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Faculty of Agriculture, Comahue National University, c.c. 85, 8303 Cinco Saltos, R.N., Argentina.

DOI: https://doi.org/10.37855/jah.2007.v09i01.10

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Abstract: Thinning is a central management activity in the production of high quality fruit required for the domestic and export market. Early thinning of fruit trees is important since it influences fruit size and the time of application affects flower bud formation for the following season. Furthermore, finding organic blossom thinners is a major challenge as hand thinning is a costly practice. At the High Valley region of Argentina (lat. 38?56' 67?59'W), lime sulphur was evaluated as flower thinner on 'Abbe Fetel' (Pyrus communis L.) pear trees trained to palmette leader. Treatments were 1) control, and 2) 7 % lime sulphur applied at 30 % bloom, using an orchard sprayer. Fruit diameter (FD) was recorded two weekly (n=20 per date and treatment). At 144 days after full bloom (DAFB), or initial commercial harvest, fruit weight and the maturity indices were determined. Fruits were then graded into size categories. Growth equations were developed using non linear regression and mean separations were computed with Student's t-test. The lime sulphur sprays significantly increased mean FD, starting from 115 DAFB. Logistic model best fitted the fruit growth vs. time curves. Percentage of fruits with <65mm diameter was 25 % for the control and 5.26 % for lime sulphur treatment. Treatment 2 increased final fruit weight by 16.5 %, as compared to the untreated pears. At 144 DAFB, thinned trees showed firmer fruits than the controls (64.4 vs. 61.7 N) and there were no statistical differences among treatments in soluble solids concentration and starch index. Consequently, data indicated that lime sulphur at 7 % was an effective flower thinning agent to enhance 'Abbe Fetel' pear seasonal fruit growth and quality.

Dipartimento S.En.Fi.Mi.Zo., Sezione di Frutticoltura Mediterranea, Tropicale e Subtropicale, Universitd degli Studi di Palermo, Viale delle Scienze 11, 90128Palermo, Italy.

DOI: https://doi.org/10.37855/jah.2007.v09i01.11

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Abstract: We investigated the vegetative and productive responses of 'Golden Delicious' apple (Malus domestica Borkh.) trees to fixed partial rootzone drying under the dry climate of central Sicily. Soil water content (SWC), stomatal conductance, yield, fruit quality, fruit growth, and vegetative growth of conventionally irrigated trees (CI), where drip emitters on both sides of each tree were left open, were compared to that of fixed partial rootzone drying (FPRD) trees where only one side of the rootzone was irrigated for the entire season thus receiving 50% of the CI irrigation water. The irrigation season started on 31 July and ended on 13 September, 2004. Wet and dry rootzone sides showed significantly different SWC from 16 August until 14 September, whereas stomatal conductance of CI and FPRD trees differed significantly starting on 24 August. Relative growth rate of CI fruit was higher than that of FPRD fruit on 27 and 31 August, but fruit size was similar during the entire sampling period and at harvest. Trees of the two treatments had similar yields, number of fruits, crop load, fruit:leaf ratio, fruit quality, tree height, wood fresh and dry weight, canopy spread area, volume and density, shoot length and number, internode length, and leaf area. FPRD trees had higher yield efficiency, thinner shoots, lower leaf water content, higher canopy density and leaf dry weight and specific leaf weight than CI trees. Our observations suggest the extent of possible water savings without loss of yield and fruit quality using this partial rootzone drying strategy in 'Golden Delicious' apple orchards of central Sicily.

Department of Crop, Soil & Pest Management, Federal University of Technology, PMB 704, Akure, Nigeria

