Postharvest treatment effects on 'B74' mango fruit lenticel discolouration after irradiation

Lenticel discolouration (LD) is a common disorder of mango fruit around the world. It results in poor appearance and disappointment of consumers. LD is exacerbated by treatment of mango fruit with gamma irradiation for insect disinfestation. The issue is problematic on the relatively new mango cultivar 'B74' and may represent an oxidative browning process. With a view to reducing irradiationinduced LD on 'B74', postharvest wax (one and three layers; 75% carnauba wax) and antioxidant (100 mM ascorbic acid, 100 mM calcium chloride, 10, 50 and 100 mM calcium ascorbate) dip treatments were investigated. Treatment of green mature fruit with three layers of wax prior to exposure to 557 Gy gamma irradiation reduced LD by 40% relative to the non-waxed control. However, the fruit failed to ripen properly as evidenced by delayed skin colour change, retarded softening and increased skin browning as compared to the controls and fruit coated with one layer of wax. Treatment with one layer of wax did not reduce LD. Mechanistically, the responses suggest that air exchange plays a pivotal role in LD. A lowered oxygen concentration in the lenticels may reduce the disorder after irradiation treatment. Postharvest treatments with the various antioxidants failed to reduce LD. Rather, all antioxidant treatments at the test concentrations, except calcium chloride, significantly increased skin browning.

Influence of mucuna fallow crop on selected soil properties, weed suppression and taro yields in Taveuni, Fiji

Two field experiments were carried out in Taveuni, Fiji to study the effects of mucuna (Mucuna pruriens) and grass fallow systems at 6 and 12 month durations on changes in soil properties (Experiment 1) and taro yields (Experiment 2). Biomass accumulation of mucuna fallow crop was significantly higher (P<0.05) than grass fallow crop at both 6 and 12 month durations. The longer fallow duration resulted in higher (P<0.05) total soil organic carbon, total soil nitrogen and earthworm numbers regardless of fallow type. Weed suppression in taro grown under mucuna was significantly greater (P<0.05) than under natural grass fallow. Taro grown under mucuna fallow significantly outyielded taro grown under grass fallow (11.8 vs. 8.8 t ha-1). Also, the gross margin of taro grown under mucuna fallow was 52% higher than that of taro grown under grass fallow. © ISHS.

EFFECT OF TEMPORARY DROUGHT AT DIFFERENT GROWTH STAGES ON SNAP BEAN POD QUALITY AND YIELD

High quality snap bean ( Phaseolus vulgaris L. ) can be produced under rain-fed conditions, provided that adequate moisture is available. However, drought may occur at any stage of growth of snap bean. The objective of this study was to evaluate the effect of drought stress at different growth stages on pod physical quality and nutrient concentrations. An experiment was conducted at the Horticulture Greenhouse, Hawassa University in Ethiopia. Drought stress (50% of field capacity [FC]) was applied at the unfolding of the fourth trifoliate leaf, flowering and pod formation, against a control with no drought stress. The drought stress treatments and eight cultivars were arranged as a factorial experiment in a completely randomised design, with three replications. Drought stress (50% FC) during reproductive stages significantly (P<0.05) reduced pod texture, appearance, and pod curvature. Drought stress increased protein and zinc concentrations by 41 and 15%, respectively; but reduced iron concentration by 15% in snap bean pods. All the tested cultivars had relatively similar responses to drought stress.

Transcriptional dynamics of the developing sweet cherry (Prunus avium L.) fruit: sequencing, annotation and expression profiling of exocarp-associated genes

The exocarp, or skin, of fleshy fruit is a specialized tissue that protects the fruit, attracts seed dispersing fruit eaters, and has large economical relevance for fruit quality. Development of the exocarp involves regulated activities of many genes. This research analyzed global gene expression in the exocarp of developing sweet cherry (Prunus avium L., 'Regina'), a fruit crop species with little public genomic resources. A catalog of transcript models (contigs) representing expressed genes was constructed from de novo assembled short complementary DNA (cDNA) sequences generated from developing fruit between flowering and maturity at 14 time points. Expression levels in each sample were estimated for 34 695 contigs from numbers of reads mapping to each contig. Contigs were annotated functionally based on BLAST, gene ontology and InterProScan analyses. Coregulated genes were detected using partitional clustering of expression patterns. The results are discussed with emphasis on genes putatively involved in cuticle deposition, cell wall metabolism and sugar transport. The high temporal resolution of the expression patterns presented here reveals finely tuned developmental specialization of individual members of gene families. Moreover, the de novo assembled sweet cherry fruit transcriptome with 7760 full-length protein coding sequences and over 20 000 other, annotated cDNA sequences together with their developmental expression patterns is expected to accelerate molecular research on this important tree fruit crop.

