RESUMEN:

ABSTRACT. Consumer awareness about health beneficial effects of secondary metabolites from fruits has increased interest in fruits with high levels of these compounds. Globally, non-traditional fruits are generating growing interest for their nutraceutical potential. Uruguay is a primary center of origin of several species of fruits with unique flavor, aroma, appearance and nutritional properties. Those traits have led to their domestication and development as commercial crops. Involved species Guayabo del Pais (Acca selowiana (Berg.) Burret); Pitanga (Eugenia uniflora L.); Arazá (Psidium cattleianum Wis) and Guaviyú (Myrcianthes pungens (Berg) Legr.) belong to the family Myrtaceae. The objective of this work was to evaluate total polyphenol (TP) content, total anthocyanins (TA) and the free radical scavenging activity (antioxidant capacity, AC) of native fruits in regard to nutraceutical potential. Guaviyú showed a range between 158-349 mg TP /100 g fresh weight; 19-75 of AC; 51-132 mg anthocyanins/100 g fresh weight. Values for Pitanga were 252-575 mg TP/100 g; 14-34 AC; 83-110 mg of TA. Arazá gave values ranging between 132-644 mg of TP/100 g; 33-68 of AC and 12-17 mg of TA. Guayabo del Pais showed a range of 129-648 mg of TP/100 g and 24-82 for the AC. This study indicated that Uruguayan native fruits have potential as valuable sources of antioxidant components. Data illustrated interesting variability both at the intra-species level as well as among different species under study, indicating a significant input for the breeding of commercial cultivars derived from native Uruguayan germplasm.

RESUMEN:

ABSTRACT. High midday temperatures in subtropical citrus growing regions can lead to excessively high leaf temperature (Tlf) and large leaf-to-air vapor pressure difference (D) in sun exposed leaves. This heat stress reduced net CO 2 assimilation (AC), growth, fruit yield and quality. 50% shading reduced average mid-day Tlf and increased AC, stomatal conductance (gs) and leaf water use efficiency, but decreased the internal concentration of CO 2 (Ci) in the mesophyll compared with sun-exposed trees throughout the season. However, shade had little effect on leaf transpiration. Heat stress increased non-stomatal limitations to AC in the mesophyll of sunlit leaves that were greater than stomatal limitations. Shade treatment reduced leaf carbohydrates but did not affect tree canopy volume or fruit size. Shading in the late fall until harvest increased orange yield and juice content more than compensated for the lower total soluble sugars (TSS) and resulted in net increases in TSS per tree. Shaded 'Navel' orange fruit developed better external color but lower TSS than sunexposed fruit. Shade did not affect orange fruit yields. In warm citrus producing regions, shading could improve photosynthesis and fruit quality especially in young trees where most of the leaves are exposed to direct sunlight. Improved fruit color, yield and/or TSS per hectare of high-value varieties could offset the costs of particle film sprays or shading in commercial orchards.

RESUMEN:

ABSTRACT. Supplementary irrigation in Citrus sinensis (L.) Osbeck 'Spring' navel and Citrus unshiu Marcow trees were studied according to fruit development stages on the northwestern region of Uruguay (32° S, 58° W) from 2000 to 2009. The effective rainfall (Pe) variability between consecutive years is bigger than the reference evapotranspiration (ETo) variability; despite the annual water balance seems to be adequate for excellent yields. Water deficit occurs at different intensities during fruit growth stages I, II and III. Supplementary irrigation was necessary in 'Spring' navel and satsuma 'Owari' during stage I and II, although 'Spring' navel requires occasionally irrigation during stage III. The major irrigation impact was to increase the fruit weight but not the number of fruits. The increment in the marketable fruit was related to the best size distribution of the fruits, also it was verified an attenuation on the alternate bearing. An inverse and significant relationship was found between the ETo/Pe ratio and the relative yield reduction in the stage I (R 2=0.73) and in stage II (R 2= 0.91); and between the ETo/Pe and the fruit weight in satsuma 'Owari', (R 2= 0.56) (R 2= 0.85) respectively. The yield reduction between trees without irrigation and all year irrigated represents 20% in 'Spring' navel and 40% in satsuma 'Owari'. Maximum water application of 1000-1200 m 3 ha -1 was required for irrigated trees on stage I and between 1800-2000 m 3 ha -1 for the stages I+II. In a close up view, supplementary water is required to reach maximum marketable yield and alternate bearing reduction in citrus production in temperate conditions.

