The influence of nitrogen application on the growth and mineral content of two African nightshade species (Solanum spp.) cultivated in Kenya

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.Key words: Leaf nitrogen, leaf to stem ratio, mineral content, nitrates, Solanum sarrachoides, Solanum villosu

The effect of liming an acid nitisol with with either calcite of dolomite on two common bean ( Phaseolus vulgaris L.) varieties differing in aluminium tolerance

No Abstract

Genetic analysis of Na+ and K+ concentrations in leaf and stem as physiological components of salt tolerance in Tomato

International audienceThe sodium and potassium concentrations in leaf and stem have been genetically studied as physiological components of the vegetative and reproductive development in two populations of F 8 lines, derived from a salt sensitive genotype of Solanum lycopersicum cv. Cerasi-forme, as female parent, and two salt tolerant lines, as male parents, from S. pimpinellifolium, the P population (142 lines), and S. cheesmaniae, the C population (116 lines). Genetic parameters of ten traits under salinity and Wve of them under control conditions were studied by ANOVA, correlation, principal component and QTL analysis to understand the global response of the plant. Two linkage maps including some tomato Xowering time and salt tolerance candidate genes encoding for SlSOS1, SlSOS2, SlSOS3, LeNHX1, LeNHX3, were used for the QTL detection. Thirteen and 20 QTLs were detected under salinity in the P and C populations, respectively, and four under control conditions. Highly signiWcant and contributing QTLs (over 40%) for the concentrations of Na + and K + in stems and leaves have been detected on chromosome 7 in both the populations. This is the only genomic position where the concentration QTLs for both the cations locate together. The proportion of QTLs signiWcantly aVected by salinity was larger in the P population (64.3%, including all QTLs detected under control) than in the C population (21.4%), where the estimated genetic component of variance was larger for most traits. A highly signiWcant association between the leaf area and fruit yield under salinity was found only in the C population, which is supported by the location of QTLs for these traits in a common region of chromososome C1. As far as breeding for salt tolerance is concerned, only two sodium QTLs (lnc1.1 and lnc8.1) map in genomic regions of C1 and C8 where fruit yield QTLs are also located but in both the cases the proWtable allele corresponds to the salt sensitive, cultivated species. One of those QTLs, lnc1.1 might involve LeNHX3