Silicon application: a potential solution to drought stress in lentil
School of Food and Agriculture,Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria-3010, Australia.
Lentil (Lens culinaris, Medik.) is the fifth most important grain legume growing in the arid and semi-arid regions of the world. Drought stress is one of the major constraints leading up to 60% production losses in lentil. Application of silicon (Si) has been shown to be a promising technique to improve drought tolerance; however, the physiological mechanisms and interactions involved are not fully understood, especially in legumes. Consequently, in the present study, glasshouse experiments were conducted to evaluate the effect of Si in drought-stressed lentil. Seven lentil genotypes, ILL 6002 and Indianhead (drought-tolerant), Flash, PBA Jumbo 2 and Nipper (moderately drought-tolerant), and PI 468898 and ILL 1796 (drought-sensitive) were subjected to drought stress at the onset of flowering. Results showed that the negative effects of drought stress have been significantly ameliorated and apparently seen by higher concentrations of chlorophyll pigments and improved photosynthetic efficiency in lentil supplied with Si. Si effect on osmoregulation decreased the membrane damage in drought-stressed lentil. Drought stress significantly increased the production of reactive oxygen species and induced oxidative damage, while added Si reversed these effects. Furthermore, the addition of Si significantly stimulated the efficiency of the glutathione-ascorbate cycle by increasing the concentrations of glutathione and ascorbate as well as the activities of antioxidant enzymes like ascorbate peroxidase, guaiacol peroxidase, catalase, superoxide dismutase, glutathione reductase and dehydro-ascorbate reductase. Furthermore, Si treatment enhanced the plant biomass and yield. Thus, Si could ameliorate adverse effects of drought stress in lentil likely by increasing photosynthetic efficiency and biochemical defence responses.