Study Of Weed Bank In Dry Farmland And Effects Of Nonbiologic Factors On The Germination Of Commom Dayflower Seeds

Seed bank of weeds in different cropping methods field was investigated in Changchun suburb, Jilin Province. The result showed that there were 8 species of weeds, belonging to 5 families, which mainly distributed in 0-10cm soil depth of dry farmlands. Seed bank of weereds in maize continuous cropping field and maize soybean rotation cropping field were composed of Chenopodiwn serotinwn L., which was dominant, Echinochloa crusgalli (L.), Beauv.var.hispidula (Retz.) HacLand Abutilon theophrasti Medic. . Seed bank of weeds in wheat continuous cropping field was composed of Amaranthus retroflexus L. which was dominant, E. crusgalli (L.) Beauv.var. hispidula (Retz.) Hack.and C.serotinum L.The ripe weed seeds in interior and edge field were the main origin of seed bank of weeds.The influences of nonbiologic factors such as different soil water content, depth of sowing, dose of fomesafen and fertilizer on common dayflower emergence were studied. Results indicated the germination of dayflower seeds decreased with the increase of soil water content .When soil water content was 40%, common dayflower rate of emergence was the highest. The deeper the seed was sowed, the lower the dayflower rate of emergence was. The depth of sowing and common dayflower rate of emergence had notable negative correlation (p<0.05). Fomesafen significantly inhibited the germination of common dayflower seeds.With the increase of concentration, the germination, the length of the radicle and the length of the plantule significantly decreased. The ED50 of the germination rate, the length of the radicle and the length of the plantule were 52.6mg/kg, 73.6mg/kg and 109.6mg/kg, respectively. A low level solution of fertilizer had stimulating effects on germination rate, the Length of the raicle and the length of the plantule. The percentage of germination, the Length of the raicle and the length of the plantule, in general, declined with increasing of fertilizer conentration.Acetic acid obviously inhibited the germination of common dayflower seeds. The germination of common dayflower seeds was inhibited by 25%, 50% and 75%, respectively, with the acetic acid concentration of 0.011mol/L, 0.017mol/L and 0.023mol/L. With the increase of acetic acid concentration, the lenth of the radicle, the length of the plantule and a-amylase activity decreased.