The blight that causes dieback of Hybrid Lily (Lilium spp.) branches is a disease that appeared recently in the region of Villa Guerrero, Mexico State. The main symptom is necrosis that descends from the tip of the stems preventing production of flowers and premature death of the plants. The purpose of this work was to identify the causal agent of the blight on hybrid lily. With Koch’s postulate, it was confirmed that the disease was caused by Botrytis cinerea.

The objectives of this study were to evaluate thermal treatments of vapor heat in the control of Anastrepha serpentina on zapote and to determine tolerance of zapote mamey fruits to the treatments. The fruits not were damaged internally by the heat treatment when exposed to 43 °C·120 min-1. The fruits reached eating ripeness in 8 days at 25 °C, with rapid changes in the pulp color and weight loss. In contrast, at 10 °C they maintained greater firmness and prolonged shelf life, but exhibited greater damage in the vascular bundles. Mortality of the fruit fly eggs and larvae was 100 % with controlled atmosphere vapor heat treatment at 43 °C·120 min-1. Fruits not were damaged by the application vapor heat; larvae were easily killed by the CA at 40 °C·120 min-1, but eggs were more resistant and hatched at 25 °C after the 8 days of storage.

The storage of sapote mamey fruits in plastic films was evaluated to determine the effect on some physical and chemical changes during postharvest. Sapote mamey fruits were collected at physiological maturity and stored in three plastic films: Ziploc®, KleenPack® and PEAKfresh®. Additionally, fruits without plastic films were used as control. Weight losses, color changes (brightness, chroma and hue), acidity tritable, pH, sugars, carotenoids and total phenol were evaluated. Control fruits showed daily weight losses of 1.9 % and ripened 8 days after harvest. The sugars and soluble solids increased during ripening, but the titratable acidity and pH did not show significant changes. Brightness and hue angle diminished and there were no changes in chroma. There were no important changes in phenols and total carotenoids concentrations. The use of plastic films delayed all changes observed during ripening of sapote mamey fruits. The plastic film KleenPack® showed the best results, retarding ripening without affecting the fruit quality. Results indicated that it is necessary to use barriers to avoid quick ripening and weight losses in sapote mamey fruits in postharvest.

The aim of this research was to determinate the effect of four-radiation levels (100, 70, 50 and 0 %) provided by plastic mesh (30, 50 and 60 % shade, and a control without mesh) on tuber biomass accumulation in exposed greenhouse plants. Giant variety tubers 15 to 17 mm in diameter were grown in perlite. Seventy-five days after emergence plants under 100 and 70 % radiation had a higher number of tubers tuber (25 a 35 %) and total and tuber biomass (50 %), net photosynthesis, absolute growth rate, net assimilation rate and net economic rate than those grown under 50 and 40 % radiation. The harvest index was 0.71 at 100 % vs. 0.51 at 40 % radiation. This general behavior was observed in samples 40, 50, 60 and 70 days after emergence. Lower radiation affects photosynthetic efficiency of potato plants, decreasing tuber and total biomass, as well as the efficiency indexes of the growth analysis.

The aim of this study was the estimation of biomass production, yield and yield components of two cultivars (‘Acerado’ and ‘Criollo’) of common bean (Phaseolus vulgaris L.) with high potential for the snap bean production, monocropped and intercropped with two cultivars of sunflower (Helianthus annuus L.) (‘Sunbright’ and ‘Victoria’). The study was done during the spring of 2006 under rainfed conditions in Tenancingo, Mexico. The variables evaluated were leaf area index (LAI), net assimilation rate (NAR), total biomass (TB), pod diameter (PD), pod length (PL), number of pods·m-2 (NP) and pod yield·m-2 (PY), which were analyzed in a randomized complete block factorial arrangement. In order to consider the degree of association between the studied variables and pod yield, an analysis of simple linear correlation was made. In cultivar factor, statistical differences were detected in NAR and PD; for the sowing systems factor there were significant differences in TB, PD, NP and PY. The interaction of cultivars * sowing system was significant in all the variables, except in NAR. The associations ‘Criollo’ + ‘Sunbright’, ‘Acerado’ + ‘Victoria’, and monocropped ‘Acerado’ had the highest PY. The variables LAI, TB and NP were correlated positively and significantly with the pod yield. The results indicate that ‘Criollo’ and ‘Acerado’, associated with ‘Sunbright’ and ‘Victoria’, respectively, respond positively to the association, constituting a favorable option for the producers of the region of Tenancingo, Mexico.

