| Drought is the mostly importance limiting factor of agricultural yielding. Improve crops water use efficiency is the key of saving-water agriculture. Canopy temperature (CT) has been considered a good indicator of a genotype's physiological fitness, and can be an effective tool in screening wheat for water efficient use and high yield, particularly with the advent of portable infrared thermometers. Field experimentation were conducted at Zhenyuan, Gansu, China, the usefulness of canopy temperature in screening wheat (Triticum aestivum L.) genotypes was examined for grain yield and water use efficiency (WUE) in 2006. Twenty three and twenty one winter wheat genotypes from dry land and Bushland,Texas,USA respectively were grown under dry land. CTs were recorded from blooming to grain filling period between 13:30 and 15:30 h on 8 clear days. Determine soil moisture before seeding and after harvest respectively. Most important, grain yield and water use efficiency were closly correlated with CT under dry land conditions. These results clearly indicated that grain yield and water stress can be predicted by tacking CT in field, which can be used by breeding programs as a potential selection criterion for grain yield and drought resistance in wheat, but the results needed to confirm further in the second study year.1 Genotypes showed great differences in CT, and the differences were presented by significant grain yield and WUE among genotypes, but the differences of ET(evaportranspiration) has not significant in genotypes.2 The relationship between canopy temperature and yield and yield components had been analysed, the results indicated that the difference of yield among genotypes was significant and the correlation between the canopy temperature and yield were highly negatively in whole stage, the values of R2of the correlation between the canopy temperature and yield were presented increased- decreased -increased as grain stage proceeded. The close relationship between canopy temperature and yield not only decided upon inheritance but also closely tied up with appropriate environment. Winter wheat variety with good genes presented low canopy temperature. Canopy temperature could be apparent physiological character of fine genotype and indirectly target to judge the propriety of planting measure.3 From blooming to grain filling, WUE was highly negatively correlated with CT, and the value of R~2 of correlation between the canopy temperature and WUE were presented increased- decreased -increased as grain stage proceeded. These results clearly indicated some genotypes had high WUE consistently and low CT, the low WUE ones had high CT values.Moreover, grain yield and WUE had closed correlation (R~2=0.8277, R2=0.795), grain yield and water stress can be predicted by taking CT values in field using portable infrared thermometers, which can be used by breeding programs as a potential selection criterion for grain yield and water use in wheat.4 For 21 genotypes from Texas, USA and 23 genotypes from dry land classified as lower CT genotypes and higher CT genotypes by CTs of 8 days respectively. The discrepancy of their CTs was 2～3℃,the yield was 1.0t/ha ,water use efficiency was 2.0kg/ha·mm. The high-yield genotypes consistently had low CT values and high water use efficiency, and the low-yield ones had high CT values and low water use efficiency.Above all, the canopy temperature of winter wheat in the stage from blooming to filling was consanguineously correlated with yield and water use efficiency, so canopy temperature could not only be regarded as a physiological target to breed excellent cultivars but also reflect applicability of planting measure, and provided instrument to choose cultivars and make policy so as to offer the theory basement for high yield and quality.
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