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

D.M. Musyimi, J.K. Chemisto and D.K. Buyela

Department of Botany, Faculty of Science, Maseno University, Kenya

Corresponding author Email: davidmusyimi2002@yahoo.com

Accepted 18 July 2012

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.

Keywords: African nightshade; chlorophyll content; chlorophyll fluorescence; growth; Sodium chloride salinity