The present research had as its main objective to learn about the microbiological composition of rhizosferes from several mountain crops: coffee (Coffea arabica L.), banana (Musa sapientum), yam (Dioscorea alata), malanga (Xantosoma sagitifolium,), higuereta (Ricinus communis) and cocoa (Theobroma cocao L.), in a brown soil with carbonates to find out if any of these habitats could become microbial sources for the isolation of bacterial inoculants for biofertilizer production. Also, to study the in vitro efficiency of 18 phosphorous-solubilizing strains isolated from rhizospheric soils in two culture media, Pikovskaya and Ramos-Callao, and, lastly, to study the influence of biofertilizers prepared from strains indigenous to Sabaneta, Municipality of El Salvador, Guantanamo Province, Cuba, in tomato (Lycopersicum sculentum Mill.) and cucumber (Cucumis sativus). Rhizospheres that were microbiologically abundant were those originating from banana and coffee. From the study on in vitro efficacy, the most efficient phosphorous-solubilizing strains in both culture media used were Sabaneta 27-1 (Sab 27-1) and Sabaneta 28-1 (Sab 28-1), which we recommended for its application in the aforementioned mountains under natural conditions. The most effective strain in tomato was Sab 28-1, and, under these same conditions, the most efficient strains were Sab 28-1 and the symbiotic nitrogen-fixing strain Sab-27 for cucumber.

With the purpose of evaluating the effects of brassinoesteroids on the germination and growth of Coffea arabica L. seedlings, several evaluations were carried out in the nursery of the farm “Virginia”, which belongs to the “Yateras” Coffee Enterprise in Cuba. The brassinoesteroid was applied at three concentrations during seed imbibition and at different seedling growth stages, resulting in 15 treatments and a no-application control. A completely randomized design was used with 80 plants per treatment, and we evaluated: germination, seedling height, shoot diameter, pairs of leaves, leaf area, and total dry and fresh mass. The data showed the stimulating effect of brassinosteroid, because results showed better plant performance when this compound was used; also, the study also showed the need for a second application at the early stages of seedling growth. Everything seems to indicate that low concentrations stimulate seedling growth.

Potato is usually propagated asexually, but the use of true seed is also feasible for this purpose, despite its low physiological quality and dormancy when seed has been recently harvested. Given that osmoconditioning improves germination and makes seed emergence uniform, we evaluated the effect of sodium (Na2HPO4) and potassium (KH2PO4) saline solutions, osmotic potentials (0, -5, -10, -15, -20, -25 atm), conditioning period (12, 24, 36, 48, 60 h), and the persistence of conditioning effect in potato cultivar Tollocan seed that was harvested 90 days early. A standard germination seed test was conducted one week and two years after seed conditioning; treatments were established under a completely random design arranged in split-split-plots with four replications using experimental units of 50 seeds. Recently conditioned seed had better performance than stored seed; viability and germination of seed conditioned in Na2HPO4 or KH2PO4 solutions improved (2 %) relative to the control. Treating in solutions with osmotic potentials of -10 and -5 atm had 69 and 61 % of viability and germination, respectively; similar results were shown by conditioning for 60 h. The highest viability (70 to 77 %) was achieved by treating in solutions of Na2HPO4 at -5 to -10 atm for 24 or 36 h and KH2PO4 from -5 to -10 atm for 12 h when compared to the control (65 %). Germination also improved in solutions of Na2HPO4 (61 %) and KH2PO4 (58 %) when compared to the control (56 %), although treatment with only water and 60 h of imbibition promoted germination more efficiently (67 %).

