No abstract

No abstract

No abstract

The total fibrous-root length of mature field-grown lettuces, which were protected from rainfall and not irrigated after establishment was less than 75 per cent of that of irrigated plants, although the corresponding root weights were very similar. Non-irrigated plants had thicker roots, less roots near the soil surface, and more at depth. Up to the time that the roots started to die, about two weeks before the lettuce were mature, the variation of root length with depth and time is described by a simple logarithmic expression.

Photocopying was found to be a rapid method of making a permanent record of a root sample. The method used produced a copy with white roots against a black background.Manual estimates of root length were made from photocopies using a light box. The number of intersections visible when laid over a copy of a white on black regular square grid was counted. Automated estimates of root length were made by scanning a photocopy with a bar code reader in place of a pen in a computer-driven graph plotter. Roots > 0.2 mm diameter were resolved with precision and speed.