The terms cultivar or variety used with genetically improved plants that come from species is generally controversial. These terms are being used indiscriminately in written and oral communication. The objective of this paper is to provide information about the proper use of this agricultural terminology. The term variety created by Linneaus in 1751, continues unchanged, and defines a plant that has been modified through accidental environmental alterations. Permanent morphological and physiological characters are what distinguish the variety. Taxonomically, variety occurs between specie and cultivar. When sugar cane crops began to be cultivated, Black Cheribon, Criolla, Cristalina, Badila, Uba, Chunnee, etc., varieties were the basis for the industry. Nevertheless, when problems arose that affected production, they were replaced with genetically improved cultivars. The varieties presently exist only in germplasm gardens. The term cultivar is an artificial neologism that originated in english, through the agglutination of parts of the expression cultivated variety (culti-var). The error in agricultural terminology occurred when cultivars were called varieties. This caused communication problems, mainly at the international level, with regards to the International Code of Nomenclature for Cultivated Plants which defines cultivated plants that have been genetically modified only as cultivar.

The objective of the paper was to morphologically characterize the fruits and seeds of 23 collections of nanche (Byrsonima crassifolia (L.) H.B.K.), that originated in the state of Tabasco, Mexico. Twenty-two digitalized characters were measured with an image analyzer for the description. The data obtained were analyzed with SAS and NTSYS programs. Three main components explained 84.16% of the total variability. Five groups were defined in the dendrogram, with a Euclidian distance of 5.58. Group I has fruit with the highest Brix degrees and percentage of pulp; Group III has the fruit with the highest area, longitude of the main axis, longitude of the lesser axis, Feret’s diameter, weight, pulp thickness, pulp weight, dry weight values and HUE value. Group IV has the highest luminosity (L) and croma (C) values. Group V has the highest volume of 25 fruits. These results demonstrate the diversity of nanche that exists in Tabasco, Mexico. The information may therefore be useful for the selection of germplasm.

The objective of this study was to evaluate the use of preservative solutions and immersion time that permit the warehousing of the flower alstroemeria for a prolonged period of time without affecting its quality. Two cultivars of alstroemeria: Silvia and Diamond, two immersion times: 3 and 9 hours, and four preservative substances: 8-hydroxyquinoline citrate (8-HQC), Amino-oxyacetic acid (AOA), bee honey (MA), 8HQC + AOA + MA and water (AN) as a control were evaluated. The variables evaluated were: weight loss, appearance of the flower and foliage, and flower opening. A random design and the multiple measurement comparison Tukey test were used to analyze the results. The 8HQC and 8HQC + AOA + MA solution generated the lowest weight loss, best appearance of the flower and foliage and stimulated the greatest opening of the flower for floral stocks in the two alstroemeria cultivars. The cultivar Silvia had the greatest results with 3 hours of immersion time achieving the lowest weight loss, the best appearance flower and foliage, as well as the best flower opening. The cultivar Diamons with a 9 hour immersion time had the best characteristics of weight loss, best appearance of flowers and foliage, and the best flower opening.

The coefficient variation (CV) of the fruit characters (number, weight, length, width, color and external texture), of the pulp (thickness, color and taste), and of the seed (weight, length and width) were determined for areas of 2.7, 5.4, 8.1, 10.8 and 13.5 m2 in order to learn the optimum size for squash (Cucurbita pepo L.) fields associated with corn (Zea mays L.). The research was undertaken at Chapingo, Mexico, in two locations: San Martin and Lomas de San Juan. Sixty families of maternal half brothers of squash corresponding to the fifth selection cycle of the combined family selection were used. An analysis of the combined variance of the locations was made for each of the field sizes studied. The field unit was 2.7 m2. The CV diminished with an increase in field size; however, the width of the seed increased from 8.1 to 13.5 m2. The maximum CV reduction occurred in color, thickness and pulp flavor; external fruit texture and seed weight. The optimum field size was 5.4 m2 for the majority of the characters, except for the number of fruit per plant.