The quality of carambola (Averrhoa carambola L.) fruits harvested at four stages of maturity was evaluated under simulated marketing conditions at 20 °C for 10 days. Stages of maturity were separated as a function of external skin color: Maturity I (green), Maturity II (green-yellow), Maturity III (yellow), and Maturity IV (orange, ripe). Fruit weight, height, and length were determined initially. Post-harvest changes in weight loss, skin color, CO2 production, and ethylene were monitored daily. Every two days we analyzed titratable acidity, soluble solids content, and firmness. Fruit size and weight were higher for fruits harvested at maturity stage IV. At harvest, and during storage, Hue values clearly helped to differentiate color among the four maturity stages. Skin color luminosity and chromaticity values were higher on ripe fruits. Cumulative weight loss during storage varied among ripening stages from 5.1 % on fruits harvested at Maturity III, up to 6.7 % on fruits harvested at Maturity I. Fruit flesh firmness decreased during storage. Green harvested fruits were firmer (1.5 kg force) than orange harvested fruits (0.4 kg force) after 10 days of storage. At harvest time, total soluble solids and titratable acidity of green fruits were 4.89 °Brix and 0.808 %, respectively, while orange fruits presented values of 6.7 °Brix and 0.412 %. No significant changes were observed on acidity and soluble solids content during storage time among different maturity stages. CO2 and ethylene production increased significantly at Maturities III and IV, reducing fruit shelf life. No ethylene was detected on fruits harvested at maturity stages I and II.

Pecan cultivar evaluation is important to determine its adaptation and long-term productive performance to a region, based on yield, crop stability through years, and nut quality. The aim of this study was to evaluate 14 pecan tree cultivars in La Comarca Lagunera region for nine years. Trees, 10 to 19 years old, were evaluated; we calculated a long-term productive index, obtained by dividing the yield efficiency (kg×cm-2) by its alternate bearing index (%), for each cultivar during the nine years of evaluation. In addition, we calculated the kernel alternate bearing index percentage during the nine years of the study. Cultivar Western was the most adapted to La Comarca Lagunera region as a nut producer because it had the highest long-term productive index (0.91), as well as adequate values for optimum yield efficiency (40 g×cm-2), a low alternate bearing index (43.9 %), and a good kernel percentage (58 %). The second most adapted cultivar was ‘Wichita’ with a long-term productive index of 0.53, a yield efficiency of 40 g×cm-2, and a high kernel percentage (62.5 %).

The aim of this study was to evaluate the rooting of nodal and internodal cuttings of ‘CHF1-Chapingo’ (Chapingo) and ‘Verde Puebla’ (Puebla) husk tomato varieties from apical and middle sections. The study was carried out in a “tezontle” layer under greenhouse conditions at Chapingo, Mexico, using a randomized complete block design with four replications. The traits measured were: rooted stem length (LTR), root length (LR), root abundance (ABR) from 0=least to 4=maximum, and rooting percentage (PER). Cuttings of ‘CHF-1 Chapingo’ had 6.50 cm in LR and 2.99 in ABR, and surpassed ‘Verde Puebla’ by 40.4 and 62.5 %, respectively. Apical and nodal cuttings ABR values of 2.67 and 2.62, respectively, were superior by 24.2 and 19.1 % to middle section and internodal cuttings, respectively. For LR, ABR, and PER, the best treatments were nodal and internodal cuttings of ‘CHF-1 Chapingo’ from the apical section, whereas the lowest expression of these traits was observed for internodal cuttings of ‘Verde Puebla’ from the middle section. Correlations between LTR, LR, and ABR with PER were r=0.47, 0.59 and 0.75, respectively, that of LR with ABR was r=0.81, and all of them were statistically significant.

We established an experiment of high plant densities for Mexican Lime [Citrus aurantifolia (Chirstm.) Swingle] at Tecomán, Colima, México, for 13 years to determine the effect of this practice on growth, production, and fruit quality. The plant densities studied were 123, 156, 200, 222 and 312 trees per hectare. We used sour orange rootstock. For the first four production years, yield from 312 trees (8 x 4 m) was higher than that of the control, 123 trees per ha (9 x 9 m) by 16.6 t×ha-1. In the last four years of production the difference between these treatments decreased to only 11.1 t×ha-1, favoring high densities. Tree height on all plant density treatments was very similar, but canopy growth was higher on plantations with trees at 9 x 9 m. After 13 years of evaluation, trees planted at 8 x 4 m were more efficient in terms of fruit production by leaf area (m2) or canopy volume in m3 than trees at 9 x 9 m. Fruit size was unaffected by plant density.

