Study On Canopy Temperature And Physiological Characteristics Of Different Millets

In order to explore canopy temperature and physiological characteristics of different millets,filed experiments were conducted at the Agriculture station 1,Northwest Sci-Tech University of Agriculture and Foresty,used infraded radiation three years(2005-2007),and a series of physiological metabolic indexes,includes content of Chlorophyll,Soluble protein content,Soluble sugar content and Malondialdehyde(MDA),Activities of superoxide dismutase(SOD),Catalase(CAT),Nitrate reductzse(NR) were tested in some varieties involved in the experiment which were representative in the grain formation and grain filling stages. The results showed that:1. In the same climate,soil and cultivating,the canopy temperature of different millets population were markedly different in natural world. Heng gu9 and Yugu 1 which canopy temperature were constantly lower than that of control during grain-filling periods were named cold typical millet,and Gufeng888,05-61,Jingu3 which canopy temperature were constantiy higher than that of control during grain-filling periods were named warm typical millet. And no matter whatever the climate and whenever the year could not change the temperature type of a variety.2. The significant differences in the canopy leaf physiological characteristics between two types are observed. From the flowering stage,the Chlorophyll content of the millet leaf decrease at a faster ratio, and there are significant differences between cold typical millet and warm typical millet. And the decreasing rates of the cold typical millet are lower than that of warm typical millet; During the grain-filling stages,Soluble protein content decreased faster,but the cold typical millet decrease slightly lower than warm typical millet,therefore,cold typical millet of Soluble protein content higher than that of almost warm typical millet; The soluble sugar content in the function leaf decrease in the grain formation stage and increase in the grain filling stage,but the Soluble sugar content of cold typical millet are always higher than that of warm typical millet during grain-filling period; The NR activities in the function leaf increase in the flowering stage,but there are no significant differences between cold typical millet and warm typical millet. During the grain-filling periods,the NR activities in the function leaf of cold typical millet decrease slower and are higher than that of warm typical millet,and there are significant differences between two types. The differences of the change of the Chlorophyll content,Soluble protein content,soluble sugar content and NR activities between cold typical millet and warm typical millet demonstrated difference of the function leaf senescence and physiological metabolic activity between the types. Therefore,those traits reflect the metabolic activities in certain millets and an indicator for the potential producton capability.There are significant differences in the activities of protective enzymes between cold typical millet and warm typical millet during grain-filling period. The activities of SOD,CAT remain a relative high level and decrease at a lower ratio along with millet to mature. MDA,the final protect of membrame super-oxiodization,accumulate at lower ratio and remains a relative lower level in warm typical millet. The differences of the changes of the SOD,CAT and MDA between cold typical millet and warm typical millet demonstrate the differences in protective active to oxygen injury. Those are the deeper inherent physiological reason to cause the difference of the millet leaf senescence between two types.3. An association study revealed that spike weight,percentage of grain weight,spike length,grian number were the main factors of grain yield, which extreme significantly and positively correlated with ear grain weigth; The grain weight significantly and negatively correlated with plant height except spike diameter.Analysis of genetic interrelations with ear grain weight revealed that there was distinct difference between cold typical millet and warm typical millet. The above genetic interrelations characters of cold typical millets are more excellent than those of warn typical millets. These illustrated that peresistered low canopy temperature as one of targeting traits in selection and breeding of millet was valued.Analysis from the millet yiled,there were no significant differences between cold typical millet and warm typical millet,that is to say,cold typical millet not necessarily have higher yield than warm typical millet. There is a link between different temperature varieties and grain yield and this is an area that needs exploration.