In developing countries, intercropping is commonly used to boost land productivity and agricultural benefits. However, in the Yucatan region of Mexico, maize (Zea mays L.) yields remain low, despite consistent fertilizer and pesticide inputs in traditional intercropping systems. Furthermore, little is known about the photosynthetic mechanisms that occur when maize plants interact with legumes, and there is a lack of understanding of how intercropping systems affect other organisms in the system, such as beneficial and insect pest population dynamics. A field experiment was carried out on the Yucatan Peninsula in 2021 to assess the impact of maize–legume intercropping systems on maize yield, physiological characteristics as evaluated by gas exchange measurements, and the abundance of beneficial insects in traditional and novel maize intercropping systems. The experiment was carried out with a randomized complete block design with three replicates. Treatments included maize intercropped with a novel legume, crotalaria (Crotalaria juncea L.), maize intercropped with a traditional legume, cowpea (Vigna unguiculata (L.) Walp.), and sole maize as a control. Significant differences in plant height were shown at growth stages V12 (45 days after sowing) and VT (60 days after sowing). No differences were observed in stem diameter, leaf area index, or chlorophyll content. The maize/cowpea intercrop increased the photosynthesis rate by 12.9% and 9.84% in the maize/crotalaria and sole maize, respectively (p < 0.001), and transpiration rate by 6.5% and 8.5% in the maize intercropped with crotalaria and sole maize treatments, respectively (p < 0.001), of maize plants. No significant effects on stomatal conductance or water use efficiency were observed, but the carbon intercellular rate was reduced by 9.74% and 9.15 when compared to the maize/crotalaria and the sole maize treatments, respectively. Overall, intercropping treatments attracted more beneficial insects than sole maize. For predators, the families that stood out were Coccinelidae, Formicidae, Araneidae, Thomisidae, Syrphidae, Chrysomelidae, Oxypidae, Vespidae, Reduviidae, Carabidae, Asilidae, Salthicidae, Dolichopodidae, while among parasitoids, the most frequent families were Eurytomydae, Braconidae, Tachinidae, Pteromalidae, Scelionidae, and Figitidae. In comparison to the maize/cowpea and maize/crotalaria treatments, the sole maize treatment resulted in a grain yield increase of 24.5% and 32%, respectively. However, sole maize was not statistically different to that of maize/cowpea intercropping. In conclusion, our findings suggest that maize/cowpea intercropping could be a viable alternative to sole maize cropping systems for enhancing maize yield and the abundance of beneficial insects, without increasing interspecific competition with the maize crop. Therefore, the maize/cowpea intercropping system represents a sustainable planting alternative for promoting maize grain yield and also promoting edible legume production within the system. Furthermore, the outcomes of this study can serve as a theoretical framework for increasing maize–legume intercropping profitability under growing conditions on the Yucatan Peninsula.

Induced systemic resistance (ISR) is a mechanism involved in the plant defense response against pathogens. Certain members of the Bacillus genus are able to promote the ISR by maintaining a healthy photosynthetic apparatus, which prepares the plant for future stress situations. The goal of the present study was to analyze the effect of the inoculation of Bacillus on the expression of genes involved in plant responses to pathogens, as a part of the ISR, during the interaction of Capsicum chinense infected with PepGMV. The effects of the inoculation of the Bacillus strains in pepper plants infected with PepGMV were evaluated by observing the accumulation of viral DNA and the visible symptoms of pepper plants during a time-course experiment in greenhouse and in in vitro experiments. The relative expression of the defense genes CcNPR1, CcPR10, and CcCOI1 were also evaluated. The results showed that the plants inoculated with Bacillus subtilis K47, Bacillus cereus K46, and Bacillus sp. M9 had a reduction in the PepGMV viral titer, and the symptoms in these plants were less severe compared to the plants infected with PepGMV and non-inoculated with Bacillus. Additionally, an increase in the transcript levels of CcNPR1, CcPR10, and CcCOI1 was observed in plants inoculated with Bacillus strains. Our results suggest that the inoculation of Bacillus strains interferes with the viral replication, through the increase in the transcription of pathogenesis-related genes, which is reflected in a lowered plant symptomatology and an improved yield in the greenhouse, regardless of PepGMV infection status.

Intercropping is the process of planting two or more crops simultaneously in the same field in order to provide greater ecosystem services (i.e. services related to sustainable land and water use, climate change mitigation, and ecosystem restoration). In southern Mexico, the cereal-legume intercropping is a traditional cropping practice that is declining overtime. This paper provides a literature review of the potential benefits and constraints of a maize-legume intercropping for small-scale farms in southern Mexico. This review explored and elucidated the different ecosystem services delivered by maize-legume intercropping systems. This information will help farmers know how to make a better use of cereal-legume intercropping systems to increase maize yields, improve their socioeconomic conditions, and enhance conservation agricultural practices in southern Mexico.

