Growth and physiological response of African nightshades (Solanum Scabrum Mill.) to Sodium chloride salinity stress

Abstract

African nightshades (Solanum scabrum Mill.) are one of the African indigenous vegetables widely
consumed in Kenyan diet as a cooked vegetable. They are known as a good source of vitamin c and they
help in boosting body immune system. Salinity is one of the most serious threats to agriculture all over the
world and one major environmental factor that limit crop growth and performance. To elucidate possible
adaptive strategies that enable this species to survive areas subjected to salinity, growth and physiological
characters such as shoot height, stem diameter, leaf area, leaf number, biomass, chlorophyll concentration
and fluorescence were studied in controls and plants subjected to various NaCl salinity levels for four
weeks. The study was conducted at Maseno University, Kenya under Glasshouse conditions. The plants
were subjected to five different levels of NaCl salinity (0, 25, 50, 75 and 100mM). High salinity levels (75 and
100mM) significantly (p < 0.05) reduced shoot height, number of leaves, leaf area, fresh as well as dry
weight of shoots and roots, stem diameter, chlorophyll concentration and fluorescence. Injuries such as
leaf senescence and abscission were not observed but some salinised plants showed signs of leaf
chlorosis. The causes of the reduction in growth of African nightshades could be as a result of decreased
water uptake, toxicity due to sodium and chloride ions as well as reduced photosynthesis which may partly
be attributed to decrease in chlorophyll concentration and loss of chloroplast activity. Based on the results
we recommend this species of African nightshades to be grown in areas with salinity levels of not more
than 75 mM NaCl.