• Authors:
    • van den Bergh, I.
    • Staver, C.
    • Reinhardt, D. H.
    • Gubbuk, H.
    • Albrigo, L. G.
    • Wuensche, J. N.
  • Source: ISHS Acta Horticulturae
  • Issue: 928
  • Year: 2012
  • Summary: This proceedings contains 54 papers dealing with cultivation and production of citrus, bananas and other tropical fruits in the subtropics. Topics discussed include the effects of climate change, different substrates, thinning, girdling, heavy pruning, fertilizer application, irrigation and water stress; grafting; pollination strategies; mechanical harvesting; postharvest treatment; drying; storage; breeding; fruit drop, set and quality; growth and physiology; as well as pests, diseases and weeds.
  • Authors:
    • Ma, C. L.
    • Wang, P.
    • Guo, P.
    • Peng, H. Y.
    • Chen, L .S.
    • Yang, L. T.
  • Source: Scientia Horticulturae
  • Volume: 133
  • Year: 2012
  • Summary: 'Sour pummelo' ( Citrus grandis) seedlings were irrigated for 18 weeks with nutrient solution containing 0 (-Al) and 1.2 mM (+Al) AlCl 3.6H 2O * 0, 10 and 500 M sodium nitroprusside (SNP), a nitric oxide (NO) donor. Leaf malate content did not significantly change in response to SNP with or without aluminum (Al) except for an increase under 1.2 mM Al+10 M SNP, while leaf citrate content decreased with increasing SNP supply. Root malate content kept unchanging with or without Al except for an increase under 500 M SNP in the absence of Al, while SNP-treated roots had a higher or similar citrate content. Al decreased or did not affect malate content in roots and leaves, and citrate content in roots, but increased leaf citrate content. Al-treated roots and leaves displayed lower or similar activities of acid-metabolizing enzymes [phospho enolpyruvate carboxylase (PEPC), NAD-malate dehydrogenase (NAD-MDH), NADP-malic enzyme (NADP-ME), citrate synthase (CS), aconitase (ACO), NADP-isocitrate dehydrogenase (NADP-IDH), phospho enolpyruvate phosphatase (PEPP) and pyruvate kinase (PK)] except that they had higher or similar activities of NADP-ME and PK and Al-treated leaves had a higher or similar activity of PEPP. In conclusion, the OA metabolism in leaves and roots is differently affected by NO and Al interactions.
  • Authors:
    • Araki, T.
    • Nomiyama, R.
    • Yokota, N.
    • Setoyama, S.
    • Kagawa, H.
    • Kotegawa, R.
    • Sato, Y.
    • Ohara, M.
    • Kawano, T.
    • Yano, T.
    • Yasunaga, E.
    • Eguchi, T.
    • Kitano, M.
  • Source: Environment Control in Biology
  • Volume: 50
  • Issue: 2
  • Year: 2012
  • Summary: In order to improve temperature and water management in the greenhouse cultivation of Satsuma mandarins, short-term water and carbon balance in intact Satsuma mandarin fruits was studied by measuring fruit expansive growth, CO 2 and H 2O gas exchange, sap flux into the fruit through the phloem and xylem, and 13C partitioning. Seventy-one days after full bloom, with day/night temperature set at 28°C/23°C and under fine weather conditions, sap flux through the xylem into the fruit showed a dynamic diurnal change which was related to changes of fruit volume. In leaves, 13C partitioning decreased from 11:00 until 23:00, remaining constant thereafter, whereas in fruits, 13C partitioning increased from 11:00 until 23:00, and then remained contrast. Investigating the cumulative water balance, 19% of water output was lost by fruit transpiration, whereas 81% contributed to fruit growth. In cumulative carbon balance, 39% of carbon output was lost by fruit respiration, whereas 61% contributed to fruit growth. Quantitative analyses of physiological responses to environmental conditions, as measured in this study, are essential for establishing energy-saving temperature management strategies.
  • Authors:
    • Desneux, N.
    • Han, P.
    • Niu, C. Y.
    • Zhou, X. W.