RESUMEN:

ABSTRACT. Fertilizers application in irrigation water (Fertigation) is considered to be an efficient method of fertilizing fruit trees, but some information is needed on the relationship between irrigation depth and nitrogen (N). The objective of this work was to know the response of apple tree to different levels of irrigation depth based on maximum crop evapotranspiration (ET c) and N fertilization. The experiment was carried out in 2008-09 summer growing season of apple trees Malus x domestica Borkh 'Gala', with a row spacing of 4×1 m (2500 pl. ha -1), seven years old, on the M9 rootstock, in a silt loam soil. The experimental design was split plots with two factors, with four complete randomized blocks. A main plot was irrigation depth according ET c:0% (only rainfall), 50, 75 and 100% of the ET c, and a submain plot was three N fertilization levels:0, 110 and 220 kg N ha -1. Soil water content (0-20 cm of soil depth), leaf minerals content (N, P, K, Ca, Mg), trunk section diameter, fruit total number, fruit diameter, weight, colour and firmness were measured. Different leaf mineral contents for N, K and P according irrigation depth were observed at pre-harvest. Nitrogen fertilization, however, only affected the leaf N content. Results indicate that it was a significant differences in yield, fruit diameter and weight response to the supplemental irrigation application. Yield for irrigation at 100% ET c, reached 40 t ha -1 and, for non-irrigation plants 27 t ha -1. Fruit diameters average was 71.53 and 62.69 mm for 100% ET c and non-irrigation treatments, respectively; and there were 70.97 and 67.88 mm for 220 kg N ha -1 and non-nitrogen treatments respectively. The differences in N fertilization on yield and fruit quality variables were not observed. Nitrogen application rates only affected fruit diameter but not yield.

RESUMEN:

ABSTRACT. Uruguay is one of the countries with favorable conditions for the development of olive tree culture. Olive oil is mainly composed by triglycerides, formed by different fatty acids which confer a main portion of its properties. Its acidic composition varies mainly with variety, local climatic conditions and fruit maturity degree. The objective of this work is to know the influence of fruit maturity stages on the fatty acid profile in the ?Arbequina? and ?Picual? varieties cultivated in Uruguay. According to skin and flesh color, fruits at six stages of maturity were used for extraction of lipids and percent fatty acid composition was determined through gas chromatography on methylated byproducts, palmitic, palmitoleic, estearic, oleic, linoleic and linolenic. Across different maturity stages and on ?Arbequina? and ?Picual? the C16:0 was constant and showed a value of 20 and 19.5% respectively, showing no significant changes. The C16:1 and C18:2 significantly increased from the M1 to the M6 stage in ?Arbequina? and ?Picual? (C16:1 increased from 1.9 to 3.3 and 1.5 to 2.2 respectively; C18:2 from 8.0 to 13.3 and 1.6 to 6.5% respectively). C18:1 and of C18:3 levels significantly decreased in oils originated from fruits with more advanced maturity (C18:1 varied from 67 to 60 and 74 to 70 respectively; C18:3 varied from 0.6 to 0.4 and 0.7 to 0.5%, respectively). With advancing maturity, C18:0 level decreased in ?Arbequina? (1.7 to 1.4%) and increased in ?Picual? (1.8 to 2.5%), both showing significant variations. With advancing maturity and on both varieties, ratios between monounsaturated and polyunsaturated fatty acids decreased, and the decrease was greater in ?Picual?. Focusing on the potential oil quality, preliminary data emphasize the importance of understanding the effect of maturity stages as related to the development of olive harvest indexes.

RESUMEN:

ABSTRACT. The strawberry fruit production in Uruguay is mainly dedicated to the internal fresh market but there are some experiences of exportation to regional and off shore countries. The crop is done in the annual hill system without the use of methyl bromide and the mean yield is about 40 t/ha. Main crop areas are located in the Northwest (Salto, 31°S) and in the South (San José, 34°S). The winter and early spring fruit production is obtained in the Northwest area with crops under low and high tunnels using short day cultivars like 'INIA Yvahé', 'INIA Arazá' and 'Earlibrite'. Transplants are locally produced in this area in greenhouse nurseries. The Southern area produces fruit in the spring with open field crops using short day cultivars like 'Camarosa' and 'Camino Real' and in the summer with day neutral cultivars like 'Aromas' and 'Seascape'. Frigo-transplants of the introduced cultivars are imported from Spain and USA. Problems of adaptation to the climatic and agronomic conditions of Uruguay have been observed in the introduced cultivars. This was translated to low yields, low fruit quality and susceptibility to diseases prevalent in the regions of production. For that reason the Strawberry Breeding Project of INIA Uruguay aims to obtain cultivars adapted to the different environments of the country. The products of this breeding project, initiated in 1992, are the cultivars 'INIA Arazá', released in 2002, with high early yield and resistance to anthracnose; 'INIA Yvahé', released in 2004, with early yield and excellent flavor, resistant to anthracnose; 'INIA Guenoa', released in 2007, with high yield, excellent fruit quality, better adapted to high tunnels and resistant to powdery mildew; 'INIA Yvapitá', to be released in 2008 for open field crop, recommended for organic production and processing, resistant to several soil, foliage and fruit diseases. New selections are in different stages of evaluation. A method of propagation was adjusted to ensure appropriated quality of the transplants.