配方施肥对薄壳山核桃苗期养分含量及光合作用的影响

Effects of the proportional fertilization on the nutrient content and photosynthesis of young grafted pecan seedlings

【目的】研究氮(N)、磷(P)、钾(K)不同配方施肥对薄壳山核桃苗期养分含量及生理特性的影响,筛选薄壳山核桃苗期的最佳施肥方案。【方法】以薄壳山核桃品种‘绍兴'2年生实生苗为砧木,优良品种‘马罕'(‘Mahan')为接穗,嫁接生长1 a后的幼苗为试验材料,采用盆栽试验,根据L9(34)正交试验设计进行3因子(N、P、K)3水平(水平1为4 g/株N、2 g/株P、1 g/株K,水平2为6 g/株N、3 g/株P、3 g/株K,水平3为8 g/株N、4 g/株P、5 g/株K)配方施肥试验,研究不同处理对薄壳山核桃幼苗全株及不同组织(根、茎和叶)养分含量(全N、全P和全K)以及叶片叶绿素含量和光合相关指标(净光合速率Pn、气孔导度Gs、胞间CO2浓度Ci和蒸腾速率Tr)的影响。【结果】配方施肥显著提高了薄壳山核桃全株及幼苗根、茎、叶的全N、全P和全K含量,且全N和全P在不同组织中的含量均表现为叶>根>茎,全K含量表现为根>茎>叶;配方施肥后的叶绿素a、b含量均在7月中旬达到最大;配方施肥对幼苗光合相关指标的影响除Tr外均显著,且表现为N>K>P的处理效应。【结论】配方施肥能够显著提高薄壳山核桃全株及不同组织养分含量、叶片叶绿素含量以及光合作用能力,试验筛选出的最佳配方施肥为T4处理组,即每株施N、P、K肥分别为6、2、5 g。

【Objective】The effects of nitrogen(N),phosphorus(P)and potassium(K)treatments on the nutrient content and physiological characteristics of young grafted pecan seedlings were studied to determine the optimum fertilization scheme.【Method】Two-year-old seedlings from native Chinese‘Shaoxing'pecan seeds were collected as rootstock and the U.S.-released pecan cultivar‘Mahan'as scion.After one year of growth,the young grafted seedlings were transplanted into pots for use as experimental materials.Based on the L9(34)orthogonal experimental design,fertilization experiments were conducted with three factors,i.e.,N,P and K,and three treatments,i.e.,N:4,6,8 g/plant;P:2,3,4 g/plant;K:1,3,5 g/plant.The effects of different treatments on the nutrient content(total N,total P and total K)of different tissues(roots,shoots and leaves)and the whole plant as well as the chlorophyll content and photosynthesis-related indicators[net photosynthesis rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci)and transpiration rate(Tr)]of pecan leaves were tested and analyzed.【Result】Proportional fertilization significantly increased the total N,total P and total K contents of the whole plant and all tissues of young grafted pecan seedlings.Among the different tissues,the total N and total P contents were the highest in leaves,followed by the roots and then shoots.Further,the total K content was the highest in the roots,followed by the shoots and then leaves.Chlorophyll a and b contents peaked in mid-July.Proportional fertilization significantly affected the photosynthesis-related indicators of seedlings,except Tr;the other indicators were present as N>K>P.【Conclusion】Proportional fertilization of pecan seedlings significantly increased the nutrient content of the whole plant and different tissues,chlorophyll content in leaves,and photosynthetic capacity.It was preliminarily concluded that the optimum fertilization ratio for pecan seedlings was that used in the last treatment,i.e.,N:6 g/plant,P:2 g/plant,and K:5 g/plant.