Mexico has a wealth of Capsicum species, which has led to the development of a large number of chili pepper landraces. A great wealth of Capsicum germplasm can be found in southern Mexico in the Yucatan Peninsula, an important area of diversification of Capsicum annuum. Specifically, in the western Yucatan Peninsula, three of the five domesticated species of Capsicum (C. annuum, C. chinense and C. frutescens) have been reported. However, information on their genetic diversity, conservation status and potential use is lacking. To generate useful information toward the sustainable use, management and conservation of these species, we evaluated the structure, diversity and genetic relationships of nine accessions of Capsicum spp., of major importance cultivated in the western Yucatan Peninsula using 42 ISSR loci. The results indicated that these accessions consisted of three genetic groups that were defined by the respective species of each accession. The level of genetic diversity was moderate and distributed mainly among accessions. The ISSR markers detected a high level of polymorphism and allowed the genetic differentiation of the C. annuum complex. The results indicated that the accessions collected in the western Yucatan Peninsula constitute a valuable genetic resource that can be used in genetic improvement and conservation programs.

The aim of this study was to determine the effect of temperature and CO₂ on seed emergence, seedling quality, and phenological stage of Capsicum chinense and Capsicum annum cultivated in four controlled growth chambers (C1: 30 °C and 400 μmol CO₂ mol⁻¹; C2: 40 °C and 1200 μmol CO₂ mol⁻¹; C3: 30 °C and 1200 μmol CO₂ mol⁻¹; C4: 40 °C and 400 μmol CO₂ mol⁻¹). Neither temperature nor elevated CO₂ influenced seed emergence, although differences were observed in seedling mortality, with high temperature affecting seedling survival in both species; the mortality rate at 40 °C was 20 and 53% in C. annuum and 45 and 58% in C. chinense at 400 and 1200 μmol CO₂ mol⁻¹, respectively. Differences were also observed in growth parameters, where positive effects were observed on leaf area, which reached 45.9 cm² in C. annuum and 23.9 cm² in C. chinense with elevated CO₂ at 30 °C, but negative effects were observed with high temperature. CO₂ enrichment increased flower and fruit production per plant. However, high temperature delayed flower phenology, increased flower abortion and inhibited fruit set. Elevated CO₂ counteracted the detrimental effects of high temperature on growth parameters and flower number, but this was not sufficient to prevent flower abortion and the detrimental morphological characteristics of fruit caused by a temperature of 40 °C.

Mexico has a wealth of plant genetic resources, including Capsicum species. In southern Mexico, specifically in the western part of the Yucatan Peninsula, Maya farmers have preserved a great diversity of chilli pepper landraces of C. annuum, C. frutescens and C. chinense. However, the morphological diversity, capsaicinoid content, conservation status and potential use of these species have not been studied. To fill this gap and generate information to support the conservation and use of these species, we characterized the phenotypic diversity and capsaicinoid content for nine chilli pepper landraces from the western Yucatan Peninsula by assessing 15 quantitative and 39 qualitative traits for 10 plants of each landrace. For quantitative variables, two groups of chilli pepper landraces were obtained by principal component analysis and cluster analysis. Group I was formed by Rosita, Bobo, Dulce, Xcat'ik1, Xcat'ik2 and Verde landraces; Group II included the Maax, Bolita and Pico Paloma landraces. For qualitative variables, three groups of chilli pepper landraces were obtained; Group I included Dulce, Bobo, Xcat'ik1, Xcat'ik2 and Verde landraces, Group II only included the Rosita landrace, and Group III included Maax, Bolita and Pico Paloma landraces. Ultra-performance liquid chromatography–photodiode array (UPLC-PDA) quantification of capsaicinoids indicated higher values in landraces Rosita (14,062.3 μg/g D.W), Bolita (5928.1 μg/g D.W), Maax (3438.4 μg/g D.W) and Pico Paloma (3138.9 μg/g D.W). The Yucatan chilli pepper landraces provide valuable diverse germplasm for morphological characteristics and capsaicinoid content that can be used in breeding and conservation programmes.

El sistema tradicional milpa, manejado mayormente bajo temporal en Yucatán, México; es importante a nivel social, biológico y ambiental. La milpa ha perdurado a través del tiempo por los conocimientos ancestrales transmitidos por generaciones. Por lo anterior, el objetivo fue conocer las estrategias de manejo realizadas por los milperos en su actividad agrícola y la conservación de la diversidad biológica. La investigación se efectuó en la comunidad maya de Xoy, Peto, Yucatán aplicando encuestas semiestructuradas al 30% de la población ejidataria que siembra maíz. La diversidad de cultivos reportada en Xoy fue de 22 variedades nativas: ocho de maíz, siete de frijol lima, cuatro de calabaza y tres de frijol común. Se detectó que la familia es el determinante para la conservación de la diversidad de especies cultivadas en la milpa con una prioridad en la conservación de semillas nativas entre los milperos.