Effects Of Different Phosphorus Levels And Apple Rootstocks On Nitrogen And Phosphorus Absorption And Utilization

Phosphorus is one of the most important mineral nutrient elements for plant growth and development.Phosphorus deficiency and excess are significantly affected the growth and development of plants.Over the years,a large amount of phosphate fertilizer has been applied in agricultural production in our country.Excessive application of phosphate fertilizer is not only a waste of resources,increased production costs,and lead to the accumulation of phosphorus in the soil,increasing the risk of environmental pollution.In addition,the situation of high phosphorus will lead to the imbalance of nutrients in plants,affecting the yield and quality of crops,and even affect the content and effectiveness of other nutrients.The absorption and utilization of nutrients by plants is also related to their botanical characteristics.There were differences among different species and even different cultivars.In this experiment,several commonly used in production of apple rootstocks as materials,effects of nitrogen and phosphorus absorption and utilization in Malus hupehensis Rehd.seedlings with different phosphorus levels.And the difference of nitrogen and phosphorus absorption and utilization characteristics of different apple rootstocks,the aim was to provide the basis for the selection of apple rootstocks and the reasonable application of phosphate fertilizer,and to improve the utilization efficiency of fruit trees.1.One-year-old apple rootstock（Malus hupehensis Rehd.）as test material,the study set seven phosphorus application levels which were 0,0.5,1,2,3,4,6 mmol·L^-1H₂PO₄^-（P0-P6）.The experiment was training with Hoagland nutrient solution and using¹⁵N markers in sand culture conditions.The effects of phosphorus levels on the growth of Malus hupehensis Rehd.and the absorption and utilization of nitrogen and phosphorus were studied.The results showed that the total biomass（dry weight）of Malus hupehensis Rehd.increased first and then decreased with the increase of phosphorus levels,and the maximum biomass of P2 treatment（2 mmol·L^-11 H₂PO₄^-）was 3.34 g,which was about 2.74 times of P0 treatment(0 mmol·L^-1H₂PO₄^-).The phosphorus absorption efficiency（PAE）increased significantly with the increase of phosphorus levels.The phosphorus utilization efficiency（PUE）and phosphorus absorption efficiency were negatively correlated,and decreased with the increase of phosphorus concentration.The nitrogen utilization rate showed the first increase and then decrease with the increase of phosphorus levels,and the maximum value of P2 treatment was16.75%,which was 8.91,1.9,1.24 times of P0 treatment（1.88%）,P0.5 treatment（8.81%）,P6treatment（13.49%）,respectively.2.One-year-old apple rootstock（Malus hupehensis Rehd.）as test material,studied on the excess phosphorus levels influence on Malus hupehensis Rehd.nitrogen and phosphorus absorption and utilization efficiency.The soil was used as acid soil in orchard in Jiaodong area,and nine phosphorus concentrations were tested,which were 0,100,200,300,400,500,600,700,800 kg/hm² P₂O₅（P0-P8）.The fertilizer used as calcium superphosphate（SSP）and urea and potassium sulfate.The urea used was ¹⁵N-urea.The results show that:in the Jiaodong area under acid soil condition,with the increase of phosphate fertilizer,the amount of the total biomass of Malus hupehensis Rehd.（dry weight）showing the characteristics of decrease after the first increase.The maximum biomass in P2 treatment（200 kg/hm² P₂O₅）was 5.26 g/plant,which was increased by 7.79%compared with P0 treatment（0 kg/hm² P₂O₅）,which was about 1.61 times of that of P8 treatment（200 kg/hm² P₂O₅）.The phosphorus absorption efficiency（PAE）increased first and then decreased and then remained unchanged.The P1 treatment（100 kg/hm² P₂O₅）was highest for 8.82 mg/plant.The phosphorus utilization efficiency（PUE）was the highest in P0 treatment which was 0.72 g/mg,and then the PUE increased first and then decreased with the increase of phosphate fertilizer.With the increase of phosphate fertilizer,the nitrogen utilization rate of Malus hupehensis Rehd.also showed a downward trend after the first rise,the maximum value in P1 treatment（21.09%）.The nitrogen utilization rate was decreased after the excessive application of phosphorus,and then maintained at the level of 15%.3.In this experiment,five kinds of one-year-old apple rootstocks[Malus hupehensis Rehd.,M.micromalus Makino,M.Prunifolia（Willd）Borkh.and M.Sievesii（Ledeb.）Roemer,M.baccata Borkh.]were used as test materials.The experiment was training with Hoagland nutrient solution and using ¹⁵N markers in sand culture conditions.The absorption and utilization of nitrogen and phosphorus in five apple rootstocks were studied.The results showed that the total biomass（dry weight）of 5 apple rootstocks from high to low were in order:Malus hupehensis Rehd.（3.20 g/plant）>M.micromalus Makino（3.15 g/plant）>M.Prunifolia（Willd）Borkh.（2.74 g/plant）>M.Sievesii（Ledeb.）Roemer（2.66 g/plant）>M.baccata Borkh（2.02 g/plant）.The phosphorus absorption efficiencies（PAE）of five rootstocks from high to low were in order:M.micromalus Makino（23.15 mg/plant）>M.Sievesii（Ledeb.）Roemer（20.79 mg/plant）>Malus hupehensis Rehd.（20.65 mg/plant）>M.baccata Borkh.（14.84 mg/plant）>M.Prunifolia（Willd）Borkh.（14.81 mg/plant）;while the phosphorus utilization efficiencies（PUE）were in order:M.Prunifolia（Willd）Borkh.（0.19 g/mg）>Malus hupehensis Rehd.（0.15 g/mg）>M.micromalus Makino（0.14 g/mg）≈M.baccata Borkh.（0.14g/mg）>M.Sievesii（Ledeb.）Roemer（0.13 g/mg）.The nitrogen utilization rate from high to low were in order:M.micromalus Makino（13.83%）>M.Sievesii（Ledeb.）Roemer（13.79%）>M.Prunifolia（Willd）Borkh.（13.48%）>Malus hupehensis Rehd.（13.39%）>M.baccata Borkh.（9.00%）.