Antioxidant profile of Stevia rebaudiana Bertoni cultivated in Portugal and submitted to different conservation conditions

The demand for natural sweeteners has been gaining more and more importance due to the great controversy associated with the use of some synthetic sweeteners as cyclamates, aspartame and acesulfame-K. The steviol glycosides (E 960) are a group of natural sweeteners of generalized use; these compounds are obtained from Stevia rebaudiana Bertoni, a sweet plant native from South America (Carocho et al., 2015). However, Stevia rebaudiana Bertoni may have other uses to be exploited, in particular due to its antioxidant capacity. This plant is already produced in Portugal but it is important to evaluate if the plant chemical composition is maintained regardless of culture conditions. Therefore, in this study, stevia samples were cultivated in Braganca (northeastern of Portugal) in a field trial with defined culture conditions. After harvesting, the plants were submitted to two different treatments: kept fresh by freezing (-20°C) and oven-dried (30°C). The antioxidant profile of the samples was studied through evaluation of free radicals scavenging activity, reducing power, phenolic compounds (HPLC-DAD-ESI/MS), tocopherols (HPLC-fluorescence) and free sugars (HPLC-RI). Significant differences were observed: while oven-dried samples showed the highest antioxidant activity and phenolic compounds concentration (mainly 5-O-caffeoylquinic acid and 3,5-O-dicaffeoylquinic acid), the frozen fresh samples had the highest values of total tocopherols and total sugars. These results confirm that the plants grown in Bragança have excellent bioactive secondary metabolites responsible for the observed antioxidant capacity.

Menires do Alto Algarve oriental : Lavajo I e Lavajo II (Alcoutim)

Neste trabalho apresenta-se o resultado das escavações realizadas respectivamente em 1998 e em 2001 nos núcleos de menires de Lavajo I e de Lavajo II, distanciados cerca de 250 m na direcção NNE e separados pelo pequeno vale do Lavajo. Os locais, actualmente, são intervisíveis, graças à implantação destacada no terreno: Lavajo I situa-se no topo de colina enquanto Lavajo II ocupa a linha de festo de uma encosta, conferindo ao local visibilidade tanto do lado sul como do lado norte. O conjunto de Lavajo I é constituído actualmente por três monólitos, todos de grauvaque: um, quase inteiro, de tendência fálica, é actualmente o maior menir de grauvaque conhecido em território português, atingindo o comprimento máximo de 3,14 m; outro, quase completo, fragmentado em três grandes blocos, possui formato estelar; o restante apresenta-se muito incompleto, dele se conservando apenas uma lasca da sua face frontal. É crível, no entanto, que pudessem existir mais monólitos, tendo em conta os abundantes fragmentos de grauvaque ali observados, quase todos com fracturas frescas. Todos os menires de Lavajo I se apresentam decorados, com destaque para o maior deles, o qual exibe complexa decoração estreitamente relacionada com a morfologia do suporte lítico. Apenas para este foi possível determinar o local de implantação, correspondente a um alvéolo de planta circular e fundo aplanado, parcialmente danificado pelos trabalhos realizados em 1994, que conduziram ao seu reerguimento, infelizmente feito de forma pouco cuidada e incorrecta, visto ter sido colocado no terreno em posição invertida. Seja como for, na zona culminante daquele pequeno cabeço, implantaram-se três menires decorados, os quais não podem ser vistos isoladamente, já que se articulariam directamente com o conjunto de Lavajo II, que se avista ao longe, do outro lado do pequeno vale do Lavajo e na linha de festo da encosta, da qual ocupa a parte média. Neste segundo local, identificaram-se quatro estelas-menir não decoradas, todas de grauvaque, das quais apenas uma, representada por fragmento de pequenas dimensões, se encontrava in situ. Foi, no entanto, possível reconstituir a posição relativa das restantes, através da escavação integral do respectivo alvéolo, correspondente a rasgo alongado, orientado Este-Oeste, aberto no substrato geológico, constituído por xistos do Carbónico Superior finamente folheados. Deste modo, é de concluir que as estelas menir se dispunham em linha, constituindo um painel lítico contínuo. No interior do alvéolo, recolheram-se diversos artefactos ali ritualmente depositados aquando da fundação do monumento, cuja tipologia indica o Neolítico Final, cronologia aliás compatível com a do conjunto megalítico de Lavajo I, tendo presente a iconografia patente nos menires. Muito embora não se conheça ainda suficientemente o padrão de povoamento da região no Neolítico Final, estes dois núcleos megalíticos podem ser interpretados como marcadores de territórios e/ou de espaços sagrados, sendo de destacar a existência, durante todo o ano, de água nas proximidades imediatas, recurso escasso e precioso, que propiciaria a horticultura. Por outro lado, a natureza das matérias-primas utilizadas na confecção dos artefactos encontrados (sílex, anfibolito), para além de outros materiais de circulação transregional muito mais alargada (fibrolite), evidencia a forte interacção destas populações tanto com o interior do Baixo Alentejo (Zona de Ossa/Morena), como com o litoral algarvio ou andaluz, compatível com estádio de desenvolvimento económico do final do Neolítico do sul peninsular. Numa vasta região, correspondente a todo o sotavento algarvio, onde o megalitismo não funerário era até agora totalmente desconhecido, os testemunhos ora estudados constituem, doravante, uma das expressões mais interessantes e significativas do Sudoeste peninsular.

