Ten potato (Solanum tuberosum) varieties were evaluated at three locations in the State of Mexico in the summers of 2004 and 2005. We estimated variance components and heritability of seven quantitative characters. Varieties were also described from 21 qualitative characters. The experimental design was a randomized complete block with four replications by environment. Statistical analysis of the experiment series was based on a random effects model for each of the seven quantitative characters. Qualitative characters were described according to the Technical Guide for Description of Potato Varieties from the National Service of Seed Inspection and Certification (SNICS). Results showed statistical significance (P£0.01) for locations, genotypes, and genotype x environment interaction for each evaluated character. Broad sense heritability was higher than 61.6 % at Raices, Metepec and San Francisco Oxtotilpan. Highest tuber weight was recorded for variety 740660 (27.8 t·ha-1), which was statistically superior to the control variety Alpha. Plant height and number of stems per plant were negatively correlated (P£0.01) with tuber weight (PTHA), but the remaining evaluated variables contributed to a significant increase in PTHA (P£0.01). In terms of foliage structure, variety 777091 was the best at Raices and Metepec, but 776943 was outstanding at San Francisco.

With the objective of studying the effect of Ca(NO3)2, we carried out pre-harvest foliar sprayings in avocado cv. Hass trees using concentrations of 0, 0.3 and 0.5% every fifteen days from the mid September 2003 until early January 2004, resulting in 11 applications. We evaluated nutrient concentration in the leaf, skin and pulp. Results indicated no increase in concentrations of N, P, Km Ca, and Mg in the leaf, skin and pulp during the first year of evaluation. We concluded that the second year presented a Ca increase in skin and pulp, but not in leaf, with residual effect evidence.

We obtained statistical models for estimating and predicting leaf area (AF) based on leaf length (L) and width (A) of basil (Ocimun basilicum) under desert climatic conditions, irrigation regime, and organic management in the meridional area of the peninsula of Baja California, Mexico. We took 500 randomized leaf samples (n=500) at three ages (young, intermediate, mature), from one hectare. The measurements obtained were correlated to generate simple linear (leaf area as a function of length and width) and multiple linear (as a function of length by width) regression equations. Leaf area positively correlated with leaf length (r=0.89) and width (r=0.97) and with width by length (r=0.97). All calculated equations significantly explained (P<0.0001) AF (variation amplitude among models with R2=0.70-0.93). These results show the feasibility of estimating AF in a predictive and reliable way from easily obtained measurements without destruction of the plant; additionally, high R2values do not necessarily indicate a good model fit for this purpose. As a whole, the best model was the multiple linear one that included length by width (R2=0.93).

This study presents the geographic and ecologic distribution of wild potatoes (Solanum L.) in the Potosi-Zacatecas Highland; these species have economic importance for self-consumption, commerce, and as a source of germplasm. The method included analysis of herbarium specimens, botanic collections, cultivation of plants in an experimental plot, and photographic material. Macro-distribution of taxons was determined by locating collection records in a geographic unit map for the area of study; and micro-distribution was resolved based on physical and biotic characteristics of locations where species lived. Recorded taxons were: Solanum brachistotrichum, S. cardiophyllum subsp. cardiophyllum, S. cardiophyllum subsp. ehrenbergii, S. fendleri, S. papita, S. pinnatisectum, S. polytrichon, S. stenophyllidium y S. stoloniferum. Out of 146 records, the Meridional Highland included 69.86 %, the Septentrional Highland 22.60 %, the High Sierras and Valleys 4.79 % and the Low Sierras 2.74 %. Taxons were found in cultivated, mezquite, and cactus areas. The Potosi-Zacatecas Highland is an important area of diversity for wild potato.

