Physiological changes during postharvest senescence of broccoli

The objective of this work was to determine the early physiological changes throughout shelf life of fresh broccoli (Brassica oleracea L. var. italica) cv. Piracicaba Precoce at 25ºC and relative humidity of 96% in the dark until complete senescence. Head inflorescences showed lack of turgidity and commercial value when weight loss reached up to 5%, coinciding with 48 hour after harvest. Chlorophyll content was stable until 24 hours after harvesting; afterwards, an intense degradation phase took place. At 72 hours, total head yellowing was observed when chlorophyll content dropped to 30% of its initial content. Peroxidase activity increased by 1.4 fold during the first six hours, dropping to its lowest level approximately 24 hours after harvesting. However, from this time on, an increment of activity was observed until 72 hours. At 24 hours after harvesting, respiration was reduced by 50%. At later stages of senescence, respiration of florets was stable, but in a lower level than that determined at harvest. Sharp reduction of starch and reducing sugars was observed within 24 hours after harvesting, followed by continuous period of decline in starch and non-reducing sugars.

Embriogênese somática in vitro em couve-comum

O objetivo deste estudo foi obter calos e embriões somáticos de couve-comum (Brassica oleracea L., var. leucocephala) e caracterizá-los por meio de observações histológicas. Foram cultivadas, in vitro, explantes foliares, sob condições assépticas, em meio nutritivo MS, suplementado com várias combinações entre 2,4-D/BAP e 2,4-D/KIN. Na fase de indução de calos (fase I), houve o desenvolvimento de calos com características embriogênicas nos meios suplementados com 5,0 mg/L de 2,4-D; 1,0 mg/L de 2,4-D e 0,1 mg/L de BAP; 1,0 mg/L de 2,4-D e 1,0 mg/L de BAP e 2,0 mg/L de 2,4-D e 0,05 mg/L de BAP, que foram selecionados para o subcultivo em meio de regeneração (fase II). Nesta fase, foram utilizados meios de cultura suplementados com reduzidas concentrações de 2,4-D, BAP e AG3, ou totalmente desprovidos destes, em que os calos permaneceram por mais 30 dias em cultivo. Os calos subcultivados nos meios de regeneração com 0,1 mg/L de BAP (R3) e 0,01 e 0,001 mg/L de BAP e 2,4-D respectivamente (R8), provenientes dos meios para indução, acrescidos de 5,0 mg/L de 2,4-D (M16) e 1,0 e 1,0 mg/L de BAP e 2,4-D (M30), desenvolveram estruturas semelhantes a embriões. No entanto, a caracterização histológica revelou a superioridade da interação entre os meios M30 e R8, para a regeneração de calos e embriões somáticos.

High pressure processing of swede (Brassica napus): Impact on quality properties

The effects of combined pressure/temperature treatments (200, 400 and 600 MPa, at 20 and 40 °C) on the physical and nutritional properties of swede roots (Brassica napus var. napobrassica) were assessed. Changes induced by high pressure processing (HPP) on the original properties of swede samples were compared with those produced by thermal treatment (blanching). All studied treatments altered the physical properties of swede, resulting in a loss of hardness and water binding capacity. The strongest alteration of texture was observed after HPP at 400 MPa, while 600 MPa was the treatment that better preserved the texture properties of swede. Blanching caused less total colour changes (ΔE) than HPP. Antioxidant properties of swede were measured as total antioxidant capacity, ascorbic acid and total phenol content. All treatments caused a loss of antioxidant capacity, which was less pronounced after HPP at 600 MPa and 20 °C and blanching. Four glucosinolates were detected in swede roots, glucoraphanin, progoitrin, glucobrassicanapin and glucobrassicin. Glucobrassicanapin and glucobrassicin contents were reduced with all studied treatments. Progoitrin content was not affected by blanching and HPP at 200 MPa. HPP at higher pressure levels (400 and 600 MPa), though, induced an increase of progoitrin levels. The results indicated that blanching and HPP at 600 MPa and 20 °C were the treatments that better preserved the original quality properties of swede.

Artificial diet for aphids - thirty years' experience

Myzus persicae (Sulzer) was reared continuously for over thirty years (until it died out in December 2008) on a totally defined synthetic artificial diet, the procedure for which is described. Development time was extended on diet compared with rearing on Brussels sprout plants (Brassica oleracea L. var. gemmifera L.), and generation time was further increased by an added pre-reproductive period of 4 days. Fecundity was reduced by about two-thirds, and mean relative growth rate in weight (MRGR) was only 60% in comparison with plant-reared aphids. Applying 2 kg/cm(2) pressure to a 10% sucrose solution extended the adult longevity of Aphis fabae Scopoli by less than I day. In contrast, a short experience of half-strength diet Caused a sharp rise in honeydew excretion by A. fabae for several hours, and alternating full-strength diet with diluted diets (including water) Caused a greater weight increase. The poor performance of aphids on diet thus seems to have a behavioural rather than a mechanical explanation. The diet, designed to give optimal performance of the aphids, has proved not to be useful for nutritional studies, as any change is deleterious. Areas of aphid research where the diet has been useful, however, are studies on repellents/attractants/toxins, role of symbionts, maintenance of genotype collections, work on parasitoid behaviour in relation to plant chemistry, and collection of aphid saliva.

