Effect of two watering regimes on the biomass and leaf Ca and Fe content of four cloned genotypes of Solanum nigrum Linn. at different physiological ages

Abstract

Solanum nigrum is an orphan crop known for its medicinal and nutritional value and phenotypic plasticity. Four genotypes, previously identified as accumulating high levels of Ca (G5 and G20) and Fe (G6 and G15), were clonally propagated. Following acclimatization, the clonal progenies were subjected to two watering regimes (50 and 100% water holding capacities) in a greenhouse and clones of each genotype were harvested at 15, 30 and 45 days of ex-vitro growth. Full water supply and aging led to the greatest biomass production by the clonal genotypes while both watering regimes resulted in overall increases in leaf water contents. Ca and Fe contents were not affected by age or changing water availability except for the G6 clones which accumulated less Fe under water stress. Genotypic variations occurred for all tested parameters except Fe content (full water supply), and Ca content, root fresh and dry weights (water stress). With age, plasticities for biomass increased, those for leaf water content decreased and remained unaffected for Ca and Fe contents. Genotypic effects were observed for shoot and root dry weight plasticities (G6 > G15). The clones of G5, G6 and G20 could be grown at 50% WHC and harvested after 15 days of ex-vitro growth as full plants for consumption but since shoot biomass was found to be a critical factor influencing Ca and Fe content, a greater number of clones will need to be propagated to gain the maximum nutritional benefit at day 15.

Keywords:

• Clonal propagation
• nutrients
• orphan crops
• phenotypic plasticity
• Solanaceae
• water holding capacity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Research Foundation (NRF) (grant numbers 81290 and 85573) and the University of KwaZulu-Natal (UKZN). We acknowledge with appreciation, the assistance of Ms T. Naidoo and Mr N. Broomhead (School of Chemistry and Physics) with the micronutrient analyses.