19982015
  • Authors:
    • Dodd, I. C.
    • Pérez-Pérez, J. G.
    • Botía, P.
  • Source: Functional Plant Biology
  • Volume: 39
  • Issue: 5
  • Year: 2012
  • Summary: To determine whether irrigation strategy altered the sensitivity of Citrus leaf gas exchange to soil, plant and atmospheric variables, mature (16-year-old) Fino 49 lemon trees ( Citrus limon (L.) Burm. fil. grafted on Citrus macrophylla Wester) were exposed to three irrigation treatments: control (irrigated with 100% of crop potential evapotranspiration, ET c), deficit irrigation (DI) and partial rootzone drying (PRD) treatments,which received 75% ET c during the period of highest evaporative demand and 50% ET c otherwise. Furthermore, to assess the physiological significance of root-to-shoot ABA signalling, the seasonal dynamics of leaf xylem ABA concentration ([X-ABA] leaf) were evaluated over two soil wetting-drying cycles during a 2-week period in summer. Although stomatal conductance ( gs) declined with increased leaf-to-air vapour pressure deficit (LAVPD), lower leaf water potential and soil water availability, [X-ABA] leaf was only related to stomatal closure in well irrigated trees under moderate (
  • Authors:
    • Espadaler, X.
    • Ribes, J.
    • Ribes, E.
    • Piñol, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 158
  • Year: 2012
  • Summary: The Heteroptera assemblage of a citrus grove and how it was affected by ant-exclusion was examined during transformation from conventional to organic agriculture. The results showed that the Heteroptera assemblage changed dramatically over the eight years of the study: at first, it mainly consisted of herbivorous lygaeids and predatory anthocorids but became dominated by predatory mirids in 2008-2009. The predator/herbivore ratio increased steadily over the eight years of the study. Ants can form mutualistic relationships with heteropteran pests. However, exclusion of ants from canopies did not affect the Heteroptera assemblage at the beginning of the study, but had a profound effect later on. In particular, ant-exclusion increased the abundance of most predatory Heteroptera, except for the myrmecomorphic mirid Pilophorus perplexus, which was approximately five times more abundant in control than in ant-excluded trees; the analyses showed that the only mimicked ant species was Lasius grandis.
  • Authors:
    • Rodriguez-Delfin, A.
  • Source: Acta Horticulturae
  • Issue: 947
  • Year: 2012
  • Summary: Hydroponics has been used during years for research in the field of plant mineral nutrition and related topics. Today the soilless culture method is the most intensive horticulture production and is being applied with success in developed countries for commercial purposes. The growing and future of hydroponics in Latin America will much depend of the developing and adaptation of less sophisticated commercial systems. These have to be cost competitive with respect to the high sophisticated technology generated and used in developed countries, using natural and local substrates, developing native or endemic crops of the Region with economical potential for its high feed or medicinal value, among others. Meanwhile, as there is a considerable decreasing of agricultural soils in the world, soilless culture would be an important production alternative in urban and peri-urban areas, mainly in undeveloped countries. Inside the context of urban agriculture, hydroponics could be applied in the cities with more simple and low cost of technologies, mainly in extreme poverty areas, as a way to spread vegetables for self-consumption and to support the family or community income. Also to create micro-companies that will generate employments. There are no official statistics on the evolution of the state of the hydroponic cultures in Latin America. The main hydroponic systems used are the drip irrigation and NFT system. According with their profits, the main hydroponic crops are lettuce, tomato, pepper and strawberry. In Andean countries like Peru, Bolivia, Colombia and Ecuador, aeroponics is being developing to obtain basic potato tuber seed, free of virus. In relation to the media used in soilless culture, there is no ideal or optimum substrate, because a great diversity in media could be used, as pure or as mix form. Among the inorganic substrates it is possible to use quarry, river and quartz sand, gravel, pumice and tezontle. Husk rice, coco fiber, peat moss and sawdust are used as organic media. The use of rock wool is not generalized in the Region, but in countries like Mexico and Chile it is mainly used in tomato crop with drip irrigation system. Brazil and Mexico are the more representative hydroponic countries in Latin America. The area of soilless culture is increasing in the Region and every day there is much interest to learn and to dominate this technique of plants production without using soil. A great number of international courses, seminaries, congresses and symposia organized in countries like Peru, Mexico, Brazil, Costa Rica and Chile demonstrate this affirmation. Finally, it is necessary to obtain a hydroponic certification, as well as the organic products, to support the hydroponic growers in our countries.
  • Authors:
    • Santana, J. A. D. V.
