• Authors:
    • Pompeu Junior, J.
    • Blumer, S.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 1
  • Year: 2011
  • Summary: The objective of this work was to evaluate the size, fruit yield and canopy production efficiency of 'Valencia' sweet orange trees, budded onto citrumelos, 'Rangpur' lime and citremon rootstocks, cultivated without irrigation. Eleven rootstocks were visually assessed for symptoms of tristeza, citrus blight and bud-union-ring incompatibility with the scion. The 'Swingle' and W-2 citrumelos induced larger and more productive trees with the same productive efficiency as the ones on 'Rangpur' lime rootstock. The F.80.6, F.80.5, F.80.3 and F.80.18 citrumelos induced plants with height and canopy diameter smaller than 2 m. The citrumelos and the 'Rangpur' lime are tolerant to tristeza and blight, and are compatible with the 'Valencia' sweet orange. Citremon is susceptible to tristeza.
  • Authors:
    • Manmohan, J. R.
    • Singh, J.
    • Kaul, M. K.
    • Bhatnagar, P.
    • Chauhan, P. S.
  • Source: The Indian Forester
  • Volume: 137
  • Issue: 12
  • Year: 2011
  • Summary: Comparative effects of drip and micro sprinkler systems under kinnow+kinnow and kinnow+poplar silvi-horti system were studied under sub tropical climate. Drip system of irrigation was found promising in maintaining better growth of kinnow plants. Kinnow+Poplar system of plantation was found superior over kinnow+kinnow system of plantation under drip irrigation system. Under this system (kinnow+poplar) of plantation, values of plant height at 70% ETC were 2.55 m, canopy volume 23.51 m 3, rootstock girth 11.13 cm, scion girth 10.76 cm, and leaf area were 16.07 cm 2. Of course, values for all these traits were higher at 100% ETc under kinnow+kinnow system of plantation over kinnow+poplar system of plantation under drip system but these were at par with each other. Irrigation of kinnow orchards at 100% ETc was found better irrespective of the systems of irrigation.
  • Authors:
    • Levy, Y.
    • Raveh, E.
  • Source: Israel Journal of Plant Sciences
  • Volume: 59
  • Issue: 2/4
  • Year: 2011
  • Summary: During the last 50 years world irrigation has doubled while water withdrawal has tripled, leading to a global water crisis. As a result, growers around the world are forced to utilize effluent water for irrigation. In Israel the main source for such water is "SHAFDAN", i.e., tertiary-treated waste water, which is characterized by high chloride content that might increase in the future. These days about 33% of Israeli citrus orchards are irrigated with this water, yet its potential effect on citrus orchards is not clear. Citrus is one of the major fruit crops of the world and is relatively salt-sensitive. Recently it was reported that continuous application of KNO 3 might reduce chloride (Cl) uptake, and thus overcome the toxic effects of salinity. We examined the effect of KNO 3 fertilization and rootstock on grapefruit's response to salinized SHAFDAN reclaimed water over four years. Trees were grafted on five different rootstocks and fertigated with two KNO 3 regimes (118 vs. 148 mg 1 -1 NO 3), and exposed to five levels of salinized reclaimed water (from 221 to 765 mg 1 -1 Cl). During the experiment, soil electrical conductivity (EC) ranged from 2 dS m -1 (above the threshold for yield reduction) to 5 dS m -1. Leaf Cl (with the exception of trees grafted on Troyer) usually kept below toxicity level, i.e., >0.4%. Cumulative yield reduction due to salinity was 37.6, 21.3, 18.2, 17.2, and 12.6 kg per tree per dS m -1 of soil paste extract, for trees grafted on 812, SO, Volk, Gau, and Troy rootstocks, respectively, reflecting their sensitivity to the osmotic component of salt stress. Enhanced application of KNO 3 did not overcome the osmotic effect of salinity. These results indicate that while using reclaimed water, the osmotic component of salinity can be of higher significance than its toxic component, and more attention should be given in the future to the rootstock/scion combination's sensitivity to the osmotic component of salinity.
  • Authors:
    • Puerto-Molina, H.
    • Sacristan-Beltri, E.
    • Melian-Navarro, A.
    • Ruiz-Canales, A.
