| Hubei province is the fourth large citrus production area in China. The citrus production decreases about 10-20% because of the weeds in citrus orchard. High levels of herbicide-resistance are caused by long time and extensive application of the herbicides. In this paper, the occurrence characteristics of weeds in citrus orchard of Hubei province were investigated, and the glyphosate-resistant of Conyza Canadensis and Eleusine indica were studied, chemical herbicides to control resistance weeds were screened, the herbicides to control weeds in citrus orchard were researched.The occurrence characteristics of weeds in citrus orchards of Yichang city, Shiyan city and Jingzhou city were studied. The results showed that, there were 112 kinds of weeds in citrus orchards in Hubei province, they belonged to 36 families. Among them, there were 87 kinds of weeds in Yichang city, and they belonged to 35 families, the dominant species were Polypogon fugax, Conyza Canadensis, Oxalis corniculata, Acatypha austrdis, Veronica persica and Sedum bulbiferum. In Shiyan city, there were 80 kinds of weeds, and they belonged to 32 families, the dominant species were Conyza Canadensis, Oxalis corniculata and Acatypha austrdis. In Jingzhou city, there were 44 kinds of weeds, and they belonged to 20 families, the dominant species were Erigeron annuus, Conyza Canadensis, Cerastium caespitosum, Veronica persica, Malachium aquaticum, Acatypha austrdis, Artemisia sylvatica, Mazus japordcus, Pinellia tenata, Rotala indices and Equisetum ramosissimum.In this paper, the glyphosate-resistant levels of Conyza Canadensis and Eleusine indica in citrus orchards in Hubei province were studied. Taking the length of new root as the index, the glyphosate-resistant level were tested by agar culture medium method, the result showed that the glyphosate-resistant level of Eleusine indica which was marked YC02 was the highest (IC50= 99.5053 mg/L), and the resistance ratio was 15.5484, and the follower was JZ06 (IC50= 27.2919 mg/L), the resistance ratio was 4.2646. Taking fresh weight as the index, the glyphosate-resistant level of Conyza Canadensis marked SY01 was the highest (IC50=10.0067 mg/L), it was 3.5382, the follower was YC03 (IC50=7.8979 mg/L), and the resistance ratio was 2.7925, the resistance ratio of YC04 (IC50=6.3008 mg/L) was 2.2278. Taking the root length as index, the glyphosate-resistant level of Conyza Canadensis marked YC03 was the highest (IC50=15.5773 mg/L), it was 6.5281, the follower was SY01 (IC50= 15.4824 mg/L), and the resistance ratio was 6.4884. The glyphosate-resistant level of Eleusine indica was assessed by whole plant assay. The result showed that the resistance level of YC02 (IC50= 1753.5240 mg/L) was the highest and the resistance ratio was 11.0211, the follower was JZ06 (IC50= 1182.6350 mg/L), the resistance ratio was 7.4330, the resistance ratio of JZ02 (IC50= 933.5887 mg/L) was 5.8677. Different glyphosate-resistant levels of Conyza Canadensis and Eleusine indica had occurrence in citrus orchard in Hubei, and the resistance of Eleusine indica was serious. The resistance and sensitive Eleusine indica were applied by 2000 mg/L glyphosate, the shikimic acid accumulated in sensitive Eleusine indica population (646.31μg/g) was 6.58 times to the glyphosate-resistant Eleusine indica (98.27μg/g)The herbicides to control the glyphosate-resistant Eleusine indica and Conyza Canadensis were searched. The inhibitory effect of quizalofop-P to glyphosate-resistant Eleusine indica was the best, and the inhibitory effect of fluroxypyr to glyphosate-resistant Conyza Canadensis was the best.The control effective, persistence and proper concentration of aminocyclopyrachlor used to control weeds in citrus orchard alone or mix with other herbicides were studied by field experiment. Gramineous weeds can be controlled completely when 60-90 g a.i./ha of aminocyclopyrachlor mixed with 1 200 g a.i./ha glyphosate, and there were also a good control effect to broadleaf weeds. Aminocyclopyrachlor is a good herbicide to control the broadleaf weeds, most of the broadleaf weeds and gramineous weeds can be controlled well when it mixed with glyphosate and rimsulfuron.There are so many different weeds in citrus orchard that make it difficult to control the weeds. To supplement the data, more survey on the occurrence characteristic of weeds in citrus orchard should be done. Is there a relationship between the resistance of Conyza Canadensis to glyphosate and the translocation of glyphosate in Conyza Canadensis and is the significant difference content of shikimate in Eleusine indica caused by the genes mutation of EPSPS, a further investigation can be done. |
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