Study On Sensitivity Of Different Maize Varieties To Nicosulfuron

Nicosulfuron is selective herbicide used in corn field. For the reason that it could get rid of perennial and annual weed with little dosage, and it is safety for the corn, the adjuvant could help decreasing the Nicosulfuron using dosage, stabilizing the effect and Nicosulfuron could be used with some other herbicide, Nicosulfuron have become the important herbicide in corn field. But recently in some areare,some corn breed have been injured heavely after using Nicosulfuron.Corn is the primary crop of our country,the breed resource is enrich,it is very probably that there are some sensitive variety in production.So it is very important for industry and agriculture to study the sensitivity of different corn variety to Nicosulfuron.This paper chooses many planted greatly corns to study, definitudes the sensitivity of different corns to Nicosulfuron, and explores the sensitive difference mechanism in pHysiological and descendibility elements. The results could be summaried as follows:1. With the method of planting in pot, the effect of nicosulfuron to maize in seedling was observed. The results showed that with the normal dosage 60g/hm2, inhibiting rate of the plant height and weight of Taiyu 2(zhengjiao), Jinzhenzhu, Taiyu 15, Zinuo and other three breeds are beyond 40% and 30%, and it is obvious that plant growing is inhibited, the leaves etiolate and new leaves twist severely and couldn't grow normally. Inhibiting rate of the plant height of Ziyu 2, Taiyu 2(fanjiao), Liaoyu 18, Ludan 50, Zhengdan 958 and some other varieties are between 30.6% and 38.1%, the sensitivity of these varieties are lower and the plant modalities are not influenced bigger; in addition, Nongda 108, Nongda 2008, Xinyu 958 and Taiyu 12 grow healthy, the resistance to nicosulfuron are higher compared with other varieties. There aren't clear injury symptoms on these plants. And the sensitive degree of other varieties is between Yudan 2002 and Xinyu 958. Finally, with bioassay method in foster utensil, sensitivity of the maize root length to nicosulfuron is detected: based on IC50, the sensitivity order is: Taiyu 2(zhengjiao)>Jinzhenzhu>Taiyu 7>Zinuo>Taiyu2(fanjiao)>Taiyu 15>Feiyu 5>Ludan 50>Hudan 2000>Liaoyu 19>Taiyu 12>Ludan 981>Liaoyu 18>Nongda 108>Nongda 2008.2. After using Nicosulfuron 4 days, ChloropHll content of tolerant variety nongda 108 and taiyu 12 begain to increase, and made the tolerant variety had higher nhotosvnthesis ability. Root activity changed little and recovered formal level in short time. The sensitive variety taiyu 2(zhengjiao)'s chloropHll content showed decreasing trend and the root activity decreased greatly that the absorbing water and manure of corn was restrained.The change of chloropHll content and root activity of different corn showed coherency trend with the injury represent in pHysiology.3. After spraying Nicosulfuron in Ieaf, ALS activity of the tolerant variety showed higher continuously, but ALS activity of the sensitive variety taiyu 2(zhengjiao) was restrained continuously. Compared with the sensitive variety, Bar enzyme of ALS activity increased in tolerant corn variety was the key cause in increasing tolerance to Nicosulfuron.4. After spraying Nicosulfuron in Ieaf, the tolerant variety have higher GSTs activity what increased the conjugation ability to Nicosulfuron. It is important way to dispel toxin of Nicosulfuron in tolerant corn variety. The GSTs activity of sensitive variety decreased greatly, so the dispel toxin of Nicosulfuron is weaker.5. Five days after spraying Nicosulfuron in Ieaf, POD activity of the tolerant variety was higher than antithese obviously,the sensitive corn's POD activity was continuously decreased.CAT activity increased little but the sensitive variety showed firstly increasing and then decreasing trend.SOD activity in the leaf of tolerant variety showed decreasing trend then SOD activity begin increasing and arrive at normal level.At the same time, SOD activity of the sensitive corn was continuously decreased. MDA content of tolerant corns showed increasing trend,but the increasing scope of the tolerant variety was little compare with the sensitive corn varieties. MDA content of sensitive corns was higher continuely. It is one course that resistant oxidant enzyme keep high activity in tolerant corn variety so as to clarify the super oxide which is harmful to corn.6. Spraying GA when using Nicosulfuron result that the restrained effect of Nicosulfuron to sensitive corn was decreased.It is showed the plant grow-regulator could relaxed the injury by herbicide. The tolerant variety of maize isn't harmed neither omethoate is sprayed for 48 hours before nicosulfuron sprayed nor for 48 hours after nicosulfuron. In contrary, the sensitive maize was harmed seriously when omethoate is sprayed for 48 hours before nicosulfuron sprayed then 48 hours after nicosulfuron. Spraying the mixture of nicosulfuron and omethoate, The activity of ALS and GSTs is visible different between the tolerant variety and sensitive variety of maize, but there are nor differences of ALS activity for the same maize when spraying nicosulfuron and spraying the mixture of nicosulfuron and omethoate; GSTs activity of sensitive maize was obviously lower when spraying the mixture of nicosulfuron and omethoate than spraying nicosulfuron.7. By test the fingerprint of sensitive maize Taiyu 2 and its parents inbred, the relative breed could be tested quickly and it could direct cultivating the tolerant maize to nicosulfuron.