Siliceous natural nanomaterials (SNNMs), i.e., diatomaceous earth and natural zeolites, have a nanoporous structure with large active surfaces that adsorb cations or polarized molecules. Such nanoporous feature determines the effects related to SNNM utilization as low-risk plant protectants and soil improvers. This work used SNNMs from Romanian quarries as carriers for foliar fertilizers applied to stone-fruit trees, apricot and peach. We determined the effects of SNNMs on the physiology, yield and fruit quality of the treated stone-fruit trees. SNNM application determined impacts specific to the formation of particle films on leaves: reduced leaf temperature (up to 4.5 °C) and enhanced water use efficiency (up to 30%). Foliar fertilizers’ effects on yield are amplified by their application with SNNMs. Yield is increased up to 8.1% by the utilization of SNNMs with foliar fertilizers, compared to applying foliar fertilizer alone. Diatomaceous earth and natural zeolites promote the accumulation of polyphenols in apricot and peach fruits. The combined application of SNNMs and foliar fertilizer enhance the performance of peach and apricot trees.

Particle film forming materials were introduced as a solution to reduce the effects of excessive solar irradiation on plant photosynthesis. Covering plant leaves with particle films leads to plant bio-stimulant-like effects: increased protection against abiotic stress and increased fruit quality. We used zeolites and diatomaceous earth carriers for foliar fertilizer, known for their application as particle film-forming material. The aim of this paper was to investigate the plant bio-stimulant-like effects of this combined two-in-one product on the yield of apple trees and their photosynthetic pigments and fruit quality. The experiments were conducted for two years, 2021 and 2022, which had different agroclimatic patterns: 2021 had a deficit of precipitation, whereas 2022 was warmer by more than +4.8 °C compared to the recorded average temperature. Applying particle film-forming material and foliar fertilizer reduces the degradation of the photosynthetic pigments by drought and excessive solar radiation by 25–30%. In the year with a deficit of precipitation there was an increased yield by an additional 11.56–12.38% and the fruit quality similarly increased. Such effects of these combined two-in-one products were limited in 2022 as the temperature was higher than normal by several degrees.