Some columnar cacti have been used in the Valley of Tehuacan and at the adjacent Mixteca Baja, Mexico, for more than 8,000 years. Currently, one can observe collection of fruits, in natural environments, or little perturbed ones, to cacti cultivation and domestication in transformed environments. The present study synthesizes recent research about the different degrees of human-Pachycereeae relationships in the Mixteca Baja, and states some inferences about domestication and the beginning of cultivation for these species. The use of 13 columnar cacti at the Mixteca Baja varies from collection of three wild species up to the selection and possible domestication of other three ones, including different degrees of cultivation of other seven species. Morphological fruit divergence among cultivated, abandoned, tolerated, and wild populations of Stenocereus pruinosus and S. stellatus suggests human selection toward bigger and heavier fruits, including some local quality attributes. Some evidences and inferences suggest the possibility that the beginning of the cultivation and domestication of these species came from the prehispanic period from a process different to that of cultivated fruits from the Mediterranean and Middle East regions.

The objective of the present study was to characterize, from a morphometrical point of view, the leaves of nine selections and eight cultivars of cherimoya (Annona cherimola Mill.) and the differences existing in leaf characteristics. Nine-leaf samples were obtained per accession, they were digitalized and morphometric measurements were made with an image analyzer. Aside from correlation, principal components and cluster analyses were used to analyze the data. Leaf morphometric characters providing most discrimination were: leaf area and angle of the fifth vein (first principal component); index of roundmess and the radius axis/length axes ratio (second principal component); petiole length and number of veins (third principal component). These three first components accumulated 80 % of the total variation. Of the characters indicated, index of roundness, petiole length, and radius axis/length axis ratio did not show any type of correlation among them nor the other previous ones mentioned. From the analysis, it was possible to separate the cultivars and selections into six well defined groups, this suggested the existence of morphometric variability for the leaves of this species, and that this variability may be useful in differentiating germplasm, and, as a consequence, in the elaboration of descriptors.

It was studied the response of potato ‘Montserrat’ in an aridosol soil to surface (SF) and sub-surface (FSS) drip fertirrigation in the greenhouse in terms of: yield, dry matter (MS) and its accumulation (TAMS), phosphorous absorption (AP) and phosphorous absorption rate (TAP) in the aerial portion of the plant (leaves and stems), root and tubers. Five plant-destructing samplings were made at 24, 37, 47,59, and 72 days after emergence (DDE). Only the root showed significant differences for FS and FSS regarding MS and AP. Even when the plant of potato kept accumulating MS through time, the highest average TAMS for fertirrigation systems happened at 37 DDE for the aerial part and root with 4.08 and 0.113 g·plant-1·day-1, respectively, the stage at which tuberization started. The highest TAMS for the tuber was at 72 DDE with 7.99 g·plant-1·day-1 and a fresh yield of 897 g·plant-1. AP showed significant differences between fertirrigation systems for the root only. In the aerial part and the root, AP had an increasing tendency that later decreased during the growth cycle, the tuber only showed and increasing tendency. The highest TAP for the aerial part and the root occurred at 37 DDE, in the tuber at 72 DDE with 0.022 g·plant-1·day-1 of phosphorous, the former resulted in the main sink for assimilates and phosphorous; thus, any fertirrigation system may be used to produce potato.

In the present study were evaluated in vitro rooting of apical buds of grape rootstocks R110 and SO4, using 0, 15, 30, 45 y 60 g·liter-1 of sucrose in the media culture and containers with and without complementary gas exchange. After establishment, the explants were kept in an incubation room at 25 ± 2 °C, with a luminous intensity of 76 µmol·m-2·s-1 and a 16-hour photoperiod. After 13 days of growth, rooting percentage and number of roots per explant showed superior values for the medium without sucrose, where there was a higher osmotic potential. The culture medium, in the containers without gas exchange, lost three times less water and the explants showed higher rooting and number of roots, than those developed in containers with gas exchange. Rooting started at seven and eight days after the explants were established, but rootstock R110 was superior to SO4 during all evaluation days.

