FOLIAR APPLICATION OF SILICON NANOPARTICLES (SiNPs) EFFECTS ON TUBER YIELDS AND CARBOHYDRATE METABOLISM IN FOUR SWEET POTATOE (Ipomoea batatas L) VARIETIES

Silicon nanoparticles (SiNPs) have been widely utilised in agriculture, however, there are limited reports on sweet potatoes (Ipomoea batatas L). In this study, SiNPs were applied as a foliar spray at a concentration of 0.01% (w/v) three times at five-week intervals after planting. Four sweet potato varieties namely ‘Karak Bakar’, ‘Tanjung Sepat’, ‘V6D215’, and ‘Pejabat’ were tested. Results showed that the foliar application of SiNPs induced changes in the tuber biomass, number, epidermal layer thickness, starch, reducing sugar and invertase levels in four sweet potato varieties. The highest tuber biomass was seen in the ‘Pejabat’ (392.9 ± 88.1 g/plant) and ‘Karak Bakar’ (456.6 ± 102.8 g/plant) varieties. SiNPs treatment also reduced the tuber numbers in all varieties except ‘Karak Bakar’ and did not significantly affect (p > 0.05) the starch and reduced sugar content in the tubers of the ‘V6D215’ variety. For all tested varieties, SiNPs treatment did not significantly alter (p > 0.05) the amylase levels and invertase in the tubers of ‘Tanjung Sepat’ and ‘Karak Bakar’. The findings of the study suggested that the effect of foliar application on sweet potatoes is variety-dependent and further study should be carried out to determine the most suitable SiNPs concentration for each variety.