关键词: 农学, 还原论, 作物栽培学与耕作学, 作物遗传育种学, 农业生态学, 生产生态学

Abstract: Comparative anatomic study shows that for the early wood of Pinus massonions,the thickness of secondary xylem and the number of tracheid layer are decreased gradually with the altitude from 700 to 1100m. At the altitude of 1300m,they are only respectively 71.21 and 57.70% of the late wood,which is considered to be related with the lower temperature at this altitude. The ratio of toacheid wall to luace and the percentage of pit density to ray area increased with altitude,being the maximum at 1300m of altitude,and the pit diameler and resin passage are decreased with it,being the minimun at that altitude. The decrease of annual formation of axial resin passage and the increase of its density w1th altitude are the results of the reduction of fracheid layer number and lumen diameter.

Key words: agronomy, reductionism, crop cultivation and farming system, crop genetics and breeding, agroecology, production ecology.