Can I increase root growth by adding auxins?
No, applying these hormones will make root elongation slow down or stop altogether. Do roots normally grow all the time? Growth in length of roots is often continuous in the tropics, though with periods of faster and slower growth. Similarly, there are often peaks in the formation of new thin roots. However, roots might stop growing completely if subjected to: • serious wilting – when water has been lost from the shoot faster than the root system can absorb it (C 13). If the shoot is beginning to wilt, the root cells will also be short of water, and may also produce different hormones (C 14); or • chilling injury – if soil temperatures fall to around 10°C, the root cells of lowland tropical trees may be seriously damaged (C 41; and D 11 in Manual 4). Is growth in thickness of roots continuous? It generally is, unless the trees become leafless (C 12). What influences how fast the roots grow? In the nursery, root growth is likely to be most rapid when: • both the species and the genetic
