Evolution Under Domestication of Correlated Attributes in Two Edible Columnar Cacti in Mexico

Stenocereus pruinosus and S. stellatus are columnar cacti from central Mexico, distributed in the Valle de Tehuacán and the Mixteca Baja regions. Both species have populations subject to three different forms of human management: wild, in situ and cultivated, growing in sympatry. The objectives of the present study were to compare variation in damage levels, defense mechanisms and fitness components between 1) both species due to differences in the intensity of management; 2) populations of both species subject to different forms of management; 3) two regions with different management practices and physical conditions, in these two columnar cacti. We estimated the percentage of damage, abundance of spines as resistance, and branching rate as a tolerance component, number of fruits produced in one year, number of seeds per fruit and percentage of seed germination as fitness components. The differences between species, forms of management and regions were estimated with ANOVA tests. A paired correlation with the measured variables within each form of management was used to observe the correlated attributes in both species. We found differences between species, forms of management and regions, mostly concordant with the domestication syndromes. More managed populations, present more damage and less resistance, without compromising fitness, which is the target attribute. Correlated attributes exhibited significant correlations in both species and forms of management. Some of them were concordant with domestication syndrome: More damage/less resistance, or more damage/more branching rate. Our results show that human management can influence the evolution of the interaction of correlated attributes like defense mechanisms, damage and fitness in these columnar cacti.

Shelf life of pitaya [ Stenocereus pruinosus Otto ex Pfeiff.) Buxb.] fruit affected by temperature and guar gum, beeswax, oleic acid, and thyme essential oil coatings

Pitaya [Stenocereus pruinosus Otto ex Pfeiff.) Buxb.] produces fruit with high commercialization potential, but its shelf life is limited to few days. The objective of this study was to apply biopolymeric coatings to extend the shelf life of pitaya fruits at 25 °C and under refrigeration at 12 °C. The following variables were handled at each temperature: fruits without any treatment (Control), fruits coated with 1,000 ppm emulsion of thyme essential oil, and fruits coated with 1% emulsion of guar gum, 7.5% beeswax, and 7.5% oleic acid, without essential oil, and with 1,000 ppm of thyme essential oil. Shelf life was 6 d at 25 °C, without the beneficial effect of coatings, but increased to 15 d with refrigeration and coatings based on guar gum, beeswax, and oleic acid, since fungal growth was delayed, and weight loss was reduced. This allowed fresh appearance without significant modification of color, firmness, pH, total soluble solids, titratable acidity, contents of soluble phenols and betalains, and antioxidant capacity.

Las estrategias campesinas de los productores de pitaya (Stenocereus pruinosus) de Santiago Chazumba

En la mixteca Oaxaqueña, la familia es aún la principal estrategia de reproducción social, donde sus miembros se articulan y forman sus mundos. En la presente investigación se busca reconocer las estrategias campesinas en el sistema productivo pitaya (Stenocereus pruinosus) en el municipio de Santiago Chazumba versus el contexto de las relaciones capitalistas de producción. Los resultados encontrados apuntan a que la lógica campesina difiere del sistema capitalista, aunado a esto las tácticas campesinas han sido condicionadas por factores ambientales, estructurales y sociales, por lo que se estudiaron las estrategias de los campesinos del municipio de Santiago Chazumba. La restricción más visible es la ambiental; sin embargo, hay otras condiciones que requieren el uso de metodologías cualitativas para reconocer que el mixteco ha desarrollado estrategias de inversión biológica, de sucesión, educativas, económicas y simbólicas que emplean de manera conjunta y simultánea, para mantenerse y reproducirse en un mundo neoliberal, donde su lógica de reproducción no es la acumulación de capital. La familia mixteca basa, entonces, su lógica en la reproducción familiar y hace uso de la plurifuncionalidad tanto en la producción agrícola como ganadera, así́ como también rentando su fuerza de trabajo. Todo lo anterior demuestra que el mixteco ha logrado mantenerse en el mundo capitalista, donde la lógica campesina difiere del sistema capitalista.

Cross-Linking Chitosan into Hydroxypropylmethylcellulose for the Preparation of Neem Oil Coating for Postharvest Storage of Pitaya (Stenocereus pruinosus)

The market trend for pitaya is increasing, although the preservation of the quality of this fruit after the harvest is challenging due to microbial decay, dehydration, and oxidation. In this work, the application of antimicrobial chitosan-based coatings achieved successful postharvest preservation of pitaya (Stenocereus pruinosus) during storage at 10 ± 2 °C with a relative humidity of 80 ± 5%. The solution of cross-linked chitosan with hydroxypropylmethylcellulose with entrapped Neem oil (16 g·L−1) displayed the best postharvest fruit characteristics. The reduction of physiological weight loss and fungal contamination, with an increased redness index and release of azadirachtin from the microencapsulated oil, resulted in up to a 15 day shelf life for this fruit. This postharvest procedure has the potential to increase commercial exploitation of fresh pitaya, owing to its good taste and high content of antioxidants.