低磷胁迫下五种苹果砧木的磷吸收与利用特性

摘要

Objectives As an essential mineral element in the plants, phosphorus can facilitate the differentiation of flower bud. However, phosphorus is easily fixed in soils when applied to soil, and mostly transferred to occluded P, which is not available to plants. Therefore, it has great significance to excavate phosphorus efficient apple rootstocks under low phosphorus stress. In this study,five one-year-old wild apple rootstocks were used as materials and their phosphorus absorption and utilization characteristics under the condition of low phosphorus stress were analyzed. [Methods]The five one-year-old apple rootstocks [M. micromalus Makino, Malus hupehensis Rehd. , M. baccata Borkh. , M. prunifolia(Willd)Borkh. and M. sievesii(Ledeb. )Roemer] were grown in low phosphorus group(LP)and control group(CK)in pots with 6 replication. The root surface area and length were determined by WinRHIZO root analysis software, and the plant phosphorus content by vanadium molybdate yellow colorimetric method. The the kinetic parameters of H2PO- 4 absorption of seedlings were determined with a water culture experiment. Firstly, the seedlings were P-starved in black bottle for 24 h and then put into the solutions of different P-concentrations for 24 h, and finally, 10 mL solutions were collected to determine the phosphorus content with Mo-Sb colorimetry. [Results]The relative phosphorus efficiencies of five rootstocks from high to low are in order of M. prunifolia(Willd)Borkh. (93. 66%) > Malus hupehensis Rehd. (87. 69%) > M. baccata Borkh. (83. 44%)> M. micromalus Makino. (74. 54%) > M. sievesii(Ledeb. )Roemer. (74. 01%). The phosphorus absorption efficiencies(PAE) from high to low are in order of M. prunifolia(Willd)Borkh. > Malus hupehensis Rehd. > M. baccata Borkh. > M. sievesii ( Ledeb. ) Roemer. > M. micromalus Makino, while the phosphorus utilization efficiencies (PUE) are in order of Malus hupehensis Rehd. > M. prunifolia (Willd) Borkh. > M. micromalus Makino > M. sievesii(Ledeb. )Roemer > M. baccata Borkh. Considering the kinetic parameters of H2PO- 4 , the values of the Vmax of the five rootstocks are in the order of M. prunifolia(Willd)Borkh. [101. 81 μmol/ (g·h) ]> Malus hupehensis Rehd. [66. 40 μmol/ (g·h) ] > M. baccata Borkh. [45. 00 μmol/ (g·h) ] > M. sievesii (Ledeb. )Roemer[44. 32 μmol/ (g·h) ] > M. micromalus Makino[41. 28 μmol/ (g·h) ]. The values of Km are arranged in turn by the following order,Malus hupehensis Rehd. (4. 05 μmol/ L) < M. prunifolia(Willd) Borkh. (8. 68 μmol/ L) < M. baccata Borkh. (12. 29 μmol/ L) < M. sievesii(Ledeb. )Roemer(12. 64 μmol/ L)< M. micromalus Makino(13. 57 μmol/ L). The total absorption surface area and length of root are highest in M. prunifolia(Willd)Borkh, lowest in M. micromalus Makino. [Conclusions]M. prunifolia(Willd)Borkh has the highest relative phosphorus efficiency and phosphorose absoprtion efficiency under phosphorus stress, exhibiting the highest growth vigor and the strongest P absorption capacity. M. prunifolia(Willd)Borkh. has the best adaptation to low phosphorus stress. Malus hupehensis Rehd has lower relative phosphorus efficiency relative to M. prunifolia (Willd) Borkh, and has the highest PUE, and its capacity to low phosphorus stress ranks after M. prunifolia (Willd) Borkh. Further analysis showed that the values of PAE in the five rootstocks were significantly and positively correlated with the surface area and length of absorption root, indicating that the root absorption area enlargement of plants could promote the acquisition of P by increasing the root surface area and length under low phosphorus stress.%【目的】磷是植物必需的矿质元素之一,能够促进植株花芽分化,但施入土壤中的磷易被固定从而变成难以利用的闭蓄态磷,使土壤中的有效磷含量降低。因此,研究和发掘磷高效的苹果砧木对于解决低磷胁迫和提高磷利用效率具有重要意义。本研究以5种一年生苹果野生砧木为试材,进行低磷胁迫处理,调查苹果野生砧木对磷的吸收和利用特性。【方法】盆栽试验以正常管理的一年生八棱海棠( M. micromalus Makino)、平邑甜茶( Malus hupehensis Rehd.)、东北山荆子(M. baccata Borkh.)、富平楸子[M. prunifolia(Willd)Borkh.]、新疆野苹果[M. sievesii(Ledeb.)Roemer]5种苹果砧木为试材。试验分为低磷(LP)和正常施磷(CK)两组处理,每个处理6次重复(6盆)。根总表面积、根系总长度分析用WinRHIZO 根系分析软件进行；植株各器官组织烘干粉碎后,用钒钼黄比色法测定其含磷量。离子吸收动力学参数的测定采用平邑甜茶水培幼苗,吸收前置于黑色培养瓶饥饿处理24 h,幼苗吸收24 h后采集营养液10 mL,钼锑抗比色法测定含磷量。【结果】5种砧木的相对磷效率从高到低为富平楸子(93.66%)>平邑甜茶(87.69%)>东北山荆子(83.44%)>八棱海棠(74.54%)>新疆野苹果(74.01%)。在低磷及正常施磷条件下,5种砧木的磷吸收效率均为富平楸子>平邑甜茶>东北山荆子>新疆野苹果>八棱海棠；磷利用效率为平邑甜茶>富平楸子>八棱海棠>新疆野苹果>东北山荆子。 H2 PO4-离子最大吸收速率(Vmax)最高的为富平楸子[101.81μmol/(g·h)],其次为平邑甜茶[66.40μmol/(g·h)]、东北山荆子[45.00μmol/(g·h)]和新疆野苹果[44.32μmol/(g·h)],八棱海棠的Vmax最低,为41.28μmol/(g·h)；平邑甜茶的Km值最低,为4.05μmol/L,富平楸子为8.68μmol/L,东北山荆子为12.29μmol/L,新疆野苹果为12.64μmol/L,八棱海棠最高为13.57μmol/L。吸收根总表面积和总根长均以富平楸子最大,八棱海棠最小。【结论】低磷胁迫下富平楸子的相对磷效率和磷吸收效率最高,在低磷胁迫下生长势最好并且磷吸收能力最强,是一种对低磷胁迫适应能力较好的苹果砧木；平邑甜茶的相对磷效率仅次于富平楸子,磷利用效率最高,其耐低磷胁迫的能力也仅次于富平楸子。进一步分析发现,砧木对磷的吸收效率与吸收根总表面积和总根长存在显著正相关关系,说明低磷胁迫下植物通过增加吸收根总表面积及总根长等方式,扩大根系吸收面积,从而增加根系对磷的吸收。