The vascular connection of apricot ‘Donra’ and ‘CP-90-5C’ selection buds during dormancy and the start of budding were studied. The observations of the xilema vascular connection throughout the structure of the floral bud were normal, reaching each ventricle of the flower verticilo of the flower; not only was the xilema observed, but also the phloem. The apricot ‘Donra’ had a high loss of floral buds under the weather conditions in the state of Mexico, which the CP-90-5C selection had irregular production due to floral bud drop. The observations of both apricots determined that the reproduction structures (pistil and anthers) were damaged during dormancy; this damage seems to be a sign that stimulates the abscission layer at the base of the buds which always occurs in the same site. The abscission of the buds was not immediate. Rather, they remained adhered in most cases until the start of the vegetative budding which strongly accelerates the bud dropping. Anther and/or pistil necrosad were most common during December, especially in the apricot ‘Donra’.

This study had the objective of characterizing 40 nopal cultivars for use as a vegetable in the nopal germplasm collection of the CRUCEN-UACh based on morphological attributes of one-year-old mature cladodes and to numerically classify those genotypes. Fourteen qualitative and quantitative variables were considered for this purpose: 10 cladodes that were undamaged by biotic or abiotic factors were selected. The analysis method was a multivariate analysis of the main components and conglomerates which allowed the grouping of the 40 nopal cultivars into five classes. The Tapón Macho, Copena F-1 and Oreja of Elefante cultivars each made up a group. The analysis of the main components showed that ‘Tapón Macho’ differed from the other cultivars because of the great numbers of thorns in its cladodes, while ‘Copena F-1’ differed for its very long cladodes, and ‘Oreja of Elefante’ differed for its curly edge and very waxy surface. The Tamazunchale, Nopalea Jalpa and Llera cultivars made up a group of compact vegetable material characterized mainly by its very waxy texture and a large L/A ratio. On the other hand, the group of 34 cultivars can be divided into at least two subclasses or subgroups. One of these subclasses can be made up of the Chihuahua, T-L, P-8 Rojo and 40. P-8 Rojo cultivars and 40 tend to have cladodes with a large number of dark colored areolas, while the ‘Chihuahua’ tends to produce oval cladodes, wide with a wavy edge and a waxy texture; ‘T-L’ has relatively longer cladodes than the other cultivars, except for the clear exceptions of ‘Copena F-1’. The rest of the cultivars make up a more compact group than the one already mentioned which is characterized by a complex combination of morphological attributes.

Petiveria alliacea (Phytolaccacea), a very important plant in traditional Mexican and Latin American herbal medicine has been used as an antirheumatic, to produce abortions, against fevers and cancer, and inflammations. It is also deemed to be an insect repellant and acaricide, probably because it contains sulfur compounds. Despite the fact that some flavonoids have been detected, its antioxidant activity is unknown. The objective of this paper was to evaluate its cytotoxic activity in five cellular and antioxidant lines of Petiveria alliacea L. The cytotoxic evaluation of various extracts was undertaken in five cellular lines according to the Monk method. The antioxidant activity of different leaf and root extracts was analyzed according to the Blois method. The aqueous extract had the largest cytotoxic effect of the five tested in the leukemia cellular line, with an inhibition rate of 70.1 % at concentration of 100 mM. The leaf butanolic extract had an antioxidant effect at a medium strength inhibitory concentration of (CI50) of 264.54 µl×mg-1