    • Carvalho, G. C.
    • Machado, V. V.
    • Daniel, R.
    • Coelho, E. F.
    • Coelho Filho, M. A.
    • Sampaio, A. H. R.
    • Santana Junior, E. B.
  • Source: Acta Horticulturae
  • Issue: 928
  • Year: 2012
  • Summary: The management of irrigation using partial root drying (PRD) was tested in an orchard of 'Tahiti' lime in the semi-arid conditions of Iacu, BA. Six treatments were evaluated: T1, T2, T3 (50% ETc PRD) with plants irrigated by a microsprinklers with its position alternating every 7, 14 or 21 days, respectively, and wetting on opposite sides of the root system; T4 (DI 50% ETc) irrigation was fixed on one side using one emitter per plant, T5 (100% ETc) was the control treatment using two microsprinklers per plant in a fixed position. In T6, at each interval of 21 days, one and two micro-sprinklers were alternatively used per plant. Results demonstrated significant differences in fruit production by the Scott Knott test (p
  • Authors:
    • Tagliavini, M.
    • Zibordi, M.
    • Ventura, M.
    • Scandellari, F.
    • Ceccon, C.
    • Tonon, G.
    • Panzacchi, P.
  • Source: PLANT AND SOIL
  • Volume: 360
  • Issue: 1-2
  • Year: 2012
  • Summary: Fruit orchards potential as carbon (C) sinks is virtually unknown. Moreover, despite their importance in the Mediterranean area, few data are available about the effect of the reduction in water availability on fruit tree productivity. Here we report the effect of two different irrigation regimes on net primary (NPP) and net ecosystem (NEP) productivities of an apple orchard in northern Italy in 2006. Trees productivity and heterotrophic soil respiration were estimated by inventory and root exclusion methods, while belowground allocation with a C mass-balance approach. The NPP of the control (7.86 +/- 0.25 Mg C ha(-1); mean +/- SE) was significantly greater than that of water stressed trees (6.53 +/- 0.12 Mg C ha(-1)), and the ratio between above and below net primary productivity (ANPP/BNPP) was 1.88 and 0.98 respectively. However, the partitioning of ANPP and BNPP among aerial organs and among fine, coarse roots, and root litter was unaffected by the water regime. Although NEP was greater in the control than in stressed trees the C gain of the system after fruit removal (NEPafr) was unaffected by water availability. This study indicated an effect of water availability on C partitioning patterns above- and belowground, although there were no significant effects on the C sink potential as NEPafr.
  • Authors:
    • Kalburtji, K.
    • Tsirakoglou, V.
    • Tsatsarelis, C.
    • Menexes, G.
    • Mamolos, A.
    • Michos, M.
  • Source: Ecological Indicators
  • Volume: 13
  • Issue: 1
  • Year: 2012
  • Summary: Energy analysis in peach orchards is useful to decide best management strategies. The objectives of this study were to evaluate (a) the energy flow among conventional, integrated and organic farming systems and (b) the effect of farming system to greenhouse gas-emissions. Sixteen farms (four conventional, nine integrated, three organic) at six locations in northern Greece were selected randomly during the years 2008 and 2009. Multidimensional data analyses were used to detect (a) clusters of farming systems and (b) associations between farming systems and production coefficients variables. Three groups of farming systems and three groups of variables were revealed. Farming systems in the same group respond more or less similarly to the production coefficients variables. Non-parametric tests concerning external variables (outputs, energy efficiency, fruit production, CO2, CH4 and N2O) showed that the variables in organic farming cluster were at average significantly lower. Similarities and/or dissimilarities among farming systems, can probably be related to farm topography, production coefficients and local farming practices. The results showed that organic farming could reduce inputs and gas-emissions. (C) 2011 Elsevier Ltd. All rights reserved.
  • Authors:
    • Jouquet, P.
    • Doan, T.
    • Rumpel, C.
    • Ngo, P.
