Washington L.C. Silva

1-Methylcyclopropene delays tomato fruit ripening

Tomato (Lycopersicon esculentum Mill.) fruits, cv. Santa Clara, were harvested at the breaker stage from commercial fields in Brazlândia, Brazil, to investigate the ability of 1-methylcyclopropene (1-MCP) to retard tomato fruit ripening. Fruit without external blemishes were graded for size (diameter = 80±5 mm) and mass (m = 130±10 g), placed inside hermetically sealed boxes, and 1-MCP was applied for 12 hours (T = 22±1°C; RH = 80-85%) at four different concentrations: 0 (control), 250, 500 and 1000 mL.L-1. Fruits were held at ambient conditions (T = 23±2°C; RH 80-85%) for 2 days and then stored inside a cold room (T = 20±1°C; RH = 85-95%). Every 3 days, during a 15-day period, fruits were analyzed for firmness, total soluble solids, titratable acidity, external color, and total carotenoids. Firmness of fruit treated with 1000 mL.L-1 was about 88% higher than control fruits after 17 days. The a*/b* ratio, an indicator of skin color, for fruit treated with 1000 mL.L-1 of 1-MCP was 38% lower than control fruits at the end of the storage period. Treatments with higher concentrations of 1-MCP delayed total carotenoids synthesis and color development. Control fruits stored for 17 days had about 190% more total carotenoids than fruits treated with 1000 mL.L-1 of 1-MCP. Postharvest application of 1-MCP was an efficient method to delay tomato fruit ripening. As 1-MCP concentration increased, ripening was further delayed. Tomatoes treated with 250, 500, and 1000 mL.L-1 of 1-MCP were delayed by 8 to 11, 11 to 13 and 15 to 17 days, respectively.

Profundidade de instalação da linha de gotejadores em tomateiro para processamento industrial

ABSTRACT Drip line placement depth for processing tomatoes crop A field experiment was carried out at Embrapa Hortalicas undersoil and climate conditions of Central Brazil “cerrado” region, aimingto evaluate the response of drip-irrigated processing tomatoes todifferent drip line placement depths (0; 20 and 40 cm). A controltreatment was irrigated by sprinkle system. Larger plant vegetativegrowth was observed for the sprinkle and surface drip treatments,while smaller growth occurred for the 40 cm-depth drip treatment.Marketable yield of the surface drip irrigated treatment (124 t.ha -1 )was 32% larger than the 40 cm-depth drip treatment, 15% largerthan the sprinkle treatment, but did not differ (p>0,05) from the 20cm-depth drip treatment. Yield increments were basically due to alarger number of fruits per plant, since final stand and mean fruitmass were not affected by treatments. Rotten fruit rate for the sprinkletreatment was 112 and 453% larger than for the treatments irrigatedby surface and subsurface drip, respectively.

Production, quality and water use efficiency of processing tomato as affected by the final irrigation timing

O estudo foi realizado nas condicoes de Cerrado do Brasil, durante o periodo seco de 2000, para avaliar o efeito da epoca de paralisacao das irrigacoes na producao, qualidade de frutos e uso de agua do tomateiro para processamento. Os tratamentos corresponderam a quatorze epocas de paralisacao, espacadas a cada 7 dias entre o florescimento e a colheita. A maior produtividade de frutos comercializaveis foi obtida quando as irrigacoes foram suspensas 21 dias antes da colheita (10% dos frutos maduros), enquanto que o maior rendimento de polpa foi alcancado quando as irrigacoes foram finalizadas 34 dias antes da colheita (20% de plantas com pelo menos um fruto maduro). O teor de solidos soluveis totais foi reduzido linearmente a taxa de 0,34 oBrix para cada 10 dias a mais com irrigacao. A maior eficiencia do uso de agua pelo tomateiro foi obtida quando as irrigacoes foram paralisadas entre 37 e 45 dias apos o florescimento, respectivamente para producao de frutos e de polpa.

