Study On Phosphorus Uptake Characteristic Of Rubber Tree Seedlings

Based on improved conventional depletion method and rubber tree seedlings as experimental subjects, experiments have studied the kinetic parameters of the uptake to H2PO4- of rubber tree seedlings. And aim at the low utilization rate of fertilizer and the affect of unbalanced fertilization to roots the experimensts have also studied the roots adaptive response under the different ratios of fertilizer and the different phosphorus levels. For rationally using phosphate fertilizer, the paper has provided reasonable bases. The major results are as follows:1. Using three kinds of linear equations to process data and receive kinetic parameters, we can receive the following conclusions by comparing of parameters. LB equation and Hanes equation are better fit than another equation. By comparison of parameters from two methods, we can see that Vmax of RRIM600 is larger and its Km is smaller in second leaves period. In third leaves period, the Vmax of GT1 is larger and the Km of GT1 is smaller. Therefore, in two kinds of 7-33-97 seedlings, the maximum uptake rate of RRIM600 to phosphorus is larger but its requirement to phosphorus density of the environment is lower at the maximum uptake rate than GT1, i.e. the uptake capacity to phosphorus is stronger than GT1 in second leaves period. But it is reverse in third leaves period.2. During different periods of rubber tree seedling, the kinetic parameters of the uptake to H2PO4- is different. In three different periods of 7-33-97 seedlings, Vmax of the first leaves period is max and the uptake capacity is strongest, followed by the second leaves periods, the third leaves period at last. This phenomenon is corresponding with the rule that Vmax reduce with the older seedling. But Km of 7-33-97 in the three kinds of seedling age is different, and the phenomenon is inconsistent with the rule of Km that the affect of seedling age is small for Km.3. Ratio of fertilizer, levels of phosphorus fertilization have a significant affect to roots growth of rubber trees. The partial fertilization experiment showed that appropriate fertilization proportion is not significant different from the overall fertilization. The height, diameter and total biomass of rubber tree seedlings reach max when the fertilization ratio is between 1/2～1/3. the experiment shows that appropriate phosphorus can promote the growth of rubber tree seedlings, especially the density is in 0.5～1.0g.kg-1, the height, diameter and total biomass of rubber tree seedlings can reach max.4. Ratio of fertilizer, levels of phosphorus fertilization have a significant affect to roots shape of rubber trees. The partial fertilization experiment shows that appropriate fertilization proportion is the same as the effect of overall fertilization. The roots length, volume and surface area of rubber tree seedling can reach the maximum value when the fertilization ratio is 1/2, and phosphorus density is between 0.5～1.0g.kg-1 s.5. Ratio of fertilizer, levels of phosphorus fertilization have a significant affect to roots activity and phosphorus content of rubber trees too. The roots vigor and phosphorus content of rubber tree seedling can reach the maximum value when the fertilization ratio is 1/2, and phosphorus density is between 0.5～1.0g.kg-1 s. Low or high phosphorus density can inhibit the uptake capacity of roots.