摘要
Crop water stress index(CWSI)is widely used for efficient irrigation management.Precise canopy temperature(T_(c))measurement is necessary to derive a reliable CWSI.The objective of this research was to investigate the influences of atmospheric conditions,settled height,view angle of infrared thermography,and investigating time of temperature measuring on the performance of the CWSI.Three irrigation treatments were used to create different soil water conditions during the 2020-2021 and 2021-2022 winter wheat-growing seasons.The CWSI was calculated using the CWSI-E(an empirical approach)and CWSI-T(a theoretical approach)based on the T_(c).Weather conditions were recorded continuously throughout the experimental period.The results showed that atmospheric conditions influenced the estimation of the CWSI;when the vapor pressure deficit(VPD)was>2000 Pa,the estimated CWSI was related to soil water conditions.The height of the installed infrared thermograph influenced the T_(c)values,and the differences among the T_(c)values measured at height of 3,5,and 10 m was smaller in the afternoon than in the morning.However,the lens of the thermometer facing south recorded a higher T_(c)than those facing east or north,especially at a low height,indicating that the direction of the thermometer had a significant influence on T_(c).There was a large variation in CWSI derived at different times of the day,and the midday measurements(12:00-15:00)were the most reliable for estimating CWSI.Negative linear relationships were found between the transpiration rate and CWSI-E(R^(2)of 0.3646-0.5725)and CWSI-T(R^(2)of 0.5407-0.7213).The relations between fraction of available soil water(FASW)with CWSI-T was higher than that with CWSI-E,indicating CWSI-T was more accurate for predicting crop water status.In addition,The R^(2)between CWSI-T and FASW at 14:00 was higher than that at other times,indicating that 14:00 was the optimal time for using the CWSI for crop water status monitoring.Relative higher yield of winter wheat was obtained with average seasonal values of CWSI-E and CWSI-T around 0.23 and 0.25-0.26,respectively.The CWSI-E values were more easily influenced by meteorological factors and the timing of the measurements,and using the theoretical approach to derive the CWSI was recommended for precise irrigation water management.
作物水分胁迫指数(CWSI)是指示作物水分亏缺状态的常用指标,CWSI计算的可靠性依赖于冠层温度(T_(c))的获取和CWSI的计算方法。本研究依据2个冬小麦生育期(2020-2022年)不同灌水条件下形成的不同土壤水分状态,研究了大气条件、红外热成像仪的高度和朝向以及一天中测定时间对CWSI计算的影响。CWSI可以通过经验方法计算(CWSI-E)和理论方法计算(CWSI-T)获取。研究结果表明,测定时的大气条件对计算的CWSI有显著影响,当饱和水汽压差(VPD)大于2000 Pa时,计算的CWSI与土壤水分条件具有相关性,只有在大气蒸散力达到一定程度,作物维持在一定蒸散量条件下,冠层温度才能反映作物是否存在水分亏缺状态。红外热成像仪高度会影响T_(c)值,下午在3 m、5 m和10 m处测得的T_(c)差异小于上午。红外热成像仪镜头向南对着冠层获得的T_(c)比向东或向北更大,这可能与不同方位叶片受光差异引起的蒸腾差异有关;测定位置越低,不同方位测定值差异越大。利用一天中不同时间获取的T_(c)计算得到的CWSI存在较大差异,中午时段获取的T_(c)(12:00-15:00)比其他时段T_(c)计算的CWSI更可靠。作物蒸散速率与CWSI-E和CWSI-T值呈负线性关系,R^(2)分别为0.3646~0.5725和0.5407~0.7213。CWSI-T与土壤有效水分(FASW)的相关关系高于CWSI-E,表明CWSI-T对作物水分状况的预测更准确。此外,利用14:00获得的T_(c)计算的CWSI-T与FASW之间的R^(2)高于其他时间,表明14:00是利用CWSI进行作物水分状况监测的最佳时间。在冬小麦生长季,CWSI-E的平均值和CWSI-T的平均值在0.23和0.25~0.26时可取得较高产量,表明适度水分亏缺利于冬小麦产量形成。相比CWSI-T,CWSI-E更易受气象因素和测量时间的影响,使用理论方法计算的CWSI较稳定可靠,可作为灌溉指标用于指导农业生产。
出处
《中国生态农业学报（中英文）》
CAS
CSCD
北大核心
2024年第9期1503-1519,共17页
Chinese Journal of Eco-Agriculture
基金
supported by the Project of State Grid Hebei Electric Power Co.,Ltd.(SGHEYX00SCJS2100077).
