Silicon uptake and its effect on dry matter accumulation in citrus trees

There is considerable evidence that silicon (Si) fertilization can mitigate the impact of biotic and abiotic stressors and increase the growth and yield of many agricultural crops, especially in monocotyledonous species. Although interest in Si nutrition has increased, there is still limited understanding of how nutrient availability, environmental variation, genetic diversity and phenological stages interact to regulate Si uptake, and dry matter accumulation in citrus. Therefore, the aim of the study was to determine Si uptake and dry matter accumulation in two citrus cultivars typically grown in sub-tropical regions, ‘Delta’ Valencia (Citrus sinensis) and ‘Nules’ Clementine (Citrus reticulata). These were treated with either potassium silicate or with silicic acid, with either foliar or root applications, during a summer and a winter season in a 2 × 2 × 2 factorial arrangement. Seasonal effects were observed, with significantly higher Si uptake in the summer season, suggesting that Si uptake may be an active process. Si uptake was significantly higher with the root drench than with the foliar application, with the highest uptake of Si into leaves and roots resulting from a root drench at 1000 mg Si L−1. Dry matter production was positively influenced by the application of Si at 1000–2000 mg Si L−1. Hence, this study provided evidence that Si uptake is affected by the timing of application, application rate, method of application, genetics and leaf age, and that Si uptake may influence dry matter content in citrus cultivars.