THE PROSPECT OF BIOGAS AMONG SMALL-HOLDER DAIRY GOAT FARMERS IN THE ULUGURU MOUNTAINS, TANZANIA

Biogas can be a clean cooking alternative where biomass is the dominant source of cooking energy and where feedstock for anaerobic digestion is available. By substituting woody biomass for energy, biogas may reduce local deforestation. Tanzania has more than 15.6 million goats. Dairy goats of different breeds are found in the mid- to high altitudes of the country. Population density has made firewood increasingly scarce and there are few energy alternatives in mountainous areas such as in the Uluguru Mountains. In Mgeta ward, Morogoro region, introduction of Norwegian dairy goats in the 1980s has improved livelihoods in the area. In this study, goat manure was assessed as feedstock for biogas and as fertilizer. Field work among small-holder dairy goat farmers in Mgeta was conducted to measure daily manure production, and to provide a basic model for prediction of the quantity of droppings which may be collected by farmers. Biogas and fertilizer potential from goat manure was compared to cow and pig manure. Buswell’s formula was used to calculate approximate methane yield. The results show that goat manure from Mgeta can yield 167 l∙kg Volatile Solids-1 (VS). Compared with other substrates approximate methane yield can be ranked as pig > guatemala grass > cow > goat. The average goat of 25 kg in Mgeta leaves 61 kg Total Solids (TS) droppings per year. It was estimated that 15 goats capita-1 would be required to meet the total cooking energy needs of small-holder households in the study location. N:P:K content in goat manure (TS) is 2:1:1, similar to cow and pig manure. Goat droppings had to be macerated to reduce particle size for anaerobic digestion. Biogas from dairy goats could be combined with the year-round irrigated horticulture production in Mgeta. Vegetable gardens in the slope below the digesters could be fertilized by gravitation with the NH4+-rich bioslurry, to save labour and increase yields.

