Garcinia intermedia, a little-known fruit tree in the American tropics

Garcinia intermedia (Pittier) Hammel, known as the lemon drop mangosteen in English and by a variety of names including limoncillo and toronjil in Mexico, belongs to the family Clusiaceae, and is distributed in the warm tropical regions of Mexico and Central America at elevations of 300 to 1,000 m. It is an underutilized fruit tree that reaches up to 20 m in height and produces yellow fruits with up to four seeds. The pulp is bittersweet and is highly valued by the rural population of the regions where it grows, where bats and spider monkeys also consume it. The fruit has medicinal properties; it is rich in benzophenones, which attack colon cancer cells. The fruit of G. intermedia has higher antioxidant capacity than the fruit of the mangosteen (G. mangostana Linn.); however, little is known about the horticultural management of this species, and basic knowledge, such as asexual propagation or postharvest conservation, has not been reported. There is no information on ex situ conservation of this species in Mexico and Central America, and no selection of outstanding specimens with high quality fruits has been made. Most of the information reported so far for this species is about its ecology and medicinal properties.

Effect of Cl- and Na+ ratios in nutrient solutions on tomato (Solanum lycopersicum L.) yield in a hydroponic system

Intensive tomato (Solanum lycopersicum L.) production in coastal areas of Sinaloa is exposed to significant amounts of Cl and Na deposited by sea breezes and irrigation water, which affects the yield of this vegetable. The aim of this study was to evaluate three percentage ratios of Cl-/anions (25/100, 50/100 and 75/100) and three percentage ratios of Na+/cations (25/100, 50/100 and 75/100) in the nutrient solution on mineral composition, dry matter production and yield of tomato. The experimental design was completely randomized with a 32 factorial arrangement and four replications. Analysis of variance and mean comparisons were performed (Tukey, P ≤ 0.05). Cl and Na concentrations in tomato leaves, stems and fruits increased significantly with increasing ratios of Cl-/anions and Na+/cations in the nutrient solution. The 75/100 Cl-/anions ratio reduced (P ≤ 0.05) the Ca concentration in leaves, while the 75/100 Na+/cations ratio decreased (P ≤ 0.05) K concentrations in leaves and stems. Both ratios reduced aerial dry biomass (48 and 25.8 %, respectively) and tomato yield (50.8 and 45.7 %, respectively). The results indicate that tomato plants grown with the 75/100 percentage ratio of Cl-/anions or the 75/100 percentage ratio of Na+/ cations absorb excessive amounts of Cl or Na, which causes ionic imbalance (especially of K+ and Ca2+) and affects dry matter production and yield.

In vitro mutagenesis in anthurium induced by colchicine

Developing new varieties of anthurium by hybridization can take 8-10 years; therefore, induced mutagenesis can be an alternative strategy to hybridization. The objective of this work was to induce mutations in A. andreanum by exposing explants obtained from vitroplants to colchicine. Explants of leaves, nodes and roots obtained from vitroplants were exposed to 0.1 % colchicine for 0, 2, 3 and 4 h. The mean lethal dose (LD50), survival, number of explants that generated callus, number of explants that formed shoots and the number of shoots per explant were evaluated. The karyotype of the presumed mutated regenerated plants was determined by the root apex squash technique. The leaves showed the highest sensitivity to cochicine. The survival of the root explants treated with colchicine was 100 %; 4 % of roots exposed for 2 and 3 h formed adventitious shoots (120 shoots). For nodes, the LD50 was found at 3.98 h; 76 and 56 % of the nodes cultivated for 2 and 3 h with colchicine formed adventitious shoots (4.4 and 3.6 shoots). The plants regenerated from the explants exposed to colchicine showed morphological changes. The chromosomal number of the regenerated vitroplants from the explants exposed for 2 and 3 h to colchicine was 2n = 29, while that of those obtained from the explants that remained on the colchicine for 4 h was 2n = 31. The sensitivity to colchicine was a function of the type of explant and the dose used. Colchicine caused the loss (monosomy) or gain of chromosomes (trisomy).