The objective of the present research was to generate information about the growth and nutrition of Mexican yellow iris (Iris pseudacorus L.). A field experiment was established with a population of 2,400 plants of Mexican yellow iris, 150 plants showing the same phenological stage (2 leaves) were selected to perform leaf and whole plant samplings during the crops’ growth cycle. It was evaluated aerial and root biomass, plant height, number of leaves, and nutrient concentration. Results indicated that the plant accumulated 61 % of its total biomass 179 days after planting. The root contributed with 39 % of the total biomass for most of the cycle. The highest concentrations of N and K in the whole plant occurred in the first 114 days, and they decreased as biomass accumulation increased. Concentrations of Mg and P stayed relatively constant during all the crop growth stage, however, the levels of Fe and Ca increased as biomass accumulation increased; then, Mn an Zn remained relatively constant during the first 39 days after transplanting, but their concentration decreased later. Cu concentration tended to decrease during the crop’s growing stage. Velocity of absorption for N, P, and K, by the plant was slow in the first 92 days; afterwards it maintained high absorption rates until the end of the growing stage. In the middle of this stage (104 days), the plant covered 60 % of its total need for N and 40 % for P and K; at the same time just 30 % of Ca and Mg needs were covered. Micronutrients showed the following accumulation pattern for all the vegetative stage: Fe>Mn>Zn>Cu.

Two experiments were conducted to compare the response of perforated polypropylene and polyethylene covers on microtunnels in sweet pepper and cucumber to yield response under plastic mulching, without cover, and a control, without mulching and cover. The resulting treatments were distributed in a completely randomized block design with four replications. Treatments showed different performance (P£0.05) for early and total yield in sweet pepper and cucumber. In cucumber, the highest gain in early yield was obtained with mulching plus a white perforated polyethylene cover (ACMB) and mulching plus a Kimberly farm polypropylene cover (ACK) with a gain over the control of 13.5 t·ha-1 (135%), the control resulted in an early yield of 9.99 t·ha-1. ACMB and ACK treatments in pepper increased total yield by 10 t·ha-1 when compared to plastic mulching but it only registered a yield of 114 t·ha-1. In cucumber, all treatments were superior to the control in early and total yield. However, plastic mulching, without cover, registered the highest early and total yield. Soil temperature in tunnels covered with perforated polypropylene and polyethylene had a similar performance.

Expression of genes encoding two pathogenesis-related plant proteins (PR-1 and PR-2) was examined in transgenic broccoli plants expressing the Trichoderma harzianum endochitinase gene and in control plants. mRNA accumulation in two-month-old plants inoculated with Alternaria brassicicola and in non-inoculated plants was assessed by RNA hybridization, using PR-1 and PR-2 DNA sequences of Arabidopsis thaliana as probes. Non-transgenic controls and transgenic controls carrying a different transgene (cry1Ac from Bacillus thuringiensis) showed accumulation of PR-1 mRNA only after inoculation. In contrast, endochitinase-transgenic plants produced PR-1 mRNA with and without inoculation. These results indicate that the PR-1 gene, normally induced by fungal infection, is constitutively expressed in transgenic plants expressing the heterologous endochitinase gene. Accumulation of PR-2 mRNA was observed in all transgenic and non-transgenic plants, with or without inoculation. This suggests that the PR-2 gene may be permanently active or developmentally regulated and is involved in functions other than systemic acquired resistance. Similar results were seen when expression of PR-1 and PR-2 was examined in endochitinase-transgenic rapeseed (Brassica napus).

In this study it was determined dry matter and nitrogen accumulation in husk tomato var. CHF1-Chapingo with the objective of having information allowing the estimation of the plant’s demand for this nutrient. We used a greenhouse open hydroponics system and evaluated five levels of N-NO3 (5, 7, 9, 11, and 13 meq·liter-1) in the nutrient solution. The highest value of biomass accumulation during the agricultural cycle (411 g·plant-1 with a yield of 2.15 kg fruits per plant) was obtained under the nutrient condition of 9 meq·liter-1 of N-NO3. The highest harvest index (0.5) was obtained under the nutrient solution of 13 meq·liter-1 of N-NO3 (355 g·plant-1 of biomass with a yield of 2.16 kg fruits per plant). We observed that, to obtain a yield of 2.16 kg of fruits per plant, nitrogen demand was 8.03 g in total aerial biomass, which is equivalent to 3.71 kg of N per fresh fruit ton.

