FOLIAR POTASSIUM FERTILISER HELPS TO INCREASE KERNEL OIL CONTENT IN <em>STYRAX TONKINENSIS</em>, A NON FOOD FEEDSTOCK

Abstract

Styrax tonkinensis is a biofuel feedstock with potential value to produce a considerable amount of non-edible oil. Whether exogenous potassium (K) spray can boost S. tonkinensis seed oil content was tested. A total amount of 0.5 g L-1 (K1) and 4 g L-1 (K2) potassium D-gluconate was applied exogenously as foliar fertilisers during fruit maturation, compared with control (CK, water) and gluconate control (0.676 mL L-1 (G1) and 5.403 mL L-1 (G2) D-gluconic acid). Higher average values of net photosynthesis rate and elevated peak values of chlorophyll a/b and chlorophyll (a+b)/carotenoid were found in the leaves that received the K applications. The superior photosynthesis behaviour was accompanied by a dry mass increment in kernel (30.1% for K1, 52.4% for K2) at 137 days after flowering (DAF). Under K treatments, lipid assembled more slowly during 37–77 DAF. The final oil concentration in kernels was similar in CK and K applications. In CK, dynamic acetyl-CoA carboxylase (ACCase) activity followed an M-shaped trend, whereas in other treatments, it only had one single peak at 57 or 77 DAF. Major increases in lipid yield per kernel were identified. The collective results highlighted the role of foliar potassium, which, in suitable concentration, may boost the total oil content per kernel in S. tonkinensis.