Screening Of Herbicides In Oat Field And Their Influence On Physiological Index, Quality And Yield Of Oat

The experiment of herbicide screening was conducted with covered oat (Longyan No.3) and naked oat (Baiyan No.2) in Crop Production Farm of Yuzhong County, Gansu Province, from March,2010to August,2011. Optimal herbicide dosage were investigated and their influence on physiological index, quality and yield of oat were studied. The main results are as follows:(1) Weeds control effectiveness of13herbicides was significant different in oat field. Of post-emergence treatments,40%Bromoxynil octanoate plus MCPA-sodium was the best with91.7%,97.5%and99.0%of15days after treatment (DAT),30DAT weeds control efficiency and30DAT weeds fresh weight control efficiency, respectively. Of pre-emergence treatments,48%Butralin was the best with53.8%,71.8%and77.1%of15DAT,30DAT weeds control and30DAT weeds fresh weight control efficiency, respectively.(2) Thirteen herbicides affected oat grain yield significantly. Naked oat had lower rate of increase than covered oat under the sametreatment. Longyan No.3produced a maximum yield (3826.6kg·hm-2, increased54.5%) under48%Butralin treatment; the same went for Baiyan No.2, but its grain yield increased33.4%.(3) Herbicides affected grain yield mainly trough affecting yield components. Oat grain yield was positively correlated to15DAT,30DAT weeds control efficiency,30DAT weeds fresh weight control efficiency, effective tillers and spikelets.(4) Combining the effect of herbicides on weed control with oat grain yield as the selection stansard, the optimal application rates of herbicides were:3750mL·hm-2for48%Butralin,1350mL·hm-2for40%the Bromoxynil octanoate plus MCPA-sodium, and12mL·hm-2for75%Tribenuron-methyl.(5) Herbicides reduced chlorophyll content (SPAD), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and Stomatal limitation (Ls) of oats. Ls decreased with the improving of intercellular CO2concentration (Ci). The effects of three herbicides on oats were different:48%Butralin and40%Bromoxynil octanoate plus MCPA-sodium had little infuence on photosynthesis;75%Tribenuron-methyl had larger impact. Response of oats to herbicides was different, covered oat was more sensitive than naked oat.(6) Three herbicides increased activity of protective enzymes in varying degree. The activity of protective enzymes restored to the control level at filling stage. The resistance of naked oat to herbicide stress was lower than that of covered oat. Among three herbicides, Butralin and Bromoxynil octanoate plus MCPA-sodium had slight adverse effect on oat; the side effect of Tribenuron-methyl was higher.(7) The responses of hay and grain quality of covered and naked oat to herbicides were different. Herbicides reduced crude protein of covered oat hay, but had no influence on neutral detergent fiber. Herbicides increased crude ash and acid detergent fiber of Longyan No.3grain. Butralin decreased its CP content. Under Tribenuron-methyl treatment, CP and crude fat of Baiyan No.2grain reduced significantly.