WOLLASTONITA COMO FONTE DE SILÍCIO: RESPOSTAS FISIOLOGICAS E PRODUTIVAS DO ARROZ DE TERRAS ALTAS E BENEFÍCIOS RESIDUAIS NO FEIJOEIRO.

Abstract

This study evaluated the effect of Si rates applied via wollastonite on photosynthetic pigments, chlorophyll *a* fluorescence, and yield components of upland rice, as well as its residual effects on subsequent common bean cultivation. The field experiment followed a randomized complete block design with five Si rates (0, 100, 200, 300, and 400 kg ha⁻¹). Chlorophyll indices (a, b, and total), fluorescence parameters (OJIP and NPQ), leaf Si content (rice: R2 stage; bean: V4-R4 stage), number of spikelets (rice), pods (bean), thousand-grain weight, and grain yield were quantified. Post-harvest soil Si content (0–0.1 m) was analyzed. In rice, chlorophyll *a* increased up to 117 kg ha⁻¹ of Si, while chlorophyll *b* and total chlorophyll decreased linearly, indicating improved light-use efficiency. Operational photochemical efficiency (ΦOp) increased, and non-photochemical quenching (NPQ) decreased, resulting in a 19% rise in spikelet number and a 10.5% yield increase at the optimal rate (100 kg ha⁻¹). In common bean, residual Si reduced photosynthetic pigments up to 230 kg ha⁻¹ but enhanced grain yield by 34.7% and maximum photochemical efficiency (ΦMAX). We conclude that Si application via wollastonite optimized photosynthesis and yield in rice, while its residual benefits improved bean productivity despite pigment alterations, demonstrating its potential in crop rotation systems.