Preharvest potassium silicate treatments influence the morphological appearance and enhance nutritional composition...

The almond industry requires new strategies to improve almond kernel quality. The use of biostimulants such as potassium silicate (KSi) is an eco-friendly and non-polluting alternative. The aim of this work was to investigate the preharvest application of KSi solutions at 2 and 20 mmol L^-1 to 'Peraleja' almond trees during two consecutive seasons to elucidate the effect on almond kernel quality at harvest.

The fresh weight, length and width of almond kernels treated with 20 mmol L^-1 KSi increased by 27%, 31% and 8%, respectively, compared to the controls. Furthermore, almonds treated with 20 mmol L^-1 KSi had a more elongated morphological appearance, while with 2 mmol L^-1 KSi almonds were more spherical. Regarding nutrients, phosphorus and potassium levels increased in almonds treated with 2 mmol L^-1 KSi, while magnesium content decreased with both KSi treatments. Total antioxidant activity and total phenolic content increased in almonds treated with 20 mmol L^-1 KSi. In addition, significant differences in fatty acid levels were observed, particularly in oleic and linoleic acids. On average, the oleic-linoleic acid ratio of almonds treated with 2 mmol L^-1 KSi was 28% higher than those treated with 20 mmol L^-1 KSi and the controls.

These results demonstrate that the preharvest application of KSi is a valuable tool, as growers can use different KSi concentrations to target specific improvements in almond kernel quality, including physical attributes and nutritional composition. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.