Nitrogen is a major plant macronutrient and its supply affects the entire metabolism of plants. This study evaluated the effect of different nitrogen concentrations in the nutrient solution: 0, 4.2, 8.4, and 12.6 mg L⁻¹ Mexican marigold (Tagetes erecta L.) var. Inca plants in an open soilless culture system under greenhouse conditions on the concentration of chlorophylls, carotenoids, phenolics, and flavonoids derived from the secondary metabolism, as well as on the antioxidant activity in different tissues. With the 12.6 mg N L⁻¹ dose, chlorophylls a, b, and total chlorophyll concentrations increased by 98.8, 11.9, and 56.6%, respectively. The highest concentrations of total carotenoids in flowers, 28–30%, were recorded in plants with doses of 8.4 mg N L⁻¹. With doses of 12.6 mg N L⁻¹, phenolic compounds and total flavonoids increased in leaves, but decreased in flowers. The low and medium N concentrations increased the antioxidant activity with respect to the control without N by 53% and 50.2%, respectively. We conclude that the applications of N in Tagetes erecta differentially affected the concentrations of photosynthetic pigments and biomolecules with antioxidant capacity, and that such effects were dependent on the doses of N tested and the plant organ evaluated.

A profile of endogenous hormones and sugars in leaves and pseudobulbs of Laelia anceps subsp. anceps (Orchidaceae) plants induced and non-induced to flowering by the effect of different doses of exogenous gibberellic acid (GA₃), considering the current and back growth structures (CGS and BGS), were investigated. A factorial experiment with five doses of GA₃ and two growth structures was designed. Adult plants with undifferentiated vegetative buds were selected and sprayed with doses of 0, 400, 600, 800, and 1000 mg GA₃ L⁻¹. The main results showed a strong interaction between GA₃ dose and growth structures, which promoted the highest kinetin (KIN) concentration in CGS. Exogenous GA₃ increased endogenous GA₃ in leaves and pseudobulbs induced (I-Leaf and I-PSB) and non-induced (NI-Leaf and NI-PSB) to flowering. For sugar concentration, the 400 mg L⁻¹ GA₃ dose promotes significant interaction with the CGS in NI-PSB. In general, the hormone profile revealed opposite balances of endogenous hormone concentrations for KIN, zeatin (ZEA), trans-zeatin (T-ZEA), indoleacetic acid (IAA), indole-3-butyric acid (IBA) and GA₃, not only for growth structures but also for vegetative organs analyzed, depending on whether the plants were induced or not induced to flowering, with the highest concentration of endogenous hormones in pseudobulbs. Likewise, different sugar concentration balances were observed. These balances of both endogenous hormones and sugars are likely to be involved in the flowering of L. anceps.

The efficacy of plant growth regulators (PGRs) has been demonstrated in the flowering of economically significant orchid hybrids, but studies of their effects in wild species with commercial potential are scarce. The effect of three doses of gibberellic acid (GA ₃ ) and 6-benzyladenine (BA), individually or in combination, and a control without PGRs, were evaluated during three flowering periods in Laelia anceps subsp. anceps , in the temporal behavior of flowering, morpho-floral quality parameters and in potential residual effects and malformations. Significant effects were observed between the experimental periods and doses used, with a single application of PGRs in the first period reducing the days to visible flower induction (DVFI), days to anthesis (DAN) and days of flower life (DFL), mainly in the first period. There were no significant differences between doses for morpho-floral quality parameters within each period, but differences existed between experimental periods, where the life and size of the flower increased in the first period, and the number of flowers and flower stems increased significantly in the second period. The doses of 2.37 mg · L ⁻¹ BA + 100 mg · L ⁻¹ GA ₃ showed highest significant consistency in the reduction of DVFI, DAN and increase of DFL and flower stems in the study. There were no floral malformations, and a positive residual effect was observed in temporal variables in the second period. Most of the doses used encourage beneficial effects in the various aspects of flowering evaluated.

Antecedentes y Objetivos: Existen fragmentos de bosque mesófilo de montaña (BMM) en el centro de Veracruz que no se han estudiado florísticamente. El objetivo de la presente investigación fue registrar la riqueza de orquídeas en un fragmento de este tipo de bosque en Chocamán, Veracruz.Métodos: Se hizo trabajo de recolección de ejemplares, así como revisión de colecciones científicas e información bibliográfica.Resultados clave: El listado incluyó 36 especies pertenecientes a 25 géneros. Epidendrum fue el género con mayor número de especies (7), seguido por Dichaea, Lycaste, Oncidium, Prosthechea y Stelis, con dos cada uno, el resto de los géneros estuvo representado por una. Cuatro especies son endémicas de México (Epidendrum longipetalum, Gongora galeata, Oncidium incurvum y Trichocentrum pachyphyllum), y dos están protegidas por la legislación mexicana (O. incurvum y Stanhopea oculata). Epidendrum magnoliae y Epidendrum cf. radioferens son nuevos registros para la flora de Veracruz.Conclusiones: La orquideoflora aquí estudiada enfrenta problemas debido al cambio de uso de suelo y la extracción ilegal para comercio, por lo que urgen medidas para su conservación.

La floricultura es uno de actividades agrícolas con mayor rentabilidad en México, y el país tiene la capacidad de ser potencia exportadora en este rubro. Diversas ventajas competitivas como su posición geográfica con puertos comerciales ubicados en dos océanos, su cercanía con los Estados Unidos como uno de los principales mercados, y la firma tratados de libre comercio que le permiten acceso a más de 40 mercados internacionales, pueden permitir que México ocupe la primera posición en la exportación de f lores a nivel mundial. Actualmente, el Estado de México cultiva casi 90% de todas las flores que se venden en el país, y aún existen zonas con potencial florícola que podrían mostrar un grado de desarrollo mayor. En este estudio se realizó una caracterización de la producción y comercialización de f lores de corte, en la región de Texcoco, Estado de México, y zonas aledañas, para generar información que apoye la toma de decisiones para mejorar la actividad. Se aplicaron cuestionarios tanto a floricultores de Nativitas y Tequexquinahuac como a comercializadores de Texcoco, respectivamente. De los datos obtenidos se concluye que la floricultura en la región estudiada tiene un amplio potencial de crecimiento, a través de la mejora del sistema de producción, tecnificación, manejo poscosecha y cadena de valor, para satisfacer no sólo el mercado local y nacional, sino para promover la exportación.

The objective of this work was to evaluate the effect of the interaction between feeding level (FL) and body condition score (BCS) on the reproductive parameters of Pelibuey hair sheep (Ovis aries). The experimental units (64 ewes) were randomly assigned to one of four treatments: low feeding level and low body condition score; high feeding level and low body condition score; low feeding level and high body condition score; and high feeding level and high body condition score. The effect of sheep body condition score was significant on the pregnancy and lambing rates. The effect of feeding level was significant on the ovulation, estrus returning, pregnancy, and prolificacy rates. The interaction effect between BCS and FL was significant on the ovulation, estrus returning, pregnancy, lambing, and prolificacy rates. The reproductive function is more sensitive to the better nutrition effects in sheep with a low body condition score.