The Resistance To Tribenuron-methyl In Lithospermum Arvense L. In Winter Wheat Fields In Part Of Shandong

Lithospermum arvense L is widely spread across much of the agricultural land in east part of Shandong. Tribenuron-methyl were lower effective on control of Lithospermum arvense L. In order to evaluate the resistance of Lithospermum arvense L to tribenuron-methyl: Whole-plant bioassay, and Seed bioassay experiments were performed. Based on the work done above, the biotype with relative higher herbicide resistance was selected, and the enzymology mechanism of resistance was discussed by the research on the target enzyme acetolactate synthase (ALS), important plant metabolic enzyme glutathione-s-transferase (GSTs), the protective enzyme (SOD, POD, CAT).The results are as follows:1. The resistance level detection of Lithospermum arvense L to tribenuron-methyl.1. The results of whole-plant bioassay tests showed that except for the wheat field biotypes from the collecting sites of Pingdu(1.33), Chengyang(2.34), others wheat field biotypes has evolved resistance to tribenuron-methyl, with a resistance factor ranging from 5.07 to 12.97. The highest resistant was Jiao Zhou with ratios of 12.97. The resistance factors of Weicheng, Jiao Nan, Hanting was 7.53, 5.31, 5.07 respectively. Results of whole-plant bioassay suggested that Lithospermum arvense L biotypes had areadly become resistant.2. The results of seed bioassay experiments showed except for the wheat field biotypes from the collecting sites of Pingdu(0.95), Chengyang(0.93), the other wheat field biotypes had developed different degree resistance to tribenuron-methyl, with the resistance factors from 1.59 to 3.89. The resistance factors of Jiaozhou, Jiaonan, Weicheng, Hanting was 3.89, 1.89, 1.86, 1.59 respectively. Both seed bioassay experiments and whole-plant bioassay showed the same results.2. The resistance mechanism of Lithospermum arvense L. to tribenuron-methyl1. In vitro, there was obvious significant difference between the sensitivity of ALS from the R and S biotypes to tribenuron-methyl. Under the effect of tribenuron-methyl, the inhibitory action of ALS to susceptible biotypes were bigger than resistant biotypes. An in vivo enzyme assay, the amount of tribenuron-methyl required to causes 50% ALS activity reduction from the Jiaozhou biotypes were 0.215μM. The GR50 values were 2.65 higher than S biotype to tribenuron-methyl. Decreased ALS sensitivity was one of causes for the resistance of Lithospermum arvense L to the tribenuron-methyl.2. The ALS activity of both R and S biotypes declined after application of tribenuron-methyl, and then increased, however that of R biotype declined much less than S biotype. 4 days later the ALS activity of R declined to 64% of the contemporary control, then increased to 75.1%, the ALS activity of S declined to 40.2%, and kept on. This may one of cause for the resistance of Lithospermum arvense L to the tribenuron-methyl. This has the same results that of In vitro.3. GSTs plays and important role in the detoxification metabolism of tribenuron-methyl. In vivo, The GSTs activity of R biotype increased, with the peak value 1.488 times of the contemporary control after 4 days, while that of S biotype increased, with peak value 1.238 times after 3 days. Both of them came to control value 7 days later. After apply tribenuron-methyl, GSTs enzyme activity of resistant biotypes were higher than susceptible biotypes from unitary level. The different of GSTs enzyme activity between resistant biotypes and susceptible biotypes was one of important causes for the resistance of Lithospermum arvense L to the tribenuron-methyl.4.After application of tribenuron-methyl, there was obvious significant difference between the SOD enzyme activity,CAT enzyme activity from resistant biotypes and susceptible biotypes to tribenuron-methyl. The SOD enzyme activity,CAT enzyme activity of R biotype and S biotype are different. Elevated SOD enzyme activity,CAT enzyme activity can increased the ability of eliminating free radical. The different of protective enzyme activity between resistant biotypes and susceptible biotypes was one of important causes for the resistance of Lithospermum arvense L to the tribenuron-methyl.