The Physiological Elements Senescence Resistance Of The Wheat And The Effect Of The Different Concentrations Paclobutrazo1 On Leaf Senescence Of Wheat

In the recent past, there has been a doubling of average global grain yield per unit area for the major cereal crops such as wheat, rice and maize. This revolution is a consequence of repeated selection and cross breeding of many productive strains. Still, a food crisis has emerged because of the rapidly growing world population. As the most important food crop worldwide, wheat is regarded as a cereal with considerable potential to increase yield, particularly in marginal agricultural areas. The senescence of wheat upper leaves is accompanied by the grain filling process, It is of great significance to study the photosynthesis during the senescence of wheat upper leaves because it contributes greatly to grain yield. Upper senescence during the grain-filling period in wheat causes a sharp decrease in wheat yield by shortening the duration of active photosynthesis. So studying the changes of the physiological characterization in the period of the senescence of wheat upper leaves,delaying leaf senescence during the grain-filling period of crops and maintaining the sustainable supply of assimilated carbon to grain is an effective strategy for increasing cereal production. Here we use the materials of"Chuannong hao"wheat, studied the physiological elements of the wheat senescence resistance and correlation analysis between the wheat senescence resistance and yield, meanwhile, we also studied the effect of the different concentrations Paclobutrazol on leaf senescence and yield of Wheat. The results are shown as follow:1 The"Chuannong hao"wheat CN17,CN148 and CN19 leaves maintained a high level of chlorophyll throughout most of the grain filling stage, and long period of high level of chlorophyll showe that the"Chuannong hao"wheat has higher net photosynthetic rate, this is the most important physiological elements of the"Chuannong hao"wheat senescence resistance.2 During the wheat senescence stage, O₂^-production will increase, the ability to remove O₂^-will reduce,this will result to destroy the biomembrane of cell and the other biomacromolecule's structure and function. It is showed that the"Chuannong hao"wheat CN17,CN18 and CN19 have a greater ability to remove O₂^-.3 The degree of general lipid peroxidation is the direct and the significant reason, its intermediate product—the free radicals and its ultimate product—malondialdehyde(MDA) will damage the biomembrane. The content of malondialdehyde of the"Chuannong hao"wheat was significantly lower than that in MY11 plants toward the end of growth season, which suggests that severe oxidation did not occur in the"Chuannong hao"wheat, so the chlorophyll maintained at a higher level compared with MY11 throughout the grain filling period.4 The soluble protein of plantlet in vitro play the metabolic pool role in nitrogen metabolism, and its content's decrease correlated nearly with wheat leaf senescence. In this study showed that the soluble protein of the"Chuannong hao"wheat higher than MY11, which suggests that the"Chuannong hao"wheat senescence extent is slower than MY11.5 The index associated senescence has the same change rule in flag leaf and the second leaf and the third leaf.6 In this stuy, according to disease index simulated senescence index, and correlation analysis between senescence index and yield, the result showed that the senescence index of wheat and yield is a real rectilinear correlation, and the higher senescence index,the weaker senescence resistance, and the lower of wheat yield. The senescence index of the"Chuannong hao"wheat CN17,CN18 and CN19 is lower than MY11,which suggests that the"Chuannong hao"wheat have more stronge senescence resistance, so higher yield.7 In this study showed that, during the wheat elongation stage, sprayed suitable concentration of the Paclobutrazol solution on the wheat leave, it was beneficial to improve physiological vigor,and delay the decrease of chlorophyll content and high net photosynthetic rate value, and increase the SOD activity and CAT activity, and defer the period of photosynthetic function of wheat leaf, harmonize the proper of yield components, and so increased the yield.