Leopoldo Partida-Ruvalcaba

Uso de Composta, Minerales Primarios Amorfos y Microorganismos para la Producción y Calidad de Tomate

This research was carried out with the aim to determine the influence of the bocashi compost, amorphous primary minerals and microorganisms in post-harvest yield and quality of saladette tomato (Lycopersicum esculentum Mill.) hibrid “Moctezuma”. The crop was carried in soil under greenhouse conditions during the agricultural cycle 2011-2012 autumn-winter. A population density of 2.5 plants m2 managed to a single stem and a separation of 1.6 m between rows was used. The bocashi compost and amorphous primary minerals were incorporated into the soil 30 days before the start of cultivation. Total and extra-large, large, medium and small tomatoes yields of eight clusters per plant and their postharvest quality were evaluated. An experimental design of randomized complete blocks with nine treatments was applied for yield variables, while a completely randomized design was used for postharvest quality variables. The highest yield (113.97 Mg ha-1) was obtained with the treatment consisting of 25 and 6 Mg ha-1 of compost and amorphous primary minerals, respectively, which exceeded 9.3% those achieved with the Steiner solution based treatments, although no significant statistically difference were found between the two averages. pH, titratable acidity and total soluble solids of fruits were not significantly affected by treatments.

Mercury and other trace metals in lettuce (Lactuca sativa) grown with two low-salinity shrimp effluents: Accumulation and human health risk assessment

Shrimp farming effluents from two sources of low-salinity water, well water (WW) and diluted seawater (DSW) (salinity, 1.7 g L-1; electrical conductivity, 2.7 dS m-1), were used to grow lettuce (L. sativa) in order to assimilate the nutrients present in shrimp effluents and produce edible biomass. The two treatments, WW and DSW, were tested in triplicate. Additionally, one hydroponic system in triplicate was constructed to grow lettuce using a nutritive solution as the control treatment (HS). The production variables of lettuce in the two crop varieties (Parris Island (VPI) and Tropicana M1 (VTM1)) showed a general trend of DSW > HS > WW with regards to the size, weight and total foliage, except for the number of leaves, which was higher with HS treatment than with WW and DSW treatments. The accumulation of Cu, Hg, Mn and Zn in edible lettuce tissue and the health risk by the intake of lettuce were evaluated. Heavy metal concentrations in edible lettuce tissue for the three treatments showed the same trend of Mn > Zn > Cu > Hg, with concentration ranges of 47.1 to 188.7, 35.7 to 66.2, 4.1 to 6.4, and 0.01 to 0.02 mg kg-1 (dry weight), respectively. Such concentrations did not exceed the safe limits (CAC, 1984). The health risk index and target hazard quotient were <1, which indicates that the population exposed to these metals due to intake from lettuce consumption is unlikely to have adverse health effects when shrimp farming effluents are used to grow lettuce plants.

Los fosfitos como alternativa para el manejo de problemas fitopatológicos

Phosphites are compounds derived from phosphorous acid used as an alternative for the control of phytoparasitic organisms and their effectiveness has been tested against protozoa, oomycetes, fungi, bacteria and nematodes; however, compared to conventional synthesized fungicides, phosphites are generally less effective at reducing damage by phytopathogens. The phosphite ion is easily transported in the plants via xylem and phloem, so it has been used in foliar application, drench of plant root and neck, injection trunk, through drip irrigation mixed in the nutrient solution in hydroponics, seed treatment, aerial application in low volume, or as treatment in immersion of seeds and fruits. The mechanisms of action involved in the prophylactic effects of phosphites are diverse and include the stimulation of biochemical and structural defense mechanisms in plants and direct action that restricts the growth, development and reproduction of phytopathogenic organisms.

Quality and Shelf Life of Lisboa Lemon within Polystyrene Containers in Refrigerated Chamber

The aim of this research was to knowing if it would improve the shelf life of the lemons that were stored in hermetically polystyrene containers closed, as same that were placed in a refrigerated chamber with temperature of 10°C inside, high relative humidity (85%) and renovation of the air by action of the compressor of the chamber. Lemons cv “Lisboa” were cut directly from the orchard and washed with chlorinated water at 150 mg⋅L−1 sodium hypochlorite. The study variables were the color of the epicarp (shell) and the endocarp (pulp), polar and equatorial diameter, firmness of the pulp and total soluble solids concentration (°Brix) in the endocarp. The tone and purity of the yellow color of the shell (epicarp) and pulp or endocarp of the oranges increased significantly within polystyrene containers and, consequently, its quality was preserved and its shelf life was extended to more than 100 days without that they have symptoms of deterioration, by losses polar and equatorial diameter or decrease in total soluble solids. Inside closed containers polystyrene the temperature decreased to 2.0°C in the refrigerated chamber, so that the principle of thermal insulation polystyrene reaffirmed, and its functionality for packaging products, such as fruits, resolve some of their physiological problems themselves, to prolong its shelf life and improve its presentation.