Alterations in carbohydrate metabolism and enhancement in tuber production in white yam (Dioscorea rotundata Poir.) under triadimefon and hexaconazole applications

The present investigation was carried out with an aim to study the effects of two important fungicides/plant growth regulators, triadimefon (TDM) and hexaconazole (HEX) on white yam (Dioscorea rotundata Poir.). Each plant was treated with I I of aqueous solution containing 15 mg l(-1) TDM and 10 mg l(-1) HEX by soil drenching on 10, 20 and 30 days after planting (DAP). Starch and sugar contents, and the activities of alpha,beta-amylases, sucrose phosphate synthase (SPS), sucrose synthase (SS) and acid invertase (AI) enzymes were estimated from leaf and tuber samples on 45, 60, 75 and 90 DAP. Results showed that TDM and HEX treatments inhibited the alpha, beta-amylase and increased the fresh and dry weights, starch, sugar and sucrose contents and SPS, SS and AI activities in white yam. The data suggests that, the application of triazole fungicides may be a useful tool to increase the tuber quality as well as quantity in white yam plants, apart from their fungicidal properties.