Exigências térmicas e tabelas de vida de fertilidade de Myzus persicae (Sulzer) (Hemiptera: Aphididae) em laboratório

Este estudo visou determinar as exigências térmicas do pulgão Myzus persicae (Sulzer), calcular tabelas de vida de fertilidade, e prever a ocorrência de adultos no campo, por meio de modelo de graus-dia. Os pulgões foram mantidos individualmente em gaiolas fixadas em folhas de couve, Brassica oleracea L. var. acephala DC, em laboratório, às temperaturas de 15, 20, 23, 25 e 30ºC. O limite térmico inferior de desenvolvimento (Tb) e a constante térmica (K) foram 2,2ºC e 165,6 graus-dia, respectivamente. O modelo de graus-dia previu a ocorrência de adultos de M. persicae para 0 a1 dia antes da data em que eles foram observados no campo. Os parâmetros das tabelas de vida estimados na escala de tempo em graus-dia evidenciaram que as temperaturas de 23°C e 25°C foram as que proporcionaram as melhores condições térmicas para o crescimento populacional de M. persicae. Nessas temperaturas observou-se o maior valor da capacidade inata de aumentar em número (r m = 0,012), o menor valor da duração média da geração (T = 303,8 graus-dia e 272 graus-dia, respectivamente) e o menor tempo necessário para a população duplicar em número de indivíduos (TD = 57,8 graus-dia).

Exigências Térmicas e Previsão de Picos Populacionais de Lipaphis erysimi (Kalt.) (Homoptera: Aphididae)

Experimentos de laboratório e de campo foram realizados de outubro de 1998 a agosto de 1999, visando estimar as exigências térmicas de Lipaphis erysimi (Kalt). Para isso, o desenvolvimento do afídeo foi estudado em condições de laboratório em couve, Brassica oleracea L. var. acephala, usando câmaras climatizadas reguladas a 10, 15, 20, 25 e 30°C, fotofase de 14h e UR de 70±10%. O limite térmico inferior de desenvolvimento de L. erysimi foi de 3,04°C e a constante térmica 132,21 graus-dia. A previsão de ocorrência de adultos no campo foi feita usando-se o método da triangulação; o pico populacional foi previsto para 0-1 dia antes da data em que o mesmo foi observado no campo.

Impacto de inimigos naturais e de fatores meteorológicos sobre uma população de Brevicoryne brassicae (L.) (Hemiptera: Aphididae) em couve

Neste estudo, visou-se avaliar o impacto de inimigos naturais e de fatores meteorológicos na população do pulgão Brevicoryne brassicae (L.), na cultura da couve, usando-se correlação simples e análise de regressão múltipla com seleção de variáveis pelo método stepwise. A amostragem de B. brassicae foi realizada por procura visual e dos inimigos naturais através de armadilhas de sucção e de solo. Formas ápteras de B. brassicae começaram a infestar a couve em julho, atingindo pico populacional em setembro. Os fatores que apresentaram correlação significativa com a população de B. brassicae, no período que abrangeu todo o levantamento populacional, foram Diaeretiella rapae (Mc'Intosh), aranhas presentes no solo, precipitação pluviométrica e umidade relativa, sugerindo que tais fatores tiveram função importante na mortalidade do pulgão. No período de maior crescimento e declínio populacional de B. brassicae, aranhas presentes no solo mostraram-se como o fator de mortalidade mais significativo relacionado com a variação da densidade populacional do pulgão.

Tabelas de esperança de vida e fertilidade para Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae) em condições de laboratório e campo

In this study, the aphid Lipaphis erysimi (Kalt) was reared at different temperatures, under laboratory and field conditions, aiming to obtain age-specific life tables. In the laboratory, L. erysimi was fed on kale, Brassica oleracea L. var acephala, and kept in incubators adjusted to 10, 15, 20, 25 and 30°C, 14h photophase and 70±10% RH. The longest mean generation time (T) was observed at 15°C (23.86 days) and the shortest at 30°C (7.18 days), while the smallest net reproductive rate (R0) occurred at 15°C (4.30) and largest one at 25°C (38.29). For the temperatures of 15, 20, 25 and 30°C, the intrinsic rate of natural increase (rm) and the finite rate of increase (λ) were 0.06/1.06, 0.24/1.27, 0.28/1.33 and 0.23/1.25, respectively. The doubling time (DT) at 15, 20, 25 and 30°C were 11.55, 2.80, 2.47, and 3.01 days, respectively. Under field conditions, the net reproductive rate (R0) of L. erysimi was larger in the winter (53.50) than in the summer (40.99), the same being observed for the mean generation time (T), which was 13.85 days in the winter and 7.57 days in the summer. The intrinsic rate of natural increase (rm) and the finite rate of increase (λ) were 0.29/1.34 and 0.40/1.63 for winter and summer, respectively. The doubling time (DT) observed for winter (2.39 days) was larger than the one observed for summer (1.41 days). The temperature affects longevity of L. erysimi and the best parameters of life table of fertility under laboratory conditions are obtained at 25°C. The data obtained in field conditions reinforced this finding. The daily fecundity was higher and longevity was smaller in the summer than in the winter, thus increasing the innate capacity of increasing in number and duplicating the population in a shorter period of time.

