小麦与蚕豆间作体系根系形态与磷吸收的定量解析

豆科与禾本科作物间作能够改变作物根系生长,但不同施磷水平下间作-根系形态-磷吸收之间的关系尚未明确。本研究通过田间定位试验和根箱模拟试验,研究不同种植模式(小麦单作、蚕豆单作和小麦-蚕豆间作)和不同磷水平下小麦和蚕豆的产量、生物量、磷吸收及根系形态特征,分析探讨不同施磷条件下小麦-蚕豆间作对根系形态和磷吸收的影响。结果表明: 根箱试验中,与单作相比,间作小麦的根干重、根冠比分别增加21.2%、61.5%,地上部干重降低14.6%,根系磷含量和总吸磷量分别提高23.8%和12.1%;间作蚕豆的地上部干重、根干重、根冠比、总根长和根体积分别增加16.5%、47.3%、24.0%、3.5%和8.4%,间作蚕豆地上部磷含量、根系磷含量和总吸磷量分别提高14.7%、26.2%和21.5%。田间试验中,与单作相比,分蘖期间作小麦地上部磷吸收量降低8.7%,而在拔节期、抽穗期、灌浆期和成熟期分别提高40.6%、19.7%、7.8%和12.4%;但种间互作导致开花期、结荚期和成熟期间作蚕豆的地上部磷吸收量分别降低9.8%、9.0%和5.2%。偏最小二乘法(PLS)回归分析表明,小麦的根表面积和根体积、蚕豆的根表面积对作物磷吸收的贡献最大,在低磷胁迫条件下,间作同时提高了小麦和蚕豆的根体积和根表面积,促进了磷的吸收。总之,在缺磷或低磷条件下,种间互作扩大了小麦和蚕豆根土接触面积,促进了苗期磷的吸收,为后期间作优势的形成奠定了基础。

Quantitative analysis of root morphology and phosphorus absorption in wheat and faba bean intercropping system.

The intercropping of legume and cereal crops could affect crop roots growth. The relationship among intercropping, root morphology and phosphorus (P) acquisition under different P levels is still unclear. With field experiments and a rhizo-box experiment, we examined the changes of yield, biomass, P acquisition and root morphology of wheat and faba bean under different planting patterns (monocropped wheat, MW; monocropped faba bean, MF; and wheat and faba bean intercropping, W//F) and different P levels. In the rhizo-box experiment, both root weight and root-shoot ratio were increased by 21.2% and 61.5%, respectively, but shoot weight was decreased by 14.6% when wheat intercropped with faba bean. Root P content and P uptake of intercropping wheat (IW) increased by 23.8% and 12.1% when compared to MW. Both shoot and root weight, root-shoot ratio, total root length, and root volume of intercropping faba bean (IF) increased by 16.5%, 47.3%, 24.0%, 3.5%, and 8.4% as compared to MF, respectively, which resulted in higher shoot and root P content and P acquisition of IF. In the field experiment, P uptake by IW decreased by 8.7% at tillering stage, but P acquisition increased by 40.6%, 19.7%, 7.8% and 12.4% at join-ting, heading, filling, and maturity stages as compared to MW. By contrast, P acquisition of IF decreased by 9.8%, 9.0% and 5.2% at flowering, podding, and maturity stages as compared to MF. Partial least squares (PLS) regression analysis showed that root surface area and total volume of wheat and root surface area of faba bean had the greatest contribution to crop P acquisition. Intercropping induced higher root volume and root surface area which resulted in higher P acquisition under low P stress. In conclusion, interspecific interaction amplified the root-soil interface zone and increased P uptake at seedling stage under low P stress, which could contribute to the intercropping advantages at later stage.