The objective of this research was to evaluate the temperature effect on the “pitahaya” (Hylocereus undatus) fruit oxidative metabolism during storage at low and room temperature. Batches of fruits, harvested in Tehuacan, Mexico’s Puebla State, were stored four days at room temperature (22±1 °C), and at 3, 7 and 11±1 °C during 7, 14 and 21 days, and four days at 22±1 °C after each cold-storage period. The total phenols content, and the poliphenol oxidase (EC. 1.14.18.1; PFO) and peroxidase (EC. 1.11.1.7; POD) activity were evaluated in the fruit pulp from the 20 treatments, including a control without storage. Four days at 22 ºC did not modify phenol content (2.4 mg·g-1) compared with control. Cold storage generated small changes in phenols and they have a tendency to increase directly with storage time and inversely with storage temperature. Low temperature inhibited, without an identifiable trend, the PFO and POD activity; seven and 21 days at 3 ºC diminished 50 % the initial PFO activity (> 10 U·g-1) and the inhibition continued after four days at 22 ºC after cold-storage. Changing to 22±1 ºC during four days, after 3±1 ºC storage, kept inhibited POD activity. On the contrary, the POD activity inhibition at 7 and 11±1 ºC was partially or totally reverted after returning the fruits at 22 ± 1 ºC. These results can be considered evidence that in the pitahaya fruits only temperatures lower than 11 ºC causes partial and non permanent cellular degradation when the storage period is of just few days.

Peach trees require pruning (specifically, fruiting shoots pruning, FSP) and fruit thinning (FT) for commercial fruit production. In the 2004-05 growing season, the interaction between FSP and FT on yield, fruit size distribution, fruit quality, fruit and shoot growth, and specific leaf weight of the ‘Victoria’ peach cultivar were studied. The experiment was conducted at the Zacatecas Experimental Station (at the Mexico’s Zacatecas State) using twenty-year old peach trees grafted on standard rootstock. The factors studied were: FSP and FT, both factors with two levels each: with and without FSP, and with and without FT. The statistical analysis did not detect any significant (P£0.05) interaction among the levels of the factors and response variables. Except for the significant (P£0.05) induction of first class fruits (5.0-4.4 cm of equatorial diameter), FT did not influence statistically (P£0.05) any of the remaining response variables. The FSP significantly (P£0.05) promoted fruit with equatorial diameters > 5.1 cm in relation to control trees (without FSP), but yield and productive efficiency were reduced (P£0.05) when FSP was applied. Average fruit weight, mesocarp, and endocarp were significantly (P£0.01) higher in fruit with FSP. However, firmness, total soluble solids concentration, fruit dry matter concentration, and specific leaf weight were statistically (P£0.05) the same between fruit without and with FSP. Results suggest that FT can be obviated in ‘Victoria peach trees, and therefore, this would reduce production costs. Both factors deserve to be studied in other peach cultivars whose reproductive structures have more ability to utilize photo assimilates.

In many studies on the growth of plants, it is necessary to evaluate the biomass, and this implies the destruction of the trees. In this work highly reliable mathematical models were generated in order to estimate the biomass of aerial organs of ‘Persian’ lime, on the base of non-destructive and easy-to-measure variables. Branches, leaves, and fruits were isolated and several characteristics as well as the biomass, and the leaves area, were measured. It was found that the amount of biomass of each type of organ is closely related with the following variables: for branches, volume calculated with the formulae of the cone and truncated cone, in the cases of non-pruned and pruned branches, respectively; for fruits, the equatorial diameter; and for leaves, the length of the sheet and its maximum width. Models were generated for each type of organ, with extremely high determination coefficients (between 0.9528 and 0.9981) and acceptable C(p) values (between 1.6696 and 16.3685, for models with 2 to 4 variables).