The present study was undertaken in a greenhouse and ferti-irrigation at Chapingo, Mexico, to evaluate the agrophenological behavior during the period of August 2003 to February 2004 of six wild harvests of Physalis peruviana L., introduced from Peru. A random design with six repetitions was used; the experimental unit was made up of 10 polyethylene containers, (40 cm high and a diameter of 25 cm) filled with tezontle sand, that were placed in rows parallel to the irrigation system; the containers and rows were separated by 50 cm and 80 cm, respectively. There was a significant difference in genotypes among the collections with regards to fruit yield, fresh fruit weight with and without peel, total plant height, and first bifurcation, diameter of the stalk, and the number of leaves per plant. On the 64th day after being transplanted, a collection from Huancayo reached the tallest plant height (85 cm), diameter of the stalk (1.33 cm), and number of leaves per plant (67). The average fruit yield was 22 t·ha-1. The number of fruit per plant, total plant height, and to the first bifurcation, and total number of leaves per plant had a positive correlation with the total yield of fruit. The phonological development of all the collections were similar over time: they germinated in 12 days, while the flowering, growth, and fruit maturity began at 42, 52 and 146 days after being transplanted, respectively. Nevertheless, the period when these stages occurred overlapped due to the habit of undetermined growth of the specie and similar responses to the production environment.

The endogamic coefficient plays an important role in the genetic improvement of agricultural crops since it is related to the effective number of a population (the ideal population number whose endogamic rate is equal to that of the population being studied) which is related to the probability of genetic derivation, to the probability of the extinction of a gene, and to the selection response. However, in the case of self steril species (such as the husk tomato (Physalis ixocarpa Brot. and some ornamental species in the genera Primula), the existing formula for the endogamic coefficient of generation t which is related to the case of the two previous generations is not applicable if the endogamic coefficients of the first two generations is unknown. The theoretical derivation of the endogamic coefficients of the first and second generations (F1 and F2) of these species was made based on the model of a population that is equal to an ideal population, except that self-fertilization is excluded and the sample size was considered in order to advance from one generation to the next to be equal to N. These endogemic coefficients were F1 = 0 and F2 = (4N-5)/{2[4N(N-1)-1]}. With these and with the endogemic coefficient of generation t previously mentioned, it is now possible to numerically determine the endogamic coefficient of whatever population is being studied.

In order to evaluate the effect of foliar fertilization with Si and bee honey on the control of wilting on the husk tomato a field experiment was installed in the Zumpango, Mexico municipality. The experimental treatments were derivations of a combination of two foliar fertilizers (NV3 and NV5), bee honey at 2 % and Si soluble (0.1 % and 0.2 %); also a control and three treatments to verify the simple effect of the foliar fertilization and bee honey. The incidence of the disease was manifested in an aleatoria form in all the treatments. The evaluated severity on the crop, made on three sampling dates, varied as a function of the treatments and lessened up to 80% in the second sample in the plants where silica and bee honey was applied to the foliage. The microscopic analysis of the leaves showed the presence of silica crystals accumulated on the walls of the xilema of the leaves that received Si vía foliar. Yields of up to 14.5 t.ha-1, were obtained in the harvest, 98 % more than that obtained by producers using traditional methods.

An experiment was made in order to evaluate the drought resistance of peanuts testing two growth habits: creeping and erect with eight nested varieties of each habit, with two levels of humidity. Twenty-two vegetable and reproductive characteristics were measured. With regards to the number of gynophores, immature pods, seed weight, intensity of leaf greenness and plant height there were statistical differences between the two levels of humidity. Plant height was superior with good humidity; on the other hand, drought induced a greater intensity in the green color. Among the twenty variables, there were statistical differences in growth habit, where the creeping variety had outstanding plant exuberance. The majority of the variable presented differences between varieties within habits, which demonstrate the phenotypic variability. With regards to the interaction level of humidity by variety within habits, flowering at 42 days, an intense green leaf color and foliole length was noted. The creeping varieties presented generic and specific effects more frequently than the erect, with the former being more frequent.

