Use of hydroponic systems to grow lettuce has increased continuously in Chile, because of the convenience of presentation and appearance of the final produce. Moreover, for fresh-cut use, lettuce produced by hydroponics is cleaner, more homogeneous and less contaminated. There are some concerns to indicate that the costs involved in its production will adversely affect profit. A comparative study was conducted using available data on growing conditions, production cost, use of water and percentage of produce waste. Hydroponic-grown lettuce is usually sold at 20 to 40% higher prices at market, compared with the same type of soil grown lettuce, both at equal presentation, including individually wrapped in plastic bags. Economic return in the hydroponic crop is US$ 170 per dollar invested in water, whereas, in the soil-grown lettuce, it is US$ 4 per dollar invested in water.

The development of baby leaf vegetables has increased due to its fast processing operations and its attractiveness as a gourmet product. Despite these benefits, the high level of nitrates in tissues create serious health problems. To reduce these levels, monitoring dose of nitrogen fertilization and harvest time are essential. The objective of this study was to evaluate the nitrate content in two cultivars of Swiss chard (baby leaf) by modifying the nitrgen content of the nutrient solution and time of harvest. Two independent trials were performed, where the nitrate content, nitrate reductase activity (NRA) and quality parameters such as color were measured in two cultivars of Swiss chard (Beta vulgaris L. cicla) with a red (E1) and orange petiole (E2), respectively. A randomized split-plot design was performed, where the main plot corresponded to N2 dose (100, 200, 300 and 400 mg N2 L-1) and subplots of different harvest times (9, 12 and 21 h). In E1, the time of harvest was the main factor on the nitrate content, where high N2 levels were found at 8 h, and low levels at 12 and 21 h, probably due to different carbohydrate levels and reducing power available to activate the NRA, which had its maximal activity at 12 and 21 h. In E2, the content of nitrates showed a high accumulation in midrib compared to lamina. In both trials, time of harvest affected the nitrate content in lamina such that early hours should be chosen to obtain low nitrate accumulation.

'Thompson Seedless' (TS) table grape could be harvested in Chile from October to March. At the Limari valley, an early production northern area, TS may have up to 45 days difference in harvesting time, in a range less than 150 km up and down the valley. We postulate that night temperature affects acids accumulation and degradation in grape berries. For this objective, 'Thompson Seedless grapevines, conducted in over head trellis system (Parron), were covered with plastic and heated overnight. Leaf and berry temperature were monitored, and berries were collected weekly and checked for soluble solids and titratable acidity, and growth (polar and equatorial diameters). Night temperature fluctuates between 2.5 degrees C to 7.0 degrees C; the average minimum night temperature of heated vines was 15.5 degrees C, while in the non-heated vines was 12.6 degrees C. In both, titratable acidity was similar up to about 10 days after veraison; then was always lower in the non-heated vines while sugar was always higher in temperature treated berries. As a consequence of that SS/acid ratio of 20:1 give treated berries an advance of 5 days in harvest. Also average berry weigh 0.61 g more that untreated ones. We conclude that, lower night temperature in early production areas in Chile, affects the SS/acid harvest index and hence, the date of harvest.

The effect of avocado cold storage on the occurrence of post-harvest physiological disorders was determined for different harvest dates, storage temperatures and storage periods. Twelve 8-year-old trees were used, with three samplings being performed every month as of January 18, 2006. Harvested avocado samples were stored for 10, 20 and 30 days at 4, 6 and 9oC and evaluated after a storage period at 20oC, once the fruit reached 0.5 0.9 k-f firmness. Evaluated parameters were fibre browning, internal browning intensity, percentage of flesh with internal browning, percentage of external spots and seriousness of grey spots. For the different parameters, avocado fruits were evaluated by means of a grading scale. The results were analyzed by ANOVA according to a factorial randomized design of 3 x 3 x 3 (harvest dates x storage periods x storage temperatures) and by the Kruskall-Wallis test when the data did not comply with the assumptions of normality and equality of variance. The results obtained indicate that for fibre browning differences were detected among treatments, attributed to harvest dates, storage periods and storage temperatures, with harvest dates as determining factors. Regarding the intensity of internal browning, percentage of pulp with internal browning, percentage of outer spots and seriousness of grey spots, no statistically significant differences among treatments were found.