Dinâmica populacional de Myzus persicae (Sulzer, 1776), Brevicoryne brassicae (Linnaeus, 1758) e Lipaphis erysimi (Kaltenbach, 1843) (Hemiptera: Aphididae) na região de Jaboticabal, SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da composição química, dos compostos bioativos e da atividade antioxidante em seis espécies de flores comestíveis

Pós-graduação em Alimentos e Nutrição - FCFAR

Plamodiophora brassicae x brassicaceas: variabilidade genética e patogênica, epidemiologia da doença e efeito de exsudatos radiculares e plantas não brassicaceas no controle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Resistance of collard greens to Ascia monuste orseis (Lepidoptera: Pieridae)

Ascia monuste orseis (Godart) (Lepidoptera: Pieridae) is a production limiting pest in collard greens, Brassica oleracea (L.) var. acephala, cultivation. Because of the overuse and harmful effects of synthetic insecticides on nontarget species, the use of insect-resistant cultivars can be a valuable strategy in pest control. In this study, newly hatched A. monuste orseis larvae were confined to the leaves of 29 collard greens cultivars under a controlled environment to investigate plant resistance. We evaluated the incubation period, duration of instars, total duration of the immature and pupal phases, the egg to adult life cycle duration, mortality per instar, total weight of fifth instar larvae and pupae (age = 24 h) and larval and pupal survival and eclosion. Antibiosis and/or antixenosis were observed in selected cultivars. The results show that Gigante I-915 (E) exhibited high larval mortality and that the Pires 1 de Campinas cultivar (P) prevented all pupae from proceeding to the adult stage. The Introdu double dagger es do municipio de Arthur Nogueira Z (Y), Cabocla (AA), Japonesa (R) and Manteiga de Mococa (M) cultivars prolonged the larval stage. Japonesa (R) and Introdu double dagger es do municipio de Arthur Nogueira Z (Y) increased the egg to adult developmental period, and the Japonesa (R) cultivar also prolonged the pupal stage. The Verde-escura (O), Crespa de Capo Bonito (I), Couve de folhas Manteiga 900 Legitima P, Alto (AB), Gigante I-915 (E) and Manteiga Ribeiro Pires I-2446 (H) cultivars reduced the larval weight of A. monuste orseis.

Couve consorciada com sorgo e feijão-guandu na ocorrência de pulgões e insetos predadores

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

Molecular and biochemical characterization of postharvest senescence in broccoli

Postharvest senescence in broccoli (Brassica oleracea L. var Italica) florets results in phenotypic changes similar to those seen in developmental leaf senescence. To compare these two processes in more detail, we investigated molecular and biochemical changes in broccoli florets stored at two different temperatures after harvest. We found that storage at cooler temperatures delayed the symptoms of senescence at both the biochemical and gene expression levels. Changes in key biochemical components (lipids, protein, and chlorophyll) and in gene expression patterns occurred in the harvested tissue well before any visible signs of senescence were detected. Using previously identified senescence-enhanced genes and also newly isolated, differentially expressed genes, we found that the majority of these showed a similar enhancement of expression in postharvest broccoli as in developmental leaf senescence. At the biochemical level, a rapid loss of membrane fatty acids was detected after harvest, when stored at room temperature. However, there was no corresponding increase in levels of lipid peroxidation products. This, together with an increased expression of protective antioxidant genes, indicated that, in the initial stages of postharvest senescence, an orderly dismantling of the cellular constituents occurs, using the available lipid as an energy source. Postharvest changes in broccoli florets, therefore, show many similarities to the processes of developmental leaf senescence.

Reclaimed wastewater: Effects on citrus nutrition

The effects of irrigation with reclaimed wastewater (RWW) were compared with well water (WW) on citrus (Citrus paradisi Macfad. X Citrus aurantium L) nutrition. The deviation from the optimum percentage (DOP) index of macro- and micro-nutrients were used to evaluate the nutritional status: optimal (DOP = 0), deficiency (DOP < 0) or excess (DOP > 0). After 11 years of RWW irrigation the influence on nutrient concentration in plants decreased in the order: B > Zn > Mn = Ca > Cu > Mg > P > K. Reclaimed wastewater irritation positively affected citrus nutrition as it rendered the concentration of macronutrients, i.e. P, Ca, and K. closer to their optimum levels (Sigma DOP(macro) = 7). However micro-nutrients tended to be excessive in plants (EDOP(micro) = 753) due to imbalanced supply of these elements in the RWW, particularly, for B and Cu. Citrus groves with long-term RWW irrigation may exercised caution in monitoring concentrations of B and Cu to avoid plant toxicity and soil quality degradation. (C) 2011 Elsevier B.V. All rights reserved.