It was evaluated the effect of irrigation and fertilization on vigor and yield of banana ‘FHIA-01’. Three irrigation systems and five fertilization treatments were compared. Yield was highest under drip and microsprinkle irrigation (77.9 and 71.3 t·ha-1) compared to flood irrigation (53.5 t·ha-1). The best fertilization treatment in the second year of the study was for the rate 200-75-150 kg·ha-1 of N-P2O5-K2O with a yield of 78.2 t·ha-1; in the first year there were no differences among fertilization treatments. Flood irrigation resulted in lower soil moisture, compared to drip and microsprinkle irrigation.

Foliar fertilization in onion has had inconsistent results, which prevent adequate management nutrition for this crop. Therefore, the present study had the objective of quantifying the effect of foliar fertilization in bulb yield and quality, through the evaluation of the activity of physiological processes, fertilizer penetration routes, and canopy nutrient concentration. To accomplish this objective, a field experiment was established in 2001, were five foliar fertilizers and a control were applied in a completely randomized experimental design with six replications. There was no increase in bulb yield and quality. There were also no significant differences in the expression of physiological variables such as CO2 diffusion, CO2 assimilation, stomatal conductance, stomatal resistance, transpiration rate, N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn foliar tissue concentration. When studying the penetration of foliar urea plus calcofluor colorant, urea entered through the stomata and, to a lower degree, through the cuticle of plants at 75 and 113 days after transplant.

The experiments where carried out at the Experiment Station of the Autonomous University of Chapingo, Chapingo, Mexico, from 1999 to 2001 under irrigation conditions. We determined the additive and dominance genetic variances, as well as within-plot environmental variance. The objective was to know about the changes occurring in these variance components as an effect of combined selection of maternal half sibs in a population of squash. Additive variance diminished more than 50 % for fruit width, pulp color, and seed height. However, seed weight and height and fruit width had a higher additive variance. In 1999 and 2000, total genetic variance was determined by gene additive effects; in 2001, dominance variance was superior to additive variance. We found a high coefficient of additive genetic variability and high heritability for most characters.

For the last three decades, nitrogen fertilizers have contributed in a significant way to increase food production. The increase attained in the production of many crops has surpassed the population increase. Nitrogen (N) provided by these fertilizers is the main mineral element that plants absorb, and it intervenes in essential physiological processes for their growth and development. Some plants can use atmospheric nitrogen, by associating themselves to prokaryotic or diazotrophic organisms, but most crops rely on the external supplementation of N from organic matter mineralization and the addition of fertilizers, so they can complete their growth cycle. The primary source of N is atmospheric nitrogen submitted to a biological or industrial fixation process. Both processes have a high energetic cost. The application of these fertilizers has been taking place in a plethoric way under the premise: “supplement increase, equal to production increase.” This assumption has had considerable environmental and economic costs, so, currently, strategies are being developed to allow for a reasonable supplementation of nitrogen to crops; to help crops reach their maximum production potential and, at the same time, preserving the environment.

The objective of the present study is to show a compilation of information in tomato and hot and sweet pepper grown under plastic mulching, combined with drip irrigation or with microtunnels. Sweet pepper under mulching needs to be irrigated preferably when soil moisture decreases to 50 % if the purpose is to increase unit area yield to 18.05 t·ha-1 (39 %) as an average of four water application methods. When mulching and flood-irrigating sweet pepper, we suggest the application of all nitrogen fertilizer before placing the plastic on the field. The use of microtunnels in sweet pepper is an excellent way to repeal insects transmitting virosis. But adequate precautions should be taken; especially in tomato and peppers, which are sensitive to higher than optimum temperatures that may cause negative effects on crop growth and yield. This happened in the present study with sweet pepper. Tomato grown under mulching with drip irrigation had a yield increase of up to 26.7 t·ha-1 (39 %) and resulted in water savings of 1,800 m3 (8,000 vs. 6,200 m3) when compared to uncovered soil with flood irrigation; likewise, it increased economic benefits for tomato growers up to 145 %. In Anaheim hot pepper, white plastic mulching allowed a two-fold yield increase (53.0 vs. 26.35 t·ha-1) when compared to the traditional growth method.

