Planting trials were carried out with four cultivars of lisianthus (Eustoma grandiflorum [Raf.] Shinn), namely ‘Mariachi Blue’, ‘Mariachi Green’, ‘Mariachi Blue Picotee’ and ‘Mariachi Pink’, in soilless culture. The objective was to analyze their productive behavior under the climatic conditions of the province of Almeria, Spain, in the summer-autumn season of 2006. Perlite B-12 was used as substrate and the planting density was 64 plants·m-2. Fertigation (pH 5.8; EC 1.5 dS·m-1) was carried out daily. Irrigation time was set at between 20 and 30 % drainage. A randomized complete block design with 30 control plants per replication was used. Analysis of variance and Fisher’s least significant difference test were performed. Precociousness, stem length, number of flowers at harvest, flowers per stem and bunch weight (5 stems) were evaluated. All cultivars showed great precociousness, between 52 and 59 days. ‘Mariachi Blue Picotee’ had the longest stem length with 68.64 cm and ‘Mariachi Blue’ had the shortest with 58.69 cm. In number of flowers per stem, ‘Mariachi Blue’ had the most with 5.59 units and ‘M Green’ the least with 4.20 flowers. Finally, in terms of bunch weight (five stems), ‘Mariachi Blue Picotee’ obtained the highest weight with 154 g, and ‘Mariachi Green’ had the lowest with 109 g. The results indicate the desirability of producing lisianthus in soilless culture under greenhouse conditions in the summer-autumn period in Almeria, because of its precociousness and flower quality.

Randomness, finite number of individuals and genetic variability among those that represent each parent of a synthetic of crop species such as onion (Allium cepa L.) and maize (Zea mays L.) can cause genetic erosion during the development of a synthetic variety. This may happen when the parents are L/2 single crosses (SCs) derived from L lines. If the inbreeding coefficient of the lines (FL) is less than 1, and the number (m) of plants that represent each SC is small, the number of non-identical by descent (NIBD) genes of each SC is a random variable (Xm). The objectives of this study were to determine: 1) the mean of Xm [E(Xm)], 2) the variance of Xm [Var(Xm)], and 3) the average loss of NIBD genes which are contributed by two lines to their SC. It was found that E(Xm) = 2 + [2 - (1/2)m-2 ](1 - FL). In addition, the average loss of NIBD genes was (1/2)m-2(1-FL) and Var(Xm) = [2m+2 - 8](1-FL)2/4m. These two results imply that when lines are pure (FL=1), the loss of NIBD genes and the instability of the number of these genes reach their minimum (zero), and approach to it from m = 8 on, more rapidly as FL becomes larger.

Limited water availability requires greater effort to maximize its efficient use. One way of doing this is through proper irrigation scheduling. This study was carried out in a vineyard in the Hermosillo Coast region, Sonora, Mexico, in order to assess the effect of reducing the annual irrigation depth on the yield and quality of ‘Sugraone’ and ‘Perlette’ grapevine cultivars. We evaluated restricted irrigation with 70 % ETc, modified irrigation with 100 % ETc with drippers spaced 50 cm apart, and a control with drippers spaced 75 cm apart and 100 % ETc, by monitoring soil moisture at 40 and 80 cm deep. Fruit number and weight, plant yield, grape diameter and soluble solids were measured. Results show that in ‘Perlette’ and ‘Sugraone’ yield and quality are maintained by restricting irrigation during non-critical plant stages, but maintaining tensions of 25-50 cb until harvest and 100-200 cb in postharvest. In Tukey’s range test (P ≤ 0.05), ‘Perlette’ responded better to modified irrigation, surpassing restricted irrigation in 2008 by 28.7 %. By contrast, ‘Sugraone’ had a better response with restricted irrigation, as it surpassed the control in number of clusters and plant yield with 42.5 and 40.7 %, respectively. In grape diameter, it surpassed the control and modified irrigation by 3.6 and 3.5 %, respectively, and increased soluble solids by 7.6 % with respect to modified irrigation.