The Citrus tristeza virus (CTV) causes a disease of regulatory interest for the Mexican citriculture. Timely and reliable sampling and diagnosis is essential for management strategies to check the spread of the brown citrus aphid, its main vector, in national territory. Because it is cheap and operationally feasible, direct tissue blot immunoassay-ELISA was compared with to DAS-ELISA, the official method for diagnosis, in order to establish an effective and efficient method for CTV detection. For the comparison, a total of 7421 trees of 11 commercial orchards of Tamaulipas, grouped by budding and infection age were tested. The direct tissue blot immunoassay technique was more sensitive and more capable of positive prognosis than DAS-ELISA in the diagnosis of CTV (P£0.028) in trees with recent and unknown infection. Buds diagnosed positive were heterogeneously distributed throughout the canopy, described by the beta binomial function (P£0.16-0.23). Based on this function and the reproducibility (93.2 %) of the results of double petiole printing suggested an optimal sample size of 10 petioles in single print. This method was 54.9 % more economical than DAS-ELISA and the diagnoses require only 17 % of the time invested for DAS-ELISA. However, due to the requirements of the current Mexican official norm (NOM-031-FITO-2000), this method is recommended as a fast technique to discriminate positive trees in field sampling to be later verified with the official method of diagnosis.

The objective of this research was to assess the growth, yield and fruit quality of the cultivars Mexican lime with thorns (‘MCE’) and Mexican thornless (‘MSE’) [Citrus aurantifolia (Christm) Swingle] grafted on to different vigorous rootstocks established in soils with two different depths. Two different sites were chosen to set up the experiments, one with shallow soil (SS) with a water table 80 to 120 cm deep, and the other with deep soil (SP). Rootstocks evaluated on SS site were Macrophylla (Citrus macrophylla Wester), Rough lemon (C. jambhir Lush), Taiwanica (C. taiwanica) Troyer citrange (Poncirus trifoliate x C. sinensis), and Sour orange (C. aurantium). The same rootstocks, except for Troyer citrange and Sour orange, were used in SP. ‘MCE’ trees had larger crown diameter and yield than ‘MSE’ in both soils. Of all rootstocks, Macrophylla supported the largest tree crown diameter and average yield of the two lime cultivars, in both soil conditions. However, this rootstock was similar to Taiwanica and Rough lemon in tree height and crown volume. Fruit quality was not affected by the rootstocks used. Soil depth affected tree performance of most scion/rootstock combinations throughout the years. On the SS site, ‘MCE’ was more productive than ‘MSE’ on all rootstocks during the six years of production; however tree growth and yield of most combinations were affected by the water table. On the SP site, Mexican thornless lime trees on Macrophylla and Rough lemon were as vigorous and productive as ‘MCE’ on the same rootstocks. The most promising combinations for the SS site were’ MCE’/Macrophylla and ‘MCE’/Troyer citrange. On the SP site, the best combinations were both ‘MCE’ and ‘MSE’ on Macrophylla rootstock.