Irrigação por gotejamento do tomateiro industrial durante o estádio de frutificação, na região de Cerrado

O estudo teve por objetivo estabelecer criterio para o manejo de irrigacao por gotejamento durante o estadio de frutificacao do tomateiro para processamento, nas condicoes de cerrado do Brasil Central. Avaliaram-se seis regimes de irrigacao, com turnos de rega entre 0,25 e 8 dias. A concentracao de frutos maduros na colheita aumentou, enquanto a producao de biomassa e o numero de frutos por planta foram reduzidos linearmente com os turnos de rega ao quais as plantas foram submetidas. A produtividade e a massa media de frutos comercializaveis apresentaram resposta quadratica aos tratamentos, tendo sido maximizados para um turno de rega de 0,8 dia. O estande final de plantas, a eficiencia de uso de agua pelas plantas, o teor de solidos soluveis totais e a firmeza de fruto nao foram afetados pelos tratamentos. A incidencia de frutos podres apresentou correlacao linear negativa com o turno de rega, enquanto que a acidez titulavel apresentou correlacao positiva. Para o manejo de irrigacao baseado no status da agua no solo, a tensao matricial critica associada ao turno de rega que maximizou a produtividade, avaliada a 20cm de profundidade, antes de cada irrigacao, foi de 10 kPa.

Gaseous irrigation control system: descriptionand physical tests for performance assessment

Irrigas is a water tension measuring system made out of a porous cup (sensor), connected to a gas pressurizing/measuring device by a flexible tube. Water tension (T) is obtained from the equation T=Td-p or T=Ts-p, where Td is the sensor desorption critical water tension (bubbling beginning), Ts is the sensor sorption critical water tension (bubbling ceasing) and p is the applied gas pressure. Differently from conventional tensiometers, the irrigas porous cup cavity is filled with air. This characteristics makes the irrigas system nearly maintenance free and also eliminates the need of making hydrostatic pressure corrections for sensor depth. The system was tested both in the desorption and sorption modes. In the first case the Richards pressure chamber was used to adjus)t the soil water tension which makes the porous cup air permeable. The water tension thus obtained was always practically equal to the Td values measured by the bubbling method, observation that is a physical validation of the barrel immersion technique for irrigas usage for irrigation management. Important for instrument dimensioning, porous cup water loss as a function of water tension measured from zero to Td was diminutive, increased with the soil water tension and was smaller in higher Td porous cups. In the sorption mode, functioning as a gaseous tensiometer, driven by a steady air-flow source, irrigas sensors yielded, directly, water tension readings ranging from zero to Ts. For irrigation scheduling purposes, commercial irrigas water tension systems can be selected according to crop critical water tension requirements.

Freqüência de irrigação por gotejamento durante o estádio vegetativo do tomateiro para processamento industrial

Objetivo deste trabalho foi o de estabelecer criterio para o manejo de agua, durante o estadio vegetativo do tomateiro para processamento industrial, nas condicoes de cerrado do Brasil Central. Foram avaliados seis turnos de rega entre 0,5 e 16 dias. O estande final e a produtividade de frutos, maximizados em regas a cada 2 dias, apresentaram resposta quadratica com a frequencia de irrigacao, enquanto a producao de biomassa foi maximizada em regas diarias. A massa media de fruto e o numero de frutos por planta nao foram influenciados pelos tratamentos; isto indica que as diferencas de producao foram causadas, principalmente, pela variacao do estande final. A profundidade efetiva de raizes apresentou resposta linear positiva com o turno de rega. As plantas irrigadas a cada 8 e 16 dias apresentaram um sistema radicular cerca de 10 cm mais profundo do que aquelas irrigadas duas vezes por dia. O teor de solidos soluveis totais, a acidez titulavel e a taxa de fruto podre nao foram influenciados pelos turnos de rega. Observou-se que para melhor desempenho do tomateiro, durante o estadio vegetativo as irrigacoes devem ser realizadas a cada 2 dias, ou seja, quando a tensao de agua no solo atingir cerca de 17 kPa.