  • Source: Journal of Economic Entomology
  • Volume: 105
  • Issue: 4
  • Year: 2012
  • Summary: The Chinese citrus fruit fly, Bactrocera minax (Enderlein) is a univoltine Tephritidae pest that infests Citrus species. Field trials were conducted in 2010 to determine the potential use of a lure based on enzymatical-hydrolyzed beer yeast as liquid bait (hereafter named H-protein bait) for B. minax in the Hubei province, China. In a citrus orchard, we compared the attractiveness among aqueous solutions of H-protein bait, GF-120 fruit fly bait, sugar-vinegar-wine mixture, torula yeast, and Jufeng attractant when used in traps and in spot sprays, that is, lures used in combination with the insecticide trichlorphon. The H-protein bait was the most attractive lure in traps, ensnaring significantly more adults than sugar-vinegar-wine mixture, torula yeast, and Jufeng attractant, in decreasing efficiency order. In spot sprays those with H-protein bait killed significantly more female and male flies within 40 min than those with sugar-vinegar-wine mixture, GF-120, Jufeng attractant, and the control. In addition, the total number of flies killed by H-protein bait during the spot spray duration was higher than other treatments. Our results demonstrated that the H-protein bait may be a useful tool in citrus orchards in China to monitor B. minax populations as well as to manage this pest when used in spot sprays.
  • Authors:
    • Mulas, M.
    • Deidda, B.
    • Zurru, R.
  • Source: Acta Horticulturae
  • Issue: 928
  • Year: 2012
  • Summary: Pruning of Clementine requires a lot of time: more than 50 days of work per hectare in the traditional forms of orchard management. Because of the high cost and the lack of specialised workers, we observe a general tendency to delay the frequency of pruning in the citrus orchards. On the other hand regular pruning is of fundamental importance to have good fruit quality, to maintain health status of the orchard, and to store their regular productivity. In order to optimise the Clementine pruning technique, reduce the time of execution and maintain a good level of yield of better quality a field experiment was designed. In 1996 a commercial orchard of 'SRA 63' Clementine located in Southern East Sardinia was selected for the experiment. Plants were grafted on 'Troyer' Citrange, twenty-year-old, spaced 7*5 m, shaped to globe, over 4 m in height, and showed an excessive number of main branches (about 7-8 per tree) with a dense canopy. The entire orchard was preliminarily submitted to a gradual shape pruning during the first four years. In 2000 two main plots of 72 plants each were designed: (A) pruning every year; and (B) pruning every two years. The orchard was observed for a further period of four years for the following characters: trunk section area; canopy size, working time for pruning; pruned wood weight; fruit yield; fruit size. In both pruning applications (A and B) the canopy was more open and green than in the past, with a improvement of the plant heath status, a reduction of the number of treatments, water for irrigation and fertilizers, less working time for harvest, and with a significant better fruit size and increase of the production value.
  • Authors:
    • Benismailc, M.
    • El-Otmanic, M.
    • Fadlc, A.
    • Hammoutib, B.
    • Salghia, R.
    • Abouatallaha, A.
    • Eljaouharic, N.
    • Kabousc, E.
    • Zianic, A.
  • Source: Der Pharma Chemica
  • Volume: 3
  • Issue: 6
  • Year: 2011
  • Summary: Capacitance probes were tested in a young citrus orchard for irrigation water saving; Cumulative water received by the plot reached 334 mm and 398 mm for the first and second year period respectively (irrigation+useful rain). Irrigations were made in 521 interventions when the lowest dose of 1.05 mm was used and in 210 interventions when the highest dose of 2.6 mm was applied. Capacitance probes were giving values statistically different compared to the gravimetric method, but with, however, a meaningful interrelationship; A good correlation was then obtained between real values and reading from capacitance probes, a value of 16% showed by the C-probe is equivalent to 22%. The parameters of growth, trunk diameter microvariations probes (LVDT) and components of yield are well correlated with Soil moisture and Vapor Pressure Deficit (VPD). Treatment 1 (T1) was better in cold period (December, January and February), while Treatment 4 (T4) was more efficient from flowering (March) and developed deep roots (more than 50 cm). Leaf water potential and LVDT showed the sensitivity of T1 towards climate changes during high evaporative demand days. Analysis of soil moisture data showed that the field capacity was maintained at not more than 30 cm soil depth for T1, which developed very superficial roots (45% at only 10 cm). The number of roots was significantly different between treatments, T4 was distinguished by a greater concentration of roots (8843), compared to T1 (4104). After 27 months from plantation, the Yield showed a performance of 46 T/ha recorded for the dose of 2.1 mm, when the fruit size was 70% of Size 1-3; water saving was about 50% and valuated at 105 l/kg produced.
  • Authors:
    • Evangelista, A.
    • Silva, T.
    • Silva, C.
    • Folegatti, M.
    • Alves Junior, J.
