Diffusion Mechamism Of Penoxsulam-Resistant Barnyard Grass[Echinochloa Crusgalli(L.) Beauv] Population In Rice Filed

As one of the three major food crops in China,the quality and yield of rice were restricted to a great extent by pests and weeds.weeds caused the most serious damage in agricultural production.Echinochloa crusgalli（L.）Beauv was one of the malignant weeds in rice fields,and damaged area was very wide.And it was easy to produce herbicide resistance,which maked it more difficult to control.It has been confirmed that Echinochloa crusgalli（L.）Beauv which from some regions was resistant to penoxsulam by our research laboratory,but the mechanism of its resistance diffusion was not yet clear.To clarify this issue,38 Echinochloa crusgalli（L.）Beauv populations which collected from Anhui,Jiangsu and Shanghai were taken as the research object,identified the sensitivity of 38 populations to penoxsulam by whole-strain bioassay,identified the tested population by SSR molecular marker technology,detected genetic diversity of simples.According to the identification results,38 populations was divided into different genetic groups.By researching the seed germination stage and seedling growth stage of plants from different genetic groups under abiotic stress,a conclusion was drawn that the stress environment had different effects on Echinochloa crusgalli（L.）Beauv from different genetic groups at the stage of germination and seeding.By comparing the vegetative growth and reproduction capabilities of penoxsulam-resistant Echinochloa crusgalli（L.）Beauv populations from different genetic groups,clarified the difference of diffusion ability.Explained the mechanism of resistance diffusion from the stages of seed,seedling and adult planting.Provided a basis for the treatment of penoxsulam-resistant Echinochloa crusgalli（L.）Beauv in different regions.The following is the result of the study:Different concentrations of penoxsulam were designed to test the sensitivity of the tested 38 populations to penoxsulam.The results showed that each population had different degrees of resistance to penoxsulam.The JJCW-1 population from Jiangsu was the most sensitive to penoxsulam with an ED50 of 0.22 g ai/ha.The AXXZ-4 population was the most resistant to penoxsulam with an ED50 of 53.16 g ai/ha,and the R/S ratio was as high as 236.43.The 3081 SSRs were screened for PCR primer development by RAD sequencing,78 pairs of SSR loci were found to be polymorphic.Detected genetic diversity by using 8 pairs of screening primers and 3 pairs of primers in the literature.The results shown that a total of 146 alleles were obtained,and the number of amplified allele bands was 19（EG₂,EG₅,and RM234）to 5（EG₃20）.Total number of alleles for the tested populations from 29（SSXB-1）to 61（JJCW-1）.The heterozygosities of the genes ranged from 0.457 to 0.739,the number of observed alleles ranged from 0.315 to 0.829,the effective number of alleles ranged from 1.051 to 1.192,Shannon’s information index ranged from 0.051 to 0.175,and the expected heterozygote showed low ang it ranged from 0.032 to 0.113;the genetic distance of the Nei gene ranged from 0.008 to 0.171;the genetic similarity of the gene ranged from 0.829 to 0.992.38 populations of penoxsulam-resistant Echinochloa crusgalli（L.）Beauv were divided into 3 genetic groups by Bayesian Analysis,8 populations from southern Anhui composed a genetic group,the 16 populations from the north of Jiangsu composed the other genetic group,and the 14 populations form Central Jiangsu,Southern Jiangsu or Shanghai composed another genetic group.By studying the germination and emergence of the seeds of penoxsulam-resistant Echinochloa crusgalli（L.）Beauv which were selected which from different genetic groups under different environmental conditions,the results showed that the stress conditions had different effects on Echinochloa crusgalli（L.）Beauv from different genetic groups at the stage of germination,and the degree of impact is higher,the worse the seed’s ability to germinate.Under the conditions of low temperature stress,water potential stress and salt stress,the effect of stress on the resistant population JHHZ-1 germination of was higher than that of sensitive population JLGY-3,but under high temperature stress,acid-base stress and depth of buried soil,the effect of stress on germination of two populations was the same.For the resistant populations from different genetic groups,the results showed that each stress had the highest impact on the germination of AXXZ-8 witch was the most resistant population.Except that the buried depth had a similar effect on JHHZ-1 and SSXB-1,the other stress conditions had a greater influence on SSXB-1 than JHHZ-1.In general.At the different sowing periods and interspecific competition conditions,the growth and reproduction abilities of the penoxsulam-resistant Echinochloa crusgalli（L.）Beauv populations which from different genetic groups were studied.The results showed that the population from 3 genetic groups showed different characteristics of vegetative growth and reproduction.At different sowing periods,the fresh weight of AXXZ-8’s competitive advantage was relatively weaker than JHHZ-1 and SSXB-1,but in the terms of the plant height,tiller number,panicles per plant,and the number of seeds per plant and 1000-grain weight,this population showed stronger competitive advantage than the two others.Under the conditions of competition with rice,there were no significant differences in the indexes of JHHZ-1 and SSXB-1,both of which showed similar competive ability,while the AXXZ-8’s aboveground fresh weight were significantly lower than the other’s under various planting densities.AXXZ-8’s plant height,number of tillers,panicles per plant and panicle weight per plant were significantly higher than the other’s in the low-density paddy rice.AXXZ-8’s ear weight per plant and the number of panicles per plant was significantly higher than that of JHHZ-1’s and SSXB-1’s,and AXXZ-8’s reproductive ability was influenced by the planting density of rice more than that of the other two populations’.The above result showed that AXXZ-8 had a lower competitive advantage than JHHZ-1 and SSXB-1 in terms of fresh weight and dry weight,but it had stronger competitive advantage in terms of plant height,number of tillers,and panicles per plant,this phenomenon reflected obvious characteristics of resource allocation theory.Under the conditions of 10℃ low temperature,40℃ high temperature and-0.5 MPa water potential and 300mM NaCl salt stress,the photosynthetic pigment content（chlorophyll a,chlorophyll b,carotenoids）,soluble protein and soluble sugar content,and the activities of antioxidant enzymes（SOD,POD,CAT）of different penoxsulam-resistant Echinochloa crusgalli（L.）Beauv populations which from 3 genetic groups were compared.The results showed that the physiological response degree of different populations to abiotic stresses were different.And the higher the response degree,the stronger the regulatory mechanism adopted in response to adversity.Under the conditions of 10℃,-0.5 MPa water potential or 300mM NaCl salt stress,the photosynthetic pigment content and antioxidant enzyme activity decreased in turn,this result showed that the photosynthetic capacity and antioxidant capacity of three groups decreased in turn.At 40℃,there was no difference in photosynthetic capacity and antioxidant capacity among the various groups.At 40℃ or-0.5 MPa water potential,AXXZ-8’s soluble protein synthesis system and soluble sugar synthesis system are more responsive to stress than the other two groups,this population had strong osmotic adjustment ability.Under the conditions of 300mM NaCl salt stress,the osmotic adjustment ability of JHHZ-1,AXXZ-8,and SSXB-1 decreased in turn.At the low temperature of 10℃,three populations had the same osmotic adjustment ability.