Study On Field Management Of Weeding And Fertilizing In Afalfa Seed Production

The studies were conducted to determine the effect of fertilization application and otherfield mangements on afalfa seed yield, yield compents and quality parameters and the controlrate of herbicides on broad leaved weeds in afalfa field in Jiuquan, Gansu province.Theresults indicated that:1.Based on Chenopodium album L．and Polygonumaviculare L. and other broad leavedweeds of weed features in afalfa seed field. Soil treatment and foliar treatment of herbicidewere applied for weed control. In the soil treatment trials, trifluralin got hightest rate with thedosage of2700ml/hm2for control Chenopodium album L．and Polygonumaviculare L.,control rate was respectly85.67%and84%, there was no significant difference between thedifferent dosage（p>0.05）, control rate was better when metribuzin dose at1200ml/hm2. Withlower doses of herbicides, control rate was decreased. Soil treatment test should be appliedwhen the weeds began to emergence, apply late would be less effective.In the foliar treatment trials, bentazone was the best herbicide for control Chenopodiumalbum L．, the hightest rate got85%with the dosage of2400ml/hm2, Imazethapyr was betterwith the dosage of2100ml/hm2. Imazethapyr was the best herbicide for controlPolygonumaviculareL., and the control rate was75.33%with the dosage of2400ml/hm2,high dosage of1actofen have negative effect on afalfa, dosage must be strictly controlled.Stem treatment should be applied early in the growth of weeds （23leaves）, the lowerweed,the greater of control rate.2Foliar application with0.25%boron significally increased seed yield, boronapplication significantly increased pods/racemes，seeds/pod，and1000seed weight, there isno effect on seed quilty. Foliar application with KH2P04increased seed yield as well（p<0.05），the prime application concentration was0.6%, seed yield record689.43kg/hm²,KH2P04application significantly increased seeds/pod，and1000seed weight, the effect ofdifferent foliar application time on seed yield was not significant.3. Phosphoms application significantly increased florets/Inflorescences，seeds/pod．Theapplication rate of160kg/hm²significantly increased seed yield, the highest seed yield record1079.81kg/hm². Phosphoms application did not show significantly positive effect onseed yield（P>0.05），but decreased hard seed rate significantly.4. Paraquat increased water losing rate of stem and leaf, which was more than50%, andthey also speeded up drying time of alfalfa plants. Paraquat did not decreased seed yield and1000seed weight, in the appropriate concentration range had no effect on germination rate.K₂CO₃increased leaf losing rate significantly，water losing rate of stem and leaf was tendedto greater by5%K₂CO₃, and did not had negative effect on seed yield and seed quilty,Na₂SO₄、CaCl₂had the same effects as K₂CO₃on drying effect, but their effect was small.