Silicon-mediated amelioration of manganese toxicity in tea plantations on acidic soils

Abstract:

What happens when acidic plantation soils release manganese faster than tea roots can tolerate? This research tested whether foliar and soil-applied silicon (Si) could lower Mn accumulation and restore photosynthetic efficiency in tea (Camellia sinensis L.) on strongly acidic Andisols near Bucaramanga, Colombia. Five Si rates (0, 50, 100, 150, 200 kg ha^-1 as calcium silicate) were applied to three-year-old bushes in a randomised block design with four replications over two harvest cycles (2022-2023). Leaf Mn concentration fell from 487 mg kg^-1 in the control to 254 mg kg^-1 at the highest Si rate, a 47.8% reduction. Chlorophyll content rose by 41.5% under Si 200, and green leaf yield increased by 23.6% over the control. Silicon appears to reduce Mn uptake through co-precipitation in the root apoplast and by raising rhizosphere pH. These results offer tea growers a practical, low-cost strategy for managing Mn toxicity without liming.