• Authors:
    • Hau, B.
    • Lourenco, S. A.
    • Stuchi, E. S.
    • Goncalves, F. P.
    • Amorim, L.
  • Source: Plant Pathology
  • Volume: 91
  • Issue: 11
  • Year: 2012
  • Summary: Citrus Variegated Chlorosis (CVC) is currently present in approximately 40% of citrus plants in Brazil and causes an annual loss of around 120 million US dollars to the Brazilian citrus industry. Despite the fact that CVC has been present in Brazil for over 20 years, a relationship between disease intensity and yield loss has not been established. In order to achieve this, an experiment was carried out in a randomized block design in a 3*2 factorial scheme with 10-year-old Natal sweet orange. The following treatments were applied: irrigation with 0, 50 or 100% of the evapotranspiration of the crop, combined with natural infection or artificial inoculation with Xylella fastidiosa, the causal agent of CVC. The experiment was evaluated during three seasons. A negative exponential model was fitted to the relationships between yield versus CVC severity and yield versus Area Under Disease Progress Curve (AUDPC). In addition, the relationship between yield versus CVC severity and canopy volume was fitted by a multivariate exponential model. The use of the AUDPC variable showed practical limitations when compared with the variable CVC severity. The parameter values in the relationship of yield-CVC severity were similar for all treatments unlike in the multivariate model. Consequently, the yield-CVC intensity relationship (with 432 data points) could be described by one single model: y=114.07 exp(-0.017 x), where y is yield (symptomless fruit weight in kg) and x is disease severity ( R2=0.45; P
  • Authors:
    • Silva, J. A. A.
    • Modesto, R. T.
    • Miguel, F. B.
    • Grizotto, R. K.
    • Vieira Jr., J. B.
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 16
  • Issue: 7
  • Year: 2012
  • Summary: The effect of a technological package implemented in a Valencia orange orchard was studied and compared with the conventional system, based on the production and quality of the fruits harvested. The technologies implemented included the densification, fertilization during implantation and training, phytosanitary treatment, weed management, irrigation and pruning. The results for the fruits from the first harvest showed that the Technified System and Irrigation (TS+I) resulted in significant increase in crop yield. This increase was higher in orchards with a higher density of 727 plants ha -1 (5.5*2.5 m spacing) or 667 plants ha -1 (6.0*2.5 m spacing). In general, irrigation concomitant with TS resulted in larger sized fruits and consequently less fruit per standard sized box, and lower soluble solids and titrable acidity. There was no effect on juice yield with the production system or spacing. It is concluded that, in this first evaluation, orchard management technologies concomitant with irrigation (TS+I) is interesting because promoted an increase in crop yield compared to conventional systems.
  • Authors:
    • Ghanbari, A.
    • Moradi, H.
    • Rabiei, V.
    • Hamedani, M.
    • Azimi, M. R.
  • Source: Biharean Biologist
  • Volume: 6
  • Issue: 1
  • Year: 2012
  • Summary: Blood orange ( Citrus sinensis) cv. Tarocco, grown in the north of Iran, was harvested at the mature stage and stored at 8, 15 or 22°C for various duration. During the storage period, weight loss, total soluble solids (TSS), total titratable acidity (TA), pH, ascorbic acid, total phenols, flavonoids, antioxidant capacity, anthocyanin and L-phenylalanin ammonia-lyase enzyme (PAL) activity were determined. The highest increase in pH, anthocyanins in the pulp and rind, flavonoids and PAL activity after 85 days of storage at 8°C were 3.6, 12.4 mg/L, 15. 8 mg/L, 142.6 mg/L and 2.5 MOL/g FW.min -1, respectively, and TSS, TA, fruit weight and ascorbic acid content decreased for fruit stored at different temperatures. Antioxidant capacity and total phenols increased during the first 45 days of storage at 8°C by 38% and 631.6 mg/L respectively. Also the results indicated a significant correlation between antioxidant activity and total phenolic compounds ( P≤0.01).
  • Authors:
    • Ibrahium, M. I.
    • Hegazy, A. E.
