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It is possible to plant seeds directly for silviculture using the treated Ash seed in overcutting fields.And before planting the field should be cultivated carefully. The intergraded temperature is about 1200℃ for budding, the suitable planting index is 30—50% of the seeds budded. The suitable temperature for planting is 7℃ the ground temperature is 5℃ and the Soil must be loosen after the emergence of the Ash sapling. 本文对水曲柳在采伐迹地上的直播更新进行了试验研究。播种前种子要进行催芽处理,催芽期间种砂有效积温应达到1200℃以上。催芽的适播指标有30—50%的种子发芽,播种时的适宜气温7℃,地温5℃并保证土壤湿度,复土厚度以2cm为宜,出苗后及时除草松土并满足幼苗的光照条件。对水曲柳采用直播更新比植苗更新具有更多的优越性。 The reactions of the photosynthesis and growth of Panax quinqusfoliuos to the factors of light and temperature were reviewed. Based on the suitable planting index of Panax quinqutheiuos, the ginseng culture fields at Liuba located in the southern slope of Mt. qinling were divided into three zones by elevation. And the relationships between the transmittancy of shade shed and the season. And the slope direction were discussed, being in the three kinds of the ginseng culture fields. 综述西洋参的光合作用,生长对光、温条件的反应特点,依据西洋参种植适宜指数将秦岭南坡留坝县参地按海拔高度分为4种区域.讨论了3类参区荫棚透光率与季节、坡向、海拔间的关系. Cropping system transition from 1949 to 1998 in Hebei province was studied. Results showed that ① changes in cropping structure is directly related to comparative benefit among crops. The decline of cotton area and the increases of soybean and vegetable areas in the last decade were the resulsts of changes in comparative benefits;② the cropping system in Hebei is mainly characterized by two cropping a year and cropping systems are tending to be integrated and higher efficient.The planting index increase... Cropping system transition from 1949 to 1998 in Hebei province was studied. Results showed that ① changes in cropping structure is directly related to comparative benefit among crops. The decline of cotton area and the increases of soybean and vegetable areas in the last decade were the resulsts of changes in comparative benefits;② the cropping system in Hebei is mainly characterized by two cropping a year and cropping systems are tending to be integrated and higher efficient.The planting index increase has resulted in the enlargement of crop sowing area by 1 51 million ha compared with that in 1952;③the directions for crop production in the future are to gain high quality,high efficiency and high yield as well and the goals are to improve the complexity and resource use efficiency. 运用定量与定性相结合的分析方法 ,研究了 194 9~ 1998年河北省种植制度变化轨迹 ,结果表明 :①种植结构变化与作物比较效益直接相关 ,90年代以来全省棉花面积下降、大豆和蔬菜面积上升都是比较效益作用的结果。②全省稳定了以一年两熟为主体的熟制体系 ,种植模式向复合、高效发展 ,种植指数提高 ,相当于比 1952年扩大播种面积 151 1万hm2 。③今后河北省种植业发展的方向是优质、高效 ,并注重高产 ,目标是提高生产系统的复合度和资源利用效率
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