【作者】 彭正萍；

【导师】 李春俭；

【作者基本信息】 中国农业大学 ， 植物营养学， 2004， 博士

【摘要】 养分在植物体内的循环和再利用，对植物维持正常生长，提高养分利用效率有重要作用。本论文通过营养液和石英砂培养方法，在不同时期缺磷条件下，研究了冬小麦CA9325和晋麦2号（JM2）的生长、对磷的吸收和在木质部及韧皮部中的运输和循环、籽粒对体内磷的利用及与库强的关系，并比较了两个小麦品种籽粒利用体内磷的差异。主要结果和结论如下： 1．在室内培养条件下，小麦生长的适宜磷浓度为0.25-1.0 mmol·L^-1。吸收H₂PO₄^-的动力学研究表明，CA9325和JM2幼苗在含有不同磷水平的营养液中培养23 d并耗竭48 h后，缺磷培养的CA9325根系对H₂PO₄^-的吸收快，亲合力高，耐低磷能力强。用传递函数模型能够模拟小麦幼苗根系对H₂PO₄吸收的动态过程。 2．只保留主茎条件下，在旗叶展开期开始缺磷。处理后30 d内对CA9325和JM2整株的干重净增量影响不大，但加速了穗部干物质和磷的积累。供磷植株中，处理后第一阶段（30 d），两个小麦品种木质部中运输的磷主要来自根系的吸收，在第二阶段（30-60 d），通过韧皮部再循环的磷量增加，占木质部中运输磷量的86％以上；缺磷植株中，籽粒磷几乎全部来自营养器官中磷的再转移，这部分磷并非直接经过韧皮部运至籽粒中，而是经过韧皮部循环至根中后，再通过木质部运输到达穗部。结果表明，植株中光合产物和磷向籽粒中的运输是相互独立的两个过程。虽然缺磷显著降低整株干重，但对两品种的最终籽粒磷含量没有影响。 3．保留分蘖条件下，分别在拔节期和挑旗期开始缺磷。两品种的对照植株的总吸磷量基本相同，但CA9325在旗叶展开前的吸磷量低于JM2，而在挑旗-灌浆期的吸磷量高于JM2，并且这一时期的吸磷量多于植株在播种一挑旗期间吸磷量的总和。随着生长的延续，两品种供磷植株的主茎、有效分蘖和整株中的磷含量不断增加，峰值在灌浆期。在拔节期缺磷和挑旗期缺磷的两品种植株中，不仅无效分蘖和根系中的磷在生长后期向主茎中转移，而且有效分蘖中的部分磷也向主茎中转移。CA9325对照植株的主茎籽粒磷含量高于有效分蘖；JM2对照植株的主茎籽粒磷含量低于有效分蘖，这主要与JM2分蘖数多有关。缺磷植株的所有营养器官和颖壳中的磷含量均低于同一时期的对照植株，并且随着生长时间的延长不断下降。 缺磷的两品种主茎和有效分蘖的籽粒磷含量均低于对照，但籽粒磷在相应的主茎和有效分蘖中所占比例高于对照。缺磷降低两品种的籽粒产量，缺磷时间越早，产量下降越多。综合结果表明，CA9325的吸磷效率高于JM2，缺磷的CA9325籽粒利用体内磷的能力强于JM2。更多还原

【Abstract】 Nutrient cycling and recycling is important for maintaining plant growth and enhancing nutrient use efficiency. In the present study, two winter wheat cultivars (Triticum aestivum L.), CA9325 and JM2, were selected to investigate their growth, P uptake and recycling in xylem and phloem, translocation of P within plant to grains, and their relationships with sink strength as affected by P withdrawal at different developmental stages. The differences of P use ability by grains between two cultivars were compared. The plants were grown either in nutrient solution in lab under the controlled condition or in quartz sand in greenhouse. The main results were as followed:1. The appropriate P supply for wheat plant growth under the present condition was from 0.25 to 1.0 mmol L-1. Kinetics and mathematics simulation of H2PO4 uptake were studied using seedlings of the two cultivars grown in nutrient solution with different P levels for 23 days and depleted 48 h. The results showed that under P-deficient condition, CA9325 had greater P uptake rate, higher affinity to P and stronger endurance to low-P. The process of H2PO4 uptake by roots of wheat seedlings could be simulated using the transfer function model.2. After vernalization of both cultivars, all tillers were removed. P was withdrawn during the flag leaf expansion. After the treatment, the study period left was divided into two phases of one month each. In the first study period, net dry weight increments of whole plant in both cultivars were not influenced by P deficiency, while dry weight and P content accumulated into spike were accelerated. P transported in the xylem of the control plants came mainly from the roots’ current uptake in both cultivars; while in the second study period, phloem retranslocation of P was increased, which accounted for 86% of P transported in xylem. In the P-deficient plants, however, almost all of the P deposition in grains was remobilized and exported from vegetative organs. These P were recycled to roots through phloem and then transported to spike via xylem, not directely transported to grains via phloem. The results suggested that dry matter and P allocation into grains were not synchronous, indicating independent regulatory processes. Although the finial dry weight of whole plant in both cultivars was markedly reduced by withdrawing P from the medium, the final P content of grains was not influenced.3. The studies were also carried out in greenhouse using both cultivars without moving tillers. P omitting from growth medium was performed either in jointing or in flagging stage. The results showed that in P-sufficient plants, total amount of P taken up by CA9325 was equal to JM2. However, CA9325 took up less P than JM2 between sowing and flagging stage, but more P than JM2 from flagging stage to grain filling stage. With the prolonged plant growth, the increase of P contents in main shoot, valid tillers and whole plants grown under P-sufficient conditions showed gradually increase and the peak of the P contents appeared at the grain filling stage. In the P-deficient plants of both cultivars with P omitting from medium either in jointing or flagging stage, P transferred into main shoot were not onlyfrom invalid tillers and roots, but also from valid tillers at the later growth stage. P contents in grains of main shoot in the P-sufficient CA9325 were higher than those in valid tillers; by contrast, that in the P-sufficient JM2 was reversed, since there were more tillers in JM2 than in CA9325. P contents in all vegetative organs and glumes of both cultivars with P omitting in jointing or flagging stage were lower than those in the P-sufficient plants, and gradually decreased with the prolonged plant growth.P contents of grains in the P-deficient plants were lower than those in the P-sufficient plants, but the percentage of P in grains to main shoot and valid tillers was higher in the P-deficient plant. At mature stage, P deficiency decreased the grain yields of both cultivars, especially in the plant with P withdrawi更多还原