DOI: https://doi.org/10.37855/jah.2007.v09i01.12

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Abstract: The effect of fertigation regimes on water transport properties (soil, plant and canopy resistances) through the plant to the canopy in the Soil-Plant-Atmosphere-Continuum (SPAC) was studied in bell pepper in a Mediterranean climate. The treatments consisted of fertigated drip irrigation in factorial combinations of three levels (amounts) of water application (daily, twice and once weekly) and application frequencies (2, 6 and 10 times per fertigation event). Leaf water potential and stomatal conductance were monitored while whole plant hydraulic conductance was estimated by the evaporative flux method, using the Ohm's law analogy (the slope of the water potential difference (Ay) versus sap fluxes). Canopy conductance (inverse of resistance) was estimated from vapour pressure deficit (vpd) and transpiration flux. Differences in the intervals between fertigation events altered the environment for root development and affected soil moisture status, stomatal conductance (gs), leaf water potential (lwp), transpiration (sap) flux, and xylem and canopy water transport capacities in bell pepper. The components of the resistance elements in the SPAC differed under the fertigation treatments. Total plant resistance (Rp) increased with transpiration flux in a linear manner in addition to a proportional decrease in stomatal (gs) and canopy conductance (gc). Canopy component constitutes the least resistance (greatest conductance) to the flow of water, estimated soil resistance was much lower than total resistance to the flow of water, and the highest within plant resistance is contained in the root system which constituted a predominant part of total plant resistance. Bell pepper has an efficient xylem sap transport system, maintains gs and plant water status under variable soil moisture regimes. Bell pepper water use is affected by soil environment, plant architectural and xylem traits. The mechanisms underlying differences in water use and plasticity of physiological functions in bell pepper under variable fertigation regimes appeared to be offered through changes in the magnitudes of component resistances of the water transport pathways in the SPAC. The implications of knowledge of the magnitudes of the resistances to water flow pathway in the SPAC to irrigation management is discussed.

Catedra de Quimica Analitica, Catedra de Fitopatologia, lnvestigador alumno. Facultadde Agronomia de la Universidad de Buenos Aires (FAUBA) Av. San Martin 4453. Capital Federal (1416), lnstituto de Floricultura -INTA-CASTELAR. De los Reserosy

DOI: https://doi.org/10.37855/jah.2007.v09i01.13

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Abstract: Disinfection by chlorination was applied to the solution of a soilless closed system of Lactuca sativa varieties, Gallega and Mantecosa. The aim was to study the effect of the addition of different doses of chlorine on the production (fresh weight and dry matter), quality (nitrates, vitamin C and nitrogen contents), and phototoxicity to lettuce (chlorosis) with regard to the chemical properties of the solution (pH, electrical conductivity EC and chlorides). Four treatments were applied: 0.55, 5.5 and 11 mg L^-1 (ppm) of chlorine and a control without addition of chlorine. The 11 mg L^-1 treatment produced a decrease in production of Gallega, presenting a 40 % lower fresh weight than the control. Both varieties presented high contents of nitrates. Gallega presented the maximum values (2920- 8158 mg kg^-1) and showed values under the permissible limit with the 0.55 and 5.5 mg L^-1 treatments. Mantecosa showed lower maximum values (3787- 5291 mg kg^-1), although with all the values above the limits of permission. The contents of nitrogen for both varieties exceeded the levels of sufficiency in all the treatments. This fact was related to the high nitrogen supply provided by the fertirrigation that contributed to the high nitrate contents. Gallega presented larger contents of vitamin C (19.3-28 mg.100g^-1) than Mantecosa (15.3?19.98 mg 100g^-1). Chlorination did not affect the chemical properties of the solution (pH and EC remained between the appropriate range for the species). Chloride contents in the nutrient solution were larger at the 11ppm doses; however the values remained under the toxicity levels for the species. For both the varieties, 0.55 mg L^-1 treatment produced the higest fresh weight and vitamin C contents and the lowest nitrate contents and toxicity symptoms (chlorosis), while 11 mg L^-1 treatment resulted more chlorosis and necrosis of leaves, diminishing the commercial quality of the plants.

Department of Horticulture Science, Box 7609, North Carolina State University, Raleigh, NC 27695-7609

DOI: https://doi.org/10.37855/jah.2007.v09i01.14

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Abstract: Flurprimidol preplant bulb soaks (10 to 40 mg L^-1) were applied to tulip (Tulipa sp. L.) bulbs for growth control. Three tulip cultivars ('Page Polka', 'Prominence' and 'Red Present') were used to determine if the efficacy of flurprimidol varied by cultivar. Flurprimidol was compared to paclobutrazol (50 and 100 mg L^-1) and uniconazole (10 and 20 mg L^-1). Flurprimidol preplant bulb soaks significantly (P < 0.05) controlled tulip plant height during the greenhouse forcing when applied to 'Page Polka' and 'Prominence' at concentrations > 15 mg L^-1 and > 10 mg L^-1, respectively. A concentration of 40 mg L^-1 was needed to control plant height during the postharvest evaluation for 'Page Polka' while concentrations > 15 mg L^-1 controlled postharvest plant height for 'Prominence'. No control during forcing or postharvest was provided by any concentration tested on 'Red Present'. The differences observed indicate that the efficacy of flurprimidol as a preplant bulb soak varied with cultivars. In order to determine optimal cultivar doses, growers will need to conduct their own tulip cultivar trials, with flurprimidol concentrations ranging between 10 and 40 mg L^-1.