Genetic analysis of the flowering date and number of petals in rose

International audience

Sustainable deployment of QTLs conferring quantitative resistance to crops: first lessons from a stochastic model

International audience

Hydro-Physical Characterization of Media Used in Agricultural Systems to Develop the Best Management Practices for operation of an Environmentally Sustainable Agricultural Enterprise

Florida is the second leading horticulture state in the United States with a total annual industry sale of over $12 Billion. Due to its competitive nature, agricultural plant production represents an extremely intensive practice with large amounts of water and fertilizer usage. Agrochemical and water management are vital for efficient functioning of any agricultural enterprise, and the subsequent nutrient loading from such agricultural practices has been a concern for environmentalists. A thorough understanding of the agrochemical and the soil amendments used in these agricultural systems is of special interest as contamination of soils can cause surface and groundwater pollution leading to ecosystem toxicity. The presence of fragile ecosystems such as the Everglades, Biscayne Bay and Big Cypress near enterprises that use such agricultural systems makes the whole issue even more imminent. Although significant research has been conducted with soils and soil mix, there is no acceptable method for determining the hydraulic properties of mixtures that have been subjected to organic and inorganic soil amendments. Hydro-physical characterization of such mixtures can facilitate the understanding of water retention and permeation characteristics of the commonly used mix which can further allow modeling of soil water interactions. The objective of this study was to characterize some of the locally and commercially available plant growth mixtures for their hydro-physical properties and develop mathematical models to correlate these acquired basic properties to the hydraulic conductivity of the mixture. The objective was also to model the response patterns of soil amendments present in those mixtures to different water and fertilizer use scenarios using the characterized hydro-physical properties with the help of Everglades-Agro-Hydrology Model. The presence of organic amendments helps the mixtures retain more water while the inorganic amendments tend to adsorb more nutrients due to their high surface area. The results of these types of characterization can provide a scientific basis for understanding the non-point source water pollution from horticulture production systems and assist in the development of the best management practices for the operation of environmentally sustainable agricultural enterprise

Effects of plant density and the number of emitters on plant growth and nitrate concentration in spinach cultivated in substrate

The effects of plant density and the number of emitters per Styrofoam box on plant growth and nitrate (NO3-) concentration were evaluated in spinach (Spinacia oleracea L. cv. Tapir). Spinach seedlings were transplanted at 45 days after emergence into Styrofoam boxes filled with the substrate and were grown during winter in an unheated greenhouse with no supplemental lighting. The experiment was carried out with four treatments, including two plant densities (160 and 280 plants/m2) and two number of emitters per Styrofoam box (4 and 8 emitters). Each planting box was irrigated daily and fertigated with a complete nutrient solution. Shoot dry weight was not affected by plant density. However, yield increased with plant density and emitter number. Leaf-blade NO3- concentration was not affected by the interaction between plant density and number of emitters, but petioles NO3- concentration was greater in treatment with 160 plants/m2 and 8 emitters. Although leaf-blade NO3- concentration was not affected by plant density, it decreased with the number of emitters. On the other hand, petiole NO3- concentration was not affected by plant density or number of emitters. Leaf-blade NO3- concentration ranged from 3.2 to 4.1 mg/g fresh weight, occurring the highest value in the treatment with 280 plants/m2 and 4 emitters. Petiole NO3- concentration ranged from 3.5 to 5.3 mg/g fresh weight, values that were higher than allowed by EU regulation.

Sensible use of primary energy in organic greenhouse production.

This document addresses the direct and indirect use of energy in European organic greenhouse horticulture (OGH) with the aim of reviewing available means for making it more environmental friendly and identifying knowledge gaps that should be addressed to attain this aim. The first observation is that there is no common regulation for energy use in OGH, which is not unexpected, since the need for climatisation is not uniformly distributed in the EU (and outside). Accordingly, the EU directive on organic agriculture does not set limitations on the use of energy, but rather promotes the responsible use of energy and of natural resources. The restrictions and rules of most private standards are slightly more stringent. Some standards have specific restrictions on the amount and sources of energy and/or on the seasonal use of energy for heating. Some standards also address processes that may affect (in)direct energy use, such as cultivation methods, mulching, lighting and growing media or substrates. However, most private standards have no or little restrictions or regulations on energy use. Accordingly, it should not surprise that very little quantitative information is available about energy use in OGH. In the present document we have filled the gaps with data with estimates drawn on energy use in conventional greenhouses. With respect to ongoing research, whereas many of the present research results about energy use and saving in conventional greenhouses are relevant (and also applied) in OGH, little research is devoted to address the energy use that is peculiar to OGH, particularly energy use for humidity control. In short, there are still a lot of knowledge gaps to improve quality and to lower energy use in organic greenhouses. The purpose of this document is a summary of present relevant knowledge about energy use and energy saving and of the perspective for improvement. In particular, the goal is to make an overview on the methods and technologies which can be used to reduce the energy use in OGH. We start from the assumption that methods and technologies that are used for reducing direct and indirect energy in conventional greenhouses can also be applied in organic greenhouses. Research on reducing energy use in conventional greenhouses is also more widely available because the area of conventional greenhouse horticulture is much larger than the area of OGH. When implementing these methods and techniques we should take into account the specific characteristics of organic agriculture like soil-based cultivation, use of organic fertilizers and the limited use of crop protection products. This document is organised as follows: first we report the results of a survey about energy use and relevant standards in the countries participating to the COST action (chapter 1); then we review the energy use for climatisation: heating (chapter 2) and humidity (chapter 3). In chapter 4 we review the available design and management means that would either reduce energy use and/or increase energy use efficiency by increasing productivity of OGH. In chapter 5 we present a short summary of existing information on indirect energy use, that is the energy required to manufacture production means (greenhouse structure and cover, fertilisers, equipment etc.) and for crop protection, particularly steaming, and briefly discuss possible savings. Finally (chapter 6) we review briefly the potential for application of renewable energy sources in OGH.

