Jaltomata procumbens (Cav.) J. L. Gentry presents seed dormancy mechanisms in its two populations, erect and decumbent, that make its germination and obtaining of plants difficult. Potassium nitrate (KNO₃) is used as a seed germination promoter by soaking in an osmotic solution. The objective was to break the dormancy of Jaltomata seeds by evaluating KNO₃. Treatments included: 2 populations (erect and decumbent), 2 soaking times (4 and 6 days) in 2 concentrations of KNO₃ solution (0.1% and 0.2%) and in distilled water used as a control. Days of germination including starting (DGS) and ending (DGE), energy period (EP), germination energy (GE), germination percentage (GP) and rate (GR) were measured. The erect population presented a more uniform germination and a lower number of DGS and DGE as well as 100% germination with the highest GR (2.56 seeds day⁻¹). No statistical differences were observed between KNO₃ and control; however, the positive effect of the KNO₃ and 4 days of soaking on the germinated seed was observed. The decumbent population exhibited a more variable germination; however, the same trend of the solution type and soaking days was observed, reaching 93.1 GP. Considering the economic and accessibility aspects of substances that promote germination on J. procumbens, distilled water imbibition and KNO₃ are recommended to accelerate the germination process.

Introduction. Jaltomata procumbens (Cav.) J. L. Gentry, used as food, is considered a semi-domesticated species (populations that have had a process of artificial selection but still have the ability to survive and reproduce without human intervention) and meets the criteria for future use. Objective. To evaluate agronomic traits of two J. procumbens populations, in greenhouse and hydroponics. Materials and methods. The research was carried out at the Colegio de Postgraduados, Campus Montecillo, Texcoco, State of Mexico, from July to December 2019. The following treatments were applied in an open hydroponic system: two populations (erect and decumbent), three electrical conductivity levels (CE): 1, 2, and 3 dS m-1 and two pruning levels (with and without pruning). The variables evaluated were: plant height (AP), stem diameter (DT), number of leaves (NH) and clusters (NR), flowers by clusters (FLR), fruits by clusters (FR), fruit weight (PF), yield (REND), and SPAD readings. Results. For both populations, their cultivation under greenhouse and hydroponic conditions promoted development in plant height, steam diameter, and fruit weight. Variability within and between populations was observed for pruning and electrical conductivity; the crop at 3 dS m-1 recorded the lowest plant height and the highest steam diameter, while at 1 dS m-1 the highest yield was obtained; for the pruning treatment, the highest values in flowers by cluster, fruit by cluster, and fruit weight were presented. Conclusion. Both populations showed the potential to be considered for studies in controlled environments.

To study synanthropic plants (weeds), weeds need to be separated from non-weeds, a difficult task due to the existing gradient in nature. A representative family of the Mexican flora (Asteraceae) and a state very rich in species (Michoacán) are used as a model for this task and additional analyses. A total of 357 weeds are listed based on a critical review of specimens and bibliographic information, as well as defined criteria. In addition, tribes, growth forms, and geographic similarities with other states are examined for endemic, more widespread native, and introduced weeds. The main difficulty in differentiating weeds from non-weeds was the lack of accurate habitat information on herbarium labels. Most species grew in both disturbed and natural environments. Nearly half were endemic to the country, with only 4% introduced. The major Asteraceae tribes had relatively similar proportions of weeds, but exotics were concentrated in the tribe Cichorieae. Floristic similarities were mainly towards south-central Mexico. Most species were herbs and less than half annuals. We contribute to the delimitation and understanding of synanthropic species.

The taxonomic status of a specimen of the genus Jaltomata recovered from the Central Highland Valley of Mexico was realized. Phylogenetic analysis was performed via Bayesian inference and maximum likelihood methods complemented with Genealogical Concordance Phylogenetic Species Recognition (GCPSR) using the PHI test. The results indicated that the specimen in study belongs to the genus Jaltomata sp. nov. supported by PHI test (φ=1.0) showing no evidence of recombination. Characteristics of corolla, pedicel and calyx, stigma, anthers, fruit, and seeds, differentiated this species. Based on the results, the name Jaltomata tlaxcala is proposed for this new species.