水培条件下不同磷水平对橡胶树幼苗根系生长发育的影响

在营养液培养条件下研究了不同磷浓度对橡胶树幼苗根系形态的影响．结果表明，不同磷浓度对橡胶树幼苗根系的质量、数量和长度等产生了显著的影响．随着磷浓度的增加，橡胶树幼苗1～4级根的平均长度、数量和总长度随着供磷浓度的增加，呈先上升后下降的趋势．其1～4级根的平均长度在低磷处理（0．002mmol·L^-1）时达到最大值，高磷浓度（0．25mmol·L^-1）与之相比分别减少了33％，50％，45％和52％．2—4级根的数量在低磷浓度（0．002mmol·L^-1）时达到最大值，最高磷（0．25mmol·L^-1）处理与之相比分别减少了78％，88％，87％．2～4级根的总长度在低磷浓度（0．002mmol·L^-1）时达到最大值，最高磷处理（0．25mmol·L^-1）与之相比减少了78％，88％，90％．

Effects of Different Phosphorus Concentration on Buddings' Growth of Hevea brasiliensis

The effects of the different phosphorus concentrations on budding growth of Hevea brasiliensis were studied under solution culture conditions. The results showed that with the increasing phosphorus concentration, the roots weight increased firstly, and then decreased. The average length of first-class roots （lateral roots originated from main roots） , second-class roots （lateral roots from 1 st-class roots） , third-class roots （lateral roots from 2nd-elass roots） and fourth-class roots （lateral roots from 3rd-class roots） increased firstly and then decreased . The number and total length of first-class roots, second-class roots, third-class roots and fourth-class roots increased firstly and then decreased. And the average length of first-class roots, second-class roots, third- class roots and fourth-class roots reached maximum value with the low phosphorus levels （0. 002 mmol ·L^-1） while reduced by 33% ,50% ,45% and 52% respectively with high phosphorus levels （0.25 mmol ·L^-1）. The number of second-class roots, third-class roots and fourth-class roots reached maximum value with the low phosphorus levels （0.002 mmol ·L^-1） while reduced by 78% ,88% and 87% respectively with high phosphorus levels （0.25 mmol ·L^-1 ）. The total length of second-class roots, third-class roots and fourth-class roots reached maximum with the low phosphorus levels （0. 002 mmol ·L^-1） while reduced by 78% ,88% and 90% respectively with high phosphorus levels （0.25 mmol ·L^-1）.