| The variety and quantity of weeds in direct-seeded rice field is a big problem which restricts the development of direct seeding rice.At present,chemical herbicide is the most important measure to control weeds in direct-seeded rice field.However,the application of chemical herbicide has high labor intensity and labor cost.Seed pelleting is a kind of technology that can prevent and control disease,insect and grass at the seedling stage,and save time and labor.However,there are no reports on the safety of herbicide seed-pelleting coating and the control of weeds.In this paper,the seed pelleting technology was used to screen pyriminobac-methyl,pyrazosulfuron-ethyl and bensulfuron-methyl,three highly effective herbicides,to study the herbicide seed-pelleting coating on the safety of direct-seeded rice and the prevention and control effect of paddy weeds,and to screen the effective herbicide pyrazosulfuron-ethyl.The optimal herbicide-seed ratio for seed-pelleting coating of pyrazosulfuron-ethyl and the distribution of pyrazosulfuron-ethyl in soil after seeding were further studied.1.The herbicide-seed ratio suitable for seed-pelleting coating of pyriminobac-methyl,pyrazosulfuron-ethyl and bensulfuron-methyl was selected by pot test.The results showed that the optimum herbicide-seed ratio of the three herbicides was 1:1000 and the germination rates were over 88%.Seed-pelleting coating with pyriminobac-methyl and bensulfuron-methyl had inhibitory effects on rice plant height,root length and dry weight,while seed-pelleting coating with pyrazosulfuron-ethyl had inhibitory effects on rice plant height and dry weight,but had no effect on root length.The seed-pelleting coating of pyriminobac-methyl and bensulfuron-methyl were not safe for rice,while the seed-pelleting coating of pyrazosulfuron-ethyl was safe for rice.2.Screening the most suitable herbicide for seed-pelleting coating by field test.The results showed that the control effect of the seed-pelleting coating of pyriminobac-methyl,pyrazosulfuron-ethyl and bensulfuron-methyl on field weeds was 5.30%,85.66% and86.64%,and the plant height inhibition rate was 0.52%,2.43% and 11.23%,respectively.Based on the control effect and the growth performance of rice seedlings,the most suitable herbicide for seed-pelleting coating was pyrazosulfuron-ethyl.3.The best herbicide-seed ratio for seed-pelleting coating of pyrazosulfuron-ethyl was selected by field test.The results showed that the control of field weeds by the pyrazosulfuron-ethyl seed-pelleting coating with herbicide-seed ratios of 0.6: 1000,0.8:1000,and 1: 1000 was 80.7%,90.1%,and 92.6%,respectively,and the increase of rice plant height were 6.39%,5.31% and 0.85%,respectively.Based on the control effect and the growth performance of rice seedlings,the optimum herbicide-seed ratio for seed-pelleting coating of pyrazosulfuron-ethyl was 0.8:1000.4.Field experiments were conducted to study the effects of different irrigation methods combined with pyrazosulfuron-ethyl seed-pelleting coating on the prevention and control of weeds.The results showed that compared with no waterlogged treatment after rice seedling emergence,waterlogged treatment had better control effect on weeds in the field.With herbicide-seed ratio of 0.8:1000,the seed-pelleting coating of pyrazosulfuron-ethyl combined with waterlogging treatment had a weed control effect of over 91.5%,and the waterlogging treatment had no effect on rice plant height.The results indicated that pyrazosulfuron-ethyl seed-pelleting coating and irrigation could effectively control weeds in paddy field.5.The distribution of pyrazosulfuron-ethyl in the soil was studied.The results showed that the content of pyrazosulfuron-ethyl in the soil increased first and then decreased.2hours after sowing,pyrazosulfuron-ethyl could diffuse to 5 cm from the horizontal direction of the central point;1 day after sowing,pyrazosulfuron-ethyl could diffuse to the maximum distance,which is 15 cm from the horizontal direction of the central point.The content of pyrazosulfuron-ethyl in the soil at 5,10 and 15 cm from the horizontal direction of the central point reached the maximum on day 1 after sowing,which were 0.02998±0.00073,0.00440±0.00012 and 0.001970±0.00007 mg/kg,respectively.The seed-pelleting coating of pyrazosulfuron-ethyl with herbicide-seed ratio of 0.8:1000had good control effect on weeds in direct-seeded paddy field and was safe for rice growth and development.Compared to commercial pyrazosulfuron-ethyl,reduced 20% application of pyrazosulfuron-ethyl,as well as reducing the labor cost when applying herbicide.Seed-pelleting coating of pyrazosulfuron-ethyl combined with irrigation treatment could control weeds more effectively. |
PDF Full Text Request