RESUMO
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.
Assuntos
Fósforo na Dieta , Vicia faba , Agricultura , Fósforo , Raízes de Plantas , TriticumRESUMO
Interspecific interactions are closely related to the intercropping yield advantage. Little attention was paid to the dynamic changes of interspecific interactions. In this study, the growth curves of wheat and faba bean under different planting patterns (wheat monocropped, faba bean monocropped, and wheat and faba bean intercropping) and phosphorus (P) fertilization levels [P0, 0 kg P2O5·hm-2(the control); P1, 45 kg P2O5·hm-2; P2, 90 kg P2O5·hm-2, repetitively] were simulated by Logistic analysis in a two-year field experiment. The dynamics of interspecific interaction were analyzed. The results showed that wheat yield was increased by 10.5%-18.6% when wheat was intercropped with faba bean as compared to monocropped wheat (MW). The yield of intercropping faba bean (IF) was decreased by 4.8%-12.3% relative to monocropped faba bean (MF). However, wheat and faba bean intercropping still showed yield advantage, with the values of land equivalent ratio (LER) and relative crowding coefficient (K) being 1.01-1.15 and 1.12-3.20, respectively. Both the yields and key growth parameters for wheat and faba bean were regulated by P level, but LER and K were not affected by P level. The maximum growth rate (Rmax) and the initial growth rate (r) of wheat were increased by 21.8%-38.7% and 20.8%-38.9% when wheat was intercropped with faba bean as compared to corresponding MW, respectively. The planting pattern had no effect on the key growth parameters of faba bean. No difference in growth curve between monocropping and intercropping crop was found under different P fertilization levels during the early growth stages. The interspecific competition was dominant in wheat and faba bean intercropping system during the early growth stages, without any intercroping biomass advantage (LER<1, K<1). Increased growth rate and decreased intraspecific competitive pressure for wheat were observed when faba bean attaining its maximum growth rate (Tmax) in intercropping system, with both intercropping biomass and yield advantage (LER>1, K>1). In conclusion, the interaction between wheat and faba bean varied with growth stages. Wheat and faba bean intercropping stimulated the growth rate of wheat during the middle and late growth stages, which was a foundation for intercropping advantage.
