Effect Of Different Ratio Of Phosphate Fertilizer On Growth Physiology And Nutrient Accumulation Of Eucalyptus Seedlings

Fertilization is one of indispensable management measures for Eucalyptus plantation,which could promote the growth of Eucalyptus,improve soil fertility,achieve high yield,high quality and effective of Eucalyptus planting,and realize the sustainable development of forest land.A large number of studies have shown that phosphorus is strongly fixed and inefficient in red soil,and phosphorus is the main limiting factor to limit the yield of trees in red soil area.The effects of calcium magnesium phosphate(CMP):monoammonium phosphate(MAP)=10:3,CMP:MAP=1:1,CMP,MAP fertilizer were studied in E.urophylla×E.grandis DH3229 seedlings.The objectives of the study were to explore the growth,physiological metabolism and nutrient accumulation under different phosphorus source nutrient release conditions.The result showed that:(1)The height,ground diameter,biomass and quality index(QI)of Eucalyptus seedlings treated with different phosphorus fertilizers were significantly higher than that of control group(CK),which showed that phosphorus fertilization could promote the growth and QI of Eucalyptus seedlings,and L4(the source of phosphorus is MAP)treatment was the best.The height and ground diameter growth of L4 and L2(the source of phosphorus is CMP:MAP=1:1)treatment were higher than that of L1(the source of phosphorus is CMP:MAP=10:3)and L3(the source of phosphorus is CMP),and we can see from the growth dynamics,L2 fertilization treatment mode growth better on early,and L4 fertilization treatment had obvious superiority and persistent.The biomass of root was higher under L4 and L2 fertilization treatments,while the stem and leaves showed higher levels of L4 and Li,and the total biomass and quality index showed the same results with height and ground diameter.The results were as follows:L4>L2>Li>L3>CK.(2)The content of malondialdehyde(MDA)of Eucalyptus seedlings decreased significantly,the activities of antioxidant enzymes such as SOD were decreased,and the contents of soluble protein and soluble sugar were also increased with different proportion of phosphorus fertilizers fertilization.The reduction extent of MDA content of L4 and L1 treatments were higher than those of L2 and L3 treatments,and activity of catalase(CAT)showed the same regularity.The activity of peroxidase(POD)and polyphenol oxidase(PPO)showed a significant decrease in L4,the content of soluble sugar with L2 treatment was the lowest,but the content of soluble protein was the highest.Although the physiological and metabolic indexes of Eucalyptus seedlings were different under 4 phosphorus sources fertilization treatments,they showed synergistic complementary effects,which could regulate the cell membrane permeability,antioxidant system and osmotic regulation of Eucalyptus seedlings.(3)Except for K element,the nutrient contents of Eucalyptus seedlings were the highest in the CK,the nutrient content of roots followed by Li treatment,the content of stem followed by L3 treatment and the nutrient content of levae followed by L2.But the nutrient accumulation of Eucalyptus seedlings was the lowest in CK,the nutrient accumulation of Eucalyptus seedlings roots under L4 and L2 treatment were higher than other treatment,while the stem and leaves showed highest levels of L4,and followed by L1,the results showed that total nutrient accumulation of L4 and L2 treatment were higher than L1 and L3 treatment,which were significantly higher than CK.The mono-ammonium phosphate as the main source of phosphorus is more conducive to the absorption of nutrients in the roots of Eucalyptus seedlings,while the addition of calcium magnesium phosphate is conducive to the root system of the transport of nutrients to the ground.(4)The effects of different proportion of phosphorus fertilizers on the nutrient contents of the pot medium of Eucalyptus seedlings were significant,the contents of many elements,trace elements and available nutrients(except nitrate nitrogen)were significantly higher than those of CK.The L1 and L3 treatments with CMP as the main phosphorus source were slightly higher than those of L2(the source of phosphorus is CMP:MAP＝1:1)and L4(the source of phosphorus is MAP),it was speculated that the utilization of nutrient for L2 and L4 treatments was higher than that of L1 and L3 treatments,so the nutrient content in the pot substrate was relatively low.In addition,the effects of different proportion of phosphorus fertilizers on the height and ground diameter of Eucalyptus seedlings were significant,the biomass and nutrient accumulation of Eucalyptus seedlings had increased,and nutrients utilization of eucalyptus seedlings was improved,the treatment of L4 which treated with MAP was best in this experiment,and follow by Li that treated with CMP:MAP=1:1.In the production practice may consider MAP as phosphorus source as base fertilizer,and CMP:MAP=1:1 as phosphorus source as top dressing.