• Authors:
    • Martin-Gorriz, B.
    • Ruiz-Salleres, I.
    • Gonzalez-Real, M. M.
    • Baille, A.
    • Nortes, P. A.
    • Egea, G.
    • Verhoef, A.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: The focus of the work reported here is the impact of severe heat stress conditions on orchards' carbon dioxide exchange rate (NEE, Net Ecosystem Exchange). NEE was monitored by means of the eddy-covariance technique over an irrigated orange-tree orchard during summer 2009 in Southern Spain. In that period, severe heat spells occurred (maximum air temperature and vapour pressure deficit up to 38degreesC and 5 kPa, respectively). Under these conditions, orange trees maintained their transpiration rates at levels similar to those observed for normal sunny days, while canopy stomatal conductance and NEE were strongly reduced, thereby leading to a marked decrease in water use efficiency. The experimental results are discussed in the context of (i) stomatal and non-stomatal limitations to CO 2 exchange and (ii) orchard respiration loss. As the frequency of extreme events is expected to increase in the Mediterranean Basin, our results suggest that water productivity of irrigated orchards may be significantly affected by climate change.
  • Authors:
    • Monserrat Delgado, A.
  • Source: Agricola Vergel: Fruticultura, Horticultura, Floricultura, Citricultura, Vid, Arroz
  • Volume: 30
  • Issue: 351
  • Year: 2011
  • Summary: Studies were conducted to determine the most important aspects to consider for the use of herbicides in citrus groves and fruit trees with irrigation. The design of strategies that suit the age of planting and soil characteristics, among others, were based on some of the factors that influence the efficacy and selectivity of the applications and its long-term profitability. To avoid the selection of hard to control weeds on the farm, some treatments described were utilized against some of the most important weed species. Some authorized herbicides in citrus production, with some observations of special interest, was also presented.
  • Authors:
    • Romero, R.
    • Duran, V. H.
    • Jimenez, J. A.
    • Garcia-Tejero, I.
    • Muriel,J . L.
    • Hernandez, A.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: Different strategies of deficit irrigation have been studied in an 11-year old citrus trees ( Citrus sinensis L. Osb. 'Navelina') grafted onto Carrizo citrange ( Citrus sinensis L. Osb. * Poncirus trifoliata L. Raf.). A sustained deficit irrigation (SDI) treatment was established, with a water supplied of 60% of the crop evapotranspiration (ET c); and a low-frequency deficit irrigation treatment (LFDI), watered according to the plant-water status. As a control a full irrigated at 100% of ET c was included. Midday stem water potential (Psi stem), stomatal conductance (g s), and micrometric trunk diameter fluctuations were measured during the maximum evapotranspirative demand period to evaluate the plant-water status, and to establish the main relationships between them. The seasonal pattern of the studied variables had a behavior consistent with the applied irrigation volumes. Significant relationships between Psi stem and g s, and the maximum daily shrinkage (MDS) were found. The lowest Psi stem and g s values were registered in the deficit treatments being the MDS significative higher in these treatments than in the control treatment. Yield response was highly influenced by irrigation strategy, being these results for LFDI significant better than SDI. Considering these results and the significant relationships between MDS and Psi stem, LFDI can be a sustainable deficit irrigation strategy, encouraging significant water savings without important impact on yield and fruit quality.
  • Authors:
    • Rodriguez-Moran, M.
    • Garcia-Olmos, B.
    • Andujar, S.
    • Navarro, J. M.
    • Perez-Tornero, O.
    • Morte, A.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: Arbuscular mycorrhizal (AM) symbiosis is thought to increase host resistance to salinity stress, a characteristic that could be interesting in areas where the scarcity of irrigation waters forces growers to use low-quality irrigation water. To test this hypothesis seedlings of the rootstocks Mandarin Cleopatra ( Citrus reshni Hort. ex Tan.), Sour orange ( Citrus aurantium (L.)) and Alemow ( Citrus macrophylla Wester) were grown in a growth chamber and inoculated with a mixture of two AM fungi ( Glomus intraradices and Glomus mosseae) (IP), or left non-inoculated (NIP). From forty-five days after fungal inoculation onwards plants were irrigated with nutrient solution containing 50 mM NaCl and, three months after inoculation, the growth, mineral nutrition and physiological response were analysed. AM fungi significantly increased all plant growth parameters studied, especially in the Cleopatra and Alemow rootstocks. In general, plant growth parameters were higher in salinized IP plants than in non-salinized NIP plants, demonstrating that AM colonization compensates for the growth limitations imposed by saline conditions. The water content was higher in IP plants of Cleopatra and Alemow but not in the Sour orange seedlings. Under saline conditions NIP Alemow plants had a strongly-decreased water content, while the water content of IP Alemow plants was similar to that of non-salinised plants. In all three rootstocks, NIP plants showed a greater degree of salt-induced foliar damage and chlorosis than IP plants. Although IP plants were not fertilised with phosphorus in the experiment, they had significantly higher levels of this nutrient in roots, stems and leaves than NIP plants both in salinised and control plants. The beneficial effect of mycorrhization appears to be unrelated with protection against the uptake of excess of Na + or Cl - by the plant. Our findings confirm that AM fungi can alter host responses to salinity stress, improving the P nutrition and diminishing chlorosis and salt damage.
