| Sclerotium rolfsii strain SC64,isolated from an invasive alien weed Solidago canadensis,is being developed into the bioherbicide product,Junkekuo.It is broadly used to control Solidago Canadensis L.and broadleaf weeds and Cyperus difformis L in dry direct-seeded rice.On the basic of the research of Tang Wei,this thesis includes:Field evaluation of Junkekuo against Solidago canadensis L.Simply cutting,plowing or treating with S.rolfsii SC64 does not sufficient to control S.Canadensis L..This treatment of combination of cutting,plowing and treating with isolate SC64 not only eliminated sexual reproduction of S.canadensis,but also damaged its underground stems.We conducted field trials to test the effect of combining cutting,plowing,and treating with different quantity of isolate SC64 in the Haizzikou,Qixia of Nanjing city on august 5,2012.These treatments can kill 91%-95.3%of Solidago Canadensis L.at 30d,and the plant mortality still get 89.5%-91.9%.We do the experiment on the basic of that in Nanjing in the suburb of Changzhou city in September.About Cutting,it bursts a large of plant because its underground stems could regenerate in a short time.The treatment of cutting+plowing can effectively control S.canadensis in short time and the plant mortality can get 90.8%.However,the effect rapidly decreases after 180d.The treatment of combination can cause 95.2%-95.5%plant mortality and different quantity of isolate SC64 get less effect in short time.But,at 180d the effect of that is different.The treatment of cutting+plowing+S.rolfsii SC64 get better plant mortality than that of cutting+plowing which is 47%?67.2%.Therefore,this treatment may develop to be an optimized control strategy for S.Canadensis without chemical herbicide.Field evaluation of cooperative application of Junkekuo and other materials to control weeds in dry direct-seeded rice(1)We first try to cooperative application of two bioherbicide Junkekuo and Kebaimei to control broadleaf weeds and parts of monocotyledonous weeds,Echinochloa crusgalli(L.)Beauv.and Cyperus difformis.Field experiment is started in field of perennial crop rotation of rice and wheat in Jiangpu of Nanjing.We test and evaluat plant mortality(%)at 7d and 21d and fresh weight reduction(%)at 21d.The result at 7 d shows that with the increase of using bioherbicide,control efficiency to weeds increases apparently.The plant mortality(%)at 7d can get 38.0%?71.0%,fresh weight reduction(%)at 21 dis 40.0%-78.0%.Obviously,cooperative application of two bioherbicide can enhance the whole control effect to weed.When Junkekuo is used in 1800 kg/ha and Kebaimei in18 kg/ha,the plant mortality(%)at 7d can reach 71%and fresh weight reduction(%)at 21d 78%,higher than chemical control test.The tests show that Junkekuo and Kebaimei can work together to control main broadleaf weeds and part of monocotyledonous weeds in dry direct-seeded rice.(2)Vinegar,as biodegradable organic matter being developed as herbicide,can completely dry the leaf tissue to make plants to die eventually by cause the rapid decomposition of the plant cell membrane.We first try to cooperative application of Sclerotium rolfsii and vinegar to control weeds in dry direct-seeded rice.Field experiment is started in field of perennial crop rotation of rice and wheat in Jiangpu of Nanjing.The experiment includes 9 treatments.We test and evaluat plant mortality(%)at 7d and 21d and fresh weight reduction(%)at 21d.The result shows that with the increase of using bioherbicide,control efficiency to weeds increases apparently.The plant mortality(%)of broad leaf weeds at 21d can get 24.1%?78.3%,fresh weight reduction(%)at 21d is 27.4%?73.1%.Vinegar has certain effect to control weed,and make certain enhancement effect to Sclerotium rolfsii strains SC64.However,as far as all weeds,the effect of cooperative application of Sclerotium rolfsii and vinegar is lower.The plant mortality(%)at 21d can get 26.5%?38.8%,fresh weight reduction(%)at 21d is 19.6%?25.4%.If we would like to get better application of Sclerotium rolfsii and vinegar to control weeds in the future,we should do more experiments and get further exploration.Development of bioherbicide Junkekuo formulation(1)We try to embed fungus mycelia in microcapsule of calcium alginate based on the biological characteristics of Sclerotium rolfsii.The mycelia obtained from 110ml mycelial suspension after centrifugation,is added to the 100ml 2%sodium alginate solution to make the mixture.Through the assembly made of funnel and burette,the mixture is dripped into 100ml 1%calcium chloride solution,at the same time,using a magnetic stirrer machine stir the calcium chloride solution to make Ca2+ to diffuse within the droplets to form a solid gel ball(diameter is about 5mm).At last,the balls are dried unde the natural wind to form solid particles(diameter is about 1.5mm).Through the result in 90 d,it indicates that the optimal temperature to keep the microcapsule of calcium alginate embedding hyphae is 4?.In pot experiment,when the dosage is 750 kg/ha,plant mortality can reach 65.57%.The efficacy of 1200 kg/ha is 76.67%higher than 75.44%of the cotton seed hull in 1500 kg/ha.In conclusion,the bioherbicide formulation of calcium alginate microcapsule embedding mycelia of Sclerotium rolfsii strain SC64 is developable.2)We first try to use crop straw powder as the carrier to make solid formulation for Sclerotium rolfsii.Firstly,the pelotons obtained by centrifugation of mycelial suspension are added to the mycelium to make higer mycelium concentration of mycelium suspensions(about 3 times).The sterilized straw powder of rice or corn and the sterilized starch(w1/w2,10:1)are putted into the beaker and stirred with the glass rod after adding to sterile water(w1/vi,5:2)until to be the modeling state.Then putting them into round plastic basin and shakeing it to make them being round granules.Granules are completely dried under the environment about 50 ?(about 4h).After drying,granules are sieved to make sure that the particle diameter is about 2?2.4mm.At last,The solid particles are stirred by a circular granulator machine,and mycelial suspension(w3/v2,3:4)is gradually added into it,stirring until the particles without touching the wall.The particles can be used when them are dried under the natural environment.The plant mortality for Solidago canadensis is 85%?100%in pot experiment at 7d.They are more effective than 45%of the treatment of cotton seed hull.Above all,straw powder granule has great potential to develop into solid formulation of strains SC64 Sclerotium rolfsii. |
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