Polymorphism And Utilization Value Of Reverse Aging Phenomenon Of Wheat Leaves

The normal sequence of wheat leaf aging is bottom-up successively aging, based onnatural leaf senescence. In recent years, we found that there are some wheat varieties withunusual sequence of leaf senescence. Flag leaf occurs aging first, then the2nd leaf. We calledit ‘Reverse aging phenomenon of wheat leaves. At present, research used methods aboutanalyzing the difference of typical samples, that is conducting a comparative analysis ofsamples between several typical varieties with different reverse aging types, or betweenreverse aging stem and normal sequence aging stem. The methods have a strong contrastivebut can not reveal the general characteristics and regularity of leaf reverse aging, because offewer samples. The present study reveal occurrence and polymorphism of reverse agingphenomenon of wheat leaves, based on a large number of field investigation and laboratoryanalysis data, with65wheat varieties as test material. The major findings are as follows:1. The distribution of reverse aging rate of wheat is positive skewness, which is notnormal. The median of the reverse aging rate is20%（10%-33%）, and the5%trimmed meanis24.4%.2. The level of wheat varieties reverse aging rate is increasing with the increasingincubation times. Appropriate later sowing makes reverse aging rate increases, but excessivepostponed could lower the rate.3. Leaf area, the rate of green leaf, the maximum volume of grain and grain-leaf radioshows the same regular patterns: High reverse aging rate wheat> media reverse aging ratewheat> low reverse aging rate wheat.4. Soluble protein content of leaf, MDA content of leaf, difference of chlorophyll contentfrom mid milk stage to dough stage, net photosynthesis rate, stomata conductance,transpiration rate show that, aging of leaves has a same regular pattern:2nd leaf> flag leaf innormal sequence aging stem, flag leaf>2nd leaf in reverse aging stem, flag leaf: reverseaging stem> normal sequence aging stem,2nd leaf: normal sequence aging stem> reverseaging stem. Soluble protein content of grain and the maximum volume of grain: reverse agingstem> normal sequence aging stem.5. Although growth of high reverse aging rate wheat and media reverse aging rate wheatstarted late, but it has a faster grain filling speed and a longer filling period. It might be thereason of why the weight of1000-kernel high reverse aging rate wheat is higher. The comparison of1000-kernel between3kinds of reverse aging rate wheat shows the laws: Highreverse aging rate wheat> media reverse aging rate wheat> low reverse aging rate wheat.6. At the whole filling stage (from anthesis to maturation stage), the average grain-fillingrate: reverse aging stem> normal sequence aging stem. At the first filling stage(from anthesisto dough stage), reverse aging stem has a significance difference at the0.01level, at the lastfilling stage(from dough stage to maturation stage), the difference between reverse agingstem and normal sequence aging stem is nonsignificant.1000-kernel weight of reverse agingstem is significant higher than of normal sequence aging stem.