Apple trees are grown in areas were irrigation water is almost always a limiting factor; therefore, new irrigation techniques for saving irrigation water need to be developed and tested for a sustainable production system for this fruit crop. During the 2000-01 growing season, we studied the effect of partial root irrigation (RPR) on tree water status, gaseous exchange, and yield and fruit quality of “Pacific RoseTM” apple trees grown in the humid region of New Zealand. Treatments included commercial irrigation (RC, control) and RPR. In general, tree water status and gaseous exchange were the same between treatments. Yield, transversal trunk section (STT), yield efficiency (yield/STT) per tree, and average fruit weight were the same between treatments, but efficiency of irrigation water use was significantly improved in tress under RPR, when compared to trees under RC. Using RPR resulted in savings of 0.15 mega-liters of water per hectare. Fruit quality, in terms of dry matter concentration, starch index, total soluble solid concentration and fruit color, was the same between treatments. Therefore, RPR could be suggested as a water-saving practice without detrimental effects on yield and fruit quality in humid environments; however, research on RPR should be carried out in arid environments.

This study was carried out from 2004 to 2006 at La Yerba (Tepic) and Emiliano Zapata (Xalisco) Nayarit, Mexico. The objectives were:to determine thrip species in inflorescences and leaves, population dynamics in foliage, and incidence in foliage of trees treated with different fertilization levels. Thrips belonged to the Aeolthripidae (three species), Phlaeothripidae (two species) and Thripidae (one species) families. For the first time for avocado in Nayarit we recorded the predator thrips Erythrothrips durango, Franklinothrips vespiformis and Leptothrips mcconelli, together with Pseudophilothrips perseae (plant phage). The highest population of the thrip complex (2.09 thrips·leaf-1) occurred in June at La Yerba; and in July for E. Zapata (4.10 thrips·leaf-1). The highest populations of thrips occurred during the flowering and vegetative growth periods; the lowest during the months of the summer precipitation. Thrip populations were 60 % higher at E. Zapata than at La Yerba. We did not detect a higher population of thrips in trees under the fertilization control treatment when compared to tress with balanced fertilization.

The objective of the present investigation was to compare yield, productivity and fruit size of plants of tomato cv. ‘Daniela’ grown in ladder-shaped canopies to commercial production systems using uniform canopies. The ladder shape was accomplished by placing in each growth bed three or four rows of plants with tips clipped at different heights and different numbers of racemes per plant, with an East-West orientation, while uniform canopies had all plant tips clipped at the same height and the same number of racemes per plant. The experiment was carried out in Texcoco, State of Mexico, from January to June 2001 in a glass greenhouse under hydroponics conditions. The experiment was established under a randomized complete block design with four replications and six treatments: three of the treatments included a ladder-shaped canopy arrangement consisting of three plant rows per bed with one, three, and six racemes per plant, respectively, were plant distance within row varied to obtain 30, 36.5 and 43 racemes·m-2. Another ladder-shaped treatment was created with four rows of plants per bed with one, two, three, and six racemes per plant at uniform plant distance within row to harvest 45 racemes·m-2. Two uniform canopy treatments were included (one with four rows of plants per bed thinned at three racemes per plant to allow harvesting of 21 racemes·m-2 and another with two rows of plants thinned to six racemes·m-2 at a density that allowed harvesting of 24 racemes·m-2). The ladder-shaped treatment with three rows per bed and 36.5 racemes·m-2 yielded 37 % more and produced 40 % more large fruits than the commercial treatments with uniform canopies. We discussed that the highest yield from the ladder-shaped canopy could have resulted from a more uniform distribution of solar radiation on the set of leaves that make the canopy, favoring a higher production of assimilates per unit leaf area and, consequently, resulting in a higher number of fruits per unit area without detraction in average fruit weight when compared to uniform canopy treatments.