In vitro propagation of select tomatillo (Physalis ixocarpa Brot. ex Horm.) plant families

The objective was to propagate select Physalis ixocarpa plants in vitro, acclimatize them and describe their phenological cycle. The in vitro response of stem apices was evaluated in families from the Tecozautla 04, Manzano Tepetlixpa and Morado San Miguel varieties. The apices were cultured in a medium containing Murashige and Skoog inorganic salts (100 %), supplemented with 0.4 mg·L-1 thiamine, 60 mg·L-1 L-cysteine, 100 mg·L-1 myo-inositol, 0.5 mg·L-1 nicotinic acid, 0.5 mg·L-1 pantothenic acid, 3 % sucrose and 7 g·L-1 agar, without growth regulators and the pH adjusted to 5.7 ± 0.1. in vitro rooting was done for 30 days, with 16 h of light at 3,000 μmol∙m-2∙s-1. The variables evaluated in vitro were seedling height, vigor, callus presence, root length, and number of leaves, roots, stems and buds. Plants produced in vitro were acclimatized and transplanted in greenhouses to follow their phenological cycle. The variables evaluated in acclimatization and phenological cycle were plant height and number of leaves, buds, flowers and set fruits. A completely randomized design was used for the in vitro evaluation, and randomized complete blocks for the greenhouse. The families with the best morphogenic responses in vitro were Tecozautla 04 and Manzano, and in phenological development they presented greater plant height. In acclimatization, survival was 100 % in all clones. in vitro responses, acclimatization and phenology depended on the variety and families.

Respuesta fisiológica de semillas de tres variedades de café a rayos gamma (60Co)

Coffea arabica L. enfrenta serios problemas de susceptibilidad a enfermedades, favorecidos por la poca variabilidad genética de sus cultivares comerciales; por ello, es importante estudiar diferentes fuentes de variación que sean útiles en el mejoramiento genético. El objetivo de este estudio fue irradiar con rayos gamma semillas de C. arabica de las variedades Geisha, Oro Azteca y Marsellesa para determinar la dosis letal media (DL50) y evaluar su respuesta fisiológica sobre la germinación, supervivencia, altura de planta (AP), diámetro de tallo (DT), altura al primer par de hojas (APPH) y área foliar (AF). Se utilizó el irradiador Transelektro LGI-01, con una razón de dosis de 752.76 Gy·h-1. Las dosis de irradiación evaluadas fueron 0, 100, 200, 300, 400 y 500 Gy. El experiment se estableció bajo un diseño factorial completamente al azar con dos factores (variedad, con tres niveles, y dosis de irradiación, con seis niveles) y tres repeticiones (225 semillas por repetición). El registro de la germinación se hizo a los 20 días después de la siembra. Las variables restantes se evaluaron 120 días después de la siembra. Los resultados mostraron que la germinación, supervivencia, AP, APPH, DT y AF se vieron significativamente afectados de forma negativa por la irradiación gamma a partir de la dosis de 200 Gy en las tres variedades. La DL50 fue de 70 Gy para la variedad Geisha, 85 Gy para Marsellesa y 90 Gy para Oro Azteca. Dosis menores a 100 Gy se pueden emplear en programas de fitomejoramiento para C. arabica.

Lead recovery in artificially contaminated agricultural soil as a remediation strategy using sunflower and vermicompost

Lead (Pb) contamination is an environmental problem that deteriorates the quality of agricultural soils; therefore, it is a priority to evaluate remediation strategies for its recovery. The aim of this research was to evaluate the effect of sunflower (Helianthus annuus) and vermicompost in the remediation of agricultural soils artificially contaminated with Pb. The treatments studied were: T1 (soil with Pb, vermicompost and sunflower), T2 (soil with Pb and vermicompost), T3 (soil with Pb and sunflower) and T4 (soil with Pb). The initial Pb value in the soil was 16.05 ppm, and 105 ppm Pb were added by dissolving Pb(NO3)2, reaching a concentration of 121.05 ppm as the initial level, higher than the national environmental quality standard (EQS) for agricultural soils (70 ppm Pb). All treatments reduced the Pb concentration in the soil below the EQS. T2 stood out by achieving a Pb recovery of 81.21 %. The Pb bioconcentration factor (BF) in the aerial part and roots of sunflower plants (T1 and T3) registered values of less than one, acting as an exclusive plant species. According to the Pb translocation factor (TF), sunflower in the presence of vermicompost (T1) behaved as a Pb phytostabilizing plant (TF < 1), and in the absence of vermicompost (T3) it proved to be a Pb phytoextractor (TF > 1).