Potato and tomato late blight (Phytophthora infestans) consistently shows great genetic diversity in the Toluca Valley, Mexico, mostly because of its sexual reproduction. Physiological races are commonly identified with differential host plants, while genotypes are determined by molecular markers. The objective of this study deals with the incidence of races of the late blight pathogen related to molecular characterization, to identify a possible conciliation of the two concepts (race-genotype). In 2006 and 2007, isolates of the pathogen were obtained from differential hosts exposed to natural infection in the field. Sequence of incidence of the races along the growth cycle in both years was similar. The indicator host plants with multiple susceptibility genes (R1,2,3,4; R1,2,3; R2,3,4) were the first ones to become infected, and the ones for races 9, 5 and 2 were the last ones in showing lesions. Mating type ratio was inconsistent along the growing cycles. Genotype 86/100; 100/100; A2 (GPI; PEP; mating type), was the most frequently identified (20% of the population, equivalent to CDA 3 in the US classification), followed by 100/100; 100/100; A2 (19 % in 2006 and 13 % in 2007, US-13). Furthermore, this genotype was the only one associated with races R5 and R8 in 2006 and with R8 in 2007. The race-genotype link was limited, for they did not match in the two years of the study. We conclude that race and genotype are independent concepts.

The objective of the present study was to evaluate the effect of biofertilizers and culture media on the tolerance to aseptic establishment and induction of organogenesis in banana tree. Explants from suckers of two genotypes of Musa cavendish AAA, cultivars ‘French Clone’ and ‘Oaxaqueño Clone’, were used. Three applications of biofertilizer were evaluated (1 g of Glomus intraradices, 1 ml of diazotrophic bacterium 11B and the interaction of both microorganisms) and one without biofertilizers. The apices were disinfected and sown in the three culture media: MS without growth regulators, MS added with 22.2 μM of indolacetic acid (IAA) and 22.2 μM of benzylaminopurine (BAP). Measurements were made of the water relations, the content of catalase and peroxidase, the explants with shoots and shoots per explant. In both clones the induction of organogenesis was increased with the addition of BAP and by previous biofertilization of the suckers. In the Oaxaqueño clone, treatments 6, 8 and 11 induced greater organogenesis, with averages between 66 and 71 % of explants with shoots and between 3.16 and 2.28 shoots per explant. For the French clone, treatments 8 and 9 increased the induction of organogenesis with the addition of BAP with averages of 66 to 83 % of explants with shoots and 1.83 to 2.16 shoots per explant. In both genotypes, the biofertilizers propitiated higher percentage of survival, higher tolerance to oxidation and less contamination. In the two genotypes, treatments 1 (Glomus intradices) and 4 (Control) produced less stress in the plants.

We assessed the effect of the Steiner nutrient solution (NS) at 25, 50, 75 and 100 % of its original concentration, in combination with 4, 6 and 8 plants·m-2, in a completely randomized experimental design, on yield and development of Physalis peruviana L. This research was carried out under greenhouse conditions from June 2010 to July 2011. The ecotype Colombia was cultivated in black plastic bags with tezontle stones and drip irrigation. The following variables were evaluated: fruit yield, number of fruits per plant, weight of fruit with and without husk, and average fruit weight. To determine the crop nutrient uptake leaf sampling were taken in the vegetative (VS) and reproductive stage (RS) and N, P, K, Ca, Mg, Fe, Mn, Zn, and B were quantified. Quality variables were total soluble solids (TSS; °Brix) and pH of the fruit. Significant differences were found for yield variables. The higher yield was obtained with plants supplied with the complete solution plus 8 plants·m-2. The nutrient solution with 75 and 100 % with 4 plants·m-2 obtained the higher individual weight of fruit. During VS the nutrient solution affected the concentration of N, K, Mg, Fe, and B; and the plant density influenced K concentration in leaf. During RS we found differences in concentration of K, P, Mg, and Mn due to nutrient solution, and Fe was affected by plant density. The TSS and pH of the fruit did not show significant differences.

