| Research the change regularity root physiological traits and macronutrient of maize elite inbred lines in its evolution, which is benefited to its breeding work.10 maize elite inbred lines were planted in pots in this experiment, from 3 typical phases in the last century of our country such as 1960s,1980s and 2000s. To study the change regularity of them in those aspects as leaf area, dry matter accumulation, root/shoot ratio, root activity, root protective enzymes activity, N/P/K contents, and kernel weight, and the sampling time were at 0d,7d,14d,21d after flowering. The main results are as following,1) The 100-kernel weight of 2000s and 1980s are both higher than 1960s, but there is little difference between each other. It can be concluded that the characters as 100-kernel weight of maize elite inbred line are improved greatly as time's fly.2) All of the maize elite inbred lines in 3 times can be consistent with the typical S-type growth curve, about the dry weight accumulation after flowering, and can were fitting by Logistic growth equation, the final growth flux and the days reaching the max growth rate are highly increased. It can be concluded that the 2000s production potency is higher than 1980s, because of the growth rate and dry matter accumulation per plant potency of 2000s is higher than 1980s. The 1980s' dry matter weight of root, stem, leaf, etc. are higher than others, but the dry matter weight of it's leaf and stem are declined slowly at the grain filling process in the late breed period. As a result,1980s' dry matter transport capacity is very low to grain, and then the grain yield is inhibited. The root-shoot ratio is 2000s<1960s<1980s in turn. The smaller root-shoot ratio is, the more dispersion amount above ground from the per unit root weight is. And more assimilation products transport to grain, less to root at the same time.The leaf area of 1980s is bigger than others, but the lower leaf area of 2000s is bigger than 1980s,anymore,the Areas of upper leaf and three ear leaves are showed rising trend, Stay-green is high and senescence speed is low.3) The contents of soluble protein is rised firstly and then dropped after flowering. The soluble protein content of 2000s is always higher than others. The soluble protein high content is the base of the strong root vigor. With the flower time advanced, the root vigor is rised firstly and then dropped showing single peak curve with the maximum at flowering 10 days. The decrease amplitude of 2000s is more slowly then others in the root vigor dropping process. The root protective enzyme activity of 2000s is higher than others, and the root activity of SOD, POD and CAT are greatly higher than others at the late breeding period. The content of MDA showed contrary trend with protective enzyme activity, it can be concluded that the dropping of root protective enzyme activity lead to the root scavenging active oxygen activity decreased, active oxygen in juried membrane, and the root senescence more. The latest maize elite inbred lines shows greater activity of scavenging active oxygen and root senescence more slowly, which is beneficial to keeping high physiological activity in grain-filling stage, thus supporting the full grain filling.4) After flowering, the 2000s shows no great differences at root nitrogen content than others, but the decrease amplitude of nitrogen content in leaf and sheath is dropped more than others; the decrease amplitude of phosphorus content in various organs is dropped more than others. The change of potassium content is similar to nitrogen.In a word, the alternate process of maize elite inbred lines in china is completed by co-evolution of root and above ground with these physiological indexes. The 2000s has high level root vigor and it can be persisted longer, the areas of upper leaf and three ear leaves can be persisted longer so that plants can product more photosynthate. What's more, the ability of transporting matter keeps in high level and the nutrient produced by root and the organic compounds produced by photosynthetic can be transported to grain fluently, and then more yield can be produced. |
