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- A investigação na Escola Superior Agrária de Elvas – potencialidades e estrangulamentosPublication . Barradas, Gonçalo; Farinha, N.; Nunes, José
- Adaptacao de 6 variedades de gossypium hirsutum l. A o regadio do caia. Analises do crecimiento, producao e qualidade da fibraPublication . Barradas, Gonçalo Júdice Pargana AntunesCon el presente trabajo se pretende contribuir para el estudio del crecimiento, producción y calidad de la fibra de Gossypium hirsutum L., cultivado en condiciones ecológicas en el perímetro de riego del Caia (Alentejo, Portugal). Con este objetivo instalamos un ensayo con 6 variedades ('Carmen', 'Celia', 'Crema', 'Flora', 'Lacta' e 'Sonia'), de ciclo medio-curto a medio-longo, sembradas en 3 fechas de siembra (19/04, 30/04 y 16/05 en 2002, 20/03, 3/04 y 17/04 en 2003), en la Finca de Comenda (38º 54’ N, 7º 03’ W). Se han verificado diferencias entre las variedades en el porcentaje de germinación y en los testes frío (18ºC, 7 días) y standard (30ºC, 4 días), registrando las semillas de ‘Celia’ y ‘Sonia’ mayores índices de vigor. La tasa de crecimiento relativa presentó una marcada tendencia decreciente, justo desde los primeros estadios de desarrollo de las plantas, mientras que la tasa neta de asimilación presentó una tendencia creciente hasta finales de Julio, decreciendo después continuamente hasta el final del ciclo, con lo incremento del índice de área foliar (LAI) y la reducción de la temperatura y del número de horas de luz. No se han observado diferencias entre las variedades o fechas de siembra en los periodos del año en que se registraron los valores máximos de LAI y del índice de crecimiento del cultivo (CGR), observándose LAI máximo con un desfase de 10 a 31 días relativamente a CGR máximo. El nudo de inserción de la primera rama fructífera (NFFB) inferior se encontró en la variedad ‘Celia’ y en la fecha de siembra más precoz. El cutout (NAWF = 5) se verificó entre el 20 de Julio (‘Celia’ en la siembra precoz) y 19 de Agosto (‘Flora’ en la siembra tardía), reduciéndose con el retraso de la fecha de siembra, en todas las variedades, el número de días después siembra (DAS) hasta el cutout. Los daños provocados por Earias sp. y Heliothis/Helicoverpa, plagas que determinaron una elevada pérdida precoz de formas fructíferas, resultaron en números de DAS hasta NAWF= 5 relativamente elevados, característicos de plantas sin una carga fructífera suficiente para transferir los asimilados disponibles del crecimiento vegetativo. Esta circunstancia, asociada a condiciones térmicas poco favorables al crecimiento y maduración de las cápsulas formadas más tarde, resultaran en reducidos índices de cosecha y bajas retenciones, principalmente en las primeras posiciones de fructificación y en los simpódios localizados más en bajo en la canópia. Se han observado diferencias significativas en la producción de algodón bruto entre variedades, con la variedad 'Celia', aquella que también evidenció más caracteres de precocidad, a atingir producciones más elevadas. Lo retraso de la fecha de siembra, aunque permita mejores condiciones para la emergencia y crecimiento inicial de las plantas, reduce la estación de crecimiento disponible, tiendo al final un efecto negativo en la producción de algodón-bruto. Así, la producción de algodón en la región del Caia exige la utilización de variedades de ciclo corto y fechas de siembra precoces, sendo decisivo conseguir una elevada retención de cápsulas en las primeras posiciones y ramas simpodiales para que lo periodo de crecimiento y maduración de las cápsulas aún coincida con condiciones ambientales favorables. No se verificaran diferencias significativas, entre variedades y fechas de siembra, en la clasificación de grado de color de las fibras producidas, aunque se tengan observado diferencias en algunos de los índices de calidad comercial y tecnológica. En la actual moldura de precios e ayudas de la Unión Europea, las productividades más elevadas se sitúan muy cerca del umbral de rentabilidad del cultivo.