    • Molina-Martinez, J. M.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: Along the Mediterranean countries, water scarcity is a structural problem. In the Southest of Spain water shortage is becoming more acute, specially in the agricultural sector. In these areas the cultivation of citrus fruits is very important but those are irrigation, intensive crops with important water requirements. In order to optimize available water offer and rationalize the demand management an increase of the efficiency of existing irrigation systems could be achieved by the improvement of irrigation scheduling techniques. During the last years, irrigation systems have undergone a modernisation process, the majority of which implied the change of surface irrigation to drip irrigation systems. These changes have been promoted both by national and regional administrations and farmers. However, the adoption of drip irrigation has not involved an adequate irrigation management and thus, these irrigation facilities have not reached high values of efficiency, as compared to the potential efficiency of drip irrigation systems. An adequate irrigation scheduling is necessary in order to increase the efficiency values mainly avoiding infiltration water losses and applying only the water required to meet crop water needs. Traditional irrigation scheduling is based on a soil water balance model as the proposed by FAO. This methodology has proven to be partially accurate for fruit trees. For this reason is important to assess some possible alternatives or complements to the FAO model. Finally, the application of several systems of irrigation scheduling for citrus trees based on water content gauges has been studied. Some results, advantages and disadvantages of these systems are analyzed.
  • Authors:
    • Yang, L.
    • Yin, S.
    • Xia, L.
    • Yu, Y.
    • Wu, D.
  • Source: PEDOSPHERE
  • Volume: 21
  • Issue: 6
  • Year: 2011
  • Summary: In the Three Gorges Area of China, soil erosion and the resultant non-point source pollution and ecological degradation have endangered agricultural ecosystems and fresh water reservoirs. Although efforts have been undertaken to reduce soil and water losses from slope land used for citrus production, information on the effects of management practices on soil fertility indices is either limited or nonexistent. This study was conducted to compare the effects of 10 years of various management practices, citrus intercropped with white clover (WC), citrus mulched with straw (SM), citrus intercropped with contour hedgerows (CH), citrus orchard land with impermeable membrane (IM), and citrus intercropped with wheat ( Triticum aestivum) and peanut ( Arachris hypogaea) (WP), as treatments on soil fertility indices with that of the conventional citrus management (CM). Results showed that the soil organic carbon, total and available nitrogen, available potassium, and water-stable aggregate (>0.25 mm) contents at the 0-5 cm depth were higher for the WC and SM treatments than the CM treatment. There was also spatial variation in soil fertility along slopes of the WC and SM treatments. The soil total and available nitrogen, phosphorus, and potassium, and water-stable aggregate (>0.25 mm) contents at both the 0-5 and 5-20 cm depths were higher for the CH and IM treatments than the CM treatment. The average soil available nitrogen and available potassium contents were higher for the WP treatment than the CM treatment, but the WP treatment had little effect on the soil organic carbon, total nitrogen, and water-stable aggregate (>0.25 mm) contents. These suggested that white clover intercropping and straw mulching were the most effective approaches to improve soil fertility in citrus orchard land of the Three Gorges area.
  • Authors:
    • Uygur, F. N.
    • Koloren, O.
    • Kitis, Y. E.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 5
  • Year: 2011
  • Summary: Weeds are one of the most important problems in newly established orchards. Especially in organic orcharding, the importance of weed management is much more than conventional orcharding. Therefore, importance of alternative methods to chemical control of weeds is increasing. This study was conducted to quantify the effects of common vetch (Vicia sativa L.) as living mulch on weeds and evaluate the availability of common vetch in organic citrus production. The study was carried out in Mandarin orchard which was established specially for this research in research and implementation area of the Plant Protection Department of Cukurova University in Turkey, in a three-year-period. Living mulch and control plots were placed between rows in newly established mandarin orchard and plots were maintained at the same locations until the end of the experiment. In this study, effects of the living mulch application on density, cover proportion, biomass, dry weight and similarity index of weed species were investigated. Overall three-years results of the study were evaluated, living mulch application reduced weed density and cover proportion average of 42.8% and 45.9% respectively compare to control. Biomass and dry weight of weeds were also reduced by living mulch in all years of the experiment. The results indicate that living mulch application by common vetch is an important alternative weed suppression method for ecological weed management.
  • Authors:
    • Carvalho, S. A. de
    • Setin, D. W.