The main problem in coriander production, during the spring-summer growth cycle in Northeastern Mexico, is “premature tip” (first visible flowering symptom) a photomorphogenic problem associated to an endogenous hormonal change. For this reason, in 2000 and 2001 three experiments were established in the Autonomus Agrarian University Antonio Narro with the objective of controlling growth and development of coriander through external applications of growth regulators, and to determine the best growth regulator treatment to avoid or delay “premature tip” (the onset of blooming) in this species during the summer season. The results show that gibberellins, GA3, accelerate “premature tip” by 4.7 days, while AIA auxin and cytokinin kinetin delayed it by 21.3 days. Plant regulator effects varied as a function of genotype, and the best combination consisted of two applications of AIA+kinetin at concentrations of 5 + 5 or 15 + 10 mg’”liter-1, respectively.

The present study was carried out with the purpose of generating information related to genetic improvement of pipiana squash, with the following objectives: to estimate, for 14 traits, the genetic parameters: mean, additive variance, dominance variance, heritability, coefficient of additive variation and phenotypic correlations, and to learn the effect of different plant densities in the agronomic performance of squash. The experiments were established in 2001 in Chapingo, Mexico, in two locations and at two plant densities per location: D1: 13,890 and D2: 9,260 plants·ha-1 of squash in association with maize (50,000 plants·ha-1) in alternating rows of each crop species. Results indicated that additive variance was of 15,184 for fruit weight and 35.98 for seed weight. When selection was practiced, dominance variance appeared. Additive variation coefficients were less than 15 % in 13 out of 14 studied characters, and heritabilities oscillated between 20.35 and 88.39 %. Seed weight (SW) varied with location and plant density, and it was higher at density one in San Martin (SW: D1=68 g·plant-1, D2=62.09 g·plant-1) and at density two in San Juan (SW: D1=74.60 g·plant-1, D2=78.40 g·plant-1).

With the purpose of studying the dynamics of dry matter (DM) and N, P, and K accumulation in potato cv. Alpha, we established three experiments in farmers’ fields during the spring-summer (SS) and autumn-winter (AW) growth cycles. Soils in this study were fertilized to prevent any limitation of nutrients. Fertilization consisted of 180 and 250 kg N ha-1 for SS and AW, respectively, plus 200 kg×ha-1 of P2O5, 300 kg×ha-1 of K2O, 50 kg×ha-1 of Ca y 22 kg×ha-1 of Mg. Irrigation was applied by sprinkles and no soil moisture stress occurred at any time in the crop. Samples were periodically taken at two locations, and they consisted of: leaves and shoots, roots, and tuber. We determined dry matter content (DM) and N, P and K uptake. Yield reached 48 t×ha-1 of fresh tuber (12.9 t×ha-1 dry matter) and 32 t×ha-1 of fresh tuber (8.3 t×ha-1 dry matter), for SS and AW, respectively. Total extraction for N, P, and K was 287, 33 and 372 kg×ha-1 for SS, and 227, 24 and 358 kg×ha-1 for AW. To obtain one ton of tuber, the crop required 6.0, 0.7, and 7.8 kg×of N, P and K for SS, and 7.1, 0.75, and 11.2 kg×of N, P and K for AW. We also show the extraction of N, P, and K by component (leaves and shoots, tuber, and root) along the development cycle.

NOTA CIENTIFICA

The financial and energetic productivity of passionfruit was evaluated to determine its potential as an option to diversify fruit production in the state of Veracruz, Mexico. We characterized the yield of four plots, in the central region of the state of Veracruz, recording production costs and income per hectare from 1997 to 1999. The financial evaluation showed that passionfruit was highly profitable with an internal return rate between 83 and 194 %, a net positive current value for all plots, and benefit-cost ratio of 2.5 and 3.9. The energetic analysis showed that the regional plots had energetic efficiencies between 0.85 and 1.30, indicating a balance between invested and produced energy, with values of energetic productivity between 180 and 300 kilograms of fruit per BTU of energy.

A review of knowledge generated in Mexico upon roots attributes of Crataegus is presented. These attributes refer to the variation in roots distribution in the soil, the variation roots size of plants subjected to water stress and the generation of number and growth of new roots during the dry season, variation in the foliation of trees. Other roots attributes investigated were the generation of buds and new roots by roots cuttings. The necessity of rootstocks selections with the desired deep-rooting ability was stressed. Such rootstocks are very desired in construction of trees of high productivity per unit of water transpired or used in irrigation. The text is complemented with schemes of water movement between the tree, its environment and, the components of trees of escape mechanism from drought.