Studies On The Difference Of Root Traits Among Maize Varieties Experienced Dry And Wet Alternating Conditions

【Object】since the engineering and the agriculture water-saving have been greatly developed, the biological water-saving - make use of the physiology and the gene potential of the plant oneself ,can be regarded as the key pathway in the future for further saving water resource wasted by agricultural production. Greatly parts of regions in the north china are dry and semi-dry lands, and the corn is a kind of main cash crop, therefore, the sieving grows a kind of anti- a dry ability variety, be subjected to the direction that the drought coerced to small- influence corn species to become many people to study now.【Methods】Under one kind of water treatments that is PEG solution modulation, five kinds of corn varieties Nongda108, Shendan16, zhengdan958, Shandan8806 and yedan13, which cultivated in different regions of China, were used as materials,【Results】1. Comparison root hair integrity, length and density among different maize varieties showed that the list of tolerance capacity under water stress is Shandan8806 ,zhengdan958, Shendan16, Nongda108, and yedan13, while the list of re-new capacity is Shandan8806, zhengdan958, Nongda108, Shendan16, and yedan13. 2. Dry-wet alternation changed sugar metabolism which was increased soluble sugar content both in leaves and roots under water stress for shandan8806 and nongda108 varieties, and then decreased it when re-watering, as a result, increased the sugar percent in roots. However, the sugar percent in roots for other three varieties did not changed. Water stress induced the content of O2- and H2O2 increased, and meantime activated the defense system, ex. SOD and CAT. After re-watering, the activity of SOD and CAT decreased. According to the decrease degree of SOD, Nongda108 and Shendan8806 sorted to the same group that is SOD activity decreased significantly until lowed control, while shandan16, zhengdan958 and yedan13 sorted to another group that is both SOD activity and O2- content located between control and water stress. At CAT activity, shandan8806 and Shendan16 belong to the same group, whereas another three varieties sorted to a group. 3. water stress make all the stomata aperture decreased for shandan8806 and yedan13, while for another three maize, a part of their stomata aperture decreased, and the rend maintain open, namely present a . After re-watering, except for Shendan16, the stomata aperture for other four varieties re-opened, while the aperture of Shendan16 still present. Compared with control, water stress make the root system hydraulic conductivity(Lpr) decreased significantly for zhengdan958, Nongda108, yedan13 and Shendan16, however, shandan8806 still maintain a higher Lpr. When re-watering, Lpr increased again. 4. The change rule of relative water conten(tRWC)is similar Lpr that means shandan8806 present a higher RWC under water stress, and when re-watering, the RWC increased for all varieties, but the biggest composition Nongda108. Integrated the gas exchange index, we found that the decrease of photosynthetic rate(Pn)is mainly due to stomata limits while there is not only stomata limits but also un-stomata limits for other four varieties.【Conclusion】Through morphogenic response, metabolism regulation, ROS defense, membrane structure and integrity maintaining and hydraulic response, maize plants acclimate to un-lethal water stress, which make a base for re-watering. When re-watering, roots activity and function get repaired as well as bring out compensation. According to the tolerance capacity under stress and the repair capacity when re-watering, we sorted the 5 maize varieties to 3 groups. One is shandan8806 and nongda108, which have a great draught resistance, and should cultured in dry and semi-dry land. The second group is shendan16 and zhengdan958, which have a mid draught resistance and should planted in irrigation region and wet and semi-wet region. Both the first group and the second group have a higher compensation effect under dry and then re-watering soil conditions, so this give peoples a signal that in dry land through add irrigation while in irrigation region through limit soil water content, all which can saving water and improve water use efficiency(WUE). The last group is yedan13, which is sensitive to water stress, and only opted to plant in wet region and has a lower potential for water-saving. In conclusion, it is clear that from the difference response of maize to dry-wet alternation water conditions, not only can we explore the mechanism for biological water-saving, but also bring a direct for maize varieties disperse in different environments.