• 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:
    • Robles-Gonzalez, M. M.
    • Virgen-Calleros, G.
    • Vazquez-Garcia, M.
    • Medina-Urrutia, V. M.
  • Source: Acta Horticulturae
  • Issue: 894
  • Year: 2011
  • Summary: This work was carried out to determine the influence of seasons of vegetative shoots on the time of flowering and to known the intervals from flowering to fruit harvest of Mexican lime trees. Two experiments on a seven years old Mexican lime trees budded on Sour Orange rootstock were established. In experiment 1, the number of vegetative (VS) and reproductive shoots (RS) on each one of 10 trees were registered weekly during one year, using a metallic ring of one square meter area placed on the tree 1.75 m from the ground. Minimum temperature and rainfall data were also recorded every week. In experiment 2, monthly, ten new vegetative shoots on each one of ten trees were tagged. These shoots were observed every week until they bloom. During the most important periods of blooming, five flowering shoots per tree were chosen to determine interval to harvest. In experiment 1, four VS and two RS flushes were observed. The first period of VS and RS started in autumn and was associated to the initiation of irrigation. The second and more important was registered in January when temperatures were the lowest of the year. Half RS and half VS were recorded during this period. The third and four flushes were mainly VS and occurred during summer months with highest temperatures and the rainy season. In experiment 2, from the vegetative shoots emerging in January, 52% formed reproductive shoots 60-85 days later and 25% also flowered sparsely four to six months later. The remaining shoots (23%) repeated their vegetative activity during June and July. Most of the vegetative shoots initiated in February showed again a vegetative activity during May to July, and only 20% of them changed to reproductive. New vegetative shoots appeared from March to July showed a vegetative activity during the next two to six months. From the vegetative shoots emerged from July to September very few (15%) transformed to reproductive during November-December and the majority became vegetative again, however, most of them changed to reproductive from January to April. Fruits initiating during the winter time lasted 130 to 145 days until harvest. But those fruits emerged during the late spring and summer months reached complete development 90 to 120 days later. These combined phenological characteristics explain the long period of harvest showed by the MLT under tropical semiarid conditions.
  • Authors:
    • Syvertsen, J. P.
    • Dunlop, J. M.
    • Melgar, J. C.
  • Source: HortScience
  • Volume: 46
  • Issue: 3
  • Year: 2011
  • Summary: Oleocellosis or oil spotting on the peel of citrus fruit is a common post-harvest injury caused by improper handling. Mechanical injury allows phytotoxic oil to leak out of oil glands and cause injury to surrounding flavedo cells, resulting in oleocellosis. Mechanical harvesting (MH) of 'Valencia' sweet orange is conducted in late spring, when the next season's fruitlets are in their early stages of development. There is a concern that mechanical injury from harvesting machines can cause oleocellosis and fruit drop of young, green 'Valencia' sweet orange fruitlets, especially late in the harvest season when fruitlets are relatively large. We evaluated the effects of winter drought stress and subsequent late-season MH with a canopy shaker on oleocellosis of 'Valencia' sweet orange fruitlets. In April, mature fruit size, juice content, total soluble solids, and acidity were unaffected by previous winter drought stress treatments. Mechanical harvesting removed ~90% to 95% of mature fruit and 20% to 50% of fruitlets depending on previous drought stress treatments and harvesting date. Beginning 1 week after the late harvest (13 June), attached fruitlets were tagged and visually evaluated approximately every other month to determine oleocellosis injury until the late-season harvest 12 months later. Only 12% of the fruitlets had oleocellosis on more than 30% of their surface area. Up to 75% of the fruitlets from the previously drought-stressed trees had less than 10% of their surface area injured after MH and 11% of these fruitlets dropped before harvest. Nonetheless, there was no significant increase in fruit drop with increased surface area injured nor was juice quality affected at harvest. Overall, fruit surface oleocellosis decreased and healed as fruit expanded, but surface blemishes did not completely disappear. Thus, fruitlet oleocellosis in late-season mechanically harvested trees was cosmetic and did not increase fruit drop nor alter internal fruit quality.
  • 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:
    • Amiri, N. A.
    • Kangarshahi, A. A.
    • Namdari, M.