Faculty of Agriculture, The University of Tabriz, PO Box 51664, Tabriz, Iran

DOI: https://doi.org/10.37855/jah.2007.v09i01.15

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Abstract: The effects of Ni concentrations in the nutrient solution on the yield, quality and N assimilation of cucumber plants were evaluated in plants grown either with urea or nitrate as the sole N source. The cucumber plants (Cucumis sativus cv RS189 and Vikima) were treated with two N sources, urea and nitrate as NaNO₃ at 200 mg L^-1, and three concentration of Ni as NiSO₄.6H₂O (0, 0.5, and 1 mg L^-1). Treatments were arranged in a randomized block design with six replicates. The highest concentration of Ni in the leaves (1.2 mg kg^-1 DW) was observed in the urea-fed plants at 1 mg L^-1 Ni concentration. Addition of Ni up to 0.5 mg L^-1 had no effect on the fruit Ni concentration in the both urea and nitrate-fed plants. Ni supplement (0.5 mg L^-1) increased the yield significantly (10 and 15% in RS189 and Vikima, respectively), in urea-fed plants but decreased when 1 mg L^-1 Ni applied to the solutions. Nitrate-fed plants had higher percentage of total soluble solids compared to urea-fed plants. Nitrate concentration of the fruits in urea-fed plants in both cultivars was approximately 50% less than those nitrate-fed plants. The reduction of nitrate concentration in the fruits became more pronounced as the Ni concentration increased in the solution. The rate of photosynthesis (Pn) in urea-fed plants continuously increased with the increase of the Ni concentration in the solution. Both N concentration and NR (Nitrate Reductase) activity of young leaves were higher in urea-fed plants at 0.5 mg L^-1 Ni concentration. Ni supplements enhanced the growth and yield of urea-fed plants by the increase of Pn, N concentration and NR activity. It can be concluded that Ni supplements (0.5 mg L^-1) improves yield, quality and NR activity in urea-fed cucumber plants.

N. Poushkarov Institute of Soil Science, National Center of Agricultural Sciences, 7-Shosse Bankya str. 1080 Sofia, Bul?garia; Acad. M. Popov Institute ofPlant Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev str., Bl. 21, 1113 Sofia, Bulgaria

DOI: https://doi.org/10.37855/jah.2007.v09i01.16

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Abstract: The influence of different fertilizer sources on head cabbage (Brassica oleracea var. capitata, cv. Pructor) yield and quality was studied. The field experiment was carried out on alluvial - meadow soil (fluvisol -FAO) pH 6.5. The trial included mineral fertilizer, farmyard manure and foliar fertilizer. The highest yield values were obtained with mineral fertilization. The best quality parameters in the cabbage leaves - dry weight, total soluble sugars, cellulose, vitamin C and nitrates content were obtained in the treatments with foliar fertilization followed by the treatments with organic fertilization. The observed decrease of N and K residuals after the harvest of head cabbage crop in comparison with the initial soil reserves indicated complete absorption of fertilizers supplied and this is a very important result from ecological point of view.

Department of Biotechnology, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran.

DOI: https://doi.org/10.37855/jah.2007.v09i01.17

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Abstract: The effect of sucrose concentration was investigated on callus induction and differentiation of embryogenic callus derived from petal explants of carnation cultivar Nelson'. Embryogenic calli were produced on MS culture medium containing 9 uM 2,4-dichlorophenoxy acetic acid (2,4-D), 0.8 uM 6-benzyladenine (BA) and different concentrations of sucrose alone or in combination with sorbitol. In constant osmotic potential medium, number of explants containing embryogenic calli was significantly enhanced by increasing the sucrose concentration. Somatic embryos were induced on a hormone-free media containing various concentrations of sucrose alone or in combination with sorbitol. Different sucrose concentrations from 50 to 150 mM significantly increased somatic embryos. No callus and embryo formed when sorbitol was the sole carbon source. In the presence of a constant sucrose concentration, increasing the osmotic potential with sorbitol led to increase in the frequency of somatic embryos. In medium containing low concentration of sucrose (50 and 100 mM), reduced development of embryos was recorded. 90% of somatic embryos were regenerated to form the entire plantlets when they were transferred onto the half-strength MS culture medium containing 3% sucrose. Plantlets also continued to grow under greenhouse condition.