Se estudió el efecto de la atmósfera modificada (AM) y la aplicación de película de quitosano en la calidad y vida postcosecha de pepino dulce (Solanum muricatum Ait).Se cosechó fruta en Ovalle, IV Región, dirigida a seleccionar dos estados de madurez, M1 y M2 basados en tamaño y color de los frutos.Los tratamientos de AM se lograron mediante diferentes empaques, bolsas de polietileno de distintas características de permeabilidad y otro con la aplicación de quitosano.Se almacenaron a 8 °C y 85% HR por 35 días.La fruta se evaluó a los 21 y 35 días y luego de 3 días adicionales a 18 ºC (simulando período de comercialización).Las variables medidas en cada oportunidad fueron deshidratación, color, firmeza, sólidos solubles, pH, acidez titulable y aceptabilidad.También se registraron las concentraciones de O 2 , CO 2 y etileno.La deshidratación se minimizó con los tratamientos con bolsas de polietileno, mientras que la película de quitosano no fue barrera contra la deshidratación.Los frutos de los tratamientos que contemplaron bolsas de polietileno selladas presentaron mayor firmeza y retención del color inicial.Mayor aceptación obtuvieron el testigo y los pepinos dulces en bolsas perforadas.

An experiment was set up to elucidate the causes of differences in harvest time in the adjacent grape-growing areas of Rapel and Sotaqui in the Limari Valley, Chile. Berry samples of `Flame Seedless' were collected from each area, from 10 days after last GA spray until harvest (December to February). Soluble solids (SS), titrable acidity (TA), and SS/TA ratios were analyzed and days from full bloom to harvest, growing degree days, and ambient temperatures were recorded. In Rapel, full bloom was 25 Sept.; the harvest by 16 °Brix, started on 3 Jan., and the harvest by 20:1 SS/TA ratio (min. 15.5 °Brix) on 28 Dec. (11, 16, and 24 days earlier, respectively, than Sotaqui). Degree-days (DD) at harvest (16 °Brix) were 1058 in Rapel and 837 DD in Sotaqui. In the last 50 days prior to harvest, berry acidity was always lower in Rapel, decreasing from 0.87% to 0.47%, while in Sotaqui berry acidity decreased from 1.96% to 0.86%. From 20 Dec. to 2 Jan., the acidity did not decrease significantly (1.96% to 1.84%), but in the next 3 weeks decreased to 0.68%. This difference in the rate of acid degradation is related to the increase in minimum night temperatures in this same period of berry growth. It is concluded that the minimum temperature-dependent rate of organic acid degradation is the main factor influencing the SS/TA harvest index parameter.

Ripe nectarine fruits cv. 'Flamekist' (firmness 9N) presenting the physiological disorder woolliness and healthy fruits were selected for a cytochemical study of the mesocarp cells. Affected and healthy mesocarp tissue were infiltrated with glycol methacrylate resin. The Schiff's reagent with periodic acid pre-treatment was used to show total insoluble carbohydrates. The beta-1,4 glucans and pectin were located using Calcofluor white MR2 and Coriphosphine, respectively. The healthy as well as the woolly fruit showed intercellular spaces in the parenchyma tissue, due to the separation of adjacent cells. There was no difference in the cell walls (cellulose fraction) of both woolly and healthy cells, since both presented intense staining, while intercellular spaces did not stain. Samples stained with Coriphosphine showed marked differences between woolly and healthy tissue. In both tissues cell walls appear clearly outlined, but in woolly tissue the intensity of the fluorescence was higher. Healthy tissue did not show stain in the intercellular spaces, while in the woolly tissue many of the intercellular spaces appeared intensely fluorescent. This indicates the accumulation of pectic substances in the cell walls and in the intercellular spaces in woolly tissue.

The effect of modified atmosphere (MA) and a chitosan layer coating over the fruit surface was studied on the postharvest life of “Pepino dulce” or Cachun (Solanum muricatum Ait) fruits. The fruit was harvested in Ovalle (IV Region, Chile) at two maturity stages, M1 and M2, based in ground color and size. MA treatments were induced by the use of sealed polyethylene film bags with different gas permeability. Then the fruit was stored at 8 oC and 85-90% RH for 35 days. Evaluation were performed at 21 and 35 days of storage and after a period of 3 days at 18 oC (simulate shelf life). The variables measured were: soluble solids, pH, titratable acidity. CO2, O2 and ethylene concentration were also measured. For acceptability the fruit was submitted to a panel. Results showed a reduction of the dehydration of the fruit in the sealed polyethylene bags, but treatment using polyethylene bags presented higher pulp firmness, and maintenance of initial color. The chitosan coating layer on the fruit surface, was not enough to avoid dehydration. The higher acceptance was obtained by check fruit and by fruit in the perforated polyethylene bags.