The horticultural performance of ginger (Zingiber officinale R.) plants cultured in vitro and propagated from rhizome sections was evaluated under full sunlight and partial shade. The experiment was conducted in Tarabana, Lara State, Venezuela, using a randomized blocks design with eight replications and four treatments. The results showed significant differences for the type of propagation and the condition of light, except for the variables number of leaves and root mass, respectively. The number of shoots, fresh and dry mass of shoots was higher in vitro propagated plants, which were shorter, than those propagated by rhizome. Rhizome mass was greater in plants propagated conventionally, but root mass was smaller than in those propagated in vitro. The in vitro plants produced numerous small rhizomes, with a high number of fleshy roots and tuberous structures at the tips. All the evaluated variables were superior in partial shade, independently of the type of propagation, with the exception of roots mass in those plants produced from rhizome sections.

Weekly measurements of growth variables were taken to follow the growth and development of young trees of neem (Azadirachta indica A. Juss), from February 1998 to May 1999, growing under warm subhumid climatic conditions. The research plantation is located at 19°10’ N latitude and 96°16’ W longitude in the state of Veracruz, México. The neem tree had a vegetative growth stage and a dormant stage during the year. The annual dormant stage was in the fall and winter with the lowest temperatures and precipitation. The growth curve is a double sigmoid. Low temperatures and a light rainfall in mid February coincided with branch sprouting. Flowering started at the beginning of the growth period; none of the sampled flowers set fruit. Flower drop and an intermediate dormant stage with growth coincided with the establishment of the driest and hottest period of the year. Defoliation began during the annual dormant state and partially overlapped with the sprouting of new leaves in spring.

Taxol, deacetylbaccatine III, and cephalomannine were measured in the foliage of Mexican yew trees growing under the shade of a forest canopy, and in a nearby site, exposed to full sunlight. Also considered in the measurements were the sex of the plants, season of the year to collect the plants, and trunk diameter. The tissue showed differences in concentration of deacetylbaccatine III in non-shaded plants, while those trees exposed to direct sunlight had greater quantities of cephalomannine than deacetylbaccatine III and taxol. Taxol concentration was slightly higher in sun-exposed trees (the concentration of taxoids varies with the sex of the plants). The male trees showed higher concentration of deacetylbaccatine III and cephalomannine than the female trees, but taxol was slightly higher in female trees than in male trees. The concentration of the taxoids also varies with the diameter class of the trees. In those trees 16 to 35 cm in diameter, concentration of deacetylbaccatine III was higher than that of taxol and cephalomannine, and in those of 5 to15 cm the order was deacetylbaccatine III, cephalomannine and taxol. January was the month in which a greater concentration of deacetylbaccatine III, cephalomannine, and taxol was observed.

The objectives of this study were to determine the viability of in vitro culture of mature avocado (Persea americana Mill.) embryos as a strategy to select rootstocks for their tolerance to excess chloride, as well as to evaluate genotypic differences between embryos of the Mexican (var. drymifolia) and West Indian (var. americana) avocado races. Mature embryos excised from seeds of the two avocado races were cultured in Murashige and Skoog medium supplemented with 2 mg·liter-1 of glycine, 10 mg·liter-1 of myo-inositol, 4 mg·liter-1 of thiamine-HCl, 30 g·liter-1 of sucrose and 7.5 g·liter-1 of agar. Furthermore salts of NaCl, CaCl2·2H2O and the mixture of NaCl + CaCl2·2H2O (ratio 1:1) in concentrations from 0.1 to 1.0 %, at 0.1 % increments, were added. Excised embryos were incubated at 27 ± 1 ºC for 21 d in darkness followed by 65 d of 18 h day and 6 h night. Percentage of germination and survival were greater for the West Indian race (24 and 11 %, respectively) than for the Mexican race (21 and 6 %, respectively). In general, water potential as well as osmotic potential were reduced as the concentration of salts increased, while the turgor potential increased. The results suggest that the avocado has some degree of osmotic adjustment.