  • Authors:
    • Baraibar, B.
    • Ledesma, R.
    • Royo-Esnal, A.
    • Westerman, P. R.
  • Source: Crop Protection
  • Volume: 30
  • Issue: 9
  • Year: 2011
  • Summary: Harvester ants from the species Messor barbarus (L.) are important seed predators in semi-arid cereal fields of NE Spain, and can contribute substantially to weed control. However, occasionally they harvest newly sown crop seeds at sowing in autumn, or ripe cereal grains close to harvest in summer, causing yield losses. A preliminary study was conducted in 34 commercial winter cereal fields to measure yield loss, and to identify factors that influence it. The area affected by ants was measured ten days prior to the anticipated harvest date. Ant colony size, nest density, crop height, weed densities and temperatures at sowing were assessed. At sowing, harvester ants did not cause yield losses (0.2% of potential yield on average). At harvest, yield losses were generally low as well (0.6%) although occasionally higher losses were recorded (max. 9.2%). Yield losses significantly increased with increasing nest density, nest size and with number of years of no-till. The results of this study show that in 2009 yield losses caused by M. barbarus were insignificant and more than offset by the benefits provided by the destruction of weed seeds.
  • Authors:
    • Ortega-Farias, S.
    • Selles, G.
  • Source: ISHS Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: These proceedings contain 79 papers on irrigation systems for horticultural crops. Specific topics covered include the following: improvement of water use for agriculture at catchment level under drought conditions; impact of climatic change on irrigated fruit tree production; effects of the irrigation regime and partial root zone drying on grape cv. Vermentino in Sardinia, Italy; effects of canopy exposure changes on plant water status in grape cv. Syrah; water use by drip-irrigated early-season peach trees; soil water content variations as water stress indicator in peach trees; reduction in the number of fruits in peach (T204) due to postharvest deficit irrigation; effects of irrigation management and N fertilizer on the yield and quality of apple cv. Gala; canopy temperature as an indicator of water status in citrus trees; effects of root anatomy on sap flow rate in avocado trees; influence of rootstock on the response of avocado cv. Hass to flooding stress; methods of selection for drought tolerance in potato; and drip irrigation for the establishment of strawberry transplants in southern California.
  • Authors:
    • Fernández-Trujillo, J. P.
    • Provencio, A. B.
    • Martínez-López, J.A.
    • Pérez-Reverte, R.
    • Pérez-Pastor, A.
    • Domingo, R.
    • Robles, J. M.
    • Pagán, E.
  • Source: Acta Horticulturae
  • Issue: 892
  • Year: 2011
  • Summary: The quality of 'Fortune' mandarin fruit ( Citrus clementine Hort. Ex. Tanaka * C. reticulate Blanco) subjected to four different drip irrigation treatments was studied at harvest and after a subsequent storage period of 50 days at 5degreesC plus a shelf-life period of 8 days at 20degreesC. Irrigation treatments consisted of a control (CTL) irrigated at 130% of crop evapotranspiration (ETc) throughout the season, and three regulated deficit irrigation (RDI) regimes. These treatments were irrigated as a CTL except during the non critical periods, when different percentage of the control were applied: 50% during stage I and beginning of stage II in RDI 1 and RDI 2 treatments, and 80 and 200% during stage III in RDI 1 and RDI 2, respectively. RDI 3 was irrigated at 50% of RDI 1 during the water deficit periods. The electrical conductivity of the irrigation water averaged 4.23 dS m -1. RDI treatments promoted a water stress integral, derived from stem water potential at midday values, of 56, 46 and 114 MPa day for RDI 1, RDI 2 and RDI 3, respectively. Fruit at harvest from RDI1 and RDI 3 treatments showed around 15% higher total soluble solids and 11 and 19% higher levels of titratable acidity, respectively than CTL (13.8degreesBrix and 20.3 g L -1 citric acid). RDI fruits showed about 5-10% lower values of extractable juice than control. The storage period reduced fruit titratable acidity compared with harvest levels. Weight loss in control fruit reached 1.4 or 2.3% w/w at the end of cold storage or shelf-life, respectively, while in RDI treatments were reduced by 0.2-0.4% w/w. Overall, the effect of water stress on fruit quality were more pronounced at harvest than after the postharvest treatments. Under water scarcity conditions RDI1 showed acceptable fruit quality at harvest and increased storability of mandarin fruit, saving considerable amounts of water.