Intercropping constitutes the traditional farming system practice used in various forms for maize production in the Yucatan peninsula. Although practiced for centuries, problems persist with competition for water, nutrients and light between crop species in traditional farming systems. Furthermore, little is known about farmers’ perceptions regarding changes to traditional maize-legume intercropping systems and their interest in novel crop adoption to increase yields in the system while maintaining the practice. The objective of this study was to investigate the maize-based traditional cropping system by assessing the underlying motives and concepts of farmers to practice intercropping in the Yucatan Peninsula and to examine the association between farmers’ level of knowledge about legumes and decisions to adopt intercropping and related practices therein. Farmer surveys were conducted in nine different regions of the Yucatan Peninsula. We selected Xoy, Euan, Muna, Mama, Tahdziú (Yucatan), Becal, Hecelchacam, Dzitbalché and San Antonio Sahcabchén (Campeche) which are representative of agroecological small-scale farming systems. We used a mixed methods case study analysis involving key informant interviews in eight associations of farmers. A sample frame with 73 farmers was selected in total during February 2021 and April 2021. Basic information such as land use, labor inputs, agricultural production and farmer’s perceptions regarding their intercropping systems were collected. Our research shows that the primary motives for intercropping were due to the ability of intercropping to offer a more diversified range of food for human and animal consumption, as well as to take advantage of different harvest periods that this practice offers. The majority of respondents were likely to favor the idea of introducing new legume species in their maize-based cropping systems. Factors such as the type of cropping system (i.e., intercropping or monocropping), access to water and level of knowledge about legumes influenced their decision to adopt intercropping in their farming systems considerably. This paper contributes to the knowledge on the current state and farmers’ perceptions of intercropping systems in the Yucatan Peninsula.

Background: Maize (Zea mays L.) is the main sustenance in the daily diet of Mexican families. As a crop, it is one of the most important in the country of Mexico, and in Yucatan state, it is grown under rainfed conditions in milpas with no mechanizable lands. In this study, an analysis of the phenotypic variability from cob collects of native maize from Yucatan state was carried out, with ethnobotanical information collected within passport data. Objectives: To introduce the genetic diversity of maize into a germplasm bank, to know the genetic diversity of native populations based on the characteristics of cob, to know its distribution, to find the potential populations in each collection area for its use in genetic improvement programs. Methodology: 66 Tuxpeños, 13 Dzit bacal, 6 Nal tel, 13 Xmejen nal, and 2 Nal xoy were collected in the southern, central, and eastern regions of the state, from January to March 2020, by sampling the four cardinal points in each community visited. A vector map of collections in Yucatan was developed and quantitative data of 13 biometric cob variables were recorded in 100 populations (crop cycles: late n=68; intermediate n=26; early n=6), a general data analysis of variance (ANOVA) and by crop cycles were made, principal component analysis (PCA), hierarchically clustered with the average linkage method and discriminant analysis were made. Qualitative data from ethnobotanical surveys with mixed questions applied to milperos at the time of collection are presented. Results: The diversity of native maize in Yucatan is made up of three main groups based on the crop cycle: late, intermediate, and early. The southern and eastern regions of Yucatan preserve greater diversity, representing 44 and 40% of the total collections, respectively. There were significant differences in all ear variables; in a late growth cycle, only the grain thickness did not show differences between populations, and in the early growth cycle the grain thickness, width, and length variables were not significant. The PCA explained 80% of the total variation, seven different groups were formed, with greater differentiation in early maize Nal tel, intermediate Xmejen nal and Dzit bacal, contrary to the Tuxpeños late maize. Ten promising populations were identified for selection in each geomorphological region: eight correspond to the southern, two to the eastern, and one to the center of Yucatan state. The main factors to select for sowing corn in the region are: white and yellow maize for yield, the resistance to weevil attack for red maize, and the perception of color and palatability in purple maize. Implications: A complete phenotypic characterization in the field is required with a special interest in red-pigmented maize. Conclusions: The interest of the milperos in conserving and sowing the different native maize are based on the color of the grain, the benefits and uses that they can obtain from them, which determine the planting area in the milpas of the different races/varieties of maize. Red grain maize is being planted in a lower area in relation to other colors. The southern and eastern geomorphological regions showed a genetic flow between them.

The aim of this study was to evaluate the concentration and distribution of a number of macro- and micronutrients in response to imbibition in habanero pepper seeds extracted from fruits with different stages of maturity and postharvest storage times, as well as in their seedlings. Fruits were harvested unripe, half-ripe, and ripe, and were subjected to storage for 0 (control), 7, and 14 days postharvest prior to seed extraction. An X-ray microfluorescence analysis was carried out on seeds pre- and post-imbibition, as well as on seedlings at 10 and 14 days after sowing. K, Ca, Fe, P, Mg, and Mn were detected by elemental analysis. The results indicated that the elements had a higher concentration and distribution in seeds extracted from half-ripe fruits and ripe unstored fruits, as well as in seeds extracted from fruits stored for 7 and 14 days postharvest. K and Ca were the elements with the highest distributions and concentrations in seeds and seedlings pre- and post-imbibition compared to the other elements. At all maturity stages, postharvest storage increased the concentration and distribution of mineral nutrients in seeds and seedlings before and after imbibition. Storage translocated mineral elements to the radicle before germination, increased meristem growth in emerged seedlings, decreased electrical conductivity, and increased germination. Fourteen days of postharvest storage increased the distribution of macro- and micronutrients in immature seeds, decreasing electrical conductivity, potentiating germination, and improving mineral element distribution in seedlings.