Abstract: In order to understand the root distribution patterns of oat under rainfall harvesting in ridges and furrows, a field experiment with completely randomized design was conducted in the Dingxi semiarid loess hilly region of Gansu, Northwest China to study the effects of different mulching materials (plastic film and soil crust) and different ratios of furrow to ridge (60∶30, 60∶45, and 60∶60 cm) on the root physiological characteristic parameters (dry weight, length, surface area, and volume) of oat. It was observed that the test root physiological characteristic parameters decreased with increasing soil depth. Under rainfall harvesting in ridges and furrows, the percentage of root dry weight in 0-10 cm, 10-20 cm, and 20-30 cm soil layers to the total root dry weight in 0-30 cm soil layer was 61%-66%, 22%-25%, and 11%-14%, respectively. The ratio of root dry weight in the sides of furrows to that in the middle part of furrows in treatments SR₃₀ (30 cm width ridges compacted with soil), SR₄₅ (45 cm width ridges compacted with soil), SR60 (60 cm width ridges compacted with soil), MR₃₀ (30 cm width ridges covered with plastic film), MR₄₅ (45 cm width ridges covered with plastic film), and MR₆₀ (60 cm width ridges covered with plastic film) was 1.2, 1.5, 2.0, 1.1, 1.3, and 1.3, respectively. The test root physiological characteristic parameters were obviously higher in the sides of furrows than that in the middle part of furrows, indicating that the plants growing in the sides of furrows were likely to produce more grains. In most cases, the root physiological characteristic parameters increased with the increasing waterharvested ridge width, and were in the order of traditional planting > ridges covered with plastic film planting > ridges compacted with soil planting. When the ratio of furrow to ridge was 60∶37 cm, the root dry weight in the ridges compacted with soil planting was the minimum; and when the ratio of furrow to ridge was 60∶27 cm, the root dry weight in the ridges covered with plastic film planting was the minimum.

Key words: Cinnamomum camphora, heavy metal, enrichment efficiency, pollution gradient, soil.