  • Authors:
    • Lezaún, J. A.
    • Lacasta, C.
    • Ciria, P.
    • Aibar, J.
    • Pardo, G.
    • Zaragoza, C.
  • Source: Chilean Journal of Agricultural Research
  • Volume: 71
  • Issue: 2
  • Year: 2011
  • Summary: Under semiarid conditions the response of cereal crops to chemical fertilizers and weed control practices with herbicides is often reduced. In fact, the economic profitability of agricultural production in many dryland regions is critically affected by high costs of inputs and low crop yields. As a solution, cropping systems like organic farming, obtaining similar yields and promoting environmental sustainability by reducing fertilizer and herbicides, could be an alternative to conventional systems. In this study, 23 trials were performed in five semiarid regions of Spain during 5 yr to compare different fertilizers and weed control methods on durum wheat ( Triticum durum Desf.) and barley ( Hordeum vulgare L.) yields. The following rotation pattern was developed on the experimental plots: fallow-barley-ground ploughed vetch ( Vicia sativa L.)-durum wheat. Plots either received organic fertilizer, chemical fertilizer, or no fertilizer. In addition, three levels of weed control were applied in cereal plots: flex-tine harrow tillage, conventional herbicide, and no weeding. The results indicated that neither the fertilization nor the weed control have effect on the yield crop.
  • Authors:
    • Alonso, J. C.
    • Magana, M.
    • Garcia de Leon, D.
    • Bravo, C.
    • Ponce, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 141
  • Issue: 1/2
  • Year: 2011
  • Summary: Organic farming is considered an important way to preserve biodiversity in agricultural landscapes. However, more work is still necessary to enable a full appraisal of the potential benefits of this way of farming, since studies differ in the evaluation of its effectiveness. Studies are particularly scarce in the Mediterranean region, where different climatic and ecological conditions prevent simple extrapolations from work carried out at northern latitudes. In the present study, an analysis of weed and arthropod communities was conducted in 28 pairs of organic and conventional fields in a dry cereal farmland in central Spain. Plants were identified to the species level, and arthropods to the family level. Pitfalls and sweep nets were used to sample respectively, ground-dwelling and plant-visiting arthropods. Abundance (total numbers of individuals), richness (total numbers of plant species or arthropod families), diversity (Shannon-Wiener index) and biomass (milligrams per pitfall/sweep-net) were calculated for each field and compared between organic and conventional fields using Generalized Linear Mixed Models (GLMMs). To explore the effect of predictor variables on weed richness and arthropod biomass, GLMMs were used. Organic fields showed higher abundance of weeds and arthropods (3.01 and 1.43 times, respectively), higher weed richness and diversity (2.76 and 2.33 times, respectively), and a 24% reduction in cereal plants. Arthropod diversity was lower in organic fields due to the presence of three dominant groups: Collembola, Chloropidae (Diptera), and Aphididae (Hemiptera). Weed richness increased as cereal cover decreased in organic fields. Total arthropod biomass was slightly higher in organic fields, and was affected by weed abundance and diversity. The differences between organic and conventional fields found in this study were higher than those reported for northern latitudes. This could be explained by the richer weed flora in the Mediterranean region, and a higher weed seed availability favored by the two-year rotation system typical of Iberian dry cereal farmland. We conclude that organic farming may contribute to preserve biodiversity in dryland cereal agroecosystems in the Mediterranean region.
  • Authors:
    • Moreno, M. F.
    • Diaz, M.
    • Roldan, J.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: Irrigation water management in the Genil-Cabra irrigation district, located in the province of Cordoba, southern Spain, was studied using three irrigation performance indicators: relative irrigation supply (RIS); relative water supply (RWS) and relative rainfall supply (RRS). All indicators have been calculated as in a global way as grouping data according to crop type, irrigation method and soil texture. All information of agronomic and hydraulic variables was incorporated in a Geographic Information System (GIS) to ease its management. Results show that applied irrigations are deficit irrigations because RIS values are relatively low. However, RWS values are greater and evaporative demand may be satisfied along crop development cycle. RRS indicator varies less than the other two and, together with RWS, permits to know the evapotranspiration fraction covers by rain water. Irrigation water management in four crops (olive, cotton, sunflower and maize) is considered to be adequate. In the case of sugar beet and asparagus, the deficit is larger. Wheat and garlic are the two crops that show inefficient management due to an excess supply of water. RWS and RIS values are higher for sprinkler irrigation than for drip irrigation. Soil type has little influence on irrigation management. In general, more water is applied to crops planted in sandy loam soils than in silty clay loam soils. The mean values of performance indicators we have calculated are very useful to know farmer's behaviour and the general trend, although the used sample is not significant to characterize the global irrigation district.