The objective of this study was to compare the yield per unit area and the time in which it can be achieved using hydroponic tomato plant production systems under greenhouse conditions, based on the formation of ladder-shaped in relation to uniform canopies. Plants were trimmed to leave only three clusters in each one, and thus limit their height to less than a meter. Plants were grouped in rows located at different heights to form four different modalities of ladder-shaped canopy and also a control was conducted with all the rows of plants located at the same height. Each ladder-shaped canopy treatment was tested at two population densities (11.1 and 15.5 plants·m-2 of greenhouse space). A randomized block design with nine treatments and three replications was used. Variables studied were: yield and number of fruits per plant and unit area, and mean fruit weight. It was found that plants in ladder-shaped canopies yielded more per unit area than those in the control with uniform canopy. In these canopies high density plants produced higher yields and number of fruit per unit area than those grown under lower density, whereas the mean fruit weight did not decrease significantly.

The nutrient status of mango trees (Mangifera indica L.) growing in Luvisol soils in Campeche, Mexico, was studied in order to identify possible deficiencies and, if necessary, decide on the need for fertilizer applications. Soil and leaf samples were collected in 48 commercial mango orchards to quantify physical and chemical properties and nutrient concentrations, respectively. Information on orchard management and fruit yield was also obtained. Regression models for predicting crop yield, based on leaf nutrient concentrations and physical and chemical soil properties, as well as technological factors, were estimated. Nutrient sufficiency ranges as an expression of the nutrient status of the trees were established. The adequate sufficiency ranges for the various nutrients were: for N, < 0.90 to 1.35 %; P, 0.07 ≥ 0.11 %; K, 0.5 ≥ 0.8 %; Ca, 3.5 ≥ 3.75 %; Mg, 0.16 ≥ 0.25 %; Fe, 75 ≥ 140 mg·kg-1; Mn, 175 ≥ 320 mg·kg-1; Cu, 6 ≥ 9 mg·kg-1; Zn, 10 ≥ 22 mg·kg-1; and, B 85 ≥ 210 mg·kg-1. Based on the distribution of the orchards in the sufficiency ranges, it was observed that there are orchards that would require fertilizer applications: P (48 %), K (52 %), Ca (62 %), Mg (56 %), Fe (73 %), Cu (65 %) and B (44 %). By contrast, the deficiencies are lower for Mn (17 %) and Zn (21 %) and were not observed for N.

Pepper is the second most important vegetable in Mexico. The aim of the present study was to collect peppers grown in the state of Tabasco, Mexico and then carry out an in situ assessment of their morphological diversity. From January to May 2013, a survey was made of 21 communities throughout the state, and data relating to 25 plant, flower and fruit variables were taken in situ from 43 collections which were subjected to principal component (PC) and cluster analysis. The first three PCs accounted for 63.14 % of the total variation among collections; the variables with the greatest contribution were fruit width, fruit weight, fruit shape, fruit apex shape, fruit shape at the junction with the pedicel, and leaf length and width. Cluster analysis of the selected variables differentiated the collections into three groups. The available evidence indicates that there is enough morphological diversity in commercial and backyard peppers grown in the state of Tabasco to be useful for breeding programs.

Polyamines are nitrogen compounds present in plants that accumulate, mainly, in response to stress conditions. Polyamines currently due to their biochemical characteristics are involved in a number of important cellular processes such as cell division, packaging of nucleic acids, DNA replication, and others. The present review compiles and analyzes current scientific information regarding biosynthesis and accumulation in cellular compartments and degradation in the cytosol of the majority polyamines (putrescine, spermidine and spermine). Transport is also explained and its role in cellular homeostasis is described and their associations with other molecules that confer activity as growth regulators, signaling molecule to modulate mitochondrial functions, influence cell proliferation and stimulation of protein synthesis that can be essential to understand their involvement in the mechanism of plant tolerance to stress.

In the State of Mexico, cut rose (Rosa x hybrida) grown under greenhouse conditions has as a commercial constraint the low phytosanitary quality of its flower buds. To improve this quality, three growth regulators containing cytokinins (two commercial products and one prepared at a dose of 0.001 ppm from a technical-grade growth regulator, all at three frequencies of application) and CP® Floral Protector (FP) were evaluated in cut Rosa x hybrid ‘Polo’ grown under greenhouse conditions in Villa Guerrero, State of Mexico. A completely randomized experimental design with 20 treatments and four replications in a factorial arrangement was used. Treatments were applied to flower buds of 0.5 cm in diameter with closed sepals. Evaluations were made according to commercial harvest criteria when the petals begin to separate from the center of the flower. The FP and application of growth regulators increased bud diameter and length (P ≤ 0.05), but there was no effect on peduncle length or the number of days to harvest. FP use prevented insect damage and increased the number of export-quality buds. CP® floral protector and growth regulators improve the quality of cut roses.

Some plants of the Brassica family have antifungal properties against various microorganisms of economic importance. These properties are attributed to Glucosinolates (GLs) by hydrolysis of the myrosinase enzyme. This study, initially under in vitro conditions, we evaluated the germination of Alternaria alternata spores on potato dextrose agar culture medium at concentrations 0.15, 0.11, 0.07, 0.04, 0.01 and 0 μg∙μl-1. Subsequently we evaluated the antifungal effect of broccoli juice by severity and incidence of damage on post-harvest quality of arugula leaves stored at 0 and 4 °C and temperature (22 ± 3 °C) for 15 days; for this, leaves were inoculated with Alternaria spores solution (1 x 106) plus broccoli juice concentration of 2.98 and 1.49 μg∙ml-1; control treatment was tested additionally. Hue angle, chroma, brightness, chlorophyll, CO2 and ethylene were the variables measured. The results showed that the minimum concentration of broccoli juice was 0.07 μg∙μl-1 with 100 % inhibition. In vivo the concentration of 2.98 μg∙mg-1 with 0 % damage and temperature of 0 °C maintained the quality parameters in excellent condition at the end of storage. So broccoli juice (GLs) can be used in postharvest to control Alternaria alternata.