| Cyperus rotundus L.is a perennial weed of the sedge family that occurs mostly in dry farmland in temperate and subtropical regions.It reproduces mainly through underground tubers,and its rapid reproduction ability and large underground tuber system have a very strong competitive advantage over crops and are so harmful that it is listed as one of the top ten malignant weeds in the world.In this study,different populations of C.rotundus L.in Hainan(HN),Hubei(HB)and Shandong(SD)were studied to clarify their growth characteristics and inter-population differences by comparing various growth parameters during growth.By comparing the control efficacy of different application treatments,we screened the agents and dosages that could effectively prevent the growth of stem and leaves and inhibit the spread of underground tubers of Cyperus rotundus L.By applying drugs to the stems and leaves of C.rotundus L.at different growth lengths,the growth of stems and leaves and tubers of C.rotundus L.at different leaf ages were investigated,and the changes of resistance of C.rotundus L.at different growth lengths were clarified,which laid the theoretical foundation for the prevention and control of C.rotundus L.The main research results are as follows:1.The study on the growth characteristics of different ecotypes of C.rotundus L.during the nutritional growth period showed that there were significant differences in growth parameters among different populations of C.rotundus L.the photosynthetic rate,chlorophyll content,relative growth rate(RGR)and net assimilation rate(NAR)of the HN population were significantly higher than those of the HB population at 30 and 60 d of transplanting(21.59% and 31.11% higher in the classical analysis and 11.24% and 4.02%higher in the combinatorial analysis,respectively).The RGR and NAR of the SD population were slightly higher than those of the HB population(11.53% and 26.63% higher in the classical analysis and 12.66%and 24.55% higher in the combinatorial analysis,respectively).In the combinatorial analysis,the relative growth rate reached the highest at 24-28 d and the net assimilation rate reached the highest at 28-32 d.During this period,the plant height growth rate increased significantly and the tuber number grew slowly,and the relative growth rate and net assimilation rate started to decrease around 60 d,corresponding to the rapid growth of tuber number.2.Eight soil treatment herbicides,including 75% halosulfuron-methyl(WG),50% prometryn(WP),and90% acetochlor(EC),were evaluated for their inhibitory effects on tuber emergence of C.rotundus L.: 75%halosulfuron-methyl(WG)had the strongest inhibitory ability,75% halosulfuron-methyl(WG)202.5 g(a.i.)/hm~2,67.5 g(a.i.)/hm~2,and 22.5 g(a.i.)/hm The efficacy of 75% halosulfuron-methyl(WG)7.5g(a.i./hm~2)and 2.5 g(a.i.)/hm~2 treatments reached more than 80.18%,which was significantly higher than other treatments except for the triple dose treatment.There was no effect of 50 % prometryn(WP)on the growth of C.rotundus L.,and the seedling emergence of each concentration treatment was basically the same as that of the control.The efficacy of 75% halosulfuron-methyl(WG),960 g/L spermacetam(EC),240 g/L imazapic(AS)and 84% cloransulam-methyl(WP)was higher than 85.31% at 3 times the recommended dosage,and 75% halosulfuron-methyl(WG),240 g/L imazapic(AS)and 84% cloransulammethyl(WP)were 100% effective and completely inhibited the emergence of tubers.Except for 75%halosulfuron-methyl(WG)and 50% propachlor(WP),the inhibition rate of tuber emergence decreased gradually with increasing dilution.3.The inhibitory effects of 240 g/L imazapic(AS),75% halosulfuron-methyl(WG)and 84%cloransulam-methyl(WP)on different leaf ages of C.rotundus L.were evaluated indoors: the dynamics of changes in plant height affected by the agents at different leaf ages of C.rotundus L.corresponded to the fresh weight control effect,and the tolerance to the agents gradually increased with the growth of C.rotundus L..And all three agents could effectively inhibit the growth of the stem and tuber of C.rotundus L.Among them,75% halosulfuron-methyl(WG)67.5 g(a.i.)/hm~2 had better efficacy,with 97.58% of stem and leaves control and 100% of underground tubers control after 10 d of growth,and the fresh weight of stem and leaves and the number of tubers did not increase after 60 d of application,but the efficacy was still as high as 98.17% and 100%,completely inhibiting the growth of C.rotundus L.The efficacy of all treatments was reduced after 30 d of growth.30 d after application,the efficacy of 75% halosulfuronmethyl(WG)67.5 g(a.i.)/hm~2 was reduced to 81.34% for stems and leaves and 73.11% for underground tubers,but it was still significantly higher than other treatments.At 60 d post-application,75%halosulfuron-methyl(WG)67.5 g(a.i.)/hm~2 treatment had better efficacy,with 84.09% of stem and leaf control,which was significantly higher than the other treatments,while 75% halosulfuron-methyl(WG)had more than 64.42% of underground tuber control in both treatments,which was similar to 240 g/L imazapic(AS)72 g(a.i.)/hm~2 treatment.However,all treatments did not completely inhibit the growth of C.rotundus L.,and its underground tubers continued to multiply.4.The results of the field efficacy tests were consistent with the results of the indoor tests.75%halosulfuron-methyl(WG)had better efficacy,with 67.5 g(a.i.)/hm~2 treatment achieving 95.76% efficacy against stem and leaves and 22.5 g(a.i.)/hm~2 treatment achieving 84.14% efficacy against stem and leaves,both of which were effective in stopping the growth of above-ground parts of C.rotundus L.and inhibiting the spread of underground tubers.240 g/L metsulfuron-methyl(AS)had similar efficacy to 75%halosulfuron-methyl(WG),and was able to inhibit the spread of tubers.The recommended dosage of 240g/L imazapic(AS)was similar to 75% cloransulam-methyl(WG),which was able to suppress the spread of tubers,but a small number of tubers still sprouted new plants at the late stage of the growth of C.rotundus L.84% cloransulam-methyl(WP)was similar to 240 g/L imazapic(AS),which was able to suppress most of the growth of C.rotundus L.,but the effect on underground tubers at the late stage was not as good as 75% halosulfuron-methyl(WG).Imazapic as was less effective than 84% cloransulammethyl(WP)at low concentrations. |
PDF Full Text Request