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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.

Carrot seeds cvs Chantenay and Amsterdam were harvested on several occasions from crops grown in 1985 and 1986, from the time they had reached or were close t o their maximum dry weight and were starting to turn brown.Maximum seed dry weight occurred approximately 40-45 days after flowering (DAF) in both cultivars. Maximum germination (International Seed Testing Association 14-day count) occurred 40 and 55 D A F in cvs Chantenay and Amsterdam, respectively, but the maximum 7-day count and the minimum coefficient of variation of embryo length did not occur until 60 D A F in cv. Chantenay and 55 t o 65 DAF in cv. Amsterdam. Percentage germination was negatively and linearly related to seed moisture content, chlorophyll a + b content in the seed coat and seed distortion, measured on a modified tensile-testing machine, the relationships accounting for 77, 71 and 64% of the variance in the 7-day germination count, respectively. The corresponding values for the 14-day count were 63, 61 and 50%. A simple field test for monitoring seed maturity is proposed.

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