磷对尾巨桉组培苗生理及养分利用的影响

Effect of phosphorus on physiology and nutrient utilization ofEucalyptus urophylla×E. grandis tissue culture seedlings

【目的】研究磷对尾巨桉组培苗生理及养分利用的影响,进而筛选出耐低磷的尾巨桉无性系,为桉树优良无性系的遗传改良提供参考。【方法】以生长一致的60日龄尾巨桉(无性系27,28,29和43)组培苗为试验材料,设置0,0.01,0.1,1.0 mmol/L 4个供磷水平,采用水培法进行试验处理,20 d后采样测定各处理尾巨桉地上和地下部分全氮、全磷、全钾含量,叶片Ca、Mg、Fe、Mn、Zn含量,叶绿素含量及保护酶(超氧化物歧化酶(SOD)、多酚氧化酶(PPO)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和过氧化氢酶(CAT))活性,丙二醛(MDA)和可溶性蛋白含量,探索供磷水平对尾巨桉组培苗生理响应及养分利用的影响,并对组培苗抗磷胁迫能力进行综合评价。【结果】(1)当磷浓度为0~1.0 mmol/L时,随着磷浓度的降低,尾巨桉地上、地下部分的全氮、全磷、全钾含量均呈下降的趋势;随着供磷水平的提高,叶片Ca、Fe、Mn含量呈先升高后降低的趋势;Mg含量总体呈下降趋势,Zn含量则变化较复杂。随着磷浓度的下降,各无性系氮磷钾利用效率呈增加趋势,低磷水平(0.01 mmol/L)下各无性系的磷利用效率依次为无性系29>无性系43>无性系28>无性系27。(2)与正常磷水平(1.0 mmol/L)相比,低磷胁迫处理尾巨桉组培苗叶片的叶绿素相对含量和可溶性蛋白含量均下降,而SOD、PPO、POD、APX、CAT活性及MDA含量均增加。(3)各无性系尾巨桉组培苗抗磷胁迫能力综合评价结果表明,无性系29在低磷胁迫时抗逆性更强,对磷的利用效率更高;无性系28和27次之,无性系43最差。【结论】低磷胁迫对各无性系巨尾桉的生长有明显影响,其中尾巨桉无性系29的抗逆性最强,是最佳耐低磷无性系。

【Objective】This study investigated the effects of phosphorus on physiology and nutrient utilization of Eucalyptus urophylla×E.grandis tissue culture seedlings and screened clones with low phosphorus tolerance,so as to provide reference for genetic improvement of excellent Eucalyptus urophylla×E.grandis clones.【Method】The 60-day-old Eucalyptus urophylla×E.grandis tissue culture seedlings(clones 27,28,29 and 43)were selected for hydroponics experiments with phosphorus supply levels of 0,0.01,0.1,and 1.0 mmol/L.After 20 days,above-and below-ground N,P and K contents and leaf contents of Ca,Mg,Fe,Mn,Zn and chlorophyll,activities of protective enzyme(superoxide dismutase(SOD),polyphenol oxidase(PPO),peroxidase(POD),ascorbate peroxidase(APX)and catalase(CAT))and contents of malondialdehyde(MDA)and soluble protein were measured.The effects of phosphorus supply level on physiological response and nutrient utilization of Eucalyptus urophylla×E.grandis tissue culture seedlings were then explored,and a comprehensive evaluation of phosphorus stress resistance of tissue culture seedlings was conducted.【Result】(1)Within the range of 0 to 1.0 mmol/L,nitrogen,phosphorus and potassium contents of above-and below-ground parts of Eucalyptus urophylla×E.grandis decreased as phosphorus concentration decreased.Leaf Ca,Fe and Mn contents increased first and then decreased as the increase of phosphorus supply level.Mg contents showed a decreasing trend,while the changes of Zn contents were more complicated.The nitrogen,phosphorus and potassium utilization efficiency of each clone showed an increasing trend with decreasing phosphorus concentration,with the decreasing order of clone 29>clone 43>clone 28>clone 27 at low phosphorus level(0.01 mmol/L).(2)Compared with normal phosphorus level(1.0 mmol/L),SPAD value and soluble protein content in leaves of low phosphorus stress-treated Eucalyptus urophylla×E.grandis tissue culture seedling decreased,while SOD,PPO,POD,APX and CAT activities and MDA content increased.(3)The comprehensive evaluation of phosphorus stress resistance of Eucalyptus urophylla×E.grandis tissue culture seedlings showed that clone 29 was more resistant to low phosphorus stress with higher phosphorus utilization efficiency,followed by clones 28,27 and 43 in order.【Conclusion】Low phosphorus stress had a significant effect on the growth of all Eucalyptus urophylla×E.grandis clones.Among them,Eucalyptus urophylla×E.grandis colnes 29 was the most resistant and the best low phosphorus tolerant clones.