With the objective of studying the effects of phosphorous fertilizer on guava (Psidium guajava L.) ‘Rica’, we conducted a field trial for three consecutive agricultural years using one-year-old plants that were growing in a red-yellow clay soil (Kanhapludalf - Soil Taxonomy) from the Jaboticabal region, São Paulo, Brasil. The treatments for the first year were: 0, 30, 60, 120, 180 and 240 g of P2O5 per plant. On the second and third years of the experiment, we used twice as much phosphorous from that of the initial rates. Results showed increases in phosphorous soil concentration in treatments receiving the highest amounts of phosphorous. However, foliar concentration and fruit production were not affected.

The objective of this study was to select, among four commonly used growth media for in vitro propagation of orchids, a medium to improve in vitro germination of immature seeds and development of proto-bulbs and seedlings, for up to eight months, in three epiphytic orchid species common to the Soconusco region, Chiapas: Cattleya aurantiaca, Encyclia chacaoensis and Brassavola nodosa, orchids with potential as ornamental plants. For evaluation we identified six variables, germination, proto-bulb and seedling development stages, number of leaves, number of roots, color and size, as indicators of growth medium contribution. Germination percentage for Brassavola nodosa was similar in all growth media, but proto-bulb and seedling development was better in two media: Knudson C (macronutrimentos Knudson C, [replacing FePO4.4H2O with FeSO4.7H2O and Na2 EDTA.2H2O]; micronutrients Knudson C) and Dalla Rosa and Laneri (macronutrients Dalla Rosa and Laneri KO7, [replacing FePO4.4H2O with FeSO4.7H2O and Na2 EDTA.2H2O]; micronutrients Dalla Rosa y Laneri KO7). Cattleya aurantiaca responded better to the Dalla Rosa and Laneri medium in all stages. For Encyclia chacaoensis, in the beginning all media darkened, and germination and the first development stages were better in the Hutner (Hutner macro- and micronutrients) and Knudson C media. At 8 months, Dalla Rosa and Laneri, followed by Hutner + activated carbon, provided best results for color, size, number of leaves and number of roots in proto-bulbs and seedlings. This study is an important part of a multidisciplinary project dedicated to the conservation of orchids and in search of new economically rentable products for coffee producers affected by the low price of their product in the Soconusco region, Chiapas, Mexico.

Normal harvesting of blackberry under traditional management in temperate climates of Mexico is concentrated in the months from May to June, a period registering the lowest price for this product. Therefore, it is convenient to move the fruiting period to the months of September to November, when the fruit has its highest market price. This has been accomplished in other species by applying growth regulators. This study evaluated the combined action of thidiazuron (TDZ) and gibberellic acid (GA3) with the objective of promoting the advancement of flowering and fruit production in ‘Comanche’ blackberry. We used seven-year-old plants, established in San Juan Tezontla, Texcoco, Mexico. On 20 July 2000 we sprayed TDZ at 100, 200 y 250 mg·liter-1, combined with GA3 at 100 mg·liter-1. In November of 2000 all plants produced flowers and fruits, including control plants (without treatment). Nevertheless, plants treated with growth promoters were superior to the control in budding, number of fruits, and production per cane. The application of TDZ at 200 mg·liter-1 plus GA3 at 100 mg·liter-1 allowed a yield of 196 g of fruit per cane, representing a seven-fold increase over the control, there was also an advance of 10 and 15 days on flowering and fruit maturity.

