Studies were conducted from 2003 to 2005 in Las Varas, Nayarit, Mexico, under field conditions with three mango cultivars. The objectives were a) to generate information about population dynamics and b) to determine the distribution of the white mango scale in mango trees. The species was identified as Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae). The developmental pattern showed three different stages: a low density period from the end of the rainy season (September) to December, a second stage of gradual population growth from March to the beginning of the rainy season (July), and the last stage of drastic fall in population during the rainy season (July-August). White mango scale on leaves was more profuse in ‘Tommy Atkins’ and in ‘Ataulfo’ than in ‘Haden’. On fruits, scale population was higher on ‘Tommy Atkins’ than on ‘Ataulfo’. Density of A. tubercularis was more abundant on the south side than on the west side of the trees. Population of the pest was also higher on the next to last vegetative flush (inner shoot) than on the last one, and average of scales was also higher on the upper surface than on the underside of the leaves.

Mirador chili is a vegetable crop of economic and social consideration in the Mirador, Chicontepec region of Veracruz, México. However, its yield is often reduced as a result of a high percentage of flower drop. This condition adversely alters yield and fruit quality. For this reason, the effect of bioregulators on the physiology and biochemistry of the chili was evaluated. When Mirador chilli field plants reached 50 % flowering, the following treatments where applied with a hand sprayer: P-Ca 100 mg•L-¹; GA3 10 mg•L-¹; ANOXA 10 mg•L-¹; BA 10 mg•L-¹; P-Ca 100 + GA3 10 mg•L-¹; P-Ca 100 + ANOXA 10 mg•L-¹; P-Ca 100 + BA 10 mg•L-¹; GA3 5 + ANOXA 5 + BA 5 mg•L-¹ and H2O (control). Plant height, flowers per plant, fruit set, seed number per fruit, yield, vitamin C and capsaicin in fruits were evaluated. P-Ca reduced final plant height. When P-Ca was combined with GA3, ANOXA or BA increases in total number of flowers, fruit set, seed number per fruit, yield and content of vitamin C and capsaicin in fruits were observed.

Eleven combinations of rootstock varieties and grafts were carried out with the purpose of evaluating the effect on number and size of stomata, as well as on the stomatal index. These variables were correlated with the height of “Persian” lime plants. The rootstocks, ‘C32’, ‘C35’, ‘Benton’, ‘Carrizo’, ‘Florida’ and ‘Morton’ citranges, ‘Amblicarpa’ and ‘Cleopatra’ tangerine, ‘Volkamerian’, ‘Flying Dragon’ lemon and ‘Sour’ orange, which was used a control, were evaluated. ‘Persian’ lime leaves are amphistomatic; on the upper face of the leaf, stomas are found only on the midrib. It was found that the rootstocks modified the number of stomata (from 287 to 331 per mm-2); these parameters were higher with ‘Sour’ orange; the stomatal index was superior in ‘Cleopatra’ tangerine (9.86) and the stomata were larger in ‘Carrizo’ citrange (25.89 μm). A lower area of four ‘Persian’ lime leaves of was found on the plants grafted onto ‘Flying Dragon’ (124 cm-2). On 10 rootstocks the height of ‘Persian’ lime plants was above 4.01 m, and crown diameter was more than 3.03 m, but on ‘Flying Dragon’ height and crown diameter were only 2.43 and 2.21 m, respectively. The number of stomas correlated positively with the number of epidermal cells (r= 0.709) and negatively with rootstock stem diameter (r= -0.449).