In this study we determined the nutritional value, forage yield and nitrate concentration in hydroponic green forage (HGF) obtained from wheat plants. Six treatments were evaluated, which consisted of T0, where solely tap water was applied; from T1 to T4, we tested nutrient solutions based on the Steiner (1961) method, which modified the ratio of NO3 -/NH4 + in mol·m-3 (T1=12/0, T2=7.3/ 0.7, T3=7.0/1.4, T4= 6.0/2.8), and T5 consisted of a nutrient solution proposed by FAO, (ratio NO3 -/NH4 + of 3.2/0.4 in mol·m-3). Wheat seeds (Rebeca F200 variety) previously soaked in solely tap water for 12 h were sown at a density of 3.2 kg·m-2 using plastic trays. We used a completely randomized design with four replications. Plant height (PH), yield per square meter (YISM), conversion ratio from seed to forage (CR), dry matter, ash, fiber, protein and nitrate concentration were measured. Treatments T2 (19.0 %), T1 (18.5 %), T3 (17.9 %) and T4 (16.75 %) had the highest concentration of protein. The lowest concentration of nitrate in the HGF was obtained in treatments T0 (3,542.2 mg·kg-1) and T3 (3,348.2 mg·kg-1). Although nitrogen was not applied to the control in T0, it showed a protein percentage of 15.3 %, which can be considered acceptable. The best treatment for the production of green hydroponic forage was T3, with a 17.9 % of protein and a nitrate concentration of 3,348.2 mg·kg-1. Applying 17.5 % N in the form of ammonium reduced the concentration of nitrate. On the other hand, with 33.3 % of NH4 + toxic effects in seedlings were observed.

In the state of Puebla, Tehuacán is the most important region in the production of tender maize (Zea mays L.) sold on the cob. The varieties used are mainly native populations, whose potential for production and quality are unknown. This study was conducted to evaluate agronomically a set of native maize populations collected in Tehuacán to determine their variation in tender maize yield and quality. In 2009, 100 irrigated varieties were evaluated in three locations; of these 95 were collected in the Tehuacán area. The remaining five were two improved varieties and three control races: Bolita, Celaya and Pepitilla. Twenty variables were measured on plant and ear. The results of the combined analysis of variance showed highly significant differences (P ≤ 0.01) among varieties, except one, indicating presence of diversity for the characteristics measured among the native maize under study. In tender maize yield, the group of 16 native populations was outstanding (P ≤ 0.05). The local variety TEH77 had the highest number of desirable traits for yield and quality of tender maize ears: average yield 9,576 kg·ha-1, 11,3 °Brix, 13.7 cm ear length, 5.5 cm ear width and 39.7 grains per row. This variety surpassed the best commercial hybrid ‘AS900’ by 52, 23, 30, 33 and 47 % in yield kg·ha-1, total soluble solids content (°Brix), ear length and diameter (cm), number of rows and grains per row, respectively.

An experiment was conducted in Achichipico, Morelos, Mexico, to assess in situ the genetic gain of four cycles of participatorymass selection, with regard to the original variety, in a sweet squash population (Cucurbita moschata Duch.) intercropped with maize. The experimental design was a randomized block design with four replications. After every four rows of maize, one row of squash without maize was sown in rows 0.9 m apart and 20 m long. Genetic gain was calculated for each selection cycle and an analysis of variance was performed on data of fourteen plant, fruit and seed traits. Genetic gain per selection cycle in flesh color and flavor was 14.1 % and 11.8 %, respectively; in fruit yield per hectare (11.8 %), fruit yield per plant (9.8 %), fruit weight (6.5 %) and seed yield per hectare (5.1 %). The analysis of variance detected highly significant differences among selection cycles only for fruit width, flesh color and flavor, while the other traits were not statistically different. A clear upward numerical trend was observed.

During field surveys conducted in 2010, severe symptoms of leaf blight, flower necrosis and fruit rot were observed in cucumber fields in Totolapan, Morelos, Mexico. Disease incidence ranged between 40 and 50 %. Fungal colonies were isolated from symptomatic cucumber leaves, flowers and fruits collected from different fields. Morphological characteristics of the colonies, conidia, and sclerotia of these fungal isolates were similar to Botrytis cinerea. A representative isolate of B. cinerea was selected for molecular analysis by amplification of the ITS region. Pathogenicity of the representative isolate was tested by inoculation of a conidial suspension on 10 cucumber seedlings and 10 fruits. Five seedlings and fruits inoculated with sterile distilled water served as controls. Control seedlings and fruits remained healthy, but grey lesions on inoculated leaves and fruits were observed five days after inoculation. B. cinerea was consistently re-isolated from leaves and fruits with lesions. On the basis of the isolation, morphological and molecular identification, and pathogenicity tests, B. cinerea was determined to be the causal agent of leaf blight, flower necrosis and fruit rot in cucumber in Totolapan, Morelos, Mexico. Additionally, the efficacy of four fungicides and the bio-control agent T. harzianum against B. cinerea in cucumber plants was evaluated in a greenhouse test. The fungicides chlorothalonil and thiabendazole showed the highest percent control, but the chemical treatments and the strain of T. harzianum did not significantly reduce the symptoms caused by B. cinerea.