肥料袋控缓释对苹果新根生长和氮素吸收的影响

为从苹果新根生长、发育角度探讨肥料袋控缓释施肥提高氮素利用率的机理，本试验以5年生苹果为试验材料，采用微根管技术对苹果新根生长动态进行连续3年的观测，同时利用¹⁵N同位素示踪技术研究肥料袋控缓释处理对苹果氮素吸收的影响。结果表明，肥料袋控缓释处理土壤的NH₄⁺-N和NO₃^--N浓度维持在12.46 mg·kg^-1以上，变异系数小于27.4%。肥料袋控缓释处理苹果新根发生数量比肥料撒施处理提高了34.2%。肥料袋控缓释处理苹果新根褐变时间为58 d，不施肥处理为34 d，撒施处理为41 d。肥料袋控缓释处理新根中值寿命为224 d，不施肥处理为142 d，撒施处理为182 d。肥料袋控缓释处理新根现存量显著高于撒施处理和不施肥处理，新根年周转率显著低于撒施处理和不施肥处理。8月底苹果根系活力以肥料袋控缓释处理最高(82.54 mg·g^-1·h^-1)，显著高于撒施处理和不施肥处理。肥料袋控缓释施肥处理来自肥料的氮占总...

Effects of Bag Controlled-Release Fertilizer on Apple New Born Root Growth and Nitrogen Absorption

This study was aimed to explore the reason that nitrogen use efficiency increased by the usage of bag controlled-release fertilizer from the perspective of apple new born root growth and development， so as to provide theoretical basis for apple rational fertilization. In field grow condition， five-years old apple trees （Malus domesica Borkh） of the cv. Red Fuji were taken as experimental materials. New born root growth dynamics of apple trees were determined using the minirhizotron technique for three consecutive years. At the same time， effects of bag controlled-release fertilizer on nitrogen utilization of apple were studied by ¹⁵N isotope tracer method. The results showed that the soil ammonium and nitrate nitrogen concentration of bag controlled-release fertilizer treatment maintained higher than 12.46 mg · kg^-1 and the coefficient of variation was less than 27.4%. The number of new born roots was increased by 34.2% of bag controlled-release fertilizer treatment than fertilizer spread application treatment. New born roots in the fertilizer spread application and unfertilized control treatments took 34 and 41 d to become pigmented， and the bag controlled-release fertilizer treatment took 58 d to become pigmented. The median lifespan of new born roots was 224， 182 and 142 d for bag controlled-release fertilizer， fertilizer spread application and three unfertilized controls， respectively. The new born roots turnover rate of the bag controlled-release fertilizer treatment was markedly lower than that of the fertilizer spread application and unfertilized control treatments but the new root exsiting was significantly higher than that of the fertilizer spread application and unfertilized control trertments. At the end of August， the root activity of bag controlled-release fertilizer treatment was up to 82.54 mg · g^-1 · h^-1， which was significantly higher than that of fertilizer spread application treatment and unfertilized control treatments. The nitrogen derived from fertilizer of bag controlled-release fertilization treatment was significantly higher than that of fertilizer spreading application treatment. The nitrogen utilization rate （23.00%）of bag controlled-release fertilization treatment was significantly higher than fertilizer spread application treatment of 17.08%. The reasons why bag controlled-release fertilizer increased nitrogen utilization rate could be largely accounted for influencing soil nutrient supply and new born root growth and development.In summary， the findings were of great significance for the further promotion of bag controlled-release fertilization in apple production and green development of apple production.