EFFECTS OF SILICON ON Theobroma cacao L. GROWING IN DEGRADED SUBSTRATES: AN ANALYSIS OF MORPHOPHYSIOLOGICAL RESPONSES AND CHLOROPHYLL A FLUORESCENCE
DOI:
https://doi.org/10.56238/arev8n5-131Keywords:
Growth, Aluminum, Iron, Cocoa, JIP TestAbstract
Silicon (Si) is considered a beneficial element due to its positive effects in mitigating several biotic and abiotic stresses. Despite the promising results reported for different crops, studies involving Si application in Theobroma cacao are still incipient and are more been commonly associated with the mitigation of biotic stress. This study aimed to evaluate the mitigating potential of Si in cacao seedlings subjected to aluminum (Al) and iron (Fe) toxicity through morphophysiological responses. The seedlings were cultivated in three substrates: organic substrate (Sor), substrate with high aluminum saturation (SAl), and substrate with high iron saturation (SFe), with or without soil application of 2 mM potassium silicate. Growth variables, chlorophyll a fluorescence parameters, JIP-test, and SPAD index were evaluated. Si application reduced Fv/Fm and PIabs values in SAl and SFe, as well as PItotal in SFe, compared with Sor. Regardless of the substrate, plants treated with Si showed inferior responses compared with plants without Si in terms of energy absorption, capture, and transfer along the electron transport chain. In addition, metal toxicity promoted reductions in growth and biomass allocation. In T. cacao, Si did not mitigate the effects of Al and Fe toxicity on the photochemical performance and growth of seedlings; however, further studies are needed to better understand the response of Si under different soil conditions and cacao genotypes.
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