| Paddy rice is an important grain crop in Heilongiiang Province with totalplanting area of more than l.4 million hectares. with the adjustInent of mlindustrial strUcture and the bosfOrm to quality and beneficial agricultUre inrecent years, Heilongiiang province has formed a quality rice production baseprelindnarily within Songhua fover Valley and Three fover Plain. There aremore than 30 kinds of common weeds in the paddy field in Heilongiiangprovince. The succession of the weeds population has occurred with thechanges of the cultivating systems and planing methods and the use ofchemical herbicide for a long time. The perendal plantS of cyPeraceae family,such as thedet staIk ScriPus triqueter JaPan ScriPus triqueter, which are calledrhizonla sParganii universally, have become malignant t'eeds which are hard tobe controIled in the paddy fields of the province.The research on the screening test of the chemicals in the laboraory showsthat sulfonamide toxic chetalcals such as Londax (bensulfuron methyl),Weinong and Setoff (cinosulfurOn) can prohibit obviously the growh ofthedetstalk scriP us triqueter and production of undersround ball stalks, and are safe torice wtth high active agent to colltrOl weeds. The biochemical teSt on thechemical sensitivity of thedet stalk scriPus triqueter demonstraes that thedetstalk scrlPu is most sensitive to the chemicals when its hibemaculum is less5cm.It demonstrates by the research on the first aPp1ication with highly activeherbicide at early stage in the paddy fields that the chemicals for the test have agood control effect toj7at staIk scriPu at early stage, Which can control 80% ofweeds after l0days of chemical aPplication. But the cothel effect decreasesobviously after 50days.Therefore, the two-time tecboque of the chemicalaPplication is recommended according to the occutring laws and bio1ogicalcharacteristics of the rhizoma sPampnii weed.The stUdy shows that it is the key stage of the first chemical aPplicationwhen the rhizoma sParganii plant is l-7cm high. The plants are weak andnumerous without new UndrgrOund tUbers fonning at thes tdrie. Most of theplans are killed after chedrical aPplication and stop growing. The key stage ofthe secondary aPpIication is when the new plam is 5-7cm high. The techniquesof two-time aPpIication of chemicals have over 90% control effect to ther]7homa mpii increasing 5-30% than that of one-time aPPlication, and7-40% to broad-leaved weeds such as the rI1homa aIismatis yeciru, mpin,and bthens D'lParthe, Which genninate at late stage. At the same time, ThetWo-time aPplication of chemicals can reduce nearly more than 60% of therhhoma sParganii tubers, and reduce the propagating source of the rhizomasParganll.ContrOlling tecboques of boce aPplication of chemica1s on rhizomasParganii weed in the paddy field f aPply 15g Londax (bensulforon methyl), or30g S9toff (cinosulfuron), or 45-90g Weinong per ha. befOre the rhizomosPNnii plants in the field are 7cm high. The chemical aPplication method:mix the soil or fenilizer with the chemicals, and keep the waer at 3-5cm for 5-7days. Apply 15-22.5g Londax (bensulfuron methyl), 3045g Setoff(cinosulfuron), or 45-67.5g 1Veinong per hIn2 with the chendcals InjXed withsoil again when the new p1ants are 5-7cm high, about l0-15 days after the firstchemical application. Keep 5-1 cm high of water layer for about 5-7day s.The demonstration of the two-time application of chemicals in many test plots within the province shows that it can not only control the weeds at early stage, but also stop the forming of rootstalks and tubers effectively with over 90% control effect. It is safe to the paddy rice, without phytotoxicity symptom. Comparing the techniques of the two-time application of chemicals with conventional rhizoma sparganii weeding method by mixing the bentazone and MCPA (dimetetrachloro), the former advances 10-15 days of chemical application ahead of time, which can prom... |
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