  • Source: AFRICAN JOURNAL OF AGRICULTURAL RESEARCH
  • Volume: 6
  • Issue: 11
  • Year: 2011
  • Summary: In this study, the citrus (orange and mandarin) production in Mazandaran province of Iran and the energy equivalences of input used in this production are investigated. Data in this study was obtained from 110 citrus orchards by a face to face questionnaire method. The results revealed that mandarin production had more energy intensive compared to orange. The major energy inputs in orange and mandarin production were diesel fuel (27 and 24%), chemical fertilizers (22 and 23%) and irrigation water (21 and 23%), respectively. The results showed that 62375.18 MJ ha -1 energy were consumed by orange orchards and 77501.17 MJ ha -1 by mandarin orchards. Energy use efficiency, energy productivity, specific energy, and net energy gain were calculated. The energy use efficiency for orange and mandarin were 0.99 and 0.77, respectively. In average, the non-renewable form of energy input was 67.14% of the total energy input used in citrus production compared to 33.07% for the renewable form. Optimal consumptions of diesel fuel, chemical fertilizers and other major inputs would be useful techniques for decreasing energy consumption in citrus production.
  • 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:
    • Bhandary, N. P.
    • Koike, Y.
    • Nishimura, F.
    • Tsuno, H.
  • Source: Journal of Water and Environment Technology
  • Volume: 9
  • Issue: 2
  • Year: 2011
  • Summary: Matsuyama region, located in Shikoku Island, Japan faces the Seto Inland Sea on the west, where the annual rainfall is relatively less than in the other areas in Japan. In such favorable condition, the cultivation of citrus fruits is popular, and there are a large number of small reservoirs for irrigation purposes. The citrus groves are distributed in hilly areas surrounding the paddy fields and residential areas so there are higher chances for the nearby water environment to get affected by leachate from the groves. This paper investigates the water quality characteristics of the leachate from the groves, and studies the changes of the leachate quality near the collecting reservoirs. It was found that the grove soils are highly acidic and the leachate contains metals and nutrients in high concentration. On the other hand, the water quality of the leachate changed after it flowed into the reservoirs, and the concentrations became lower. It is understood that chemical and biological reactions help remove the contaminants in the reservoir, and from the standpoint of self-purification, reservoirs play an important role. This paper also discusses the kinetics of the self-purification and the quantitative estimation based on the experimental results.
  • Authors:
    • Sheffield, K. J.
    • Abuzar, M.
    • Whitfield, D. M.
    • O'Connell, M. G.
    • McClymont, L.
    • McAllister, A. T.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: SEBAL-METRIC estimates of evapotranspiration (ET) were derived from Landsat-5 imagery of Sunraysia Irrigation Region of Victoria, Australia. Paired estimates of ET and vegetation cover, NDVI, were derived from an image taken mid-season on 5 January 2009. NDVI and ET were attributed to land use based on data provided by SunRISE21 Inc. Relationships between ET, scaled by field measured reference tall crop evapotranspiration, ET r, and NDVI for the dominant almond, citrus and grape crops showed that the evaporation ratio (ET/ET r) was strongly related to NDVI. These findings suggest that SEBAL-METRIC satellite remote sensing approaches offer an affordable and robust method for the deviation of NDVI-based block-customised estimates of crop coefficient (K c) for almond, citrus and grape crops.
  • Authors:
    • Crusciol, C. A. C.
    • Garcia, . A.
    • Castro, G. S. A.
    • Rosolem, C. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: Especially under no-tillage, subsuface soil acidity has been a problem, because it depends on base leaching, which has been associated with the presence of low molecular weigth organic acids and companion anions. The objective of this study was to evaluate exchangeable base cation leaching as affected by surface liming along with annual urea side-dressing of maize and upland rice. Treatments consisted of four lime rates (0, 1500, 3000, and 6000 kg ha -1) combined with four nitrogen rates (0, 50, 100, and 150 kg ha -1) applied to maize ( Zea mays) and upland rice ( Oryza sativa), in two consecutive years. Maize was planted in December, three months after liming. In September of the following year, pearl millet ( Pennisetum glaucum) was planted without fertilization and desiccated 86 days after plant emergence. Afterwards, upland rice was grown. Immediately after upland rice harvest, 18 months after surface liming, pH and N-NO 3-, N-NH 4+, K, Ca, and Mg levels were evaluated in soil samples taken from the layers 0-5, 5-10, 10-20 and 20-40 cm. Higher maize yields were obtained at higher N rates and 3000 kg ha -1lime. Better results for upland rice and pearl millet yields were also obtained with this lime rate, irrespective of N levels. The vertical mobility of K, Ca and Mg was higher in the soil profiles with N fertilization. Surface liming increased pH in the upper soil layers causing intense nitrate production, which was leached along with the base cations.