Histological studies of immature inflorescences from Gerbera jamesonii were carried out, with the purpose of to determine the onto-genic origin of the adventitious shoots. No cultivated capitulum of 8 - 12 mm and in vitro cultivated explant of 30 days were analyzed. In immature inflorescences we observed that the explant did not have vegetative buds and there was no presence of meiosis micro-sporocites and macrosporocites. In the cultivated explants, the adventitious shoots were differentiated de novo from flower somatic cells.

Mexico is considered as a diversity center for major Tagetes (Asteraceae) species. Since prehispanic age Tagetes erecta and Tagetes patula traditionally have been used as ceremonial flowers, in addition today they have promissory uses in sustentable agriculture, food, medicine, industry and ornamental, however domestication knowledge of these species is limited. Domestication of wild plant is able to change the morphology and development of plant species. In this study, growth analysis technique was used contrasting Tagetes erecta and Tagetes patula species, and regarding to their domestication level. Based on the apical and lateral meristems, it was determined that the flower initation (FI) ocurred 56 days after planting; in addition, flower development (FI to blooming) required 84 days in Tagetes erecta and 104 days in Tagetes patula. Tagetes erecta showed a more uniform seed germination, less branching in stems, lower biomass yield per plant, a shorter life cycle, higher values of the root/stem ratio and higher rates of relative growth and net assimilation than Tagetes patula. For this reasons, Tagetes erecta was considered to be in a higher level of domestication than Tagetes patula.

Forty tomato varieties were evaluated in 1996 in Tlajomulco de Zúñiga, Jalisco to compare some agronomical traits and identify the best varieties. A randomized complete block desing with four replicates was used. Varieties 114 (Salamanca), 175 (Tamazula) and 125 (original Rendidora) were the earliest in floral buttons, flower and fruit production. Tamazula’s landrace genotypes 161, 180, 153, 185, 174, 152, 176, 187, 173, 54, 186, 183, 184, 175 and 162; 119 (Manzana), 179 (Colima), 71 (Nayarit), 125 and 200 (impro-ved variety: CHF1-Chapingo) showed the highest yield. They are interesting form future research. Uncultivated varieties were the lat-test in floral buttons development, flower and fruit production, and showed the shortest height, branch length and the lowest yield.

With the aim of defining the best commercial hydroponic tomato system under greenhouses, with respect to yield and annual productivity, four production variants based in one stem per plant were compared: a) decapitation of the terminal bud to leave one truss per plant with a population density of 24 plants⋅m-2 (1R24), b) decapitation of the terminal bud to leave two trusses per plant with a population density of 16 plants⋅m-2 (2R16), c) decapitation of the terminal bud to leave three trusses per plant with a population density of 12 plants⋅m-2 (3R12), and d) control without dacapitation of the terminal bud with five trusses per plant and a population density of 6 plants⋅m-2. Floradade, a semideterminate cultivar, was used. The experiment was conducted under a randomized blocks design with six replicates, where each production variant was considered as a treatment. Each experimental unit had a surface of 10 m2 (paths not included). Variables analized were: yield per square meter and its components (mean fruit weigth and fruit number), days from transplant to final harvest, mean truss weigth, mean truss fruit number. Inside each treatment, mean weigth and mean fruit number of each truss were compared (with the exception of 1R24). There were not significant diferences among treatments with respect to yield or its components, but tretament 1R24 reached its final harvest statisticaly earlier than the others. This means the possibilty of more production cycles per year (till 5) and, in consequence, more productivity in an annual basis. As the number of trusses left per plant increased, the mean weigth and fruit number per truss diminished. The tomato production system with more potential of annual productivity and profitabilty was 1R24.

Two experiments, one per specie, were conducted to evaluate mungo bean (Vigna radiata) and “pipiana” squash (Cucurbita argy-rosperma) seeds as sprouts. The experimental units were 10 g of mung bean and 20 g of squash seed. Levels of three factors were tested: desinfection with NaCl (30 min; 10 and 20%); ilumination (dark and shadow; no direct light) and days after sow to harvest (5, 7 and 10 in mungo; 4, 5 and 6 in squash). The best significant trials, based on sprout yield, taste and transformation index: seed to sprout, were 10% of NaCl, darkness and harvested 7 day after sowing (das), with 45.53 g sprout yield and transformation coeficient of seed to sprout (CT) of 4.75 times; Whereas in squash the best trial was similar but harvesting at 4 das, obtaining 47.9 g of sprouts and 2.39 of CT.

