| Development of livestock industry is one of the key contents of "13th Five Year Plan" of agricultural sector in Qingyang City, Gansu province, the production and use of high quality forage is high related to livestock industry development. There are rich resources of winter wheat(Triticum aestivum. L) in east Gansu. It is widely demonstrated to use tillering stage winter wheat for forage while harvesting grain at maturity as dual-purpose way to improve the economic return system. To ensure grain yield stable, plants need actively support from external environmental and physiological factors after grazing and clipping. In order to investigate regeneration growth characteristics and physiological mechanisms of winter wheat after clipping. we set up a greenhouse experiment and a field trial from 2013 to 2015, with late-maturity variety of winter wheat Longyu 4(LY4) and Longyu5(LY5) and early-maturity ariety Yunhan(YH), to explore the effect of clipping at early tillering on their growth and physiological characteristics of the whole reproductive growth. The main results are as follows:1.Under the greenhouse experiment, within 20 days after clipping, above and underground dry matter, leaf area, root area and root length of winter wheat were lower than control, while LY4 had a smaller declination compared to LY5 and YH at maturing stage. Dry matter of aboveground and underground of LY4 with clipping residue at 6 cmm height(RE-6) were respectively 35%, 60% lower than control(P<0.05), while with clipping residue at 3 cmm(RE-3) were respectively 53%, 73% lower than control(P<0.05). The water soluble carbohydrate(WSC) content in aboveground of LY4, LY5 and YH were 19-72%, 30-65% and 24-79% lower than control respectively and WSC content in content underground significantly declined by 26-67%、27-53% and 33-51% with RE-6. The soluble protein content of LY4 in leaf were significantly increased after clipping, which of LY5 and YH were only elevated in RE-6. Activities of POD in stem and SOD in leaf of winter wheat with RE-6 were significantly increased compared with control(P<0.05), stems SOD activity of the three varieties were increased in RE-3 treatment.2. Under the field experiment, the winter wheat was clipping on tillering stage at sowing year. Compared to uncut control, the dry matter of LY4 at anthesis decreased by13%(P<0.05), For LY5 and YH, the DM of decreased from jointing to filling stage, grain yield and harvest index(HI) under clipping treatments increased by 4% and 5% respectively(P<0.05). The grain yield and HI under late sowing treatment(Sept 30 th) were higher than both early sowing(Sept.10th) and regular sowing treatment(Sept. 20th). net photosynthesis in flag leaf of late-maturity varieties were higher than early-maturity variety. Wherein, the net photosynthesis, stomatal conductance, intercellular CO2 concentration and transpiration rate of flag leaf of LY4 was increased 13%, 47%, 20% and 18%(P<0.05) respectively under clipping treatment, the intercellular CO2 concentration, and transpiration rate of LY5 was increased by 39%, 33%(P<0.05) after clipping. WSC content of winter wheat was higher than control at heading, however, lower at flowering and grain filling stage.3. The soluble protein and antioxidant enzyme activity in shoots increased at early recovery growth under clipping treatments, which means that the resistance of plant was enhanced, and it is beneficial to to restore substance for over winter. Clipping treatment enhanced the photosynthetic characteristics of late-maturity varieties at flowering with late sowing, which provided sufficient nutrients for grain filling, and ensured stable grain yield. For dual proposed winter wheat varieties in the Loss Plateau should have late-maturity varieties and delayed the sowing dates, which will maintain grain yield stable under dual-purpose. |
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