  • Source: Engenharia Agricola
  • Volume: 31
  • Issue: 2
  • Year: 2011
  • Summary: The aim of this study was to evaluate the effect of different irrigation levels on canopy and root growth, productivity, and fruit quality of young Tahiti acid lime trees. The experiment was installed in Piracicaba, Brazil in a 1.0-ha orchard plot with 'Tahiti' acid lime trees, grafted on Swingle citrumelo rootstock and carried out from August of 2002 to May 2005. Each treatment was assigned to a drip irrigation level, based on ETc as follows: (T1) non-irrigated, (T2) 25%, (T3) 50%, (T4) 75% and (T5) 100% of ETc determined by weighing lysimeter presented in the orchard plot. Trunk diameter and tree height were evaluated monthly. The roots were evaluated when the trees were 30 and 48 months old. The yield and fruit quality was evaluated in 2004 and 2005. The results showed that irrigation did not influence root distribution in depth, and trees irrigated with 75% and 100% ETc showed horizontal root distribution concentrated until 0.6 m from the trunk. Irrigation did not improve the quality of fruit. Yield increased in all irrigated treatment, but the most efficient yield mean per unit of water applied was the 25% ETc treatment.
  • Authors:
    • Intrigliolo, D.
    • Castel, J.
    • Ballester, C.
    • Castel, J.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 6
  • Year: 2011
  • Summary: The effects of mid-summer regulated deficit irrigation (RDI) treatments were investigated on Clementina de Nules citrus trees over three seasons. Water restrictions applied from July, once the June physiological fruit drop had finished, until mid September were compared with a Control treatment irrigated during all the season to match full crop evapotranspiration (ET c). Two degrees of water restrictions were imposed based on previous results also obtained in Clementina de Nules trees ([Ginestar and Castel, 1996] and [Gonzalez-Altozano and Castel, 1999]). During the RDI period, deficit irrigation was applied based on given reductions over the ET c, but also taking into account threshold values of midday stem water potential (psi s) of -1.3 to -1.5 MPa for RDI-1 and of -1.5 to -1.7 MPa for RDI-2. Results showed that water savings achieved in the RDI-2 treatment impaired yield by reducing fruit size. On the contrary, the RDI-1 strategy allowed for 20% water savings, with a reduction in tree growth but without any significant reduction in yield, fruit size nor in the economic return when irrigation was resumed to normal dose about three months before harvest. Water use efficiency (WUE) in the RDI trees was similar or even higher than in Control trees. RDI improved fruit quality increasing total soluble solids (TSS) and titratable acidity (TA). In conclusion, we suggest that the RDI-1 strategy here evaluated can be applied in commercial orchards not only in case of water scarcity, but also as a tool to control vegetative growth improving fruit composition and reducing costs associated with the crop management.
  • Authors:
    • Intrigliolo, D.
    • Yeves, A.
    • Sanz, F.
    • Castel, J.
    • Ballester, C.
    • Castel, J.
  • Source: Acta Horticulturae
  • Issue: 922
  • Year: 2011
  • Summary: In citrus trees, regulated deficit irrigation (RDI) can be a useful irrigation strategy to reduce water supply without affecting yield. Previous studies conducted in this sense have determined irrigation water savings achieved by RDI but less is known about the actual transpiration values of the RDI trees. This information is crucial to properly carry out a water balance of an RDI orchard. In an experiment performed during 2009 on mature 'Clementina de Nules' citrus, we determined sap flow (SF) of well irrigated and RDI trees by means of the compensation heat pulse method. SF was measured in two trees per treatment instrumented with one unit of two different gauge types per tree, determining heat velocity at four different xylem depths. SF values obtained at 30-min intervals during the entire experimental period were compared with whole canopy gas exchange measurements carried out during two representative days with custom designed Mylar plastic chambers. Plant water status was determined by midday stem water potential measurements (Psi stem). Results showed that absolute SF values clearly underestimated tree water use. After calibrating SF against canopy gas exchange determinations, corrected SF values appeared more reasonable but it also increased tree-to-tree variability (CV from 0.08 to 0.17). The transpiration ratio (SF RDI/SF control) had a somewhat decreasing trend during the water restriction period according to Psi stem, but recovering before the irrigation was resumed to normal dose. Overall, the results highlight some of the problems and uncertainties when using a limited number of sap flow sensors for detecting plant water stress and for accurately measuring transpiration.
  • Authors:
    • Benchabane, M.
  • Source: IOBC/WPRS Bulletin
  • Volume: 62
  • Year: 2011
  • Summary: After studies (2006-2009) of the states of fading of citrus fruits in the Mitidja (Algeria), we noted a troubling epidemic evolution in some orchards where the death rates reached proportions of 5 to 10%. The symptomatologic diagnosis indicates the presence of a strong likeness between the different biotic reasons possible without the presence of symptoms typical and/or of revealing signs of the known diseases (bacteria and virus). The diagnosis of laboratory confirmed their absence. The isolations achieved from the roots and soil put often in evidence the presence of Fusarium flora dominated by Fusarium solani and Fusarium oxysporum species. The implication of these species is joined to the pedological features and to the technical practices, notably the irrigation.