Effects of nitrogen level on purslane antioxidant activity.

The high antioxidant activity of purslane, Portulaca oleracea L., gives it a high nutritional and functional value. The commercial production of purslane has increased in Portugal, making it necessary to know the effects of inputs, mainly nitrogen, on the antioxidant activity. The main goal of this study was to evaluate the influence of nitrogen application on purslane antioxidant activity. The experiment was carried out with for treatments: 30, 60 and 90 kg/ha of nitrogen. Plants of golden-leaf purslane were grown in Styrofoam-boxes filled with substrate and fertigated two times per week, over four weeks with ammonium nitrate solution (16.9% NO3-N and 16.7 NH4+-N). The increase in the nitrogen level decreased the water-soluble proteins content. However the ascorbate, phenols content as well as antioxidant activity measured by FRAP method was not affected by nitrogen level. Plants shoot antioxidant activity, measured by DPPH method decreased significantly in the treatment with 90 kg N/ha (26.20 g/g gallic acid). On the other hand, plant shoot antioxidant activity mediated by peroxidases was higher in treatment 30 kg N/ha (0.459 µmol min-1/mg prot.). Application of 60 kg N/ha allowed a vigorous plant growth without disturb its antioxidants and conservation properties.

Nitrate and potassium concentration in fertigated soil cultivated with wine vines.

In the semiarid region of Brazil the use of irrigation systems for applying fertilizers in horticulture is the primary means for incorporating nutrients in the soil. However, this technique still requires its use in wine vines to be assessed. In view of this, this study aimed to assess nitrate and potassium concentrations in soil fertigated with nitrogen and potassium fertilizers in 3 wine grape growing cycles. A field experiment was conducted with ?Syrah? wine grapes, in Petrolina, Pernambuco, Brazil; it assessed five nitrogen doses (0, 15, 30, 60 and 120 kg ha-1) and five K2O doses (0, 15, 30, 60 and 120 kg ha-1) applied by drip irrigation system with two emitters per plant, with a flow rate of 4 L h-1. The experimental design used was the factorial split-plot, making up 13 combinations arranged in 4 randomized blocks. Soil solution samples were collected weekly with the aid of porous cup extractors for all treatments and at depths of 0.4 and 0.6 m by determining nitrate and potassium concentrations and electrical conductivity. Increased levels of both nutrients in the irrigation water increased the availability of nitrate and potassium in the soil solution. The highest nitrate and potassium concentrations were found in the second growing cycle at both depths studied.

Estimativa do fator de bioconcentração de pesticidas em maçãs.

O objetivo desse trabalho foi estimar o fator de bioconcentração (BCF) de trinta e seis pesticidas do sistema brasileiro de produção integrada de maçãs (PIM) e indicar quais deles devem ser monitorados em maçãs. Foi assumido um cultivo hipotético de macieiras e usado o modelo de Paraíba (2007) [Pesticide bioconcentration modelling for fruit trees Chemosphere, v.66, p.1468-1475, 2007].O modelo relaciona o BCF com características da planta e do pesticida.