With the purpose of finding a product, with less toxicity for plants and humans, to replace the use of hydrogen cyanamide (H2CN2) as a budbreak promoter in ‘Flame Seedless’ grape, the following treatments were evaluated: 1) 150 mg·liter-1 of thidiazuron (TDZ) + 2 % of citroline, 2) 150 mg·liter-1 of TDZ + 6 % of citroline, 3) 300 mg·liter-1 of TDZ, 4) 300 mg·liter-1 of TDZ + 4 % of citroline, 5) 450 mg·liter-1 of TDZ + 2 % of citroline, 6) 4 % of citroline, 7) 2.5 % of H2CN2, and 8) control with no application. Application of 300 mg·liter-1 of TDZ produced the best budbreak, 64 and 61 %, respectively, highest daily growth rate (3.4 and 3.1 cm, respectively), and highest shoot length (122 and 115 cm, respectively), 70 days after being applied. Application of 6 % citroline affected bud break 25 % less than the control. The highest number of bunches per shoot (1.29) was obtained with 300 mg·liter-1 of TDZ.

Forty-eight epidemic outbreaks of the papaya ringspot potyvirus (PRSV-p) in cv. Maradol Roja in Paso de Ovejas, Veracruz, Mexico, were analyzed, under different plant densities, application of 2.5 % neem aqueous extract, and roguing of plants with initial symptoms of the PRSV-p. The logistic model had the best fit to 47 epidemic curves. Analysis of variance of incidence and severity data based on “area under the curve of disease progress” and “adjusted rate for the logistic curve Rho” variables, resulted in highly significant differences (P£0.0009) in the variables density and elimination of plants with initial symptoms. Plant density of 2,734 plant·ha-1 obtained the lowest accumulated incidence. Roguing of plants with initial symptoms lowered and delayed damage caused by the PRSV-p. Although neem extract application was significant compared to no extract application, it was not as decisive as the other two management tactics.

It was evaluated the production and fruit quality of 65 18-year-old soursop trees grown from seed with the purpose of initiating selection and breeding studies. Eight vegetative and fruit variables were measured in 1988: trunk diameter, leaf area, average weight of fruit·tree, production of fruits·tree, total soluble solids and fruit juice acidity (malic acid %) at the ripen-for-consumption stage, and fruit skin color at harvest (L and Hue). These traits were evaluated using cluster (C) and canonical discriminant (CD) multivariate statistical analysis techniques. Cluster analysis resulted in three soursop tree groups; their linear characterization was carried out using CD. Groups 1 and 3 included high-producing trees with an average yield of 34.2 kg·tree-1; showing a shiny green fruit skin. Soursop trees from group 3 had the largest trunk diameter (83 cm) and the highest malic acid concentration (1.4 %) in the fruit.

Numerical classifications in biology have been based on genetics and phylogenetics. This research report presents the case of developing a strategy for an objective ordering and numerical classification in terms of fruit mass and shape (prickly pear, tuna, or nochtli) of the genus Opuntia. The advantages of principal components (PC’s) in ordering Opuntia accessions are described, and the convenience of using cluster analysis for the same purpose is discussed. A way of defining the number of groups on statistical fundaments is described. Likewise, the importance of involving fruit attributes with higher prediction value is considered, as well as a correct strategy attribute scale and weighing. The first two PC explain 62 % of the total variation from eight variables (total weight, skin weight, edible portion weight, polar diameter (PD), equatorial diameter (ED), volume ratio, and sugar content (°brix) of 29 accessions of prickly pear cactus. The orthogonal space defined by PC1 and PC3 identifies the accessions ‘Mango’, ‘Burrona 1’ and ‘Naranjón Legítimo’ as the genotypes with the most skin, an attractive feature for post-harvest handling. Cluster analysis, using Euclidean distance as a similarity index, helped to differentiate five statistically different groups, and the accession ‘Tapon Aguanoso’ made a group of its own, which was explained because it’s the only wild material of the 29 studied.

Thirty two cactus collections from the Central Mexico region were studied using the RAPD (Random Amplified Polymorphyc DNA) technique; they included commercial cultivars and prickly pear and vegetable cacti. We tested 46 10-base primers. Nine of them were selected, which were associated with 56 polymorphic bands. The RAPD technique separated the materials into eleven discrete groups.The coefficient of relatedness (CR) varied from 0.32 between Val and BUR up to 1.0 in genotypes CP18 and ‘Reyna’. Cultivated cacti were grouped together and showed CR values higher than 0.8, suggesting that they originated from a small group of related cacti parents. CR between wild and domesticated cacti was 0.65. Entries CP18 and ‘Reyna’ could be redundant. The similarity between ACNF and RCNF corresponded to their phenotypic resemblance. This pair can be used as a basis in the search of molecular markers for fruit color.

