Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genot...Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genotypes for yield under dryland and irrigated. Forty winter wheat genotypes were grown under irrigation and dryland. CTDs were recorded after heading between 1 330 and 1 530 h on 6 clear days for dryland and 9 days for irrigation. Drought susceptible index （DSI） for each genotype was calculated using mean yield under dryland and irrigated conditions. Genotypes exhibited great differences in CTD under each environment. The dryland CTDs averaged 1.33℃ ranging from -0.67 to 2.57℃, and the average irrigation CTD were 4.59℃ ranging from 3.21 to 5.62℃. A low yield reduction was observed under dryland conditions relative to irrigated conditions for high-CTD genotypes. CTD values were highly negatively correlated with DSI under dryland, and genotypes of CTDs = 1.3℃ in dryland condition were identified as drought resistant. For 21 genotypes classified as drought resistant by DSI, their CTDs were 1.68℃ for dryland and 4.35℃ for irrigation on average; for 19 genotypes classified as drought susceptible by DSI, average CTD was 0.94℃ in dryland and 4.85℃ in irrigation. The high-yield genotypes consistently had high CTD values, and the low-yield ones had low CTD values for all measurements in dryland. After heading, genotypes maintained consistent ranking for CTD. Regression results for CTD and yield suggested that the best time for taking CTD measurement was 3-4 weeks after heading in irrigation but any time before senescence in dryland. Crop water stress index （CWSI） calculated from CTD data was highly correlated with CWSI calculated from yield, which suggesting traditional costly CWSI measurement may be improved by using portable infrared thermometers. Most importantly, grain yield was highly correlated with CTD under dryland （R^2 = 0.79-0.86） and irrigation （R^2 = 0.46-0.58） conditions. These results clearly indicated grain yield and water stress can be predicted by taking CTD values in field, which can be used by breeding programs as a potential selection criterion for grain yield and drought resistance in wheat, but a second study year is needed to confirm further.展开更多
The implication of the revelation of the inverse leaf aging sequence（ILAS） of wheat needs to be probed in theory and practice.Since 2005,the comparison experiment of the ILAS and the conventional leaf aging sequence...The implication of the revelation of the inverse leaf aging sequence（ILAS） of wheat needs to be probed in theory and practice.Since 2005,the comparison experiment of the ILAS and the conventional leaf aging sequence（CLAS） has been carried out to measure the canopy temperature and some important biological parameters of wheat.In nature,there existed the phenomenon that the wheat leaves aged in an sequence opposite to the conventional sequence and some of the leaves of ILAS wheat aged sequentially differed from those of CLAS wheat,i.e.,the penultimate leaves rather than the flag leaves aged last among the leaves at different leaf positions;in correspondence with the inverse leaf aging sequence,there appeared an unconventional leaf color structure at the late fruiting stage,which had yellow upper leaves and green lower leaves,opposite to the conventional leaf color structure that had green upper leaves and yellow lower leaves;the chlorophyll concentrations,soluble protein concentrations,transpiration rates,and net photosynthetic rates of the penultimate leaves of ILAS wheat unconventionally surpassed those of their flag leaves as their growth moved forward from one stage to another stage,and the ILAS wheat characteristically presented cold canopy temperature,i.e.,a cold tail canopy temperature at the late fruiting stage,or a cold canopy temperature at the whole fruiting stage;because ILAS wheat was unique in physiological process,its kernel weights were obviously higher than those of CLAS wheat,which closely related to the ＂relay＂ kernel-filling mode,which was different from the kernel-filling mode of CLAS wheat under which the flag leaves act as the main nutrient supply source at the whole fruiting stage.This study provided a new idea and approach for the theoretical exploration on wheat fruiting and aging,wheat yield further improvement,and cold type wheat and cold tail wheat breeding.展开更多
基金This study was financially supported by the China National 863 Program(2002AA2Z4011)the China National R&D Program(2004BA508B09)Texas wheat breed and physiology program.These assistances are gratefully acknowledged.We also thank Gail Petersion and Melanie Allred for their assistance when the study was going on.
文摘Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genotypes for yield under dryland and irrigated. Forty winter wheat genotypes were grown under irrigation and dryland. CTDs were recorded after heading between 1 330 and 1 530 h on 6 clear days for dryland and 9 days for irrigation. Drought susceptible index （DSI） for each genotype was calculated using mean yield under dryland and irrigated conditions. Genotypes exhibited great differences in CTD under each environment. The dryland CTDs averaged 1.33℃ ranging from -0.67 to 2.57℃, and the average irrigation CTD were 4.59℃ ranging from 3.21 to 5.62℃. A low yield reduction was observed under dryland conditions relative to irrigated conditions for high-CTD genotypes. CTD values were highly negatively correlated with DSI under dryland, and genotypes of CTDs = 1.3℃ in dryland condition were identified as drought resistant. For 21 genotypes classified as drought resistant by DSI, their CTDs were 1.68℃ for dryland and 4.35℃ for irrigation on average; for 19 genotypes classified as drought susceptible by DSI, average CTD was 0.94℃ in dryland and 4.85℃ in irrigation. The high-yield genotypes consistently had high CTD values, and the low-yield ones had low CTD values for all measurements in dryland. After heading, genotypes maintained consistent ranking for CTD. Regression results for CTD and yield suggested that the best time for taking CTD measurement was 3-4 weeks after heading in irrigation but any time before senescence in dryland. Crop water stress index （CWSI） calculated from CTD data was highly correlated with CWSI calculated from yield, which suggesting traditional costly CWSI measurement may be improved by using portable infrared thermometers. Most importantly, grain yield was highly correlated with CTD under dryland （R^2 = 0.79-0.86） and irrigation （R^2 = 0.46-0.58） conditions. These results clearly indicated grain yield and water stress can be predicted by taking CTD values in field, which can be used by breeding programs as a potential selection criterion for grain yield and drought resistance in wheat, but a second study year is needed to confirm further.
基金supported by the National Natural Science Foundation of China (30270766,30470333)
文摘The implication of the revelation of the inverse leaf aging sequence（ILAS） of wheat needs to be probed in theory and practice.Since 2005,the comparison experiment of the ILAS and the conventional leaf aging sequence（CLAS） has been carried out to measure the canopy temperature and some important biological parameters of wheat.In nature,there existed the phenomenon that the wheat leaves aged in an sequence opposite to the conventional sequence and some of the leaves of ILAS wheat aged sequentially differed from those of CLAS wheat,i.e.,the penultimate leaves rather than the flag leaves aged last among the leaves at different leaf positions;in correspondence with the inverse leaf aging sequence,there appeared an unconventional leaf color structure at the late fruiting stage,which had yellow upper leaves and green lower leaves,opposite to the conventional leaf color structure that had green upper leaves and yellow lower leaves;the chlorophyll concentrations,soluble protein concentrations,transpiration rates,and net photosynthetic rates of the penultimate leaves of ILAS wheat unconventionally surpassed those of their flag leaves as their growth moved forward from one stage to another stage,and the ILAS wheat characteristically presented cold canopy temperature,i.e.,a cold tail canopy temperature at the late fruiting stage,or a cold canopy temperature at the whole fruiting stage;because ILAS wheat was unique in physiological process,its kernel weights were obviously higher than those of CLAS wheat,which closely related to the ＂relay＂ kernel-filling mode,which was different from the kernel-filling mode of CLAS wheat under which the flag leaves act as the main nutrient supply source at the whole fruiting stage.This study provided a new idea and approach for the theoretical exploration on wheat fruiting and aging,wheat yield further improvement,and cold type wheat and cold tail wheat breeding.
