Study On The Ecology And Biology Characteristic And Controlling Method Of Malignant Weed Convolvulus Arvensis In Alfalfa Seed Product Field

Weeds are one of the critical factors that affect output and quality of alfalfa seed in the course of alfalfa seed production. And malignant weed Convolvulus arvensis is the dominant of weed population in seed product field. The existence, sprouting characteristic, and seed livingness of Convolvulus arvensis seed were studied in different alfalfa seed field. And distributing, quantity and change of Convolvulus arvensis root were studied in different seasons. Based on the study of Convolvulus arvensis seed, we can conclude that, the hard seed rate of new seed is very high, but the hard seed rate of seed living through the winter descends, and the hard seed rate of seed living through the winter in soil descends evidently, and the seed livingness is lower .The sprouting ratio of seeds in superstratum soil (0-5cm) are lower than seeds in substrate soil (5-15cm). The soil can protect Convolvulus arvensis seeds. Through the investigation to the existence of different year Convolvulus arvensis seeds in the soil of alfalfa seed field, we can draw the following conclusions, In spring, the Convolvulus arvensis seeds in the utilized second year and third year field mainly distributed in 0-5cm, and a few in 5-25cm, and no Convolvulus arvensis seeds in 25cm below .By sampling investigating the utilized one year field, a few sampling point has Convolvulus arvensis seeds. This shows that the field was light harmed by Convolvulus arvensis .In the utilized 10year elementary species field, the quantity of Convolvulus arvensis seeds was more, but the harm was light, caused by burning –field in spring .In latter summer investigation, caused by new seed rain, the quantity in superstratum soil of the utilized 3-4year field increased, and this can prove that the Convolvulus arvensis disserve in alfalfa seed field are increasing year by year .By the investigation to the root quantity of Convolvulus arvensis in alfalfa seed field ,the root mainly exist in 0-30cm in spring .After one growing season ,the root in superstratum soil are descended ,and there are little change in the 30cm below .The sprouting period of Convolvulus arvensis seedling concentrates greatly ,And the sprouting seed was 85.64%of the whole year .The seeds stopped sprouting after the middle of July . From the weedicide filter examination, we can conclude the affection of 2.4-D are best, but the toxicity to alfalfa are large. But the toxicity can be reduced, if the atomizer were given direction muzzle .The results about the period to chymic cleantillage to Convolvulus arvensis are as following .In spring the resistance of Convolvulus arvensis is lowest, but the affection of cleantillage can be lower caused by Convolvulus arvensis sprouting out of order .The resistance of alfalfa is strongest in latter summer, before harvesting seeds, and it is the best period to cleantillage. There are two natural enemy to Convolvulus arvensis, tyta luctuosa and chrysomelidae, and it has a perfect future by using chrysomelidae to control Convolvulus arvensis.