The objectives of this study were to evaluate Tepary bean (Phaseolus acutifolius) and common bean (Phaseolus vulgaris L.) with different levels of resistance to Fusarium oxysporum f. sp. phaseoli (Fop), using DNA markers, and to trace the inheritance of DNA associated markers. Crosses were made between Tepary Pinto x Pinto Americano and Pinto Americano x Bayo Blanco contrasting levels of re¬sistance to the fungus to obtain F1 and F2 segregating progenies. To search for the DNA associated markers, seedlings from parents and F2 were inoculated with a suspension of 2.5 x 105 fungus conidia•mL-1. DNA from selected susceptible and resistant plants based on the presence of symptoms of wilting or chlorotic leaves and plants without wilting symptoms, respectively, were used to track DNA markers associated with contrasting phenotypes of resistance and susceptibility. Molecular analysis was done with DAF-PCR technique using the random primers A-01, A-04 and A-13. DNA polymorphisms were observed in F1 populations indicating the formation of hybrids between P. acutifolius and P. vulgaris. In F2 dominant markers were detected in P. acutifolius associated with resistance to Fop.

Petunia (Petunia x hybrida Hort. Vilm.-Andr.) is an annual ornamental species with a long flowering period; it is easy to grow and has a wide range of shapes and sizes. Furthermore, it is a species tolerant to salinity, which makes it a very versatile plant for a more sustainable landscape approach in marginal soils. Given the need to seek substrates alternative to peat moss for commercial production, this research evaluated the effect on indicators of growth, flower and seed production of three substrates: agricultural saline soil (T1), agricultural saline soil supplemented with 30 % (v/v) compost of cattle manure and crop residues (T2), and agricultural saline soil containing 80 % (v/v) of the same compost (T3). Addition of 30 % compost (T2) markedly improved plant growth (P≤0.05); plants were taller and produced flowers with seeds. On the other hand, addition of 80 % compost significantly decreased soluble Na+ and Cl- in the substrates, and although this treatment (T3) produced the largest shoot diameter, more sprouts, leaves and flowers (P≤0.05), plant height was not the highest, and plants were more susceptible to lodging than those of the other treatments and did not produce seeds. Lodging was provoked by a higher production of dry biomass, as a consequence of higher N and K contents in leaf tissue. It was concluded from this study that up to 30 % (v/v) compost made from cattle manure and crop residues to amend saline soil significantly improves growth in petunia plants and maintains flower and seed production.

This study determined the effect of three kinds of packaging and three storage temperatures on “Puebla” variety Manzano hot pepper fruits obtained from plants cultivated under greenhouse conditions. A 3x3 factorial design with three replications on 324 fruits was used; the experimental unit was a package with three fruits. Six evaluations were made during a period of six weeks after harvesting. The results showed that three kinds of packaging (Styrofoam tray with pliofilm and a laminated rigid tray) had a positive effect on the postharvest quality of the fruits, and that storage at low temperatures prolonged shelf life. The combination of plastic film packaging and storage at 12 ºC and 5 ºC prolonged the quality of the fruits, delaying the change in color from green to yellow and decreasing losses in weight, firmness and citric acid. The vitamin C content of the fruits was not affected by the type of packaging or low temperatures. Nevertheless, it is recommended that the peppers be consumed as soon as possible because after 30 days their values decrease up to 40 %.

This study was conducted in the experimental fields of the Chapingo Autonomous University, located in Chapingo, State of Mexico. The aim was to collect and characterize new early (precocious) and parthenocarpic squash (Cucurbita pepo L) genotypes for the development of varieties suitable for greenhouse production. Forty-six parthenocarpic bush-type round zucchini genotypes were obtained and characterized agronomically. The genotypes were identified and selected from among 5000 plants of a purposelyconstructed population of broad genetic base, which represented a system efficiency of 0.92%. Of the 46 genotypes, 28 produced round fruits, 12 had oblong fruits, six had flattened fruits and one yielded cylindrical fruit. There were 41 genotypes with shallow ribs, four with intermediate ribs and one without ribs. Seventeen genotypes exhibited sweet pulp, 10 with intermediate pulp and the 19 with insipid pulp. Six genotypes yielded mature fruits with 30 mm thick. The 46 partenocarpic genotypes obtained were classed into three groups: group 1, plants with intermediate-length internodes exhibiting round, heavy, thick-shelled fruits with many large seeds; group 2, plants with short internodes, producing small light-weight, elongated thin-shelled fruits with few small seeds; group 3, plants yielding long, round, thin-skinned fruit with many small seeds.

