, Volume 68, Issue 1, pp 75-96

Root development of vegetable crops

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Summary

Measurements were made at intervals during the growth of seven different vegetable crops grown on the same soil to find how far root development and crop growth could be described by simply derived equations and to find how far the parameter values varied from crop to crop.

For each crop K1 ln W+W, (where W is total plant dry weight, t ha−1 and K1 is equal to 1 t ha−1) was linearly related to time from emergence, as in past experiments.

The derived equation $$\ln L = c_j + b_j \ln W - mt$$ where L is total root length per unit area, t is time from emergence, cj and bj are coefficients that depend on the crop (j) and m is a coefficient having the same value for all crops, removed 89.4% of the total variance in ln L. The best fit was obtained with a value of m that implied that about 3% of the root carbon was mineralized each day.

Generally the logarithm of root density declined linearly with increasing depth. Most of the variation between the gradients of these relations for the different crops was removed by a single regression against logarithm of total root length.

The main discernible differences between species in their rooting patterns were that root length for a given top weight of legumes was about half that of non legumes, that the development of storage roots was associated with a less steep decline in root density with depth than for other crops and that onions were exceptional in that the depth to which their roots penetrated did not change appreciably during much of the growing season.

A single linear relationship between root depth and top weight (r 2=0.85) covered all non-leguminous crops except onions and another relationship (r 2=0.80) covered the legumes.