缺磷胁迫对核桃幼苗生长及生理特征的影响

【目的】探讨核桃幼苗在缺磷胁迫下的适应性及其机理。【方法】以核桃幼苗为研究对象，设置不缺磷(对照，CK)、中度缺磷(MP)和重度缺磷(SP)3个处理进行盆栽试验，测定核桃幼苗长势和生理指标，分析缺磷胁迫对核桃幼苗生长和生理活动的影响。【结果】(1)在缺磷胁迫下，核桃幼苗地上部分生物量和根系生物量均显著低于CK，而根系活力和酸性磷酸酶活性却高于CK，且总体上随着缺磷程度的加重和处理时间的延长变化更明显；(2)在缺磷胁迫下，核桃幼苗叶片的叶绿素a、叶绿素b和类胡萝卜素含量、净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)均显著低于CK，且随缺磷程度加深降低越明显。另外，各处理P_n在处理中后期出现上升现象，G_s和T_r在60 d后显著下降；(3)整个实验过程中，各处理超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量总体均以CK最高，其次为MP处理，SP处理最低。但缺磷处理中后期能提高核桃幼苗SOD和POD活性以及...

Effects of Phosphorus Deficiency Stress on Growth and Physiology of Walnut Seedlings

  Objective  To explore the adaptability and mechanism of walnut under phosphorus (P) deficiency stress.  Method  The effects of P deficiency on the growth and physiological traits of Walnut seedlings were studied with control (CK), moderate P deficiency (MP) and severe P deficiency (SP).  Result  (1) Under the stress of P deficiency, the aboveground biomass and root biomass of walnut seedlings were significantly lower than that of CK, but the root vigor and acid phosphatase activities were higher than these of CK, and it became more severe with the increase of P deficiency; (2) under P deficiency, the contents of chlorophyll a, chlorophyll b and carotenoid, net photosynthetic rate (P_n) , stomatal conductance (G_s) and transpiration rate (T_r) in leaves of walnut seedlings were significantly lower than those of CK. In addition, the P_n increased in the middle and late processing, G_s and T_r decreased significantly after 60 days. (3) during the whole experiment, the activities of superoxide dismutase, peroxidase, catalase and the content of malondialdehyde (MDA) were the highest in CK, the next was in MP treatment, and the last was in SP treatment. However, the activities of SOD and POD, and the contents of MDA increased in the middle and late stage of P deficiency, but the contents of proline (PRO) and soluble sugar were not significantly different.  Conclusion  The results showed that walnut could increase the input to the root by self-regulation under low P stress in order to improve the absorptive capacity. At the same time, the stress resistance can be enhanced by inhibiting the formation of photosynthetic pigment, reducing the photosynthetic capacity of leaves, and enhancing the activity of cell protective enzyme system.