The effect of lead-contaminated soil in hybrid squash “Termo” (Cucurbita pepo L.) was studied. The hybrid was grown in blackpolyethylene bags in the field. The variables evaluated were distribution of biomass production, plant height, chlorophyll content and lead accu¬mulation in root, stem, leaf, flowers and fruits. The treatments were 0, 65, 300 and 1000 ppm lead applied to soil through Pb(NO3)2. The randomized complete blockdesign with six replicates was used, and the experimental unit was a blackpolyethylene bag with two plants. Plant height and chlorophyll content evaluations were performed 50 days after transplantation, and fresh weight, dry weight and lead accumulation 52 days after transplantation. It was observed that plant height was significantly lower when lead was applied at any dose. The highest biomass accumulation in root and stem was produced with 300 ppm and in fruit with 65 ppm lead, while total biomass and SPAD units (chlorophyll) were not affected. In the case of edible structures, flowers had higher metal accumulation than fruits. Flowers showed the highest lead accumulation when lead doses were low. This suggests that it is appropriate to assess the content of heavy metals in agricultural products for human consumption, even when they come, supposedly, from uncontaminated soils.

Mexico is considered the domestication center of tomato (Lycopersicon esculentum Mill.). However, there is scarce information available to allow the use of native forms of this species. The objective of this study was to evaluate some characteristics of agronomic interest of seven genotypes from the states of Guerrero and Puebla, grown hydroponically in a greenhouse, and compare them with a commercial “cherry” tomato hybrid (H-790). Days to flowering and days to maturity in the first cluster, plant height, stem diameter, fruit length and width, number of loculi and fruit weight were assessed. Number of fruits and yield in six clusters were also assessed. In the characteristics days to flowering and days to maturity in the first cluster, plant height, stem diameter, fruit length and width, number of loculi, fruit weight and yield, at least one native genotype exceeded (P ≤ 0.05) the control (H-790). In number of fruits in six clusters, the JCPRV-43 and JCPRV-05 genotypes were similar (P ≤ 0.05) to the control (43.9). Stem diameter was the only characteristic where the control (18.1 mm) was better (P ≤ 0.05) compared to the native genotypes evaluated. It is concluded that owing to their agronomic characteristics, most of the assessed native genotypes can be cultivated as “cherry” tomatoes, and some of them could be utilized as a source of germplasm in breeding programs of this species.

In Argentina, lettuce (Lactuca sativa L.) is the most common vegetable used in salads, while amaranth (Amaranthus mantegazzianus Pass.) is characterized by its high production of green matter, with high protein and mineral levels; both species are considered accumula¬tors of nitrate, so in order to avoid health problems for the consumer, the European Commission regulates the levels of nitrate in lettuce. In order to assess the accumulation of nitrates in both species and evaluate the protein levels and dry matter content, a trial was conducted at the Faculty of Agronomy, UNLPam, Santa Rosa, La Pampa, Argentina. On December 28, 2009, crisp lettuce was transplanted and amaranth was sown. Four levels of fertilization were added for both species: 1) Compost base: 10 dm3•m-2 moderately composted manure, 2) Double Compost: 20 dm3•m-2 moderately composted manure, 3) Compost base + 30 kg•ha-1 urea and 4) Compost base + 60 kg•ha-1 urea. An experimental design of randomized complete blocks with five replications was employed; significant differences in nitrate levels between species and levels of fertilization were obtained. The values in lettuce were 2.9 % dry basis and 2,634 mg•kg-1 fresh-1 and in amaranth 4.1 and 4,764, respectively. In the case of fertilization levels, compost base with 10 dm3•m-2 manure differed from other treatments, for both species studied. Under evaluation conditions, amaranth exceeded the thresholds stipulated by the European Commission. Protein levels showed significant differences between species (20.2 % in lettuce and 24.8 % in amaranth).

The use of antagonistic yeasts to control diseases in postharvest apples reduces environmental risks. Knowing the modes of action of the antagonists is essential in order to use them at a commercial level. Two modes of action of four yeast strains against Penicillium expansum Link were studied. Antibiosis was evaluated by means of dual cultures and antibiograms, and nutrient competition using culture microplates containing semipermeable polytetraflourethylene (PTFE) filters. The absence of inhibition haloes in the dual cultures and in antibiograms showed the antagonists’ inability to produce antibiotics. Germination of P. expansum conidia was about 95 % in all of the different growing media in the microplates when antagonistic yeasts were absent. However, it significantly declined (anywhere from 10 to 20 %) in the presence of any of the yeasts. When the yeasts were separated from the fungus by means of the filter, germination of P. expansum only increased significantly with the strain 22-111 (Pichia guilliermondii) in all the media, obtaining a low correlation coefficient for the germination index of both treatments (r = -0.303), which assumes a direct interaction between the antagonist and the fungus. In contrast, with strains 38-432, 24-23a and 22-24a conidia germination was very similar to that obtained when the yeasts were directly in contact with conidia (r = 0,999 and r = 0.995, respectively), which suggests that nutrient competition is their main code of action.

The quality of cut flowers is affected due to long periods of exposure to warm temperatures, water stress and mechanical damages. Several studies have identified technical issues to prolong the life of cut flowers, standing out the use of preservative solutions which may also inhibit ethylene biosynthesis. Cobalt chloride (Co) effects on weight, consumption of solution, SPAD units in leaves, content of nitrogen, cobalt, potassium, calcium, magnesium and iron, and postharvest life in stems of ‘Star Gazer’ and ‘Star Fighter’ Oriental Hybrid Lilium were evaluated. Floral stems were obtained from Villa Guerrero, Estado de México, and transported in dry conditions to the laboratory, where a 2 x 5 factorial experiment in a completely randomized design was conducted. Solutions containing sucrose as a carbon source at 4 % and the following Co concentrations: 0.0, 0.1, 0.2, 0.4 and 0.8 mM were used. This establishes that 0.1 and 0.2 mM Co delayed the symptoms of senescence in Lilium stems.

In Mexico most of sapote mamey (Pouteria sapota (Jacq.) H. E. Moore and Stearn) trees have a length over 10 m, making difficult to harvest their fruits, therefore fruits are often damaged. Fruit preservation in different packaging causes damage to varying degrees. We evaluated five postharvest handling techniques in terms of postharvest fruit quality: T1, fruits harvested without damages, individually pac-ked in carton boxes; T2, fruits dropped from 10 m high, captured in jute sacks, packed in bulk using plastic boxes; T3, fruits dropped from 10 m high on a mattress and packed in bulk using plastic boxes; T4, fruits dropped from 4 m high to moisture soil and packed in bulk using plastic boxes; and T5, fruits dropped from 10 m high, caught and packed in jute sacks. Fruits were stored at room temperature (25 ± 1 °C); fruit quality was evaluated on days 1, 3, 5, 7 and 9 after harvest (DAH). Treatment T1 recorded the highest firmness, the lowest pectin methylesterase activity and total soluble solids content (°Brix); and the lowest changes in lightness (L*), and chroma(C) in comparison with treatments T4 and T5 (7 and 9 DAH). Differences in hue angle (H) were observed after 9 day (DAH), where treatment T1 showed higher values than T5. Malic acid percent and weight loss did not show significant differences among treatments.