Abstract:

In order to study whether the understory planting of Isatis indigotica could be helpful to improve the land utilization and the production of Radix Isatidis, the authors chose diploid Isatis indigotica and tetraploid Isatis indigotica as the test materials, planted them for a full growth cycle and carried out the research depending on different canopy densities understory: canopy density less than 0.3 as mild canopy closure (C1), canopy density of 0.3-0.6 as moderate canopy closure (C2), canopy density above 0.6 as severe canopy closure (C3), and open field cultivation as control (C0). The results showed that Isatis indigotica was typical heliophyte, yet it had wide light adaptability, which could adapt to the weak light environment with less than 30% canopy. The photosynthetic capacity of tetraploid Isatis indigotica was better than that of diploid, but in weak light condition, the diploid Isatis indigotica was better-adapted than tetraploid Isatis indigotica, and the moderate canopy density understory was suitable to planting diploid Isatis indigotica. In less than 30% canopy density understory, planting tetraploid Isatis indigotica could get high benefits in production. In more than 30% canopy density understory, diploid Isatis indigotica should be chosen to plant.

Key words: Isatis indigotica, diploid, tetraploid, canopy density, forests economy, Chinese medicinal materials, photosynthetic rate