The Capsicum genus is one of the most useful plants taxonomic groups throughout the world. Although the species C. annuum includes the largest amount of cultivated pepper types and varieties, there are cultivars from other species under domestication process. The caribe or chiltepin cultivar of C. frutescens is currently under this process due to its outstanding physical and biochemical characteristics, and its potential ability to withstand drought and saline conditions. This work was developed to calculate their preliminary compositional nutrient diagnosis (CND) norms and to identify its nutrient interactions. The target yield for fresh fruit production of this cultivar was assessed through the CND approach, as well as the corresponding optimum ranges of macronutrients (N, P, K, Ca, and Mg) foliar content, which are called CND nutrient norms. These norms were defined using a minimum yield of 7.16 t·ha-1. The statistical principal component analyses, performed using estimated CND nutrient indexes, allowed us to identify the following nutrient interactions: positive N-P and Ca-Mg, and negative N-Ca, N-Mg, P-Ca, and P-Mg.

Chinene is a fruit native from Mesoamerica and belongs to the Lauraceae family. Chinene pulp consumption is recognized as a good nutritional source in tropical regions of Mexico and Central America. However, little is known about its nutrient content. Lipid analyses of chinene fruit pulp were carried out during two consecutive years using gas chromatography. Oleic and palmitic acid concentrations were comparable to those found in ‘Hass’ avocado cultivar. In other study, the chinene morphology from several locations of the central region of Veracruz, Mexico, was measured. Large variation in size, weight and pulp content was found. The pattern of fruit growth follow a simple sigmoid curve with 1635.11 accumulated heat hours above 6 oC from set to harvest.

Ataulfo is the most important mango cultivar in Mexico’s Nayarit state with almost 7,000 hectares planted, most of them replacing Tommy Atkins and Haden cultivars. However, the main problem of ‘Ataulfo’ is the high quantity of partenocarpic fruits, which do not have any commercial value, affecting the growers’ economy. In order to know the magnitude of this problem, a randomized sampling of commercial orchards was done in four producer counties. The number of ‘normal’ and partenocarpic fruits per tree (10 randomized trees by orchard and 10 inflorescences by tree) were quantified. The sampling was done considering the following factors: a) altitude above sea level, b) Tree age, c) Ataulfo orchards located close to Tommy Atkins ones, and d) Ataulfo orchards located 200 m further than ‘Tommy Atkins’ ones. The quality of normal and partenocarpic fruits was also evaluated. It was observed that San Blas County had the highest presence of partenocarpic fruits (54.3 %), and Santiago Ixcuintla County had lower presence (27.3 %). Also in San Blas County, it was found that orchards located at altitudes higher than 400 masl had more presence of partenocarpic fruits (96 %) compared to those located less than 200 masl which had only 34.6 % of this kind of fruits. In Tepic County, the younger trees showed lower percentage of partenocarpic fruits (1.7 %) than trees older than 10 years old, which showed 47 %. Also, it was observed that ‘Ataulfo’ orchards located very close to those planted with ‘Tommy Atkins’ had less partenocarpic fruits. The patenocarpic fruits were shorter than ‘normal’ ones but they were sweeter.

The objective of this study was to evaluate the effect of 1-MCP (0 y 300 nl·liter-1) and different levels of hot water treatment (0, 52 °C for 5 min and 46 °C for 110 min) on the physiology and quality of ‘Keitt’ cultivar mangos. The respiration rate, weight loss, firmness, pulp color, total soluble solids and diseased fruits were analyzed. The 1-MCP effect changed with the hot water treatment. In fruits without hot water treatment, 1-MCP decreased respiration rate; it did not affect weight loss; it maintained four fold the fruit firmness and delayed pulp color change and total soluble solids increase. However, in the 5 min hot water treatment, 1-MCP augmented the respiration rate; it did not affect weight loss and kept twice the fruit firmness while slowing down pulp color change and total soluble solids enhancing. The hot water treatment for 110 min significantly affected the effectiveness of 1-MCP to maintain firmness and avoid weight loss. The 1-MCP did not show any effect on controlling diseases, but the hot water treatment for 5 min reduced more than fifty percent the number of diseased fruits. Finally, it was observed that 1-MCP in combination with hot water treatment for 5 min extended the shelf life for five additional days and may be a good alternative for markets not requiring quarantine hot water treatment.