For the regeneration of plant genetic resources of monoecious species certain artificial crosses produce desirable effective population sizes but the cost is high. To avoid the cost of these crosses, random mating of the sample can be used. The sample can be taken completely at random, as in the ideal population (IP), or randomly taken at each of two stages (IPTS): first n families and then m individuals of each selected family. Further, since the concept of efective population size as a measure of the effectiveness of the sampling and reproduction strategies to regenerate populations is not always well known as the concept of inbreeding coefficient is, it was derived for IPTS as a measure of the efficiency of the IPTS method of regeneration. This derivation was based on the calculation of the contribution of each of six sources (selfings and crosses) of the inbreeding coefficient already active in the second regeneration cycle (F2,E). The calculations were made based on a probabilistic approach applied to the concept of identity by descent. It was found that with IPTS, F2,E decreases as m is closer to 1 and its minimum value occurs when m = 1, and only when m = 1 and n > 1 is smaller than IP’s. This implies that, for regeneration purposes, for a sample of size x, a random individual from each of x random families should be included in the sample.

Husk tomato, because of its cultivated area and its constant increase in per capita consumption, is considered one of Mexico’s main horticultural species. It is grown in almost all agriculture regions of the country, but the mean national yield per hectare of this crop is below its potential. Prohexadione-Ca (P-Ca) is a growth retardant recently named as a promising alternative for improving production and produce quality in modern horticulture. In this study, the effects of P-Ca on vegetative and productive growth as well as on the chemical properties of husk tomato fruits were assessed. The growth retardant was applied twice at 0 (control), 125, 175 and 200 mg•L-1. The first application was done when plants showed the first flower buds; the second application was 20 days later. The study was established in open field using a randomized block design and a DMS (Pd”0.05) statistical test. It was demonstrated that P-Ca significantly reduced plant height, increased number of fruits and yield (200 mg•L-1) per plant, vitamin C content in fruits (175 and 200 mg•L-1) and catalase activity (175 mg•L-1). Other parameters such as weight and size of fruits, protein content, peroxidase activity and nutrient content were not affected by P-Ca.

The influence of interstock in anatomical and physiological leaf characteristics were evaluated in ‘Hass’, ‘Fuerte’, ‘Colín V-33’ and ‘Duke 7’ used as interstocks and final grafts. Stomatal density, epidermal cell density, stomatic index and stomata polar diameter were as¬sessed in leaf blade. In cross sections of the central vein and petiole of the leaf: area, perimeter, length of the minimum and maximum axis, roundness index and Feret diameter of xylem vessels were determined. Thickness of the upper and lower epidermis and thickness of palisade parenchyma I layer were measured in leaf cross sections. Physiological variables were CO2 assimilation rate, stomatic conductance, CO2 internal concentration, stomatic resistance, transpiration rate and leaf temperature. ‘Colín V-33’ as interstock induced higher stomatal and epidermal cell density and thicker palisade parenchyma I. In the intra genotype comparison, ‘Hass’ and ‘Fuerte’ with interstock increased stomatal density 18.8 and 17.8 %, respectively, while ‘Duke 7’ caused a 25.4 % reduction. Epidermal cell density increased in ‘Fuerte’ (23.3 %) with the presence of the interstock. ‘Fuerte’ and ‘Duke 7’ with interstock increased the thickness of the lower epidermis in 14.9 and 12.1 %, respectively, while ‘Hass’ and ‘Colín V-33’ with interstock reduced epidermis thickness by 19.5 and 1.0 %, respectively. ‘Hass’ as interstock promoted a higher CO2 assimilation rate than that promoted by ‘Duke 7’. ‘Colín V-33’, as a rootstock, showed lower stomatic resistance than ‘Duke 7’.