- Seed weight, seed vigor index and field emergence in six upland cotton cultivars.Publication . Barradas, Gonçalo; Lopez-Bellido, Rafael J.In regions where a short growing season is combined with low soil temperatures at sowing, field emergence and stand establishment is one of the most critical stages in cotton production. This study evaluates the relations between seed weight, seed vigor index and field emergence on 6 upland cotton (Gossypium hirsutum L.) genotypes, grown at Alentejo (Portugal). Leaf area per cotyledon, cotyledons to total leaf area and to total dry weight ratios were also analyzed. Seed vigor index, the sum of cold and standard germination tests, showed significant differences between genotypes, and different year to year soil temperatures had a significant impact on seedling emergence. No significant correlations were found between field emergence and seed weight or seed vigor index. However, poor positive linear relationships were found between seed weight and seed vigor index, as well as between standard test and field emergence. Probably, the expected impact of seed quality on field emergence was overlapped or confused by the influence of other factors (soil crusting) than temperature physical stress exerted over seeds. Cotyledons per total leaf area and dry weight represent important proportions of the entire plants during the relatively long seedling period often observed in the cotton crop grown on marginal spring weather conditions.
- Genotype and planting date effects on cotton growth and production under south Portugal conditions – II. MonitoringPublication . Barradas, Gonçalo; Lopez-Bellido, Rafael J.Monitoring is a frequent practice in the high-yielding cotton producing regions, furnishing precious information to decision making during the growing season and contributing to understand growth and development of cotton plants. The aim of this work was to determine the influence of cultivar maturity type and planting date on the main monitoring indexes: plant height (H), number of main-stem nodes (MSN), height-to-node ratio (HNR) and number of nodes above white flower (NAWF). Six genotypes and three sowing times were studied in one field experiment over two seasons at Comenda Experimental Station, Alentejo, Portugal. Best regressions of H and MSN to accumulated degree days (DD) along the season were quadratic models, with significant differences between genotypes and years. Consequently, heat unit’s requirements per each new cm height and new main-stem node (plastochrons) increase linearly. Between genotype H differences were find just after first-flower (550 DD), whilst MSN differences were find only after first open boll (1000 DD). Both differences emphasize until the end of the season. Inter-annual differences were also find in H, at first-flower (500 DD) and in MSN, a bit earlier (400 DD). No planting date influence on H or MSN were detected. Best regressions of HNR to DD were inverse models, also with significant differences between genotypes and years. ‘Celia’ and early planting dates presented lower NFFB. Behavior of NAWF since first-flower to cutout (NAWF = 5) was well explained by linear models, regression coefficients (NAWF decrease per day) showed only between genotype differences. Contradictory signs of maturation types were find. Low H and MSN plastochrons and low final vigor index suggests precocity but, in contrary, relatively high NFFB, initial vigor index, final H and high number of days to cutout, suggests late maturing tendencies of our studied cultivars as a whole. Planting date can be underlined as a management practice with relatively low influence on H, MSN, HNR and NAWF evolution. However, especial attention must be given on the influence of planting date on NFFB, once this monitoring index is strikingly linked with precocity, feature particularly important for regions with growing season duration constrains. Further annual monitoring data and analysis is necessary in order to allow their use as decision making tools available to the main cotton producing regions of southern Iberian Peninsula.
- Genotype and planting date effects on cotton growth and production under south Portugal conditions. III. Boll set percentage, boll location, yield and lint quality.Publication . Barradas, Gonçalo; Lopez-Bellido, Rafael J.Assimilate diversion of vegetative growth, reinforced by inadequate temperatures to growth and maturation of bolls later set in season, resulted in poor harvest indexes and low retention, mainly at the first fruit positions and on lower fruiting branches. Significant differences of seed-cotton production between genotypes were observed, and higher values were attained by variety Celia, presenting more short season characters. The delaying of the planting date, while allowing better emergence and initial growth of the plants, shorten the available growing season and has a negative impact on seed cotton production. Thus, in Caia region, short season cultivars and early planting dates are best suited to cotton production, also being important to achieve high boll retention in the first positions and fruiting branches, in order to approach the boll growth and maturing period with more favourable environmental conditions. Fiber color grading shows no significant differences between varieties and planting dates, although differences were found in some of the commercial and technological quality measurements.