The Jack fruit demand has increased significantly due to its flavor and pulp color. Most of the Mexico’s Nayarit State production is intended for exporting to the USA. However, due to its relative short shelf life and sensitivity to chilling injury, exported fruits are shipped by plane generating high freight costs. It is stated that 1-Methylcyclopropene (1-MCP) delays the ripening process, extends shelf life and maintains quality of several fruits. Thus, the objective of this research was to evaluate the effect of 1-MCP on the physiology and quality of jack fruit stored at 20 ºC. Fruits were harvested at physiological ripening stage, washed, and treated with 1-MCP at 100 and 300 nl·liter-1 in sealed chambers for 12 h at 20 ± 1 ºC; 85 ± 5 % RH keeping a control. Respiration rate, ethylene production, total soluble solids, titratable acidity, fruit and pulp firmness, pulp color and weight loss were studied. 1-MCP did not affect most of the quality variables; however, it significantly delayed respiration rate, ethylene production and pulp softening extending the shelf life for eight and 12 days at 100 and 300 nl·liter-1, respectively.

In apple trees, leaf sheet area and shoot biomass are basic variables in growth, source-sink relationships and productivity researches. The aim of this studio was to build empirical mathematical models using multiple linear regression techniques to estimate leaf sheet area (LSA) and shoot biomass in “Agua Nueva II” young apple trees. All linear regression models obtained have high precision (R2 above 0.969). LSA (in square centimeters) was estimated with the model LSA= -3.24140(MWS) + 0.67616(MWS)2 + 1.63287(MWS)(LS/MWS), where MWS stands for maximum wide of leaf and LS for leaf length. The dry weight of leaf sheet (DWLS) was estimated with the model DWLS= 0.02699(LSA) + 0.00021917(LSA)2. The dry weight of petiole (DWP) was estimated as DWP = 0.00384(LSA) - 0.04432(LS/MWS) + 0.02291(LS/MWS). The dry weights (in g) of radical system (DWRS), of stem (DWS), of principal stem (DWPT), of large branches (DWBL), of medium branches (DWBM), and of short branches (DWBS) are a function of fresh branch volume (FV). The formulae of truncated cone was used to calculate FV (in cubic centimeters); for this, it was required proximal (basal) and distal (apical) diameters of branches, and its length. The branch dry weights were estimated with the following models: DWP = 0.66882(FV), DWPT = 0.55902(FV), ln(DWBL) = 0.77462[ln(FV)], DWBM = 0.49349(FV) and DWBS = 0.57297(FV). The model for dry weight of radical system (DWRS) is function of length and distal diameter of trunk: DWRS = 10.80747(LPT)(DDT) + (-01.37171) (DDT)2 The length and diameter variables in leaf, trunk, stem and branches were expressed in centimeters.

The biomass of plant organs is a very useful variable for studies on growth, source-sink relationships and productivity. Inasmuch its measure implies the dry in stoves, it is necesarily destrucive, not representing a problem in annual and little plants but it is very difficult in big ones, such as fruit and forestal trees, including the apple trees. In this work, models generated by regression estimate biomass of several organs of plants of apple cv. Agua Nueva 2 and have high precision, given by the high values of the coefficient of determination (R2 over 0.972), and by the values of the statistic of Mallow, very near the number of the independent variables. Normally, one variable had a high participation in each model. For long and short branches (arrows and spurs included), the variable volume calculated by the formula of cone and truncated cone for non-pruned and pruned branches, respectively, was the main one (partial R2 between 0.933 and 0.995). For the model of fruit bomass, the main variable was the minimum polar diameter in the cuadratic form (partial R2 of 0.974). For the models of the young and mature leaves, the main variable is blade lenght (partial R2 of 0.936 and 0.962, respectively).

