| Climate warming is an indisputable fact, which is one of the major characteristics of global climate change. Global climate will further warm with a greater level of daily maximum temperature than daily minimum temperature, be warmer in the north than the south, in winter and spring than in summer and autumn. Wheat is one of the major crops in China. The global climate warming is more severe in spring and winter, which impacts the winter-wheat even greater. The growth, yield and quality of wheat, under the condition of asymmetric warming climate, are concerned by international society. Hyperspectral technology is an effective way to continually, rapidly and dynamically monitor the large scale crops. With the changing trend of global climate, we set up the Free Air Temperature Increase (FATI) system in winter wheat field in Nanjing, Jiangsu, China during2012to2013. Under different warming treatments in day and night in the experiment, we studied the winter wheat responses in growth, yield and its quality, and combined with remote sensing technology to set up the estimation model of growth and yield in winter wheat. The main results were show as follows:(1) In the three ways of warming, the temperature of AW treatment was increased more than others, then the DW treatment, the NW treatment was the last one. But the three treatments had not significant difference, all them kept about2℃warmer than CK. In the temperature change of canopy, earth’s surface, underground5cm and10cm, the canopy was heated directly, which had an obvious effect. Then temperature decreased, until underground5cm it got the lowest and began to rally.(2) The results showed differential simulating warming changed the growth and development characteristics of wheat:the growth stages in advance, especially AW, then DW, the last NW. Jointing advanced more than other stages. High temperature contributed to plant height of winter wheat:AW>DW>NW>CK. The day and all-day warming were significantly improved in the leaf chlorophyll content of wheat, but the one in NW treatment was decreased. The plant dry weight of AW and DW treatments increased significantly. It was good for adding the yields. NW treatment had difference effect on Yangmail3and Xumai31, the plant dry weight of Yangmail3decreased11.02%, while the Xumai31increased6.07%. Day and all-day warming were improved the dry weight of spike, the NW treatment of Yangmail3and Xumai31were reduced about5%.(3) Asymmetric warming increased the nitrogen contents in leaf, stem and grain of winter wheat, especially in AW and DW treatments. The soluble sugar and sucrose content in leaf and stem of winter were decreased under asymmetric warming. There were significant difference during anthesis to21days after anthesis, the same with different gluten winter wheat. The effect of Night and day warming on soluble sugar content of winter wheat leaf was remarkable. Compared with leaf, the soluble sugar was decline largest under AW treatment, with no significant difference in DW and NW treatments. Asymmetric warming decreased the soluble sugar to N ratio in leaf at booting stage. In3warming treatments, the soluble sugar to N ratio of leaf was lowest in AW treatment.(4)The length of spike increased significantly in DW treatment, but decreased in NW treatment. With the increase of temperature, both the number of panicles per unit area and sterile spikelet per spike were decreased. DW and AW treatments could significantly increased the yield of winter wheat, it could be used in different gluten winter wheat. The change of winter wheat yield were complex, it was decreased13.19%in Yangmai13, but increased1.58%in Xumai31.3different warming treatments decreased ear per area and grains per ear. The1000-grain weight were increased under AW treatment, but increased under NW treatment. Warming was mainly increased the wheat yield by increasing the number of spike. Asymmetric warming decreased the starch content in grain, increased the amylase content, the ratio of amylase to amylopectin increased. Warming significantly increased globulin and gliadin content, decreased ratio of glutenin to gliadin.(5)The canopy spectral reflectance of4different warming treatments in winter wheat of Yangmai13and Xumai31had significantly difference in near infrared platform at booting stage. The reflectance appeared DW> AW> CK> NW. In the visible band, the reflectance of NW was lower than other treatments. The correlation analysis of growth index and spectral parameters in winter wheat showed:the r2of PND920and P_Area920with chlorophyll content was high. NDVI, which composed of810nm and560nm respectively, had the highest coefficient of determination with LAI. Vari-Green, which combined with green, red and blue bands, can be used to establish the high accuracy model to estimate the nitrogen content in leaf of winter wheat. Booting stage was the best yield estimation period. P_Depth560, NDVI (560,450) extremely significant correlation with yield, can be used to estimate crop yield. |
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