Investigation on the Growth Rule of Root System of Winter Wheat in Semiarid Red Clay Soil Hills Age structure and biomass accumulation of Acanthopanaxgiraldii population in west Sichuan plateau STUDY ON THE FLOWER MASS OF BLACK LOCUST AND MANAGEMENT OF NECTARIFEROUS FOREST IN TAI HANG MOUNTAIN Orthogonal experiments on cultivation of Phyllanthus urinaria Change in growth and nutrition compostion of domesticated Allium mongolicum