In this study the growth and yield response of Solanum retroflexum Dun. (nightshade) and Brassica rapa L. subsp. chinensis
(non-heading Chinese cabbage) to N, P and K availability in the soil and the interaction effects of these three nutrients were
determined by means of pot experiments in a greenhouse. S. retroflexum was most sensitive to the availability of nitrogen
in the soil. Sufficient nitrogen needed to be available to achieve optimum growth but adding too much adversely affected
biomass production, suggesting a fairly narrow optimum range for nitrogen availability. The production of the crop was also
dependent on the adequate availability of phosphorus and potassium but any adverse effects due to excess availability were less distinct than for nitrogen. In the case of B. rapa subsp. chinensis, an optimum availability range was identified for N and K and a critical level of availability for P. The decline in biomass production caused by adding N in excess of the optimum
was reversed by applying both P and K at rates that were in excess of the respective optima.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1000786 |
| Date | 05 June 2007 |
| Creators | Van Averbeke, W, Juma, KA, Tshikalange, TE |
| Publisher | Water SA |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | Tshwane University of Technology |
| Relation | Water SA |
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