- Genotype and planting date effects on cotton growth and production under south Portugal conditions – I. Phenology and growth analysisPublication . Barradas, Gonçalo; Lopez-Bellido, Rafael J.Genotype earliness and date of sowing are two of the most critical aspects in the management of cotton (Gossypium hirsutum L.) in Mediterranean climates, where low temperatures at sowing and low temperatures and raining during boll period and harvest are the main weather constrains of the season length. The aim of this work was to determine the influence of cultivar maturity type and planting date on phenology and growth indexes. Six genotypes and three sowing times were studied in one field experiment conducted in 2002 and 2003 at Comenda Experimental Station, Alentejo, Portugal. No significant differences were accounted between genotypes in each phenological phase periods and in the whole growing season durations. Inversely, planting date delay had a clear impact on shortening of some phenological periods, namely, planting-emergence (-7.5 days), emergence-first square (-19 days) and first flower-first open boll (-15.5 days). The poor heat unit accumulation and unfavorable high-day and lownight temperatures registered after 15 August deeply affected the boll period duration, which surpass the standards higher limit intervals referred for California and Andalusia. Logistic growth asymptote (A) varied significantly with genotype (64.9 to 229.5 g plant-1) and year (84.1 to 165.6 5 g plant-1) but without any regular pattern between planting dates. The number of days after planting to reach maximum growth rate (C) decreased significantly with planting date delay (122.8 to 98.7 DAP) and varied significantly between both years (104.6 to 117.7 DAP). In contrary, the B constant (maximum relative growth rate) experienced no significant differences between the two factors in study (0.075 g g-1 day-1). Genotype and planting date had significant impacts on RGR (0.065 to 0.105 g g-1 day-1) and NAR (8 to 13 g m-2 day-1), in the beginning of the season and on G (1.7 to 3.4 g plant-1 day-1), LAI (2.6 to 4.6) and GCR (13.1 to 26.7 g m-2 day-1) in the mid and late season. The two former growth indexes reach higher values in the early growth stages, decreasing deeply thereafter until the end of the season. On contrary G, LAI and CGR presented a bell shaped distribution pattern along the season, with peak CGR taking place 15 to 30 days after the beginning of the flowering period and peak LAI 22 to 30 days after peak CGR. However, data analyses of those growth indexes reveal inconsistent variation patterns among the two studied factors. It was concluded that further studies using a larger range of maturity type cultivars are necessary in order to provide valuable phenological and growth indexes baseline values for cotton grown in the southern Iberian Peninsula.
- Border Effect in Iberian Interregional TradePublication . Mourato, Joaquim; Ferreira, Ricardo Carvalho BrunoRegardless of their formal existence, borders do have an effect of diminishing trade. The reduction that the existence of a border causes on potential trade flows is classified as “border effect”. The present paper provides an estimation of such effect on the Portugal -Spain border. For this, interregional trade relations are considered. All 20 peninsular NUTII regions are concerned. Data used are the interregional Iberian trade matrices provided in Ferreira (2008). A model for these flows is conducted using, among several other explaining factors, the existence of a national border between regions. Thus the border effect is predicted. On this paper we provide an estimation of border effects by economic sectors, showing that different industries experience in different manners the consequences of borders
- Jatropha curcas, a promising energy crop for MozambiquePublication . Suzana Ferreira-Dias; RODRIGUES, JOANA; Miranda, Isabel; Gominho, Jorge; Vasconcelos, Manuel; Barradas, Gonçalo; Pereira, H.; Bianchi de Aguiar, F
- A rede de ensino superior em Portugal – perspetiva institucionalPublication . Mourato, JoaquimO desafio de tecer algumas considerações sobre o sistema de ensino superior português e a sua rede, é um tema aliciante mas assaz complexo, sobretudo dada a ponderação das reflexões conflituantes suscitadas nesta área. A necessidade da reforma do ensino superior em Portugal é uma das temáticas mais debatidas nos últimos anos pela sociedade portuguesa. Este assunto tem presença obrigatória em todos os programas de governo da última década e faz parte integrante dos discursos dos dirigentes das instituições de ensino superior e das associações estudantis, bem como de académicos e pensadores. A comprovar estes factos constata-se o aumento de teses académicas e publicações nesta área.
- Variability in oil content and composition and storage stability of seeds from Jatropha curcas L. grown in MozambiquePublication . Rodrigues, Joana; Miranda, Isabel; Gominho, Jorge; Vasconcelos, Manuel; Barradas, Gonçalo; Bianchi-de-Aguiar, Fernando; Ferreira-Dias, Suzana; Pereira, H.This study evaluates the variation in oil content and composition of Jatropha curcas L. seeds from 12 origins, grown in Mozambique, under the same edapho-climatic and agronomic conditions. The seeds had oil contents from 37% to 45% (d.w.). The oils were rich in oleic (mean 40%) and linoleic (mean 40%) acids and poor in linolenic acid (mean 0.22%), with high content of beta-sitosterol (71% of total sterols), low acidity and low levels of oxidation products, making them adequate for biodiesel production by alkaline-catalyzed transesterification. Thehighlevels of gamma-tocopherol(69–182 mg/kg)may explainthehighoxidative stability exhibited by the oil during 6 months of storage at 28 or 35 ◦C. Conversely, seeds storage under high temperatures and humidity promoted the growth of fungi responsible for oil degradation. Therefore, under tropical climate conditions, when oil conversion to biodiesel is not possible immediately after fruit harvest, it is better to extract the oil and store it under closed containers without contact with oxygen and light, to preserve its quality, than to store the seed