  • Source: Citrus Research and Technology
  • Volume: 32
  • Issue: 1
  • Year: 2011
  • Summary: Citrus Sudden Death (CSD) a citrus disease of indeterminate causal agent, imposed changes to the Sao Paulo state citrus nursery tree production, with the substitution of the Rangpur lime for tolerant rootstocks as Swingle citrumelo, which, however, is less resistant to water deficit. The use of inarched nursery trees, combining resistance to water deficit and to CSD, can be interesting for planting in areas of risk, sparing the need of irrigation. The objective of this research was to evaluate different containers and grafting methods for the production of Valencia sweet orange nursery trees with double-rootstocks: Rangpur lime and Swingle citrumelo. Two containers (0.05 dm 3 and 0.25 dm 3 leaching tubes) and two grafting methods (inarching and spliced approach grafting) were evaluated for production of double-rootstocks. The comparison was performed against the single patterns (Rangpur lime or Swingle). Plant growth before and after grafting was evaluated in the final evaluation, the volume and mass of roots and mass of scion dry matter were measured. Single and double rootstocks grown initially in tubes of 0.25 dm 3, and Valencia nursery trees produced on the same container, demonstrated higher growth. Valencia nursery trees on Swingle citrumelo and Rangpur lime double rootstocks presented similar growth to trees grafted on Swingle citrumelo single rootstock. However, considering the potential of such type of nursery trees, its production may be held by sowing different rootstocks in the same tube of 0.25 dm 3, performing the graft by inarching method and the transference to bags where the canopy bud is grafted.
  • Authors:
    • Stuchi, E. S.
    • Souza, M. C. de
    • Goes, A. de
  • Source: Crop Breeding and Applied Biotechnology
  • Volume: 11
  • Issue: 1
  • Year: 2011
  • Summary: A citrus scab disease, caused by Elsinoe fawcettii, is currently found in all citrus areas throughout Brazil. That being, given the importance of this casual agent, the behavior of tangerines and hybrids influenced by this pathogen was evaluated under natural infection conditions. This study was performed with plants around 15 years old without irrigation; 100 fruits of three plants were collected during harvest season, using a grade scale varying from 0 (absence of symptoms) to 6 (severe symptoms) the level of disease severity was determined. Among the cultivars, citrus scab resistance was observed in Citrus deliciosa, C. tangerina, C. nobilis; a mandarin hybrid ( C. nobilis * C. deliciosa) and a satsuma hybrid ( C. unshiu * C. sinensis). Among the other genotypes, symptoms were observed with levels of severity ranging from 1 to 3, indicating moderate resistance.
  • Authors:
    • Carvalho, D. F. de
    • Botrel, T. A.
    • Souza, W. J.
    • Silva, L. D. B. da
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 15
  • Issue: 8
  • Year: 2011
  • Summary: The use of localized irrigation using microtube as emitter under turbulent flow regime can be a technically feasible alternative. The objective of this study was to evaluate the performance of a fertigation system in nursery of citrus plants (greenhouse) projected by universal mathematical model, using the microtubes as emitters, under turbulent flow rate and to compare the development of the fertigated plants by microtubes to the system that use the traditional method with hoses. In the size of the length of the emitters was considered the K coefficient of localized energy dissipation using a microtube with internal diameter of 0,761 mm. The fertigation system presented great performance with clogging degree, Christiansen uniformity and emission uniformity values equal to 0,50; 99,95 and 98,21%, respectively, after 160 days of study. Plants that were grown using fertigation with both microtubes and hoses showed no difference as regards to stem diameter and height. Thus, the use of the microtube under turbulent flow rate presented technical feasible for fertigation system.
  • Authors:
    • Germana, C.
    • Intrigliolo, F.
    • Giuffrida, A.
    • Stagno, F.
    • Continella, A.
  • Source: Acta Horticulturae
  • Issue: 889
  • Year: 2011
  • Summary: During three consecutive years, in a citrus orchard planted with Tarocco 'Meli' and 'Scire' on sour orange ( C. aurantium L.) were verified the differences of the plant water status and the possibility to build an empirical model to estimate the psi pd utilizing stem water potential (psi md) and vapor pressure deficit (VPD md) measured at midday. The first results showed statistical differences during the irrigation season in the two clones water potential. These difference permitted to separate the data of Tarocco 'Meli' and 'Scire'. As a result, two empirical models were built. The 2nd degree equation (Psi pd=a+b 1Psi md+b 2VPD md) was obtained by considering the Psipd as dependent variable, the Psi md and the VPD md as explanatory variables. ANOVA applied to the multiple regression resulted highly significant with P-value