Jointingheading was the most critical stage in which cold damage affected the yield of wintersowing maize.
拔节—抽雄期是低温冷害影响冬玉米产量的关键期，另一个次关键期为抽雄—开花时段。
2
Tractors that should now be ploughing land for sowingwinter grain have been mobilised to dig trenches round fields to stop forest fires encroaching on farmland.
本来应该开垦土地、播种冬季作物的拖拉机，现在被用来挖掘防火沟，以防止大火蔓延到农田。
3
To study expressions of yield under conditions of small sowing dosage for winter wheat, the autumn-sown experiments in two years were conducted during 2001 to 2003 in Beijing.