Studies On Autotoxicity And Mitigation Measures Of Foxtail Millet Continuous Cropping Obstacles

Foxtail millet has the characteristics of drought resistance and cold tolerance,and the grain has rich nutritional value and high economic value.However,foxtail millet is one of the crops that can?t be continuous cropping.With the plant areas of foxtail millet have been increased rapidly,it is easy to caused continuous cropping obstacles.A completely randomized designed experiments were conducted in order to explore the mechanism of foxtail millet continuous cropping obstacle and to find the mitigation measures.Taking the experiment varieties of Zhangza 13 and Jingu 21 and the experiment of materials of foxtail millet straw,leaf and root.Four concentrations of the undiluted,10 fold dilution,50 fold dilutionand 100 fold dilutions were set by water extracts method.Effects of water extracts from different parts of foxtail millet were analyzed on germination and seedling growth by germination and pot experiment.To reveal the autotoxicity laws of water-soluble substance of foxtail millet different parts.Taking the experiment fertilizers of organic manure and biochar.Tow fertilizers were separately divided into 100,200,400 Kg/mu by field experiment to analyze the effects of organic manure and biochar on relieving continuous cropping obstacles of foxtail millet,and found the appropriate amount.The main results as follows:1.There are allelochemicals in the water extracts of different parts of foxtail millet,and their effects on seed germination were as follows.High concentration could inhibit it?s growth,whereas low concentration could promote it.Compared with the control,the Undiluted treatment was significantly inhibited the root length,bud length,fresh weight and dry weight of germinated seeds,and RI value was negative,which was significantly allelopathic inhibition.However,the allelopathic promotion of the solution of 10 fold,50 fold,and 100 fold dilution in the germination process of different foxtail millet.According to the comprehensive synthesis effect index,the allelopathy order of water extracts from different parts of foxtail millet was straw > root > leaf.2.The water extracts of different parts of foxtail millet could effects on seedling growth were as follows.High concentration could inhibit it?s growth,whereas low concentration could promote it.Compared with the control,the Undiluted treatment was significantly inhibited the plant height,leaf area,biomass,chlorophyll content,photosynthesis and protective enzyme activity of seedling,and RI value was negative,which was significantly allelopathic inhibition.However,the allelopathic promotion of the solution of 10 fold,50 fold,and 100 fold dilution in the seedling growth of different foxtail millet.In addition,the allelopathy order of water extracts from different parts of foxtail millet was straw > root > leaf under the same concentration.This conclusion is consistent with that of seed germination.3.The main reason of continuous cropping obstacle of foxtail millet is autotoxicity by germination and pot experiment.On this basis,field experiments were conducted to effectively relieve the obstacle of continuous cropping of foxtail millet by increasing the application of organic manure and biochar.Different fertilizer treatments had certain effects on the emergence rate,plant height,leaf area,biomass,photosynthesis,protective enzyme activity and soil enzyme activity of continuous cropping foxtail millet.Compared with the control,100 and 200 kg/mu organic manure and biochar increased the emergence rate of different foxtail millet,while 400 kg/mu organic manure and biochar significantly inhibited the emergence rate of foxtail millet,which decreased by 14.7% and 19.4%,23.1% and 15.3% respectively.The plant height,leaf area,biomass,photosynthesis and protective enzymes activities of foxtail millet could be increased at seedling stage,jointing stage and heading stage with different amounts of fertilizer.At the same time,100 and 200 kg/mu organic manure and biochar significantly increased soil enzyme activity in continuous cropping foxtail millet during the whole growth period,while the soil urease and sucrase activity under 400 kg/mu treatment was significantly lower than that under control during 20-30 days.In addition,compared with the control,the yields of ?Zhangza 13? treated with 100 and 200 kg/mu organic manure and biochar were respectively increased 4.88%,57.48% and 40.37%,44.49%.The yields of ?Jingu 21? treated with 100 and 200 kg/mu organic manure and biochar were respectively increased 10.96%,10.96% and 27.39%,which could significantly increase the yield of millet,while the yield of Jingu 21 treated with biochar decreased by 2.23%,but there was no significant difference.The effective spike numbers of different foxtail millet treated with different fertilizer of 400 kg/mu was significantly lower than that of the control,which is related to the fact that the rate of emergence of foxtail millet seedlings is significantly lower than that of the control in the seedling stage,and eventually resulted in yield reduction.In conclusion,the 100 and 200 kg/mu organic manure and biochar could promote the growth of foxtail millet,increased its yield and achieve a certain mitigation effect.This study will provide theoretical reference for the efficient production of foxtail millet.