The Study Of Screening Identification Indice Of Senescence And The Physiological Characteristics In Wheat

Triticumaestivum Physiological characteristicsL is the second widely planted crops and its sown area is about 27% of the arable crop land of our country.It plays an important role in food security .The improvement of wheat output is an important measure to guarantee food security and solve the problem of population and land shortage. Grain filling stage after anthesis is the most important period in process of yield formation,and it is chiefly derived from photosynthesis assimilating products of its flag leaves.However, grain filling stage is just accompanied its senescence of flag leaves.Therefore,its senenscence is reflected in series changes of physiological and biochemical characteristics of its flag leaves and seriously effect the output and quality of seed.The basic characteristics of good mature of wheat is the senescence of its function leaf and grain filling in parallel.And if the function leaf senescence starts much ealier and faster than the process of grain filling,it belongs to senescence.In wheat breeding practice, early-mature and senescence of wheat are often intertwined, so, how to correctly distinguish them and establish a scientific identification index has important theoretical and practical value.In this study , with 23 pieces of Huanghuai Wheat varieties (lines) as study materials which growth process are different during the last period, the stay green feature of the flag leaf and hull and the grain filling enrichment process are determined so as to establish the identification index of wheat senescence; The physiological and biochemical characteristics of different type senescence wheat are studied so as to identify senescence and provide basis for wheat breeding against early senescence.The main results are as follows,1.With the deviation square sum of cluster analysis , 23 species (lines) is divided into 4 different levels of aging categories, namely, the early-senescence type, the slightly early- senescence,the good mature type and the yellow ear but green leaf type by comprehensive analysis of the change of the content of flag leaf and its ratio to the conten of hull chlorophyll,grain weight and plumpness (dry grain volume / theoretical maximum volume). Grain plumpness can be used as the simple,fast and reliable identification index of wheat senescence; And the contrast of the conten of flag and hull chlorophyll can be used as the preliminary identification index in the fileds.2. By the established identification index of wheat senescence,23 varieties (lines) is divided into 4 different levels of aging categories: Typeâ… , the yellow ear but green leaf type, which flag leaf stay green for a long time and the ear turns yellow in good time;And this type include 7 varieties (lines) which are Abo,Zhongyu 6,Zhengnong 16,Qinmai187,Annong 91168,Han 6172 and Zhoumai13-1; And its plumpness is high, which is above 63.94%; Typeâ…¡, the good mature type, which flag leaves color change synchronizes with ear color ;This type include 4 varieties (lines) which are Xiaoyan 6,Wenmai 6,86 (77) and Yutong Me23; And its seed are fullness which plumpness is 61.94% ~ 62.42%; Typeâ…¢, the slightly early- senescence type, which grain-filling is slightly lagging behind the leaf senescence and its grain are thin which plumpness is 58.87% ~ 60.12%;This type include Annong 33,Lu 13,9125 and 20491-1; Typeâ…£, the early-senescence type, which flag leaf turns yellow significantly earlier than its hull and the grain is thin ,which plumpness is 53.67%~57.02%;This type include 8 varieties (lines) which is 925-6,98302,9411,38,9168,9125,924-1,98301 and 96309.3,Flag leaf physiological changes of different senescence type are different:For the yellow ear but green leaf type, the activity of the superoxide dismutase (SOD) and peroxidase (POD) of their flag leaf is higher and decreased more slowly ,their MDA content are lower and increased more slowly,the flag leaf net photosynthetic rate are higher and decline more slowly; For the good mature type, the activity of the superoxide dismutase (SOD) and peroxidase (POD) of their flag leaf is high and decreased slowly ,their MDA content are low and increased slowly,the flag leaf net photosynthetic rate are high and decline more slowly; For the slightly early-senescence type, the activity of the superoxide dismutase (SOD) and peroxidase (POD) of their flag leaf is relatively high and decreased relatively rapidly ,their MDA content are relatively low and increased rapidly,the flag leaf net photosynthetic rate are relatively high and decline relatively slowly; For the early-senescence type, the activity of the superoxide dismutase (SOD) and peroxidase (POD) of their flag leaf is relatively low but decreased more rapidly ,their MDA content are relatively low but increased more rapidly,the flag leaf net photosynthetic rate are relatively high but decline more rapidly.