Root Characteristic Of Inbred Lines Of Maize In Different Aluminum-tolerance

The morphological and anatomical characters, the physiological characteristics of element absorption, organic acid secretion and root activity as well as the hereditary character of Al-tolerance were studied in 9 inbred lines of maize and part of their cross and backcross generations that had different reactions to acid soil by the means of nutritional cultivation and 3-compartment root box. The main results were as follows:1 .The evaluation of Al-tolerant inbred lines in nutrient solution with aluminum and the screening results in acid soil kept basically consistent. There was significant correlation between the relative seminal root length (RSRL) and the Al-tolerance of the inbred lines of maize. That means RSRL can be used as a simple, convenient and accurate index for Al-tolerance estimation. There were significant different of morphological and anatomical characters between two typical inbred lines.2.The methods of pre-treatment (concentration and chromatography et al) excreted by root and HPLC detection of organic acid had been improved. DEAE chromatography columniation was first directly used in the collection and concentration of organic acid exuded by the root system, which was also compared with the reclaim ratio acquired by rotation evaporation concentration. The results shows that the method of DEAE chromatography columniation has a good reclaim ratio, thus can be directly used in extraction and concentration of organic acid exuded by the root system, especially in the occasion of many samples. Some methods of RP-HPLC detection of organic acid had been comparatively studied. RP-HPLC detection method of some 7 organic acids had also been perfected.3.The secreting characteristic of organic acid of both inbred lines of Z01 (Al-tolerant) and Z02 (Al-sensitive) in full nutrition solution with Al was comparatively studied. The results firstly shows that the Al-tolerant genotype can exuded lots of malate. Some experiments on organic acid dynamically secreting was also conducted in a certain period, which shows the secreting quantity of organic acid (mainly malate) of the two lines changed with the Al treating time. Aluminum stress could significantly increase the malate quantity secreted by Z01, and it's relative secreting quantity reached a peak value after 3 days treated with aluminum.The relationship between the activity of Malate Dehydrogenase and the organic acid secretion by root in maize had been firstly studied, which shows both NADP-Malate Dehydrogenase activity and malate content of Z01 in root obviously increased and thecontent of malate changes with the secretion quantity in a positive linear way. Aluminum stress also obviously increase the malate quantity secreted by Z01 when planted in CaCl2 solution with aluminum. Experimental results showed that, malate secreted by root in Al-tolerant inbred lines Z01 maybe was a biochemical characteristic to adapt Al stress. Malate secreted by root maybe was synthesized by the way of PEP→OAA→Malate.Both the types and content as well as the quantity of organic acid secreted by the root had been studied. The results shows, there is difference of genotype in organic acid secreting in various inbred lines. Malate, citrate, succinate, acetate and maleate are detected in the secretion of root, among which succinate and malate were most commonly found. There is no corelation between the total amount of organic acid in the root and the ability of Al-tolerance of inbred lines.There was significant difference of soluble sugar secreted by root between two typical inbred lines after 3 days of treating with Al, the amount of soluble sugar secretion of Al-tolerant inbred lines obviously higher than that of Al-sensitive lines, but finally they came back to the control level as the time elongation. On the control state, only citric acid was detected in bleeding sap in both lines, but a great deal of succinate could be detected in Z01 (Al-tolerant) when treated with Al4.There are differences of nutrient characteristic found in the experiment. The aver...