The aim of this work was to isolate and select Bacillus strains according to their ability to produce antibiotic substances useful in the control of postharvest diseases of tropical fruits. Fifty strains were isolated from the surface of tropical fruits and from soil samples. Eight strains showed better in vitro inhibition rates versus postharvest fungi of tropical fruits. Lipopeptidic antibiotics were extracted with 1-butanol and analyzed by high-pressure liquid chromatography (HPLC) with a C18 column VARIAN®. The mobile phase was acetonitrile (0-80 % v/v). The isolated strains produced antibiotics from the family iturin A and surfactin. The strain Pla10 produced the highest concentrations of iturin A and surfactin. Iturin A fractions had fungicidal activity, but the surfactin fractions did not show any activity. However, when both fractions were applied together, a synergistic effect was obtained during the inhibition of Colletotrichum sp. from mango. The strain Pla10 was identified as Bacillus subtilis.

This study was conducted to measure nitrogen concentration and response to water stress in pecan seedlings [Carya illinoinensis (Wangenh) C. Koch]. The experiment consisted in observation of growth and development of plants started from Western Schley pecan seeds. Seedlings were subjected to different treatments: irrigation with N supply, irrigation without N, water stress with N supply, and finally, and water stress without N. The following variables were assessed: plant height, trunk diameter, chlorophyll by SPAD and methanol, number of leaves and leaf area index, proline and biomass. The results showed that Western Schley pecan seedlings with N supply and water stress reduced the concentration of Nt and N-NO3 by 21.73 % and 61.84 % respectively, leaf area and trunk diameter by 53.4 % and 36.5 %, respectively, but increased proline content by 39.41 %. With irrigation and in the absence of N, chlorophyll content decreased by 20 % and stem biomass by 58.34 %. Finally, the relative water content in stem and root decreased 61.54 % and 60.17%, respectively.

The efficient use of water resources is mandatory for the dry chili producing area of Zacatecas. The objective of this study was to compare two types of partial rootzone drying (PRD) against commercial irrigation (CI) in relation to yield and fruit quality, irrigation water use efficiency (IWUE), and pepper wilt incidence (WI) of chilli cv. ‘Mirasol’. PRD treatments were PRD50 on which 50% of CI was applied alternately to both sides of the root zone, and PRD50+20 which was similar to PRD50, but additionally 20% of CI was applied to the drying side of the root system. PRD50 and PRD50+20 promoted water savings compared with CI. The fruit quality categories of dry chili and yield were similar among treatments, but yield tended to decrease in PRD50 and PRD50+20 in 2009. The IWUE tended to increase in PRD50 and PRD50+20 relative to CI. In 2008 WI was the same among treatments, but in 2009 it increased in the PRD treatments. Soil water saturation by continuous precipitations after irrigation events partially explained the increase in WI, and therefore the reduction in yield in the 2009. Nevertheless, PRD50 tended to increase IWUE by 28 % and to reduce the volume of water applied by 32 % with respect to CI. Therefore, the RPR is a promising strategy for sustainability of this production system.

The present study aimed to evaluate the growth of tomato plants in a substrate made from sand (70 % based on volume) plus 30 % particles of pumice 2.38 to 3.35 mm in diameter, to set the frequency of irrigation that does not affect plant development, and to determine the presence of contaminants in the substrate. Tomato seedlings were transplanted in a pumice-sand substrate and subjected to three irrigation frequencies (daily, every three days and every six days).The development of tomato plants was assessed over time and data of plant height, root length, and number of leaves and flowers were recorded. The substrate was analyzed at the beginning and end of the experiment. The results show that tomato plants in sand substrate with pumice and water every day grew more. Water consumption was 600 mL per day at the time of peak demand. The initial moisture retention of the substrate was 44.40 %, of which 56 % was available, conditions that can be exploited in the production of crops in greenhouses.

The pecan tree is a highly profitable horticultural tree species that grows in the northern states of Mexico. This crop requires high applications of chemical fertilizers, particularly nitrogen. The feasibility of substituting the use of conventional fertilizers for organic amendments has been considered. Organic fertilizers supply organic matter and improve the soil while providing nitrogen and other nutrients for plants. This research was carried out in order to evaluate the effect of increasing amounts of compost on the yield of pecan trees, its effect on both soil nitrogen and organic matter concentration, as well as on the foliar absorption of nutrients. The application of compost increased both yield and quality values, as well as soil organic matter and inorganic nitrogen content, relative to the control. The foliar concentration of nutrients in treated trees fell within the sufficiency ranges.

