| East Gansu is located in the Loess hilly-gully zone, where most traditional forage come from relatively low quality crop residue of corn, wheat, soybean crop and other by-products. The severely shortage of high-quality forage or feed in late winter and early spring, which limited the development of local livestock production heavily. It has been confirmed that wheat can be dual-purpose used as forage at vegetative growth stage and harvest grain after regrowth. However, further research are still needed to determine that how to take advantage of variety s and sowing time to control the production performance and economic profit of dual-purpose winter wheat. This study was carried out in Longdong Loess Plateau region from 2013-2015, to explore agronomic traits differences of different varieties of winter wheat(late-mature varieties Longyu 4(LY4) and Longyu 5( LY5) and early mature variety Yunhan(YH) under different sowing date after clipping. The main results are as follows:1. In 2014, winter wheat was sown on regular date(September 20th), 10 d ahead(September 10th) and 10 d delayed(September 30th). Clipping at tillering stage(3cm stubble height). The cumulative degree day for turning green stage to the main growth stages had no difference with control, but there were significant difference at major growth stages under different sowing date. The accumulated degree day for both late-mature varieties LY4 and LY5 increased by 118 ℃.d and 137 ℃.d(P<0.05) respectively compared with early mature variety YH at jointing to heading stage. 2. Clipping increased the proportion of tillers by 2% for all three varieties(P <0.05), and reducing material consumption at vegetative growth stage. The plant height, leaf area index and biomass of LY4 and LY5 were spectacular reduced 21%~28%(P <0.05), 12%- 15%(P <0.05), 20% to 32% after clipping at early growth stage. But it can gradually recovered in the late regrowth stage. 3. The harvesting winter wheat forage was 0.54 t DM/ha with regular sowing date, while 1.77 t DM/hm2 and 0.17 t DM/ha forage were obtained for early or late sowing, respectively and it can be can carried respectively 2, 7 sheep and 0.7 units(SU) 120 d per hectare. At harvest stage the grain yield was 4.56 t/ha, 4.72 t/ha and 6.12 t/ha, increased by 5%,-8% and0.8% respectively compared with uncut control. The water use efficiency for grain of LY4, LY5 were 17.9kg/ha.mm, 17.5kg/ha.mm respectively, water use efficiency of dry matter was 33.0 kg/ha.mm and 33.3 kg/ha.mm were higher than early-maturing variety YH. Comprehensive indicators found that late maturing varieties LY4 and LY5 have obvious advantages, it have be more suitable for grain and forage product. 4. Winter wheat was grazed for a 20-days short-term at tillering stage with under two grazing intensities, some total of 3.6 t/ha and 5.1 t/ha green forage produced under grazing intensity of 35 SU/hm2 and 80 SU/hm2, respectively. The leaf area index under two grazing intensities increased by 10%, 25%, respectively at jointing stage, the DM production in 35 SU/hm2 grazing intensity was 28% significantly lower than the control at grain filling stage. Harvested grain yield was 5.1 t/ha to 5.6 t/ha, that had no significant different with no grazing control. The body weight gain of animal was 1.3 kg/sheep with grazing 20 d, The economic return of winter wheat-sheep system was increased 1209 and 1261 RMB/ha than a single grain system. Above all, a dual purpose winter wheat system mixed cropping and grazing should use late- mature winter wheat variety, and sowing 10 d delayed, which could produce a satisfactory total output. |
