The successful production of quality container ornamental crops requires knowledge and understanding of the unique environment found in a container, and how it is affected by the physical and chemical properties of the growing medium. The fundamental aspects and importance of the most relevant physical and chemical properties in growing media are covered in this review, along with rec-ommendations for their management in the production of ornamental crops.

In order to obtain the effect in the intensive production of apple pepper (Capsicum pubescens, R., L. y P.) and reproductive beha-viour it was evaluated four shade levels (90, 70, 50, 30%) and control treatment (0% shade). Vegetative behaviour was evaluated in terms of length, diameter of the main stem; the number and length of branch of the main stem; the number and length of the shoots, the number and length of the branches; dry and fresh weight of foliage and root. Reproductive behaviour was evaluated in function of the flower number. The experiment started on August 18, 1996 to January 1997, in the Cerro de la Estrella, Mexico City, in green-house conditions and using dripping irrigation. The experiment design consisted of random blocks, with three repications. Correla-tions matrices were realized and regression equations resulted for the variables that presented the smallest regression mean square error. Six samplings were taken for the stem of three random plants for experimental unit and one destructive sampling was done in nine random plants for treatment. The development of the control plants was in disadventage and was affected by sunlight in sum-mer; plants under the 90% of shade treatment presented elongation because of the low level of sunlight, the 30 to 70% of shade treatments, promoted vegetative and reproductive development.

Effects of three concentrations of potassium on stomatal conductance and chlorophyll content were studied on three different culti-vars of amaranth (‘Azteca’, ‘Mercado’ and ‘Nepal’), 104 days after sowing. The plants were grown in pots filled with washed river sand as sustrate. Nutrient solutions with different potassium levels were applied to the sustrate; moisture was maintained at field ca-pacity. Pots were arranged in a randomized block desing, with 7 treatments and 4 replicates. Without potassium addition, the culti-vars Mercado and Nepal showed stomatal conductances of 78.0+8.9 and 103.7+13.9 mmol.m-2⋅s-1, but with 6 meq⋅liter-1 the conduc-tances were increased to 97.3+11.4 and 110.7+2.4 mmol⋅m-2⋅s-1, respectively. Higher levels of chorophyll were found in cultivars Mercado and Nepal irrigated with the same concentration of potassium. The Azteca cultivar was not affected on its stomatal conduc-tance or chlorophyll content by any of the potassium treatments.

To determine the possibility to artificially cross different and genetically distant genotypes of husk tomato (Physalis ixocarpa Brot.) and to study their combining abilities, with two wild and three cultivated genotypes an study was undertaken via a 5x5 diallel. Cros-ses were made in a greenhouse at the Universidad Autónoma Chapingo (Chapingo, Méx.) during the winter of 1993-94. Crosses and parents were evaluated in the experiment station of this institution during the summer of 1994. Only from three crosses was the-re enough seed for the diallel with direct and reciprocal crosses. This is why the studied diallel was 3x3. ‘Salamanca’ produced the highest effect of general combining ability for fruit yield at first harvest, fruit weight, plant height, and fruit volume. On the other hand, in terms of nonadditive gene action, ‘Salamanca’ x ‘Rendidora’ showed an 138.7 % of heterosis with respect to the best progenitor for fruit yield at first harvest. Taking into account the high yield and heterosis this cross must be considered as an important one in the planning of the development of a hybrid varieties.

The present study was carried with the purpose to determine the effect of different available soil moisture content (ASMC) levels of wastewater on husk tomato fruits, quantify population fluctuation of fecal coliforms and helminth eggs on fruit, as well as to evaluate the effect of sodium hypochlorite (SH), inmersions in microdyn, soil addition of green manure and chicken manure over the microor-ganisms. A randomized block design with four replications was conducted. During the first phase of the experiment, treatments T5 (80% ASMC), T4 (60% ASMC) and T3 (40% ASMC) provided the highest fruit yield 12906, 11234 and 10319 kg⋅ha-1, respectively. The fecal coliforms quantifications showed hight microbiological contamination and in minor grade with helminth eggs. During the 2nd experimental phase, it was possible to reduce fecal coliforms contamination on fruit by inmersion in SH at 20 ml⋅liter-1 of water during 20 and 25 min.

Karyotype and meiotic chromosome behavior were studied in 10 races of husk tomato (Physalis ixocarpa Brot.). The chromosome number in all genotypes was 2n=2x=24. Based on centromere position, there were metacentric (m), submetacentric (sm) and subte-locentric (st) chromosomes in three karyotypes : i) 4 m + 6 sm + 2 st; ii) 4 m + 7sm + 1 st and 4 m + 5 st + 3 st. It was observed a polymorphism in satellited chromosomes: Karyotype i) exhibited one or three sats, ii) exhibited two sats and iii) exhibited four sats. The chromosome size ranged from 1.65 to 2.77 μm. At diakinesis the observed frequency of bivalents varied among genotypes (bi-valents 6.98 to 9.40; univalents 8.78 to 9.14). The variation in chiasmata frequency per nuclei was positively correlated (r= 0.96) with frequency of bivalents and negatively (r= - 0.96) with frequency of univalents. The high frequency of diakinesis univalents did not af-fect normal segregation of chromosomes during anaphase I. Pollen viability ranged from 72.23 to 97.01%.

The research was carried out in wild mexican plum (Spondias purpurea L.). Flowers, vegetative buds and floral buds were sampled. When the floral initiation occurs four tunic layers were evident in the apical bud, the meristem is small and flat. Inflorescences appear as a protuberance in the felogen, and the buds of secondary flowers developed just under the principal flower. The secondary flow-ers follow a basipetal differentiation. The staminate flowers show rudimentary carpels and the pistillate flowers has staminodes, where the microsporal mother cells degenerate during meiosis in the prophase I. In the pistillate flowers, there is ovary and embryo sac development; nevertheless some of them present abortion.

Plum pox or sharka, a viral disease induced by plum pox potyvirus, severely affects the production of Prunus species in Europe. This disease was detected in 1993 in Chile and so far, it has not been reported in any other American country. Due to the economic impact of this disease in countries where it is prevalent as well as to the commercial trade with regions that have, or may potentially have this pathogen, it is of great concern for the Plant Regulatory Mexican System. Latest developments concerning the biology, epidemiology, and disease management are provided in this paper to assure awareness among growers and professionals involved with Prunus production. Knowledge and understanding of this virus will be fundamental to guaranty success in any attempt to detect and eradicate it if eventually arrives to México.

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