A STUDY ON FACTORS EFFECTING THE ROOTING AND SURVIVAL RATE OF POPULUS HOPEIENSIS CUTTINGS
Wang Youmin Gao Baoshan (Dept of Soil Conservation)
Populus hopeiensis Hu et Chow is an important tree species for soil and water conservation in the loess plateau of China. However, it is very difficult for rooting of cuttings of this species The authors havestudied the environmental factors and internal mechanisms which influence the survival rate of these cutting, and some results are reported here.1.By the provenance test, Wu-qi provenance is screened as the bestone with a survival rate up to 90% and a greater growth, yield.2.The roots developed from cuttings can be divided into cortical rootand callus root.The former comes from root primordium formed at the end of stem pith ray during the earlier year, and the latter from callus root primordium newly formed in the callosity.3. Raising soil temperature can help rooting cutting of . The cortica. roots will be predominant when the soil temperature is lowen, and more callus roots will form when the soil temperature is higher. When the accumulation of daily soil temperature (≥10 ℃) is above 500 ℃, most of the cuttings can take root. The survival rate of seedlings can be increased by using plastic film to raise soil temperature.4.The survival rate of cuttings will decline sharply where the soil total salt content is up to 0.2% and Cl- or SO42- contents are up to 0.02%, respectively.5. The survival rate of cuttings is related to the absolute nutrient contents in the cuttings and has no relation with its percentage content This is the reason why the survival rate is low for the thin or short cuttings.