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以土橘(Citrus chuana Hort.)和枳(Poncirus trifoliata Raf.)为试材,在砂培条件下,研究不同供磷条件下其生物量、磷素积累量、根系性状的差异,从根系性状差异的角度阐述2种柑橘对低磷胁迫的响应特征及适应机理,为找出影响柑橘磷素(P)吸收的主要因子和通过根系塑性提高养分利用效率的遗传改良提供参考依据。结果表明:枳砧木磷效率为91.22%,土橘为53.24%。低P胁迫下枳砧木P吸收效率显著降低(降幅70%),P转移效率、P利用效率显著提高(增幅分别为59%、300%);土橘P吸收效率、P转移效率显著降低(降幅分别为87%、6%),P利用效率显著提高(增幅200%)。土橘根冠比在低P胁迫下显著增加,增幅为120%,而枳根冠比却显著降低,降幅为24%。低P胁迫下2种柑橘砧木的根系总长度、总表面积、体积、平均直径、根系游离氨基酸总量、脯氨酸和羟脯氨酸含量都显著降低。试验表明,相较而言枳为P高效柑橘种质,土橘为P低效种质。增大根冠比,降低根系总长度、总表面积、体积、根尖数、根系游离氨基酸总量和脯氨酸含量以降低P吸收、转移效率,提高P利用效率是柑橘种质适应低磷环境的突出表现,这在P低效种质土橘中表现尤其明显。而P高效种质枳在低磷环境中却能保持正常的根尖数,降低根冠比并提高P转移效率,同时羟脯氨酸含量与P转移效率呈显著负相关。
Taking Citrus chuana Hort. And Poncirus trifoliata Raf. As test materials, the differences of biomass, phosphorus accumulation and root traits under different phosphorus supply were studied under sand culture conditions. Differences in the response characteristics and adaptive mechanism of two kinds of citrus to low-phosphorus stress, in order to find out the main factors affecting the absorption of citrus phosphorus (P) and to provide reference for the genetic improvement of nutrient use efficiency through root plasticity. The results showed that the phosphorus efficiency of Trifoliate orange rootstock was 91.22% and that of soil orange was 53.24%. The P uptake efficiency of Poncirus trifoliata rootstock decreased significantly (-70%) under low-P stress, and the P transfer efficiency and P utilization efficiency increased significantly (by 59% and 300% respectively); P absorption efficiency and P transfer efficiency decreased significantly Respectively, 87%, 6%), P utilization efficiency increased significantly (increase of 200%). Soil tanzanopyroids significantly increased under the low P stress, an increase of 120%, while the Zhizu root and shoot ratio was significantly reduced, a decrease of 24%. The total root length, total surface area, volume, average diameter, total free amino acids, proline and hydroxyproline contents of two citrus rootstocks under low P stress were significantly decreased. Tests showed that, compared with Citrus aurantium P efficient citrus germplasm, soil orange P inefficient germplasm. Increasing the ratio of root to shoot, decreasing the total root length, the total surface area, the volume, the number of root tips, the total amount of free amino acids in roots and the content of proline to reduce the P uptake and transfer efficiency and improve the utilization efficiency of P are suitable for citrus germplasm to adapt to low phosphorus environment Outstanding performance, which is particularly evident in P. inefficient soil orange. However, the high-efficient P. mongholicus P could maintain the normal root tip number, lower the root-shoot ratio and increase the P-transfer efficiency in the low-phosphorus environment. Meanwhile, the content of hydroxyproline was negatively correlated with the P-transfer efficiency.