Avaliação técnica e econômica do espaçamento de gotejadores em tomateiro para processamento cultivado em fileiras simples e duplas

Technical and economic evaluation of drip spacing for processing tomatoes under single- and double-row planting systems Processing tomatoes crop response to drip spacing (10 cm and 30 cm) and planting systems (single- and double-row planting, and a lone drip line) was evaluated in Brasilia, DF, Brazil. A control treatment with single-row planting system was sprinkle irrigated. Marketable yield for 10-cm drip spacing was 10% higher than for 30 cm. Yield from drip single-row treatments was 9% higher than from double-row ones. Yield from sprinkle irrigated plots did not differ from the 30-cm drip spacing and double-row treatment, but was at least 15% lower than from other treatments. Rotten fruit rates were not affected by drip spacing factor, but were higher in doublerow treatments. In the control treatment, rotten fruit occurrence was at least 68% higher than in the drip treatments. Greater economic efficiency was obtained for the 10-cm drip spacing and single row system treatment (12.7%), followed by drip spacing of 10 cm and double-row planting (7.5%). The revenue rates for those treatments were 1.42 and 1.39, respectively.

Desenvolvimento de plantas, produção e qualidade de bulbos de alho sob condições de deficiência de água no solo

The experiment was carried out at Embrapa Hortalicas, Brasilia, Brazil, aiming to evaluate the response of garlic plants to different water regimes in the soil at two development stages. Treatments, arranged in a factorial scheme 4 x 4, resulted from the combination of four water tensions in the vegetative stage (20; 40; 80; and 160 kPa) and four in the bulbfication (20; 40; 80; and 160 kPa). Plants submitted to soil water deficits in any crop stage had the vegetative growth, marketable yield, bulb size, and water use efficiency reduced up to 70%, 63%, 31%, and 57%, respectively. Plant vegetative growth and bulb yield were negatively affected even for moderate water deficit in the soil (40 kPa).The number of bulbs per unit of area was linearly reduced only when the plants were submitted to water deficits in the vegetative stage. Percentage of dry and secondary bulb growth, and bulb weight losses were not statistically affected by tensions between 20 and 160 kPa.

Produção e qualidade de alho sob regimes de água no solo e doses de nitrogênio

The study was carried out at Embrapa Hortalicas, Brasilia, Brazil, in order to evaluate the effects of three soil water tensions (15; 35 and 70 kPa) and three nitrogen (N) levels (20; 100 and 500 kg.ha-1) on yield and quality of garlic bulbs of a secondary growth susceptible cultivar. Greater vegetative growth, total yield and average bulb weight were obtained under tensions between 15 and 19 kPa and N levels between 52 and 97 kg.ha-1. The marketable yield was maximized for 15 kPa tension, and it was linearly reduced with increasing N levels. The percentage of bulbs with secondary growth was affected by the water tension, N and the interaction of both factors, with minimum value obtained for the combination of 70 kPa tension and 20 kg.ha-1 of N. The percentages of dry bulbs and mass loss between 60 and 120 days after harvest increased linearly with N, however, they were not affected by water tension treatments. Hence, to maximize marketable yield of cvs. susceptible to secondary growth both high frequency irrigation regime is recommended, despite favoring secondary growth, and minimum N application.

Economical efficiency of sound irrigation scheduling technique for processing tomatoes

A agua e um dos principais fatores que afetam a producao e a qualidade de frutos do tomateiro. Embora existam inumeras tecnologias disponiveis para o manejo racional da irrigacao, a grande maioria dos produtores ainda irriga de forma inadequada. Um metodo simples, pratico e criterioso para manejo e o do balanco de agua no solo com base no tanque classe A. Objetivou-se neste estudo avaliar a vantagem economica gerada pelo uso do tanque classe A para o manejo da irrigacao do tomateiro na regiao do Brasil Central. Simulacoes foram realizadas utilizando-se sistemas por aspersao convencional portatil e pivo central para areas irrigadas ate 100 ha. A introducao da tecnologia gerou incrementos da receita liquida de R