The relationships of fertilization to quality and susceptibility to internal browning of Zacatecas-type local race peach fruits under cold storage were studied. The research was conducted in an orchard with 10-year-old seedling trees. Six fertilization treatments were evaluated: T1, 100-20-00; T2, 150-50-80; T3, 200-20-100; T4, 100-20-00+F; T5, 150-50-80+F; T6, 200-20-100+F (kg·ha-1 of N, P2O5, and K2O for T1, T2 and T3 and kg·ha-1 of N, P2O5 and K2O plus foliar application of Poliquelâ for T4, T5 and T6). Parameters evaluated were firmness, color, titratable acidity, total soluble solids, and ethanol and acetaldehyde content. Total phenols, polyphenoloxidase, and phenylalanine-ammonialyase. Soil fertilization with the lowest nitrogen content plus foliar application increased flesh firmness, which persisted during storage at 5 ºC as well as later at room temperature. Foliar applications with high potassium content improved fruit color. Soil fertilization with higher nitrogen content reduced fruit firmness, while potassium increased phenol content. Foliar fertilization improved fruit color and increased the activity of phenylalanine-ammoniumlyase and reduced polyphenoloxidase. Both soil and foliar applications significantly changed total soluble solids, malic acid and ethanol. Higher nitrogen fertilization increased acetaldehydes. Fruits stored under refrigeration, as well as those later exposed to room temperature, ripened normally.

In Mexico, overexploitation and disturbance of the natural habitat of parlor palm (Chamaedorea elegans Mart.) imply a high risk of extinction for this species. This collection resource confronts serious problems in its sexual propagation because of its seed persistent dormancy, making it necessary to generate knowledge to warrant conservation and sustainable production of parlor palm. In the present study we evaluated the effects of different treatments for increasing physiological seed quality and accelerate germination, which included different concentration and immersion periods in hydrogen peroxide solutions (H2O2), different concentrations of giberellic acid (GA3); mechanical scarification and two temperature levels (25 and 30 °C) during germination. Results indicated that seed immersion in solutions of GA3 at 2,000 mg·liter-1 for 24 h, en previously scarified seed, increased viability and germination from 3 to 25 and from 4 to 7 % respectively. When environment temperature was 30 °C and the seed was previously immersed in H2O2 and GA3 solutions, viability and germination reached values of 26 to 31 and 15 to 16 %, respectively.

The paclobutrazol is a growth inhibitor used in ornamental species with bushy growth habits because of its broad spectrum of action, facilitating the obtaining of compact plants in a short time. Concentrations of 0.0, 50, 100, 200 and 400 ml·liter-1 of paclobutrazol were applied every two weeks on plants of Dahlia pinnata Cav. After seven applications, the concentration with the best response was 400 ml·liter-1, obtaining plants 45.30 cm tall, with short internodes, thicker stem, higher chlorophyll content, and more heavier voluminous tuberous roots than the control.

For lack of socioeconomic and production information on anthurium (Anthurium andreanum Linden) cultivation in the state of Veracruz, Mexico, a census was conducted during the year 2000 with the technique of structured survey that concentrated data relative to the following aspects: Identification and organization, infrastructure, cultivated area, commercialization, and perceived problems. The most important results were that 119 growers were located in six regions, Córdoba, Fortín, Ixtaczoquitlán, Los Tuxtlas, Tepatlaxco and Coatepec; for 6.72 % the primary activity is anthurium cultivation; the average age of the plantations is of 9.48 years; 55.47 % have small properties, while the rest is public land. The cultivated area was 5.23 ha with 380,862 plants; in 1999, 907,590 flowers were marketed at an average price of $3.98 (Mexican pesos) per flower, the total income for sale of flowers, potted plants and leaves was $ 4’391,972.00; the main problems expressed by the producers were commercialization, low quality, pests and diseases, financing and agronomic management. The results demonstrated that it is a recent activity, varying among cases, and cultivation on small areas with high revenues; the largest production is in Fortín and Córdoba.