The objectives of the present research were to determine the effect of three substrates on establishment of mycorrhizal symbiosis between Glomus mosseae BEG-25 and G. mosseae BEG-132 and poinsettia plants and on plant development and quality, and to compare plant response to inoculation with commercial fertilization practiced by growers. The substrates consisted of: S1=a mixture of leaf mould+ volcanic rock + peat moss + perlite (9:3:2:2, v/v); S2=peat moss + vermiculite (2:1, v/v) and S3=volcanic rock. Fertilization treatments consisted of non-fertilized plants and plants fertilized with Peters® 8-45-14 (N-P2O5-K2O) during the initial 20 days, and with Peters® 7-40-17 thereafter. Plants growing on S1 plus fertilization had the highest plant height (40.8 cm), number of leaves (63.4), shoot dry weight (26.3 g), leaf area (2,518.8 cm2) and bract area of the main inflorescence (1,163.1 cm2), while the highest root dry weight was observed in G. mosseae BEG-132 inoculated plants on S1 and those from S2 plus fertilization. Anticipated flowering, 6 – 3 days, was observed in plants on S1 compared with plants grown on S2 and S3. The highest root colonization was observed not only in plants inoculated with G. mosseae BEG-25 (66 %) and G. mosseae BEG-132 (80 %), but also in non-inoculated plants (56 %), all of them in S1, suggesting that this substrate contained native mycorrhizal fungi. However, none of the mycorrhizal treatments improved plant nutrition. S1 was the best substrate for the establishment of mycorrhizal symbiosis. Fertilization with Peters® in S1 was the best treatment for plant growth and quality.

The tomato (Lycopersicon esculentum Mill.) is one of the most consumed horticultural crops around the world and that most produced in greenhouses. It is of interest, then, to develop production systems that increase yield and quality. The objective of this study was to evaluate a production system of tomato plants pruned to a single stem leaving only three clusters per plant. The system consists of arranging plants in sets of five rows of rectangular containers oriented north-south, and located at different heights to form a double stair-like canopy. The studied factors in morphological and yield traits were two different container heights between contiguous rows (40 and 50 cm), and three population densities (25, 30 and 35 plants·m-2). Additionally, the effect of the position of each row was evaluated for the same variables. A complete random design with arrangement in split plots with six treatments and five replications was used; the experimental unit was 20 plants. The plots corresponded to different heights among contiguous rows of plants and the subplots to population densities. The highest number of fruits·m-2 (342) was obtained with the density of 35 plants·m-2 and the lowest (274) with 25 plants·m-2, and the tallest plant height (135 cm) was registered with level differences of 40 cm between contiguous rows. The yield per surface unit did not differ for any of the two studied factors. The plants located in the upper row had higher yield (1342 g·plant-1), smaller plant height (120 cm) and larger stem diameter (1.44 cm) than those grown in the lower and intermediate rows.

Given the natural and cultural importance of columnar cacti in Mexico, in an indigenous Mixtec community in which these species have been used and managed for centuries, the infraspecific traditional classification and the morphological variation of 41 characters of stem, flower and fruit in 15 land races of pitaya (Stenocereus pruinosus) were studied. Key informants identified 25 land races, using stem and fruit traits; 10 of these landraces were the most popular, and 15 were analyzed using principal components and cluster analyses. Three principal components explained more than 50 % of the variation and cluster analyses defined five groups of land races. Three selection tendencies were identified: large and heavy fruits, long and many thorns, short and few thorns. Yield per plant, harvest season, hardness of peel, moisture content and fruit color were not evaluated, but are used for selection by farmers.

Among the main problems that limit production and productivity of husk tomato are the availability and high cost of irrigation water, as well as inefficient use of this resource. Current production systems are not efficient due to, among other reasons, the large volumes of water supplied. The objectives of this study were to assess the effect of different irrigation water treatments and plastic mulching on husk tomato crop production in a fertigation system and also to optimize the irrigation water in order to improve crop productivity. The experiment consisted of a complete randomized design with three replicates, with a 5 x 2 factorial treatment design consisting of five levels of irrigation: 40, 60, 80, 100 and 120 % of reference evapotranspiration calculated using the Penman-Monteith equation, and two levels of plastic mulching, with and without. The results indicate that there were significant differences between mulching and irrigation levels for fruit yield and water productivity. Using plastic mulching increased fruit yield by 56.6 %, and irrigation water efficiency by 57.3 %; water use was reduced 60 % by calculating the required water volume with the Penman-Monteith equation.

