Ecophysiological plasticity of Theobroma cacao L. clones in response to the structure and microclimate of agroforestry systems in Mexico

Abstract

Background: Cocoa is a species commonly cultivated under agroforestry systems (AFs), when microclimate conditions are adequate, it achieves high growth rates and seed yield. Questions and Hypotheses: How do four cocoa varieties respond to open (OC) and closed (CC) shade tree canopy conditions within AFs? We hypothesized that cocoa functional traits values correlate with microclimate conditions in the CC. Studied species: Theobroma cacao L. (Malvaceae). Study site and dates: Papantla, Nautla, Veracruz; San Pedro, Oaxaca. Rainy season, 2018. Methods: Three AFs were selected; either one with OC and CC zones, photosynthetically active radiation (PAR), vapor pressure deficit (VPD), air temperature (Ta) and relative humidity (RH) were registered. Cocoa tree and leaves functional traits were evaluated in four regional cocoa varieties, in ten individuals per variety, canopy condition and AFs. Results: Higher values of PAR, VPD and Ta, and lower RH were recorded under OC than in CC. Cocoa tree height, stem diameter, fruit production, SLA (Specific Leaf Area), LWC (Leaf Water Content) and SS (Stomatal Size) were higher for Nautla. Only the cocoa clone Inifap8 displayed higher height and fruit production than the other varieties. Conclusions: Veracruz and Oaxaca states have AFs with microclimatic conditions where cocoa cultivation can potentially develop. However, it is essential to incorporate our understanding of the adaptive responses of cocoa to particular shade trees canopy structure. Cocoa leaf traits, SLA, LWC and SS, may be used as indicators for enhancing management and sustainability in AFs in the face of climate change. Translate stop Translate stop