| Foxtail millet seedlings are weak,and easily be influencued by herbicides,especially direct spraying in the grain field are more likely caused phytotoxicity,which brought about Production reduced or even no harvest.Film mulched hole seeding was an important technique for dryland millet seeding,It has been widely applied in mountainous drylands,and new problems have emerged: the film-covered hole has less weeds under the film and weaker growth,but the inter-membrane weeds It not only affects the normal growth of millet,but also reduces production,and affects mechanized cultivating and harvesting in the later stage.In response to this problem,Zhangzagu 10 and Jingu 21 were used as experimental materials to select two kinds of dinitroaniline herbicides,trifluralin and pendimethalin,and different doses were set(trifluralin:3.00,6.00,9.00,12.00 L/hm2;pendimethalin:3.00,6.00,9.00,12.00 L/hm2),Clear water control(CK),Soil treatment was carried out before seedling of millet after sowing.The safety of two herbicides to millet was investigated from seedling emergence rate,morphological index,photosynthetic characteristics,physiological index and yield.The main results are as follows:1.Investigation of the emergence rate: The treatments of trifluralin and pendimethalin all have a certain inhibitory effect on the emergence rate of millet.When the dose of trifluralin was 3.00 ~ 6.00 L/hm2 and the dose of pendimethalin was 3.00 ~ 9.00 L/hm2,The emergence rate of millet was lower than that of the control,but the difference was not significant and it was relatively safe;When the dose of trifluralin was 9.00 ~ 12.00 L/hm2 and the dose of pendimethalin was 12.00 L/hm2,the seedling emergence rate of millet was significantly inhibited.2.Investigation of agronomic traits: Plant height,leaf area and fresh weight of millet decreased with the dose of trifluralin and pendimethalin.When the seedlings emerged for 10 d,both herbicides significantly inhibited the plant height,leaf area and fresh weight of millet at the dose of 12.00 L/hm2.The other treatments were not significantly different from the control;when the seedlings were 20 d,The Herbicides gradually take effect.When the two herbicides were at the dose of 9.00 ~ 12.00 L/hm2,the plant height,leaf area and fresh weight of millet were significantly inhibited,and the other treatments were not significantly different from the control.Pesticide applying with the extension of time,the effect of herbicide on plant height,leaf area and fresh weight of millet was gradually relieved after 30 days of emergence,but the dose of 9.00 ~ 12.00 L/hm2 of trifluralin and 12.00 L/hm2 dose of pendimethalin still exerts significant inhibition on plant height,leaf area and fresh weight of millet.3.Investigation of photosynthetic fluorescence parameters: With the increase of the dose of trifluralin and pendimethalin,the SPAD value,Pn,Gs,Tr,Fv/Fm,Y(II),ETR and q P of millet leaves The parameters showed a downward trend,while the Ci and NQP values showed an upward trend.When the dosage of two herbicides ranged from 3.00 ~ 6.00 L/hm2,there was no significant difference in photosynthetic fluorescence parameters between the treatments and the control.With the advancement of the growth period,the indicators were alleviated,but the dose of 9.00 ~ 12.00 L/hm2 of trifluralin and the dose of 12.00 L/hm2 of pendimethalin still significantly inhibited the photosynthesis of millet leaves.4.Investigation of SOD,POD activity and MDA content: SOD,POD activity and MDA content of two millet treated with trifluralin and pendimethalin increased with the increase of spraying dose.At 10 d after emergence,the SOD,POD activity and MDA content of the two herbicides except 12.00 L/hm2 were not significantly different from those of the control,and the other treatments were significantly higher than the control;Herbicides gradually took effect 20 days after emergence.,the millet was under stress,and the activity of the protective enzyme system in the millet plant was enhanced to adapt to the adversity,eliminate the damage and protect itself.The SOD,POD activity and MDA content of the two millet treatments are increased,the SOD,POD activity and MDA content of trifluralin and pendimethalin at doses of 3.00 ~ 6.00 L/hm2 did not reach significant levels compared with the control,the SOD,POD activity and MDA content of trifluralin and pendimethalin at doses of 9.00 ~ 12.00 L/hm2 were significantly higher than those of the control;With the extension of application time,the stress gradually eased 30 days after emergence,However,the SOD,POD activity and MDA contents of trifluralin at 9.00 ~ 12.00 L/hm2 dose and pendimethalin at 12.00 L/hm2 dose were still significantly higher than those of the control group.5.Investigation on the control effect of weeds: The effect of trifluralin and pendimethalin on grass weeds was better than that of broadleaf weeds,and the dosage of trifluralin and pendimethalin increases.The control effect of 3.00 ~ 9.00 L/hm2 trifluralin on grass weeds and broadleaf weeds reached 93% and 86% at 25 days after millet emergence.and the fresh weight control was up to 89% and 79% at 25 days after emergence of millet;after 40 days of emergence,millet reached 87%,80%,87%,and 88%.The effect of pendimethalin on grass weeds and broadleaf weeds was up to 88% and 82% at 25 d after emergence,and the fresh weight control was up to 90% and 81%;after 40 days of emergence,millet reached 94%,73%,92%,and 80%;Both herbicides reached the maximum at the dose of 12.00 L/hm2,and the control efficacy and fresh weight control efficiency of the strains reached over 98%.6.Investigation of yield: Trifluralin and pendimethalin have different effects on the yield of Zhangzagu 10 and Jingu 21.The dose of 6.00 L/hm2 of trifluralin and the dose of 9.00 L/hm2 of pendimethalin resulted in significant increases in both millet yields.,while the doses of 9.00 ~ 12.00 L/hm2 of trifluralin and the 12.00 L/hm2 dose of pendimethalin Both caused a significant reduction in the production of millet.The other treatments did not reach a significant level compared with the control,which ensured the yield of millet and was safe for millet.In the late growth stage of millet,weeds caused serious damage to millet,resulting in a low yield in the control area.In summary,the application of trifluralin in the film-covering valley field is recommended to be 6.00 L/hm2,and that of pendimethalin was 9.00 L/hm2,which has no significant effect on the emergence rate and agronomic traits of millet,and can effectively control the weeds in the valley film.It does not affect the physiological and photosynthetic characteristics of millet,reduces the environmental pollution of herbicides,and provides a safe growth environment for millet,which ensures the yield of millet and was safe for millet. |
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