Effect of Calcium Silicate Slag on Drought Stress in Rice Production.

Silicon (Si) has been reported to reduce drought stress on many agricultural and horticulture crops. However, few studies have evaluated this effect with rice. Calcium silicate slag is a source of Si that has been effectively reduced fungal disease when applied to rice. In order to determine the role of calcium silicate slag on drought stress in rice production, a greenhouse study was performed. Two moisture treatments (flooding and 50% field capacity), 4 slag rates (0, 1000, 2000, 4000 mg kg^-1), and 2 application methods (surface application and incorporation) were compared. Results showed that slag amendments significantly increased soil pH. Soil Si extracted by 0.5 M acetic acid gradually increased as the slag rate increased. Surface application improved soil available Si compared to incorporation. Application of slag at 4000 mg kg^-1 significantly improved fresh and dry biomass compared to untreated control under flooded condition. Under drought stress, leaf sugar concentrations tended to increase with increasing slag amendment, whereas proline and carbon isotope discrimination (δ¹³C) in rice leaf tended to decrease. Results indicate that calcium silicate slag may help reduce drought stress in rice production.