Citrus Root System Preferably Uses the Macropore Space to Explore Compacted Soil

Artificial macropores are low resistance pores channels to plant rooting, allowing access to water and nutrients in compacted soils (Yellow Oxisoil Dystrocohesive). We investigated how artificial macropores (AM) and numbers of vertical distribution in column of compacted soil affect plant growth, root system distribution and gas exchange of citrus plant subjected to a continuous soil water extraction. Five treatments were evaluated in a completely randomized design experiment with five replications. A plant of ‘Rangpur’ lime (C. limonia Osbeck) per PVC tube with 0.15 m of external diameter and 0.5 m of length was the experimental unit. The entirely soil profile of the control treatment (Ctrl) was filled at density of 1.3 g cm-3. The following treatments the shallow profile (0 – 0.16 m) was filled with weak soil (1.3 g cm-3) and underlying (0.16 m to 0.5 m) filled with compacted soil (1,6 g cm-3): no macropores channels (Comp); one vertical macropore (1 mpc); two vertical macropores (2 mpc); three vertical macropores (3 mpc); and five vertical macropores (5 mpc). The artificial macropores (1 mm) builded with wire of stainless steel crossed the compacted profile. The images of root system revealed the preferential way to the macropores when plants were subjected to compacted soil. The macopores relief the effect of strong soils in relation to gas excange root architecture of young plants of ‘Rangpur’ lime.