Five potato genotypes were established in rows separated by 90 cm and plants by 30 cm in Metepec, in the state of Mexico, during the rainfed season of 1996. During the 85 days after their emergence, at intervals of 7±1 days, five plants with complete genotype competition were harvested by genotype to determine the total biomass of the plants and their organs, and the total foliar area, with which different efficiency indexes were estimated. During the vegetative stage, the relative growth rate was 0.10 a 0.40 g·g-1·d-1, agreeing with the genotype and plant organ, later diminishing until becoming negative. The net assimilation rate and of economical net assimilation fluctuated between 0.01-0.10 and 0.001-0.017 g·cm-2·d-1, respectively when tuberation began, and between 0.21-0.57 and 0.035 a 0.054 g·cm-2·d-1 during full tuberation; in both cases the Alpha Norteña and C-771A11 genotypes were outstanding. Between development days 43 and 57, the growth rate of the crop increased up to 184 and 264-386 g·m-2·d-1 in the precocious and late genotypes, respectively, and later diminished. The maximum rate of biomass accumulation in the underground organs was from 239 to 306 g·m-2·d-1, in the underground organs in the genotypes of undetermined habits at 85 days after emergence. The harvest index fluctuated between 48 and 92 %, and had a greater expression in the genotypes Alpha, Norteña and C-771A11. The majority of the genotypes had a high total yield of tubercles per plant due to the high values of relative growth rate and the growth rate of the tubercles, as well as the net economic assimilation rate. The greatest yield of commercial tubercles (1017 a 1164 g·pta-1) was due to the higher number of commercial tubercles per plant.

Breccias, like broccoli, cauliflower and cabbage, are important crops in Mexico because of their nutritional quality, anticancer properties and because their production generates income from their export. Broccoli, cauliflower and cabbage seeds were treated in order to determine the optimum osmotic conditioning and its effect on physiological quality. Broccoli, cauliflower and cabbage seeds, as well as an untreated control, were placed in Polietilenglicol 6000 solutions of an osmotic potential of 0, -5, -10, -15 and -20 was used for 8, 16 and 24 h, after which the standard germination test was made. The treatments were made under a random experimental design with four repetitions; the experimental unit was a Petri dish with one hundred seeds. The treatment with bidistilled water showed better results than with the osmotic solutions and the absolute control, without a statistical difference between these treatments: germination increased 4 % with the broccoli seeds conditioned for 24; in the two cabbage cultivars there was an increase of between 15 and 30 %, while the cabbage increased 93 % when conditioned for 8-16 h, and the plantlets and the radicules, were longer.

This research was undertaken in the Valle del Yaqui, Sonora, Mexico, to learn about the effect on yield and postharvest life of nine different nutrition schemes using N, P, K, Ca and Mg applied to the soil of tomato (Lycopersicum esculentum Mill.) crops under the condition of gravity irrigation. Tomatoes are the second most important vegetable worldwide. In Mexico it generates many jobs and represents a large amount of money from its export; its fertilization is presently based on experiences extrapolated from similar regions, which has been useful in obtaining acceptable yields, though not those hoped for. Therefore, nine fertilizer schemes using combinations of N-P-K-Ca-Mg: 50-50-50-25-25, 100-50-100-00-00, 150-100-100-25-25, 200-120-120-00-00, 250-150-200-00-00, 300-150-300-25-25, 350-200-300-00-00, 400-200-400-00-00, 450-250-300-25-25; were applied to the soil in kg·ha-1. The combination 200-120-120-00-00 was designated to be the regional control. The informed result about yield and fruit stored at 20ºC for fifteen days that was analyzed every five days was: titulable acidity, soluble solids, a resistance to penetration and weight loss. The most outstanding results were: the treatments 200-120-120-00-00 and 300-150-300-25-25 had statistically significant differences with regards to the number and weight of fruit with quality within the norms.