Guava is a fruit very susceptible to cold and develops cold damage symptoms at temperatures equal or less than 5 oC, which reduce post-harvest life of the product. The objective of the study was to evaluate the effect of methyl jasmonate (MJ), during storage at low temperatures, on quality of guava cultivars. Guava fruits from Hawaiian Red (HR) and Hawaiian White (HB) cultivars were treated with concentrations of 0, 10-4 M and 10-5 M of MJ before storage at 5 oC for 15 d. Each five days, 15 fruits were transferred to 25 oC for 2 d to evaluate performance of shelf life. Additionally, we evaluated ethylene production (PE) and respiration rate (VR). Likewise, fruit quality was evaluated by determining the percentage of weight loss (PP), percentage of titratable acidity (AT), pH, total soluble solids (SST), hue angle (AM), firmness (F) and general appearance (AG). Treatment with MJ did not modify PP, F, PE, VR, AT, pH and SST. However, MJ reduced changes in AM and AG for both cultivars during the 15 days of storage when compared to the controls. We conclude that treatment with MJ suppressed the development of symptoms from cold damage (DF) in guava fruits at 5 oC without negative effects in maturation and organoleptic quality.

The State of Chiapas has a wide array of cultivated mangoes which could potentially be important for plant breeding of this species. Phenotypic characteristics of fruits and trees are useful indicators in differentiating Chiapas landrace mangoes from commercial ones, but they are not precise. In this study we determined the isoenzymatic diversity of 16 collections of mango landraces and five commercial varieties grown in the Soconusco Region, Chiapas, Mexico, using seven isoenzymatic systems. The analyzed mango landraces have the following common names: Coche, Piña, Madura verde, Canela, Amate, Tecolote, Oro, Tapanero, Manilón, Alcanfor, Manzana, Manililla, Blanco, Melocotón, Amatillo, and Pomarrosa; the improved varieties were Ataulfo (50 to 70 year old), Tommy, Atkins, Kent and Manila. Twenty polymorphic markers were located, but none of the enzymatic systems, by itself, allowed differentiation of each of the mangoes studied; however, combination of the enzymatic systems GPI-1 and GPI-2, generated unique patterns that allowed characterization of the different mangoes. The dendrogram suggested the presence of 83 % of similarity among the analyzed varieties, resulting in three groups: one group included Pomarrosa mango, which was clearly different from the others. A second group included landraces with similar fruit characteristics, with a high amount of fiber and sugar and without commercialization traits. The third group included commercial mangoes and some landraces that are commercialized locally that share similarities for some fruit traits, such as the absence of fiber in the pulp and high sugar content.

The present study was carried out in two ‘Persa’ lemon orchards, each one with a different soil type, with the objective of understanding dry matter and nutrient distribution in citrus organs and determining their nutrimental value. Orchard 1, 12-years-old, was growing in a clay-sandy soil; and Orchard 2, 9-years-old, in a clay soil. The method of study consisted of extracting four whole trees per orchard to divide each one of them into its different organs: leaves, flowers, fruits, branches, trunk, and roots. The variables measured included fresh and dry weight of each organ. We determined nutrient concentration using chemical analysis: N, P, K, Ca, Mg, B, Cu, Fe, Mn, and Zn. Data from both orchards underwent analysis of variance and mean comparison tests separately. Fibrous roots (< 1 mm diameter) for both orchards presented high micronutrient concentrations, particularly Fe and Mn. For both orchards, nutrients extracted in higher quantity by the fruit were K and Ca; and Zn and Cu in less quantity. Regarding biomass distribution, trunk and stems provided 60.32 %, roots represented 26.93 %, and leaves 9.41 % of tree total dry matter; while leaf N represented 17.5 % of the total plant in Orchard 1. This represented 1.85 times more nitrogen in relation to leaf dry weight. Similar data were obtained from Orchard 2. Cu and N were the most required nutrients in both orchards.

