An increased plant capacity to efficiently use the poorly available pools will be very helpful in citrus production. Information on the various mechanisms evolved by citrus rootstocks to optimize soil phosphorus (P) access is limited. Thus, the objectives of this study were: To evaluate P acquisition efficiency (PAE) in Thomson Navel Orange (Citrus sinensis L. Osbeck.) plants grafted on three rootstocks and adaptive mechanisms developed by each to these rootstocks to increase P uptake in one calcareous soil. For this purpose, a pot experiment was conducted in a completely randomized design with three replications. Treatments consisted of three rootstocks of citrus, including Sour Orange (SO), Swingle Citrumelo (SC) and Troyer Citrange (TC). 18 months after planting seedlings in pots, plants were harvested and the rhizosphere soils were separated. Dissolved organic carbon (DOC), the population of fungi and bacteria, microbial biomass P (MBP), alkaline (AlP) and acid (AcP) phosphatases, available P (P-Olsen), and P fractionation according to the modified Hedley’ sequential fractionation procedure were determined in the rhizosphere soils. After the harvest, P acquisition efficiency of plants (PAE) was determined. The results of this study showed that SO promoted higher scion P uptake and increased PAE. The fungal and bacterial population, MBP, AcP in the SO rhizosphere soils was greater than the SC and TC rhizosphere soils (P < 0.05). P availability closes the root surface of SO rootstock was higher in comparison to the other rootstocks. Moreover, the effect of the rhizosphere on various fractions of P was under rootstock control. The highest amount of exchangeable P and Fe and Al soil P in the rhizosphere soils was found in SO grafting, while the lowest P associated with Ca compounds and residual P in the rhizosphere soils was found in SO-grafting. This necessarily implies the P mobilization of poorly available pools are vital mechanisms for P acquisition by plants on SO in this P-poor soil. In conclusion, the results of the present study showed that different PAE of rootstocks may be associated with the various mechanisms of action of each rootstock involved in P absorption.

提高植物利用率以有效利用稀缺资源库将对柑橘生产非常有帮助。关于柑橘砧木为优化土壤磷（P）获取途径而发展的各种机制的信息有限。因此，本研究的目的是：评估汤姆森脐橙（柑桔）中的磷获取效率（PAE）L. Osbeck。）植株嫁接到三种砧木上，并且每种砧木都开发了适应机制，以增加一种钙质土壤中P的吸收。为此，在完全随机的设计中进行了3个重复的盆实验。处理包括三种柑橘类砧木，包括酸橙（SO），奇特尔Citrumelo（SC）和Troyer Citrange（TC）。在盆中种苗18个月后，收获植物并分离根际土壤。溶解有机碳（DOC），真菌和细菌的种群，微生物生物量P（MBP），碱性（AlP）和酸（AcP）磷酸酶，可用的P（P-Olsen）以及根据改良的Hedley'序列进行P分馏确定了根际土壤的分馏程序。收获后 确定了植物的磷获取效率（PAE）。这项研究的结果表明，SO促进了接穗P的吸收和PAE的增加。SO根际土壤中的真菌和细菌种群MBP，AcP均大于SC和TC根际土壤（P <0.05）。磷的有效性封闭了SO砧木的根表面，与其他砧木相比更高。此外，根际对根际对各种磷含量的影响。SO嫁接中根际土壤中交换性P和Fe和Al土壤P的含量最高，而SO嫁接中根际土壤中与Ca化合物相关的P和残留P最低。这必然意味着，缺乏可利用的水池的磷动员是植物在这种贫瘠的土壤上以SO吸收磷的重要机制。