The use of vermicompost from organic waste has been increasing in different parts of the world as source of high quality organic fertilizer. The objective of this research was to determine if the vermicompost may supply partial or completely the tomato (Lycopersicon esculentum Mill.) nutritive requirements of N, P, and K for an adequate growth, yield, and quality. During the 2004-2005 autumn-winter season, four treatments of organic and inorganic fertilization were evaluated in the Big Beef and Red Chief genotypes under greenhouse conditions. The treatments were T1 = sand + vermicompost mixture (50:50% v:v) + chelated micronutrients; T2 = sand + vermicompost (50:50% v:v) without micronutrients. , the T3 = sand + inorganic fertilizers (control) and T4 sand + vermicompost extract. The treatments were distributed in a completely randomized design with a factorial arrangement 4 x 2 with four replications. The results showed that fresh weight, total biomass and plant height were reduced in the organic fertilizer treatments. The yield in both hybrids was 20 % higher (P£0.01) in T3 than in T1, the second best treatment. The organic fertilizer treatments (T1 and T2) have higher soluble solids, fruit number, and K absorption, also flowering started 10 days earlier. Based on the production obtained, this study showed that T2 did not supply completely the nutritive needs of these hybrid tomatoes.

The study of internal water relations or water balance within the plants and crops in dry zones is relevant to understand the physiological processes involved in the production and adaptation to the environmental conditions where a water deficit prevails. Since some time ago, several authors have proposed different concepts to describe the water status within a plant. The aim of this work is to analyze some of the popular methods commonly used to study plants or crops under water stress. Such methods are based on the measurement of the water potential and its components, as well as the transpiration process. An analysis of the pressure-volume curve is useful to calculate the osmotic potential and the turgor pressure. This possibility is relevant to get a deeper undersanding into the study of plants and crops growing under different water-stressed environmental conditions, and to compare genotypes, genetic lines or varieties of a plant species. Several sources and possibilities of error must be considered in order to collect useful information to propose valid conclusions, in basic or applied research. Such considerations must include a precise estimation of the physiology of the plant or crop under study, taking into account other features as plant age, season and time of measurement, health status and overall performance at the whole plant level.

In this research it was evaluated the effect of type as well as date of pruning on red raspberry ‘Malling autumn Bliss’ in Guerrero, Chihuahua, Mexico. One-year-old plants were used, spaced 0.5 m between plants, 0.6 m width in hedgerows, and a between rows spacing of 1.5 m. The nutrient supply was done by using 60 ton·ha-1 of dry bovine manure incorporated at 10-15 cm depth. Drip irrigation was used with emitters spaced 1 m. During 2001, pruning at ground level in March 15, April 15, and May 15 were performance, also pruning of the cane portion that fruited the previous year on March 15. During 2002 only pruning at ground level was done on March 15, April 15 and May 15. The results indicated that pruning at ground level in March 15 gave the highest yields in both years with 7.4 and 5.0 ton·ha-1, respectively. Pruning in May 15 delays blooming and harvest date, and fruit size is small. Fruit size ranging from 1.8 to 3.6 g, is obtained with pruning in March 15 and April 15. The highest number of new canes was obtained with pruning on April 15.

El movimiento de aire causado por la ventilación en los invernaderos es un factor importante que afecta la uniformidad de sus condiciones climáticas y consecuentemente la uniformidad y calidad del crecimiento de las plantas. La predicción de las condiciones climáticas de los invernaderos es realmente importante para tomar las acciones apropiadas para controlar el clima interno. En este trabajo se compararon un modelo mecanicista y otro basado en la dinámica de fluidos computarizada para determinar su precisión para predecir las temperaturas internas de los invernaderos en las condiciones climáticas mexicanas. Los resultados muestran que el modelo mecanicista tiene un mejor ajuste a las temperaturas internas (R2 = 0.97) que el basado en la dinámica de fluidos computarizada (R2 = 0.94). Sin embargo, ambos modelos pueden ser usados como herramientas ingenieriles para el diseño de invernaderos.