The effect of irrigation and fertilization on post harvest quality of zapote mamey (Pouteria sapota) was evaluated. Twenty year-old trees developed from seed were irrigated at two frequencies: traditional (every 10 days) and 20-millibares controlled (every 3 days). Irrigation was combined with four fertilization rates 0, 1, 1.5 and 2 kg of NPK per tree. Evaluated variables on fruits at physiological (MF) and commercial maturity (MC) were the followings: acidity, total soluble solids (SST), firmness, color (L, a, b), phenols and total carotenoids, weight loss (WL) and NPK concentration. The 20 mb-controlled irrigation improved pulp appearance (brightness) during MC and increased carotenoid concentration. Fertilization improved fruit quality, increasing carotenoid concentration and reducing weight loss by transpiration. In addition, 2 kg NPK treatment resulted in higher brightness of fruits at MC and 1.5 kg NPK produced fruits with dark red pulp. The fact that firmness of fruits on MF was reduced by applying 1.5 and 2.0 kg NPK requires careful handling of sapote fruit during harvest season avoiding lesions and buises that may affect the normal ripening process.

The content of free ellagic acid (FEA) and the anthocyanin profile were determined in “Autumn Bliss” variety red raspberry fruits (Rubus idaeus L) in different ripening stages and grown in two locations. The FEA and anthocyanins were analyzed by reverse phase High Performance Liquid Chromatography (RP-HPLC). Rripening stage and growth location affected FEA. The fruits with deep red color (degree 3 ripening) from San Mateo Acatitlán, Mexico, had the highest FEA content, with a value of 5.38 mg·kg-1 of fresh fruit. the anthocyanin profile was more complex as fruits advanced in maturity. In the inmature fruits only four anthocyanins were observed, while in the completely mature fruits there were eight. In the completely mature fruits the anthocyanins with the highest relative percentages were: cianidin 3- soforoside (46.2 %) and cianidin 3-(2-glucosyl rutinoside) (25.9 %). The maximum levels of FEA and the highest number of anthocyanins were present in the completely mature raspberry fruits, this stage is characterized by the deep red color of the fruits, and is when its consumption is recommended.

Hybridization as a method for plant breeding may create improved varieties with higher fruit yield and quality by taking advantage of the combining ability and heterosis between the crossed parents. Six landrace varieties (five collected in Mexico and one in Peru) of manzano hot pepper (Capsicum pubescens R & P) and all their possible direct single crosses were evaluated, for heterosis and general and specific combining abilities (GCA and SCA) for fruit yield and quality. Plants were grown under greenhouse conditions and drip irrigated with a complete nutrient solution. Analyses for GCA, SCA and heterosis were based on the Griffing’s fixed model of diallel design method II, and on analysis II of Gardner and Eberhart. Significant GCA effects were found for fruit yield, fruit volume, pericarp thickness, seed number and weight per fruit, and on locule number per fruit. The highest GCA values were registered in landrace ‘Puebla’. The highest heterosis relative to the best parent was found in the cross ‘Zongolica x Puebla’ for fruit yield (51 %), in ‘Peru x Chiapas’ for fruit volume (33 %), in ‘Puebla x Peru’ for seed number (22 %), and in ‘Puebla x Chiapas’ for seed weight (38 %) and locule number (18 %). These hybrids also showed high SCA values. ‘Puebla’ was the best landrace as a parent in hybrids. It had the highest frequency of high yielding hybrids with high fruit volume and pericarp thickness, compared with the other five landraces. Thus, hybridization can be a useful method for breeding manzano hot pepper to exploit combining abilities and heterosis.