采用石英砂培养方法并去除或保留分蘖，研究了旗叶期缺磷对大穗型小麦CA9325和多穗型晋麦2号（JM2）生长后期旗叶光合和蒸腾速率、干物质和磷在体内分配以及最终产量的影响。结果表明: ⑴旗叶期缺磷一段时间后降低小麦旗叶的光合和蒸腾速率。不同供磷水平下，去蘖使小麦旗叶光合和蒸腾速率大都高于同期未去蘖的；⑵旗叶期缺磷几乎导致两品种所有器官和整株干物质和磷的积累降低，去蘖的小麦籽粒干物质和磷总量占整株的比例均高于未去蘖的，说明缺磷促进小麦各营养器官的磷向籽粒转移；⑶主茎干物质和磷的积累以CA9325高于JM2，而JM2则以分蘖占优势，这与JM2分蘖数较多有关；⑷ 不论供磷还是缺磷，未去蘖的CA9325籽粒产量低于JM2，而去蘖后则相反。不同库容量的CA9325千粒重和籽粒磷含量均高于JM2。全生育期供磷条件下的磷吸收效率，以未去蘖的CA9325显著高于JM2，去蘖后两品种间无明显差异。
P is an important nutrient element in plant, and P deficiency is one of the major factors limiting crop production. P recycling and distribution are remarkable in plant growth, especially under P deficiency condition. In this paper, the photosynthetic and transpiration rates of flag leaf, dry matter and P distribution in each organ, final yield of grain and P uptake efficiency were studied using large-spike cultivar CA9325 and multi-spike cultivar JM2, by remaining or removing tillers. The wheat plants were grown in spots with quartz sand, and watered with nutrient solution (KCl replaced KH2PO4 in P-deficiency treatment). The results were as follows: (1) Photosynthetic and transpiration rates of the flag leaf in two wheat cultivars were decreased and their photosynthetic functional periods were shortened after a short time of P deficiency. Those in plants without tillers were higher than those with tillers, and those in normal P treatment were higher in JM2 than in CA9325 (Fig.1,2). (2) In P-deficiency treatment, the dry matter weight and P accumulation in almost all organs and whole plant of both cultivars were decreased, especially in grains and whole plants. The percentages of dry matter and P in grains of the plants without tillers to whole plant were higher than those with tillers, which showed that P deficiency stimulated the transportation of dry matter and P from vegetative organs to grains (Table 1,2). With or without P in the nutrient solution, the percentages of dry matter and P of grains to whole plant in two wheat cultivars were about 40% and 65%, respectively, which showed dry matter and P allocations to grains were not synchronous. (3) The accumulations of dry matter and P in main shoot and the percentages of which to whole plant were higher in CA9325 than in JM2, but those in tiller were higher in JM2 than CA9325 because of their different spike types (Table 1,2). (4) 1000-grain weight, grain yield and P content and spike number per plant in two wheat cultivars were decreased under P deficiency at the flag leaf expanding stage. In the treatments with or without P, 1000-grain weight in plant without tillers was significantly higher than those with tillers in the same wheat cultivar. In the plants with tillers, grain yields were less in CA9325 than in JM2, but it was on the contrary in the plant without tillers. 1000-grain weight and P content of grains were higher in CA9325 than in JM2, no matter the tillers were kept or removed. P uptake efficiency was higher in CA9325 than in JM2 when the tillers were not removed; while these were no significant difference between them when the tillers were removed (Table 3). The possible mechanisms of P distribution and utilization were also discussed.
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