Silicon fertilisation decreases brown rust incidence in sugarcane

Abstract

Few studies have focused on the effect that silicon fertilisation has on the incidence of brown rust in sugarcane, even though this crop is Si-accumulating and Si addition has been shown to have positive effects in other plant-pathosystems. The objective of this study was to quantify brown rust development in sugarcane after the addition of silicon fertilizer to texturally distinct soils over three sugarcane cropping cycles. One experiment was conducted for three years with sugarcane grown in 100 L pots receiving four levels of silicon fertilizer (0, 185, 370, 555 kg ha−1 Si), with three different soil types (Quartzipsamment-RQ; Rhodic Hapludox-LV; Rhodic Acrudox-LVdf), in randomised blocks design with four replications. Silicate fertilisation increased Si concentrations in the soil and sugarcane leaves. The incidence of brown rust was influenced by Si rates and soils type for the plant cane and second ratoon. For the plant cane, Si application reduced the maximum rust incidence, which was estimated by the b1 parameter of the monomolecular model, with values reaching 29%, 41% and 47% for the RQ, LV and LVdf, respectively. For the RQ, the b1 value was reduced by 20%, 20% and 59% of the control treatment values for the 185, 370 and 555 kg ha−1 Si application rates, respectively. There was a significant reduction in brown rust incidence as a function of increasing leaf Si concentrations in all soil types. These results suggest that Si fertilisation could play an important role in the management of brown rust for sugarcane.