  • Source: World Applied Sciences Journal
  • Volume: 18
  • Issue: 5
  • Year: 2012
  • Summary: This work aimed to evaluate the efficiency of different organic solvents such as, methanol, ethanol, dichloromethane, acetone, hexane and ethyl acetate for extraction of (flavonoids and polyphenolic) compounds(TFC and TPC respectively) from the orange peel. Also, the effect of these solvents on the yield percentage, chelating activity, antioxidant/radical scavenging capacity and reducing power ability of the produced extracts were investigated. The results revealed that all extracts of the orange peel exhibited variable antioxidant activity. Specially, the ethanolic extract showed the highest (p
  • Authors:
    • Ollitrault, P.
    • Urban, L.
    • Dhuique-Mayer, C.
    • Curk, F.
    • Hussain, S.
    • Luro, F.
    • Morillon, R.
  • Source: Scientia Horticulturae
  • Volume: 134
  • Year: 2012
  • Summary: Two autotetraploid (4*) trifoliate orange ( Poncirus trifoliata (L.) Raf.) rootstocks and the corresponding diploid (2*) rootstocks were compared for their impact on clementine "Commune" ( Citrus clementina Hort. ex Tan) production and on rootstock/scion physiology. Cumulative fruit yield, fruit quality (sugars, organic acids, carotenoids, hesperidin) and scion physiology (stem growth, leaf starch, sugars, chlorophyll content, phenolic content and gas exchange parameters) were investigated. The cumulative fruit yield over 11 years was lower in 4* rootstock/clementine associations and correlated with reduced vigor of the clementine scion. Fruit quality criteria were not affected by the ploidy level of the rootstocks, with the exception of hesperidin content, which was higher with 4* than 2* rootstock/clementine associations. Leaf chlorophyll and phenolic contents were higher with 4* than 2* rootstock/clementine associations. In leaves, the rate of photosynthesis and stomatal conductance was much higher with 2* rootstocks; however, the maximum electron transport rate was lower when compared to the 4* rootstocks. Similarly, leaf starch and sugar contents were much higher with 4* than 2*. Taken together, these results demonstrate that the use of 4* rootstocks dramatically changes both tree physiology and fruit yield, without promoting large changes in fruit quality criteria.
  • Authors:
    • Singh, M.
    • Jhala, A. J.
  • Source: Weed Technology
  • Volume: 26
  • Issue: 3
  • Year: 2012
  • Summary: Soil-applied herbicides are commonly used for broad-spectrum residual weed control in Florida citrus. Groundwater contamination from some soil-applied herbicides has been reported in citrus growing areas in Florida. Indaziflam is a new soil-applied herbicide recently registered for broad-spectrum weed control in Florida citrus. There is no information available on leaching behavior of indaziflam in sandy soil. Experiments were conducted to compare leaching of indaziflam with five commercially used residual herbicides in a Florida Candler soil under simulated rainfall of 5 or 15 cm ha -1. Herbicide movement down soil columns was measured by visually evaluating injury and harvesting aboveground biomass of the bioassay species annual ryegrass. Ryegrass was not injured and plant biomass was not affected beyond 30 cm when indaziflam at a recommended rate of 73 g ai ha -1 was leached through the soil column. Leaching of indaziflam increased with increasing amounts of rainfall. For example, indaziflam leached up to 12.20.8 cm (values are expressedSD) and 27.22.6 cm at 5 and 15 cm ha -1 rainfall, respectively. The herbicide ranking from high to low mobility at 15 cm ha -1 of rainfall was bromacil=norflurazon>indaziflam>simazine=pendimethalin>diuron. Overall results suggested that indaziflam leaching was limited in Florida Candler soil in this study; however, field experiments are required to confirm the leaching of indaziflam under natural rainfall situation.
  • Authors:
    • Naidu, M. V. S.
    • Kailaimannan, R.
    • Venkaiah, K.
  • Source: Madras Agricultural Journal
  • Volume: 99
  • Issue: 4/6
  • Year: 2012
  • Summary: Some important physico-chemical parameters of irrigation water of guava orchards in Prakasam district were evaluated for the criteria of the irrigation water quality. Thirty water samples were collected from three different mandals of the Prakasam district. The present study revealed that pH was neutral to moderately alkaline, Electrical Conductivity (EC) was high, Sodium Adsorption Ratio (SAR) was low to medium and Residual Sodium Carbonate (RSC) was good to marginal. So, initiative must be taken to reduce salt accumulation in the soil through drainage and adopting the highly salt tolerant crops like cotton, mustard and tamarind for the better utilization of the land.