two peach cultivars (‘Diamante’ and ‘CP-888’) were evaluated, and two plant densities (333 y 444 trees·ha-1), with and without manure application (0 and 40 kg·tree-1·year-1), and with and without limited auxiliary irrigation (0 y 240 liter·tree-1·year-1) in an interspersed crop system with peach trees and maize and bean under rainfed conditions in residual-moisture soils in the state of Puebla, Mexico. Treatments were arranged in the field under a randomized complete block design. Each block was divided into two sub-blocks. Maize and bean were seeded in alternate bands on both sides of the row of trees. The variables evaluated were: fruit weight, equatorial and polar diameter, firmness, color, total soluble solids, phenylalanine ammonia-lyase (PAL) and polyphenoloxidase (PPO). Fruits from peach trees cv. CP 88-8 under a high plant density, with manure and irrigation, showed the highest fruit weight; and less firmness under low plant density without manure and irrigation. Fruits had higher equatorial and polar diameters at both plant densities, with manure and with and without irrigation. Phenylalanine ammonia-lyase activity was higher at the higher plant density with manure and irrigation. Polyphenoloxidase activity was lower at both plant densities, with and without manure, and with and without irrigation. Color was higher for both cultivars at the lowest plant density, with manure and irrigation. Color intensity was higher in fruits of cv. Diamante under both plant densities without applying manure and irrigation; for cv. CP 88-8 color intensity was higher at both plant densities with and without irrigation. No statistical significant differences were observed for yield.

The results were obtained on some types of Crataegus germplasm collection either on trees grown from seeds (single tree data) or from selected wild trees, reproduced by grafting to seedling stock (5 to 8 trees per type). Collateral shoots, emerging at the thorn base, were shorter, thinner, and mostly vegetative in nature (89.67 %). The lateral shoots, appearing in the thorn-free zone, of the extension growth, were larger and more frequently terminated with inflorescences (29.96 %). Fifty percent of collateral buds remained dormant, while all lateral buds bursted. The collateral shoots were in 78.4 % equal or shorter than 10 mm, while 86.9 % of lateral shoots were longer than 10 mm. It seems, that the thorns controlled the shooting of collateral buds, the size of emerging shoots and the formation of flowering shoots. The degree of such action was modified by the particular selection. Thus, the thorns might modify the tree productivity by slowing down the process of collateral shoots differentiation and by reducing, temporarily or permanently, the number of buds shot per node by half.

The most used dissimilarity coefficients in numerical taxonomy are those corresponding to different taxonomical distances. In the present paper we performed a review about the distance c2. This distance has advantages over the Average or Euclidian taxonomical distance, because it allows to perform non-exact hypothesis testing to determine existing statistical equality between pairs of operative taxonomical units obtained from the probabilistic distribution of c2 with one degree of freedom, and it uses the significance level (a) as a similitude measure. The cutting height for a dendrogram, obtained in a cluster analysis based on this matrix can be determined; thus, the researcher, when choosing the desired a level for placing groups together, does not need to calculate other dendrogram partitioning tests such as the cubic clustering criterion or Hottelling’s pseudo statistic t2. To illustrate the advantages of the c2 distance, compared to the Euclidian and Manhattan distances, we show an example with hawthorn genotypes (Crataegus spp.) using cluster analysis validated with canonical discriminant analysis. We found that the c2 distance was the best option.

The present research was carried out in the community of San Miguel Tulancingo, Oaxaca, where we evaluated three substrates and three varieties of tomato to determinate growth habit in hydroponics under greenhouse conditions. Data were analyzed using a completely randomized experimental design. We found that river bed sand shows a better balance for aeration capacity (16.79 %), with good moisture retention (23.98 %) and the highest production with 850.98 g·plant-1. The three tomato varieties did not show statistical differences for fruit production with a value of 766.21 g·plant-1 for variety Super Rio Grande. The best combination substrate-variety combination was sand- ‘Super Rio Grande’ with 994.52 g·plant-1, while the lowest production was obtained with debris- ‘Lobo’ with only 443.02 g·plant-1.

Chamaedorea elegans Mart. is a species that belongs to the Palmae family, which has been collected and cultivated in Mexico with ornamental aim. Because of the economic importance that this species has in the Veracruz State, it was planned to identify the environmental factors that influence its geographical distribution with the purpose of supporting the planning of its cultivation and conservation. The relationships between the geographical distribution of C. elegans and selected environmental variables were studied using generalized lineal models of binomial type. The statistical analysis indicate that of the seven selected variables, the mean annual temperature, the mean annual precipitation, the surface drainage and the landform influence its distribution (P£0.05). Considering the variables that had statistical significance and by means of the geographical information system “Bioclimas” it was determined that the potential distribution of this species covers 72 % of the surface of the Veracruz State.