Effect of three different agronomic conditions on biochemical profile and diversity in the rhizosphere of banana plantations infected with Fusarium oxysporum Race 1

Soil microorganisms play an important role as a link in the transfer of nutrients from the rhizosphere. The physical and chemical properties of soil, the metabolic profiles of microbial communities and different crop management practices can enhance our understanding of hizospheric interactions. This study aimed to establish differences in microbial communities associated with banana crops and the biochemical profile in farms under different agronomic conditions. Seven farms with different levels of intervention, management, and fusariosis severity were analyzed. The biochemical profile of the microbial community was determined using EcoPlates and the main substrates consumed by the microbial communities were identified through multivariate principal component analysis (PCA). Seven microorganisms were selected as indicators of nutrient cycles, pathogenicity and soil health. Also, soil chemical indicators were determined through a complete mineral analysis. For the physiological profile of soil microbial populations, it was observed that farms with the same management tend to be metabolically very similar. In the PCA, two principal components explained 90 % of the variance in the data. It was also determined that the genus Bacillus is predominant in all farms and that farm 4 (medium intervention) presented the most favorable values in all factors analyzed. The effective cation exchange capacity values are highlighted in the chemical analyses, which determined that all farms have a high fertility level. The metabolic profile, diversity and richness of each of the different farms were affected by the type of agronomic management used.

Endosymbionts associated with Diaphorina citri, vector of Candidatus Liberibacter asiaticus

iaphorina citri is considered the most dangerous citrus pest because it transmits Candidatus Liberibacter asiaticus, the causal agent of Huanglongbing (HLB). Like other hemiptera insects, D. citri has developed mutualistic interactions with prokaryotic organisms known as endosymbionts. This symbiosis can be obligatory, when the interaction occurs with a primary endosymbiont, or facultative, when it is a secondary endosymbiont. Symbiosis is essential for various physiological functions, but some endosymbionts can adversely affect the psyllid's abilities. D. citri is associated with a great diversity of endosymbionts, with Candidatus Carsonella ruddii, Candidatus Profftella armatura, Candidatus Wolbachia spp. and Candidatus Liberibacter spp standing out. The aim o symbiotic relationship, prokaryotes, Candidatus Wolbachia, transmission of Candidatus Liberibacter asiaticus.

Uso de retardadores de crecimiento vegetal en plántulas de jitomate (Solanum lycopersicum L.)

Un sistema alternativo de producción de jitomate consiste en establecer tres ciclos cortos de cultivo al año manejados con alta densidad de población (9 plantas·m^-2 21 ) y despuntes tempranos. Para lograr lo anterior, es necesario alargar la fase de almacigo hasta dos meses. En este estudio el objetivo fue evaluar el efecto de tres retardadores de crecimiento (Uniconazol, Paclobutrazol y Propiconazol), con una o dos aplicaciones (a los 25 y 50 días después de la siembra [dds]) y dos dosis por retardador (baja y alta), sobre la calidad de la plántula de jitomate del híbrido comercial DRD 8537. A los 31, 49 y 66 dds se evaluó la altura de planta, el diámetro de tallo y el número de hojas. A los 66 dds, además de lo anterior, se evaluó el área foliar, el peso fresco y el contenido de materia seca de la planta. Los retardadores afectaron la altura, el diámetro, el peso fresco y la materia seca. El número de aplicaciones no tuvo efecto significativo, y la dosis alta redujo la altura y el área foliar. Los retardadores permitieron alargar el periodo de la plántula en almacigo a dos meses, sin afectar su calidad. El Paclobutrazol fue el retardador que tuvo mejor respuesta en la reducción de la altura y el área foliar, lo que se traduce en plántulas más compactas.

Biocarbón de cascarilla de arroz como sustrato en el crecimiento de plántulas de pepino

El biocarbón es un material rico en carbono derivado de residuos vegetales y que se obtiene mediante técnicas termoquímicas en un ambiente limitado de oxígeno o en ausencia de éste. El objetivo fue evaluar las propiedades físicas de mezclas de biocarbón de cascarilla de arroz como componente de sustrato y su efecto en el crecimiento de plántulas de pepino. Los tratamientos fueron: biocarbón de cascarilla de arroz (BC) y turba comercial (T; Sunshine mix 3), así como mezclas de ambos en diferentes proporciones (20:80, 40:60, 60:40 y 80:20 %, respectivamente). Para la caracterización física se evaluó la granulometría, la densidad aparente, la porosidad total, la porosidad de aireación y la porosidad de humedad. Adicionalmente, se determinó la concentración nutrimental. Para evaluar el efecto del biocarbón en el crecimiento de plántulas de pepino se consideró la longitud de tallo, el peso fresco de biomasa aérea y de raíz, el área foliar, el peso seco de biomasa aérea y de raíz, y el contenido relativo de clorofila (lecturas SPAD). Se encontró que la adición de hasta 40 % de BC al medio de crecimiento universal (turba) no altera las propiedades físicas de porosidad total, porosidad de aireación y porosidad de retención de humedad; además, el crecimiento de plántulas de pepino en mezcla de BC al 20 % es similar en longitud de tallo, biomasa fresca, biomasa seca y área foliar a las plántulas cultivadas con 100 % de turba.