈负相关。3)在相同水分胁迫下,大豆冠层温度J21低于C08 1.83～2.47 K,蒸腾速率J21高于C08 0.13～0.14 mm·h~(-1)。本研究与传统方法相比,所需要的参数较少,避开了空气动力学阻抗等难获取的参数,对农田尺度更具有适宜性,更能揭示不同农田环境下作物的蒸腾时空异质性,在农业水分高效利用和节水品种筛选上有十分重要的科学意义。

Transpiration characteristics of different soybean varieties based on the Three-Temperature Model and thermal infrared remote sensing

Transpiration is an important process in the water cycle and is the key parameter to accurately quantify water use efficiency. Thus, it is of great importance for studying the relationship between the carbon and water cycles and for developing water-saving agricultural practices. The major objective of this study was to quantitatively study the transpiration rate of soybean plants of different varieties and under different water stress conditions, to identify differences in temporal and spatial characteristics, and finally, to provide a reference for the selection of drought-resistant and water-saving soybean varieties. Therefore, two soybean varieties (C08 and J21) were selected as the research objects and two water stress conditions (75%A0] and 37.5%A1] of the local empirical irrigation quota) were used for each variety. Based on the Three-Temperature Model (3T model) and using thermal infrared remote sensing, transpiration was quantified in the different soybean varieties under different water stress conditions. The diurnal variation in transpiration rate of the soybean plants under different water stress conditions was basically consistent with temperature, net solar radiation (R_n), and canopy temperature (T_c), showing a single-peak curve that first increased and then decreased, reaching a peak at value between 1.2 mm·h^-1 and 2.5 mm·h^-1 at noon. Moreover, the canopy temperature and transpiration rate of soybean plants under different treatments showed obvious spatial heterogeneity. Under different water stress conditions, C08 and J21 soybean varieties showed canopy temperatures in the order A0 < A1, with means of 6.55 K and 5.91 K, respectively. Transpiration rates were in the order of A0 > A1, with averages of 0.28 mm·h^-1 and 0.29 mm·h^-1, respectively. Transpiration rates were positively correlated with irrigation and negatively correlated with canopy temperature. Under the same water stress conditions, canopy temperatures were in the order of C08 < J21, with the mean canopy temperature of J21 1.83-2.47 K lower than that of C08. In addition, transpiration rates were of the order J21 < C08, with the mean transpiration rate of the J21 soybean variety 0.13-0.14 mm·h^-1 higher than that of the C08 soybean variety. Thus, the J21 soybean variety consumes more water than the C08 variety under the same conditions of water stress. In combination with crop growth indicators, such as leaf area index (LAI) and crop yield, these data provide an important reference for improving crop water productivity in the future. Compared with traditional methods, the method used in this study has some advantages. The 3T model requires fewer parameters which are easy to be measured through introducing the concept of reference soil. The high-resolution thermal infrared instrument used here can reach the millimeter scale and meets the accuracy requirements of crop transpiration rate measurement in the farmland microclimate environment. Therefore, crop transpiration estimation based on the 3T model and thermal infrared remote sensing technology is convenient and accurate and is of scientific significance in promoting efficient agricultural water use and selecting water-saving crop varieties.