String beans a vegetable of high nutritional quality and there is a tendency in Mexico to increase its consumption. It was therefore the objective of this research to identify varieties of string beans adapted to the Valley of Mexico with different growth habits based on their productivity and quality on two planting dates. An experiment with 36 varieties of beans (31 had a determined growth habit while 5 had an undetermined) was established on May 21 and June 15, 2001 in Texcoco, in the state of Mexico. The flowering dates, date of cutting, physiological maturity, total production, and length of the string beans was noted, as well as the seed yield. The protein and crude fiber content of the string beans were evaluated on the first date of planting (PFS). Significant differences (P£0.01), were found in all the quantified variables. The drop in temperature, the photoperiod and the hydro availability reduced the number of string bean cuts of eight of the PFS and of five of the second. The varieties with undetermined habits had a higher total yield of string beans and seeds. Ejotero 50, OR 900 and US No. 3 varieties had an average higher total yield of string beans in the PFS and may be used in early plantings. US No. 3, E10-1, F2 and E10-2 varieties were outstanding on the second date and may be used in late plantings. During the last two planting dates, Bayo Alteño showed a resistance to diseases and a high string bean and seed yield so it can therefore be planted for a double purpose (string beans and grain) and as a progenitor in genetic improvement of string beans. The obtained yield and quality show that it is possible to produce string beans in the Valley of Mexico.

The purpose of the present study was to determine the participation of ethylene in the abscission process of the fruits of three species of Opuntia, and their relationship with the production of CO2 during the growth and maturation of the fruit. The concentration of ethylene CO2, pH and titulable acidity in four phases of maturation (initial: M1; intermediate: M2; maximum: M3; and final: M4) of the fruits of O. matudae, O. oligacantha and O. amyclaea was measured. The greatest concentration of ethylene and of CO2 in O. amyclaea was obtained in the M3 phase, coinciding with full maturity and the maximum dropping of fruit which suggests that the production of these gases is related to the abscission process of the fruit. With O. matudae and O. oligacantha the greatest concentration of ethylene was found in the M1 phase, indicating that this might be functioning as a developmental and maturation trigger for the fruit, but not sufficiently to stimulate abscission in them. The maximum production of CO2 in these two species occurred in the maximum maturation phase (M3), and could be related the coloration change and to the transformation of acids into sugar in the fruit.

The objective of the research was to determine the color and antocianines content in the mature fruit from 162 collections (plants) of chile guajillo, made in locations in Zacatecas, Durango and Jalisco, which are states where the largest areas with this crop are cultivated. The Hunter (L, a and b) parameters were used to determine the color from which the hue, chroma, and luminosity (L) were determined. The chile collections from of Vaquerías, municipality of Ojuelos, Jalisco and from Luis Moya, Zacatecas, had the fruit that was the least red and had similar antocianines content (values of between 0.83 and 1.00). The collections from Nuevo Día, Zacatecas had a greater average content of antocianines. The general analysis between plants demonstrated that the majority of the collections were in the red color scale, but collections P64, P83, P124 and the P75 were outstanding. With regards to antocianines content, there was much variation, although the collections P150, P133, P128 and P144 had the highest content.

The objective of this research is to establish the hormone and nutrient requirements to induce the germination of the spores of Nephrolepis exaltata (L.) Schott in vitro and to obtain plantlets. In the germination phase, spore disinfection occurred in 96 %, with a 100 % survival inoculate rate. The germination was similar in the crop mediums used; 32 % of the spores germinated within 28-30 days after being planted. Prothallic development succeeded optimally in IV medium, with continued volume, multiplication and diameter growth jointly reaching an average of 4.6 cm at 180 days of spore germination. Prothallic growth, in MS medium at 50 %, was on the average 2.5 cm in diameter at 125 days after the planting of the spores. While in MS medium at 100 %, the growth was 1.2 cm in diameter on the average at 120 days, without further development. The addition of 0.01 mg·litro-1 of gibberellic acid to medium V was sufficient to obtain a production average of 26.6 plantlets. The generation of sporophytes (plantlets) obtained in MS medium at 100 % of salts and with concentrations of 0.01 and 0.10 mg·litro-1 of AG3. The root development occurred spontaneously in the same medium used to form the sporophytes or when the plantlet was established in soil with relatively high humidity.