Study On Difference Of Canopy Temperature Of Malting Barley And Physiological Characteristics

Usually, filling-legume period of malting barley in China is in this stage that atmospheric temperature is rising fast, especially in the later period of filling-legume, high temperature often harms plants, that led to declining of grain weight of malting barley and increasing in protein content, this is a serious influence on the yield and quality of malting barley. This paper continuously observed the canopy temperature of 6 different malting barley varieties after anthsis for 2 years with infrared thermometer, and a series of physiological metabolism parameters and agricultural characters in 2006 and 2007.The results showed that:1. There was a obvious difference among canopy temperature of different malting barley after flower, 95-83,D-18 and Favorit were continuously low and Ganpi4,Harrington and 99-6 were continuously high. That showed the marked difference phenomenon of canopy temperatures of different malting barley varieties population. According to the method of definition for wheat temperature type by Zhang Songwu, we called the former cool varieties and the later warm varieties.2. The observation of the diurnal fluctuation of canopy temperatures showed that the highest canopy temperature of different barley in one day was at 13:00～15:00,and at the same time, the difference of different varieties was also the most.3. The trend of chlorophyll content of barley after flower was firstly incremental and then descendant. The degradation rate of chlorophyll content of cool barley was low and its content was obviously higher than warm barley's in later of growth. The soluble protein content of leaf raised firstly and then declined, but the declining rate of cool barley was slow and warm barley was opposite, that led to the soluble protein content of cool barley obviously higher than warm barley. The MDA contend of barley leaf raised by index with the gradual senescence of function leaves,but both the accumulation speed and the accumulation amount of MDA of cool barley were slower and less than warm barley. Chlorophyll and soluble protein content of cool barley was high, degradation speed was slow and damaged condition of membrane system was tiny, so their leaves could maintain normal activity and keep higher production of photosynthesis, these were beneficial for improving yield and quality. 4. The protective enzymes SOD, CAT et al. of leaf of cool barley was declining after flower with growth progress, but the declining rate of SOD, CAT of cool barley were lower than warm barley, and it was more obviously in later growth. These characters of protective enzymes high activity and low declining speed of cool barley was propitious to clear active oxygen and alleviate the harm of membrane system, these could defer senescence of leaf.5. During filling-legume period, NR activity of malting barley raised sharply firstly and then declined fast and declined slowly finally, but NR activity of cool barley was higher than warm barley, and the declining was slower, especially in the latter growth. These showed that cool barley had a higher capability than warm barley to use nitrogenous fertilizer, had the basis of high yield.6. Net photosynthetic rate of different leaf position of different barley varieties declined with approaches of autumn period. At the same period, net photosynthetic rate of different leaf position of the same barley variety was flag leaf > 2nd leaf from up>3rd leaf from up. More closed to the later of filling-legume, more significant difference in net photosynthetic rate between cool barley and warm barley, and cool barley was significantly higher than warm barley. With the growth gone, the difference of transpiration rate of different temperature type barleys was more obvious, cool barley was significantly higher than warm barley. Stomata factor and non-stomata factor could effect on photosynthetic during the period of senescence of barley leaves, and non- stomata factor was important limiting factor, but non- stomata factor of cool barley had a more superior.7. With senescence of barley, root bleaching raised firstly and then declined. Root bleaching sap of cool barley was more than warm barley, this showed that root system of cool barley had a hearty function that could offer more physiological metabolism materials in later growth. 8. All of Ear weight, Ear grains weight,1000-grains-weight of cool barley 95-83,D-18, Favorit were significantly higher than warm barley Ganpi4, Harrington and 99-6, these showed that filling-legume characteristic of cool barley was better than warm barley. But, Harvest index of cool barley was significantly lower than warm barley.this showed that the canopy temperature has the tremendous influence to the grain weight,but cool barley not necessarily have higher yield than warm barley, There is a link between different temperature varieties and grain yield and this is an area that needs exploration. The relation of the canopy temperature and the yield will be studied in the future.