Abstract:
Plant growth, leaf nitrogen and nitrate-N, and chemical content of two African
nightshades, Solanum villosum and S. sarrachoides under different nitrogen levels
was investigated in field experiments in 2001 and 2004. Plants were supplied with
0, 1.3, 2.6 and 5.2 g N/plant. Both African nightshade species responded similarly
to nitrogen supply. Leaf area and dry matter production of plants supplied with
nitrogen was 4-8 times that of plants not supplied with nitrogen. Plants supplied
with nitrogen had significantly higher specific leaf area but had a lower leaf to
stem ratio (p≤0.05). Leaf nitrogen concentration was significantly higher (p≤0.05)
in plants supplied with nitrogen. However, when expressed on a leaf area basis,
the differences in the leaf nitrogen content between nitrogen treatments were
minimal. Leaf blade nitrate-N tended to be high in young plants especially those
that were supplied with nitrogen. The species showed significant differences
(p≤0.05) in the mineral content. It was concluded that African nightshade
responded to limited nitrogen by drastic reduction in leaf area to maintain the leaf
nitrogen content.