The ovules of Spondias purpurea are slightly campylotropous, bitegmic, crassinucellate, pendulous, and with a special funicular pro-tuberance on a well developed funicle. During anthesis the ovules accumulated callose and lignin in a group of nucellar cells con-tiguous to the chalazal end of the embryo sac. In the field, pollination is not a limiting factor for setting fruit, and abortion of ovules and seeds is not caused by a lack of pollen. The main stage of ovule abortion occurs in preanthesis, and these abortive ovules do not develop a nucellus nor an embryo sac. A second stage of abortion occurs four to five weeks after anthesis. The total percentage of abortion of ovules varies from 55% to 84%. The mature embryo is straight with a short axis (5% to 10% of the total length of the embryo).

The content of B was determined monthly at north and south sides of the tree canopy, in leaves and autumn and winter inflorescen-ces of the ‘Colín V-33’ avocado, in order to know the seasonal variation of B. The results show that the content of B in leaves did not change with tree phenology, but values were of insufficience (39.2-48.7 μg.g-1 of dry weight). Minor content of B was registered in in-florescences than in leaves, and an apical dominance by this element was observed. Differences between B content on leaves and inflorescences were not found either north and south sides of the canopy or between autumn and winter inflorescences. The results suggest an homogeneous distribution of B in the plant through the time

They were carried out foliar sprays on cv. Hass avocado trees with different concentrations of Ca (NO3)2, which were 0% (control), 1, 2, and 3%. The nutrient content was evaluated in leaf and fruit mesocarp, as well as the sampling zone within the tree and the correlation be-tween Ca and other elements. The results obtained in leaf indicate that exists an increase in P, Ca, Zn, Mn and Mg the one which was greater than the control. Finding that the treatment at 1% was the best. In the mesocarp of the fruit it was found a drop in Zn and Mn, resulting the control the better treatment. In regard to the sampling zone within the tree, in leaf as in mesocarp were not found differences concerning this factor. It was found a positive correlation among Ca in leaf and the elements Mg and Mn, both in leaf. In the case of Ca in mesocarp of fruit, this correlated negatively with P, K, Zn and Mn of the fruit.

Evaluation of thirteen sweet orange varieties grafted on ‘Swingle’ citrumelo was curried out at the Bebedouro Citrus Experimental Station, São Paulo State, Brazil. A randomized block desing was used, with towo plantas each plot and four replications, planted in December, 1990. The results from 1994-1996 showed that the scions with the highes wolumen in m3 were ‘San Miguel’, ‘Werly Va-lencia’ and ‘Berry Valencia’, whereas those presenting the smallelst volume were ‘Folha Murcha’ and ‘Natal Murcha’, their average volume during the three cycles being 13.35, 10.56, 10.44, 4.91 and 5.20 m3, respectively. The highest production per plant was reached by ‘Telde’, ‘San Miguel’, ‘Vaccaro Bllod’ an d’Bidewells bar’, wiht 89.3, 86.0, 85.2 and 80.5 kg, respectively. The highest yied per m3 of scion was reached by: ‘Folha Murcha’, ‘Vaccaro Blood’, ‘Telde’ and ‘Valencia 1’ with 20.0, 9.8, 9.6 and 9.2 kg on average during the three years, respectively. The varieties ‘Lue Gim Gong’, ‘Natal’, ‘Valencia Late’ and ‘Valencia 2’ showed an intermediate behaviour.

In studies of the growth of plants the destruction of the organ is required to evaluate some variables, such as fresh weight (FW) and, more important, dry weight (DW). With fruit trees, like the peach tree, this procedure implies a hard and expensive work, besides the elimination of many valuable trees, considering the abundant replications that must be evaluated because of the variability of the components (twigs and stems, mainly). In this work regression models that estimate the above variables of branches and do not re-quiere the destruction of the plant were searched. The FW on branches can be estimated with the base of the volume calculated with the formulas of the cone and the truncated cone, the number of leaves (as indicator of the number of buds) and the relation between the lateral and adaxial-abaxial diameters, and models for different advance of lignification having R2 between 0.9446 and 0.9812 and C(p) quite aceptable (between 1.299 and 5, for models with 1 to 4 variables) were generated. It was found a general model that estimates the dry weight of branches (DW = -0.7484 + 0.5804 FW) and four more, one for each grade of branch hard-ness, all with R2 between 0.9802 and 0.9980 and C(p) of 2.0.