The aim of this study was to evaluate the effect of the variety and calcium salts on quality of fresh-cut pear tomatoes. The study was divided into two experiments: the first was conducted to determine which genotype was more feasible for making fresh-cut tomato products (Cuauhtémoc vs IntenseTM). For that purpose, firmness, color, pH, acidity and total soluble solids were evaluated. The second experiment was conducted to determine the effect of 3 % calcium chloride and 3 % calcium lactate on the selected fresh-cut tomato genotype, IntenseTM. The same variables of the previous experiment were evaluated. In experiment I, the genotype IntenseTM was 42 % firmer than the Cuauhtémoc genotype, and also it showed a brighter and more defined color. From experiment II, 3 % calcium chloride showed the best results in terms of firmness, with 50 and 100 % firmer fresh-cut tomatoes as compared to 3 % calcium lactate and control samples, respectively. No significant differences in color and chemical variables were observed. The IntenseTM tomato genotype provides better quality, and when combined with a calcium salt, it makes a better fresh-cut product with a longer shelf life.

In Nayarit, the climactic conditions during the last five years have caused heterogeneous phenological behavior in ‘Manila’ mango. This situation has induced a high reduction in yield and low fruit quality. The objective of this study was to determine the effect of paclobutrazol (PBZ) and potassium nitrate (KNO3) on flowering, harvest time, yield and fruit quality of ‘Manila’ mango. The study was done during 2008-2009 and 2009-2010 in a ten-year-old ‘Manila’ orchard. Dosages of PBZ (0, 10, and 20 ml/tree) and KNO3 (0 and 4 %) were tested. In every treatment, physiological and reproductive aspects were evaluated. During the first cycle (2008-2009), the PBZ treated trees reached 70 and 90 % flowering, while the control trees had only 50 % flowering. During the second cycle (2009-2010), the start of flowering was 23 days earlier in PBZ + KNO3, while the PBZ treatment alone advanced flowering 15 days compared with the control trees. The PBZ treated trees had a flowering percent between 94 and 98, whereas the control trees had only 64.4 % flowering. Results showed that PBZ ensured abundant and advanced flowering in ‘Manila’ mango. In addition, in both cycles PBZ increased the yield more than twice when compared to control trees.

The soursop fruit (Annona muricata L.) is an important fruit in the national and international markets, but marketing is limited by the fruit’s short shelf life. The fruit reaches ripeness five days after harvest at physiological maturity when stored at 25 °C and 8-9 days at 13 ± 2 °C. The objective of this study was to evaluate the effect of three wax emulsions on the shelf life of soursop fruit: Carnauba Type III, carnauba with silicone oils, and candelilla, and 1-methylcyclopropene (1-MCP), alone or in combination with emulsions. The fruits harvested at physiological maturity and treated were stored at 13 ± 2 °C. We analyzed the changes in weight loss, total soluble solids, titratable acidity, pH, external color, brightness and firmness in the whole fruit. The emulsions did not delay ripening of soursop, but decreased weight loss of fruits. The 1-MCP at 1,000 nL•L-1 for 12 h did not delay ripening of soursop, but firmness of the fruits remained higher from the day of harvest to 6 days of storage, while the combination of 1-MCP + emulsions delayed ripening of soursop from six to seven days longer than the control. The application of 1-MCP at 1000 nL• L-1 for 12 h combined with carnauba-silicone oil wax emulsions carnauba or candelilla and stored at 13 ± 2 °C is a possible alternative for extending the shelf life of soursop fruit.

The use of bioregulators is a common horticultural practice to improve crop yield and quality. Currently, salicylic acid (SA) is considered a plant growth bioregulator. The objective of the present work was to study the effect of different dosages of SA on biomass accumulation, pigment concentration, photosynthetic activity, nutrient content and productivity of jalapeño pepper (Capsicum annuum L. cv. Chichimeca). Salicylic acid was applied to the nutrient solution at incremental dosages: 0.025 mM, 0.05 mM, 0.1 mM, 0.2 mM, 0.4 mM and 0.8 mM, plus a control without SA. Our results indicate that SA applied to jalapeño pepper plants significantly augmented the production of leaf, root and total biomass, mainly at dosages of 0.1 and 0.2 mM. Treatments with 0.1 and 0.2 mM of SA also increased jalapeño pepper fruit yield per plant. In addition, photosynthetic activity exhibited a trend similar to that of biomass accumulation and yield per plant; plants treated with 0.1 and 0.2 mM of SA showed maximum photosynthetic activity. With regard to nutrient content, it was observed that at higher biomass accumulation and yield per plant there was a smaller nutrient accumulation, due perhaps to the dilution effect. We conclude that treatments with 0,1 and 0,2 mM of SA play a role of biorregulador of the growth in jalapeño pepper.

The present research was conducted to evaluate the effect of bovine manure with a solarization treatment on the “jalapeño” pepper (Capsicum annuum L.) production. Four dosages of solarized manure (20, 40, 60 and 80 Mg•ha-1), as well as one dose of chemical fertilizer as a control (160 and 80 kg•ha-1 of N and P, respectively) were evaluated. Total yield was significantly different among treatments; the highest yield value (58.07 Mg•ha-1) was obtained with the treatment of 40 Mg•ha-1 manure. Regarding yield per picking (harvest), generally at the third picking (90 days after the transplant) the maximum values (13.4 Mg•ha-1) were found. The treatment of 80 Mg•ha-1 generated 1st and 2nd quality fruits with more than the 94 % of the total production.