| Foxtail millet is cultivated as a rich nutrition and strong resistance cereal crop,and has become an important content of the national modern agriculture technology system.In recent years,the technology of mechanized plastic mulching and hole sowing was vigorously promoted,breaking through the technology problem on avoiding thinning and preserving the seedlings in the foxtail millet field,but the weeds harm becomes the key issue restriction foxtail millet modern production.Currently,although weed control has much methods,chemical weed control is a kind of the best effective way.The present study was carried out to investigate the difference herbicide resistance mechanism of 3 foxtail millet,e.i.,Zhangzagu 3,Zhangzagu 5,Zhangzagu 10 and Jingu 21,using multi-index comprehensive analysis of the relationship among photosynthesis indexes(net photosynthetic rate,transpiration rate,stomatal conductance),P700 and chlorophyll fluorescence parameters,active oxygen metabolism,antioxidant enzymes and antioxidants,target enzyme content,the plant hormones,and research the key factor of resistance of different hybrid millet varieties and its function characteristics,in order to scientific and rational use of herbicides in the valley of hybrid production,minimize herbicide key,in order to provide theoretical guidance and technical reserves and achieve high efficiency,high yield,high quality hybrid millet in large-scale production.The main research results are as following:(1)There are fewer weeds under the plastic membrane,but there are many kinds of weeds in the plastic membrane.The experiment results showed that the recommended dosage 9 pre-emergence herbicide were relatively safe for the hybrid variety Zhangzagu 10,using precision orientational spraying between plastic mulch.At this dosage,no difference was found among foxtail millet seedling growth,root activity,antioxidant enzyme activity,weed population reduction.Thus,precision orientational spraying between plastic mulch can greatly avoid foxtail millet seeds or seedlings direct contact with herbicide,reduce the occurrence of phytotoxicity,and expand the application range of herbicide.(2)Through the analysis of the phytotoxicity of' foxtail millet,using pot and field experiments,the research explore security and its suitable concentration for treatment for foxtail millet seedlings (Zhangzagu 3,Zhangzagu 5,Zhangzagu 10,Jingu 21).The experiment results shulted fluroxypyr treatment increased foxtail millet seedlings O-2,H2O2 and MDA content,suggesting that fluroxypyr treatment induced the oxidative damage and membrane lipid peroxidation for foxtail millet.Analysis of antioxidant enzyme system(SOD,POD,CAT,APX,GR)and antioxidants(AsA,DHA,GSH and GSSG)dynamic changes,we found that foxtail millet could improve the activity of antioxidant enzymes and the content of antioxidants to increase herbicide resistance,reduce the cell membrane damage due to the accumulation of reactive oxygen species,in order to enhanced the adversity adaptability for foxtail millet.In order to comprehensively assess the the change of the physiological indexes of foxtail millet were analyzed by principal component analysis,the first,second,and third principal components characteristic value of the cumulative contribution rate was 86.4361%,including the majority of information on the foxtail millet main resistance properties,the first principal component represents the superoxide dismutase,the second principal component represents peroxidase,the third principal component represents catalase.Therefore,the three principal components can not only reflect all relevant information,but also well showed the combined contribution of the physiological and biochemical indexes for foxtail millet under herbicide stress.Secondly,fluroxypyr as an exogenous substances can broke the hormone balance inside foxtail millet,showing that the GA and Zr content of four foxtail millet varieties increased at first and then decreased with the increase of fluroxypyr concentration;while IAA and ABA increased gradually,inducing stomatal closure,break the balance plant hormones and lead to metabolic disorder.With the extension of time,the honnone imbalance of hybrid millet had recovery,and high concentration induced severe phytotoxicity in Jingu 21.In a word,the concentration(?2 L ha-1)had less effect on the biomass and yield of hybrid milletin harvest,which can be used as postemergence herbicides in foxtail millet field.(3)Sethoxydim concentrationthe(?1.5 ha L-1)has no effect on the growth of hybrid millet,such as chlorophyll content,photosynthesis and chlorophyll fluorescence parameters(including PSI and PSII parameters),and no phytotoxicity symptoms.However,sethoxydim treatment has obvious injure on Jingu 1,such as bleach chloroplasts,tissue necrosis,growth reduction etc.,which showed that sethxoydim increased the Y(NPQ)and Y(ND)value,and reduce the Y(NO)and Y(NA)value in Jingu 21,leading to accumulate excess light energy in plant,reduce the ability of non-photochemical heat dissipation,increase eventually the content of reactive oxygen species.Secondly,sethoxydim treatment affected the ability of photosynthesis and transpiration,net photosynthetic rate(Pn),transpiration rate(E),amd stomatal conductance(Gs)have been inhibited in four foxtail millet varieties,and with the increasing sethoxydim concentrations,the amplitude of photosynthetic indexes increase.The photosynthetic indexes gradually returned to control levels with time lasted in hybrid millet,and Jingu 21 was death,suggesting that sethoxydim induced brief inhibitory effect,and eventually did not produce obvious inhibition to biomass,which is also a self protection mechanism of the crops under stress.(4)Cyclohexanediones(e.g.,sethoxydim)are known to be inhibitors of plastid acetyl-CoA carboxylase(ACCase)of monocotyledonous plants and provoke plant deatn.In this study,with the increasing sethoxydim concentrations,ACCase activity first increase and then decrease;however,the ACCase activity of Jingu 21 seedlings reduced gradually,and with the delay of sethoxydim treatment time,the ACCase activity of Jingu 21 seedlings also reduced gradually,which showed the hybrid millet have well sethoxydim degradation ability and the ACCase in hybrid millet is not sensitive to sethoxydim.In addition,the hybrid millet showed excellent resistance to sethoxydim in the appropriate dosage range,Zhangzagu 5>Zhangzagu 3>Zhangzagu 10.(5)3 herbicides in different concentrations have certain influence on production and production index of Jingu 21,Zhangzagu 5,Zhangzagu3,and Zhangzagu 10,mainly reflecting on the panicle length,panicle diameter,panicle weight and grain per weight,and four foxtail millet varieties have significant positive correlation(P<0.01)on yield and yield components(panicle length,panicle diameter,panicle weight,grain per weight,1000-grain weight).By contrast,herbicides have higher influence on phytotoxicity and yield of Jingu 21 than that of hybrid millet,and different varieties have different sensitive in different concentration. |
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