  • Source: Soil Biology and Biochemistry
  • Volume: 50
  • Year: 2012
  • Summary: The use of organic matter (OM) amendments is widespread in tropical countries and may be beneficial for soil carbon storage. Interactions between earthworms and OM amendments in tropical soils are largely unknown. The aim of this study was to investigate the effect of bioturbation on the quantity and chemical composition of OM in soil amended with compost and vermicompost. Our approach included comparison of soil samples amended with compost, vermicompost or chemical fertilizers in the presence or absence of earthworms during a one-year greenhouse experiment. The soils were submitted to a regular cultivation cycle. After one year, we analysed bulk samples for soil OM elemental composition and characterised its lignin and non-cellulosic carbohydrate components. Our results showed a decrease of the carbon and nitrogen content in soil amended with chemical fertilizers. Vermicompost amendment led to unchanged OC content, whereas the compost amendment increased the soils OC content compared to initial soil. The addition of earthworms reduced OC and N content in soils with organic amendments. This is in contrast to soil amended with mineral fertilizer only, where the presence of earthworms did not have any effect. Bioturbation influenced the lignin signature of the soils, and to a lesser extent the non-cellulosic carbohydrate signature. In conclusion, compost amendment combined with bioturbation influenced the quality and quantity of SOM and as result carbon storage and its biogeochemical cycling in tropical soils. Implications for soil fertility remain to be elucidated.
  • Authors:
    • Hellweg, S.
    • Pfister, S.
    • Juraske, R.
    • Stoessel, F.
  • Source: Environmental Science & Technology
  • Volume: 46
  • Issue: 6
  • Year: 2012
  • Summary: Food production and consumption is known to have significant environmental impacts. In the present work, the life cycle assessment methodology is used for the environmental assessment of an assortment of 34 fruits and vegetables of a large Swiss retailer, with the aim of providing environmental decision-support to the retailer and establishing life cycle inventories (LCI) also applicable to other case studies. The LCI includes, among others, seedling production, farm machinery use, fuels for the heating of greenhouses, irrigation, fertilizers, pesticides, storage and transport to and within Switzerland. The results show that the largest reduction of environmental impacts can be achieved by consuming seasonal fruits and vegetables, followed by reduction of transport by airplane. Sourcing fruits and vegetables locally is only a good strategy to reduce the carbon footprint if no greenhouse heating with fossil fuels is involved. The impact of water consumption depends on the location of agricultural production. For some crops a trade-off between the carbon footprint and the induced water stress is observed. The results were used by the retailer to support the purchasing decisions and improve the supply chain management.
  • Authors:
    • Easter, M.
    • Alvaro-Fuentes, J.
    • Paustian, K.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 155
  • Year: 2012
  • Summary: The interactive effects of climate change and atmospheric CO 2 rise could have potential effects on both soil organic carbon (SOC) storage and the capability of certain management practices to sequester atmospheric carbon (C) in soils. In this study, we present the first regional estimation of SOC stock changes under climate change in Spanish agroecosystems. The Century model was applied over a 80-yr period (i.e., from 2007 to 2087) to an agricultural area of 40,498 km 2 located in northeast Spain under five different climate scenarios. The model predicted an increase in SOC storage in the 0-30 cm soil depth in all the climate change scenarios tested (i.e., ECHAM4-A2, ECHAM4-B2, CGCM2-A2 and CGCM2-B2). Among climate change scenarios, SOC stock changes ranged from 0.15 to 0.32 Tg C yr -1. The Century model also predicted differences in SOC sequestration among agricultural classes. At the end of the simulation period, the greatest SOC stocks were found in the rainfed arable land under monoculture and no-tillage (MC-NT) class and in the grape-olive (GO) class with average stocks greater than 80 Mg C ha -1. On the contrary, both the alfalfa (AF) and the cereal-fallow (CF) classes showed the lowest SOC stocks with predicted values lower than 60 Mg C ha -1. Under climate change conditions, Spanish agricultural soils could act as potential atmospheric C sinks. Nevertheless, both the magnitude of the change in climate and the adoption of beneficial management practices could be critical in maximizing SOC sequestration.
  • Authors:
    • Iqbal, K.
    • Khurshid, W.
    • Hassan, I.
  • Source: Journal of Agricultural Research
  • Volume: 50
  • Issue: 1
  • Year: 2012
  • Summary: A study was conducted during the year 2009 to find out the factors responsible for decline in guava ( Psidium guajava) yield. For this purpose three districts Sheikhupura, Kasur and Faisalabad, Pakistan were selected being core area for guava cultivation. To examine impact of various inputs on guava production, the Cobb-Douglas production function model was used. Factors which caused decline in guava yield were found to be physical beating of flowers, excessive intercropping and number of sprays. The physical beating of flowers (-0.317 coefficient value) and intercropping (-0.200) proved as two major depressing factors. Intercropping in both summer and winter seasons went in a long way in depressing yields. Flower shedding by beating with clubs proved to be more significant (-0.317). It was found that productivity decline can be arrested as well as be reversed with adequate number of irrigations, proper use of fertilizers and adopting good management measures.