The research was performed during 1998-2003 in commercial ‘Hass’ avocado orchards under the semiwarm climate of the state of Nayarit, México. The objectives were: a) to determine the effect of the presence of fruit on shoots of the winter vegetative flush on floral development, b) to investigate the effect of tree fruit load and orchard location (altitude above sea level) on floral development, and c) to document the pattern of floral development of winter and summer vegetative flush shoots. Winter shoots emerged at the end of January and February, the summer vegetative flush in July. The pattern of floral development of the vegetative shoots of the winter flush was not affected by the presence of fruit on individual shoots, tree fruit load (100 kg·tree-1) or altitude of the orchard (900 vs. 1,200 m above sea level). The complete process of floral development of apical buds from closed bud (Stage 1) to anthesis (Stage 11) required from 367 to 371 days for shoots of the winter flush, but only 225 days for shoots of the summer flush. Shoot age (winter or summer) had no effect of the date of anthesis, which occurred in February.

A multiyear research (1998 to 2006) was undertaken with the goal of developing field management tools to improve the productivity of ‘Hass’ avocado orchards in the semiwarm climate of Nayarit. The objectives were: a) to quantify the effect of ambient temperature on floral development of ‘Hass’, and b) to develop and validate prediction models to prognosticate critical stages of floral phenology. Floral development of ‘Hass’ was related to ambient temperature and mathematically modeled. Floral development on shoots of the winter flush was correlated to chilling days accumulated (CDA) at temperatures £ 21 °C, as well as the accumulated intervals between daily maximum and minimum temperatures (ACINT). In the case of summer flush shoots, they were associated to CDA with temperatures £ 19 °C, £ 20 °C and the ACINT. Two floral development prediction models ere obtained for winter shoots, winterCDA £ 21 (R2 = 0.99) and winterACINT (R2 = 0.96). In the case of summer flush shoots three prediction models were developed, summerCDA £ 19, summerCDA £ 20 and summerINTAC, all of them with R2 = 0.99.

The Purepecha Sierra in Michoacan is considered the most important avocado producing region in the world. Factors restricting production have not been properly identified. They require undergoing reseach to propose better crop management alternatives conducive to high yields and optimal fruit quality. In this study we evaluated soil fertility in avocado orchards and determined the nutrimental state of the crop through foliar analysis applying Kenworthy’s balance indexes procedure. We collected soil and foliar samples from avocado (Persea americana Mill.) cv. Hass orchards within an area of 35,000 ha in the region. Soil fertility diagnosis indicated strong acid pH, low to very low levels of organic matter, P, Mn, and inorganic N; high to very high concentrations of Cu, Fe, K, Ca, B and Zn; and intermediate levels of Mg. Foliar concentration intervals generated for avocado in the Purepecha region showed differences from values determined by other researchers for different avocado producing regions from other countries. Estimated Kenworthy’s balance indexes helped to determine, in general terms, that: Zn, Mn, and Cu were present at deficient levels below normal, B was present in excess, and K, N, Mg and P in normal concentrations.

We evaluated the effect of three treatments: a) aluminum sulfate 0.6 g·l-1; b) 400 ppm of 8-hydroxyquinoline sulfate (8-HQS); pulse with silver thyosulfate (STS 0.025 mM) for 20 minutes; and distilled water as a control; on water consumption, fresh weight, flower diameter, total soluble sugar concentration in petal and longevity of Rosa cv. Royalty. Water consumption decreased significantly for the control on the ninth day, unlike the other treatments, which maintained their water consumption above the control until the end of the experiment. The lowest rate of fresh weight loss was observed for aluminum sulfate (Al), followed by STS, HQS and the control, in that order; this suggested a possible inverse association with post-harvest life. Flowers treated with aluminum sulfate resulted statistically different on their optimum ornamental status at 9, 10, 11, 12 and 14 post-harvest days, which were analyzed using the Kruskall-Wallis test. Flower diameter was higher for flowers treated with STS (9 cm), followed by aluminum sulfate (7.6 cm); the latter sustained flower aperture for two days longer than STS. Regarding the concentration of total soluble sugars at the stages of bud and open flower, there were no significant differences among treatments or flower stages (P>0.05).