  • Authors:
    • Joshi, K. G.
    • Syed, I.
    • Kazi, S. S.
  • Source: African Journal of Agricultural Research
  • Volume: 7
  • Issue: 29
  • Year: 2012
  • Summary: Field experiment was conducted for two successive years on sweet orange to evaluate the effect of multi-micronutrient on yield and quality attributes of sweet orange grown on Inceptisols of Aurangabad district of Maharashtra, India. The result indicates that the number of fruits per tree increased with the application of balanced dose of NPK along with multi-micronutrient from 426 to 554. Similarly, weight of fruit per tree was ranged from 72.42 kg/tree in control to 143.80 kg/tree in the treatment receiving multi-micronutrients through soil. Productivity was also enhanced from 20.06 to 39.83 t/ha due to application of multi-micronutrients along with recommended NPK. The quality of the fruits in terms of juice, TSS, fruit girth, ascorbic acid content, reducing and non-reducing sugar increased with the application of multi-micronutrient and NPK either applied through soil or fertigation, whereas, acidity of the fruit juice was found highest in untreated control as compared to balance nutrient application.
  • Authors:
    • Sil, A. C. da
    • Azevedo, F. A. de
    • Correa, F. E.
    • Kupper, K. C.
  • Source: Scientia Horticulturae
  • Volume: 134
  • Year: 2012
  • Summary: The objective of this research was to study the viability of Bacillus subtilis (ACB-69) to control the casual agent in postbloom fruit drop, Colletotrichum acutatum under field conditions. During the 2007/2008 crop season, B. subtilis was tested in 5% (5*10 8 cfu ml -1) and 10% (1*10 9 cfu ml -1) concentrations on 'Pera' sweet orange ( Citrus sinensis (L.) Osbeck) plants grafted on Rangpur lime ( Citrus limonia Osb.), in Botucatu, Sao Paulo, Brazil. The same treatments were repeated in the 2008/2009 crop season with and without adding a carbon source (molasses 5%) to 'Valencia' sweet orange plants grafted on Rangpur lime. Additional experiment was conducted to determine the most appropriate flower growth stage to apply the biocontrol agent. The biological products were applied with an air assisted sprayer in all experiments with the intention of evaluating the practicality of this type of sprayer. A weekly application of B. subtilis (5*10 8 cfu ml -1) reduced the quantity of symptomatic flowers by 47% while the chemical treatment only had an 18% reduction. On the other hand, B. subtilis (10% or 1*10 9 cfu ml -1) applied weekly or applied one week before to the "green bud bloom" stage (like a preventive control) provided a greater average number of effective fruits (ANEF). The addition of a carbon source at the time of application, did not favor the antagonistic activity of bacteria. In controlling postbloom fruit drop, the best time to apply B. subtilis was observed in the open flower stage when the percentage of symptomatic flowers was evaluated. However, when the bacterium was applied in all flowering stages there was a greater average number of effective fruits. The use of air assisted sprayer helped implement the antagonistic on a commercial scale.
  • Authors:
    • Larbi, P. A.
    • Salyani, M.
  • Source: Computers and Electronics in Agriculture
  • Volume: 87
  • Year: 2012
  • Summary: An expert system (ES) has been developed to assist citrus spray applicators in planning and evaluating their sprayer operations. The ES is partitioned into two parts: (1) spray planning (procedures and calculations for sprayer calibration as well as suitability of spraying under given weather parameters) and (2) spray evaluation (estimation of overall spray deposition, ground fallout, and drift as percentages of the total spray discharged at orchard scale). The first part is based on established procedures and the second part is built on the previously developed spray deposition model. The latter includes a "What-If" analysis function that gives feedback on changes in input variables and the corresponding outputs. Testing of the ES revealed that the trends in the outputs, reflecting the effects of application rate, travel speed, foliage density, and percent missing trees were in general agreement with literature. The ES was evaluated by five individuals with diverse experience in spray applications. Overall, the ES was found useful for calibration and evaluation of spray applications in citrus.