Division of Agriculture Faculty, University of Arkansas atMonticello, P.O. Box 3508, Monticello, Arkansas 71656, USA

DOI: https://doi.org/10.37855/jah.2007.v09i01.18

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Abstract: Field studies were established in 2004 and 2005 to determine the effects of transplant drench and foliar applications of organic-complex Ca, B, K amendments and a yield enhancement product, 'Perc Plus^TM', on the flowering, fruiting, fruit yield and market value of Italian-cv. 'Classica' and large-fruited cv. 'Amelia' tomato (Lycopersicon esculentum Mill.). Treatments were an organic yield enhancement applied as a transplant drench and then foliar 7 days later (TD); once a week foliar amendments of organic-complex Ca, B, and K nutrients beginning at first bloom for 4 weeks (FA); a combination of the drench and foliar treatments (TD+FA); and a control (CON). Fruit-set of 'Classica' was significantly higher for the FA and TD+FA than the other treatments in 2004, however there was no effect on yield and quality of harvested fruit. Flowering and fruit-set of 'Amelia' were not affected by drench and/or foliar amendments in either year. Total fruit yield and quality of the treated plots were not significantly different than the CON for either cultivar or year.

Department of Crop Science, University of Nigeria, Nsukka, Nigeria; Department of Crop Science, Akperan Orishi College of Agriculture, Yandev, Benue State, Nigeria.

DOI: https://doi.org/10.37855/jah.2007.v09i01.19

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Abstract: Six genotypes comprising a landrace and a hybrid from each of the three Musa major genomic groups were evaluated in a soilless potting mix. Effect of genotype on most of the growth parameters was non-significant. But the uptake (total quantity accumulated, distribution pattern and tissue concentration) of N and K was significantly (P < 0.05) influenced by genotype (G), age of plant at sampling (AP) and G x AP interaction. Dessert bananas had higher N uptake while 'PITA 22' (a plantain hybrid) demonstrated an exceptional propensity for K uptake. Nitrogen and potassium concentration varied with tissue, genotype and age of plant at sampling. Nitrogen concentration in roots and leaves decreased with plant age while it increased in the corm. Potassium concentration in roots, corm and leaves increased progressively with plant age in all the genotypes. Significant differences in the quantity of N and K accumulated per plant, even though all the genotypes were planted in the same potting mix, suggested differential nutrient mining capacity of the genotypes. Implying that nutrient uptake and consequently nutrient demand varies with genotype, supplemental application would vary accordingly. The study suggested that genotype that had higher nutrient uptake will impoverish the soil faster, and thus require more external nutrient inputs to maintain/restore soil productivity.

Department of Applied Biological Sciences, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan

DOI: https://doi.org/10.37855/jah.2007.v09i01.02

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Abstract: Sugars play indispensable roles in many metabolic processes in plants. In broccoli, the level of sugars, particularly sucrose, rapidly decline few days after harvest. This study investigated the influence of exogenous application of 10% (w/v) sucrose to broccoli heads during storage at 20^oC. Hydration of the head was slowed down by sucrose treatment compared with the non-treated heads which gained weight by about 5% of the initial value at the end of the experimental period. Furthermore, sucrose application enhanced ethylene production as well as respiration rate. Glutamine synthetase (GS; EC 6.3.1.2) activity was higher in the florets of sucrose-treated heads but, like the non-treated heads, the activity continuously declined until the end of the storage period. The relatively higher GS activity during the early period of storage caused the delay of the onset of ammonia accumulation by about a day. In the branchlet portion, GS activity was higher in the sucrose-treated heads until day 2 but declined thereafter. The decline in GS activity in this portion, however, did not result to ammonia accumulation.

Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkycho, Hirosaki, Aomori, 036-8561, Japan.

DOI: https://doi.org/10.37855/jah.2006.v08i02.23

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Abstract: Effect of light irradiation on the accumulation of phenolic compounds was investigated in the flesh slices of three apple (Malus domestica Borkh.) cultivars. 'Fuji' and 'Jonathan' with red skin and 'Orin' a yellow-green one were used in this study. The irradiation was carried out at 10, 17, 24 and 30C for 96 hours, using a mixture of white plus ultraviolet fluorescents. Phenolic acids, anthocyanin and flavonols were the phenolics that increased rapidly by irradiation whereas flavanols, procyanidins and dihydrochalcones did not change in either mature or in ripe fruits of all the three cultivars. There was a positive correlation between anthocyanins, phenolic acids and flavonols in examined cultivars both at the mature and ripe stages. Optimum temperature for the synthesis of phenolic acids, anthocyanins and flavonols was 24C regardless to the maturity stage and variety. Total phenolic content of 'Fuji' increased through ripening but it decreased in 'Jonathan' and 'Orin'. Therefore, the irradiation to the flesh might be a very useful method for the study of the regulation mechanism of the phenolic compounds accumulation.

KaHo Sint-Lieven Campus Rabot, Departement Industrieel Ingenieur, Gebr. Desmetraat 1, 9000 Gent Belgium; Faculdade de Ciencias da Nutrigao e Alimentagao, Universidade do Porto, Rua Dr. Roberto Frias, 4200 - 465 Porto, Portugal; Corresponding author: Escol

DOI: https://doi.org/10.37855/jah.2006.v08i02.24

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Abstract: The ripening of tomato fruit is a highly regulated process during which colour, flavour, aroma and texture change in a coordinated manner. This research work aims to correlate the colour changes measured objectively with the lycopene concentration in tomatoes during ripening at room temperature (21 and 26?C). These results were compared with colour and lycopene content of pink and light red tomatoes stored at 14?C, temperature used to prevent ripening and therefore extend the shelf life of the fruits. The duration of heat treatment at 100?C was previously optimized in order to release the maximum lycopene from chromoplasts during extraction. An a* value of 20 for the peel corresponds to an increase of lycopene content of Caruso tomato from 9 to 43 mg/100 g TSS, at room temperature. The shelf life of pink and light red tomatoes can be extended to two weeks at 14?C without loss of lycopene content, presenting the same content as green tomatoes ripened at room temperature for one week.

UniversidadNacional de Mar del Plata, Argentina; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONI-CET), Argentina. .Corresponding author: Moreira Maria del Rosario, Grupo de Investigacion en Ingenieria en Alimentos, Facultad de Ingenieria,

DOI: https://doi.org/10.37855/jah.2006.v08i02.25

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Abstract: Changes in lettuce leaf quality (ascorbic acid contents and microbial populations) at two abusive temperatures (8 and 15?C), simulating the commercial storage conditions for fresh vegetables were analyzed. A storage temperature of 8?C was chosen to simulate abusive refrigerated storage and a storage temperature of 15?C was chosen to simulate room temperature. Quality indicators evaluation in samples, stored at abusive temperatures were compared with sample from optimal storage temperature (0?C). First order kinetics is assumed for ascorbic acid degradation. Ascorbic acid degradation rate in lettuce leaves stored at abusive temperatures was from 2.7 to 2.9 times faster than at 0?C. The growth curve of total microbial counts was fitted with the Gompertz and Logistic models. These models allowed us to predict the vegetable microbiological shelf life. Temperature is the controlling factor for lettuce shelf life and quality; microbial quality was retained 1.6 and 4 times longer at 0?C with respect to 8 and 15?C, respectively.

Jahad-e-Daneshgahi, Urmia University, Urmia, Iran; Department of Horticulture, Shahid Chamran University of Ahvaz, Ahvaz, Iran; Department of Horticulture, Urmia University, Urmia, Iran.

DOI: https://doi.org/10.37855/jah.2006.v08i02.26

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Abstract: In this study, UV-C irradiation (1.435><10^-4 w cm^-2) was used to maintain fruit quality of 'Red Delicious' and 'Golden Delicious' apple cultivars during storage. Apple fruits were irradiated in three different treatments (0, 5 and 15 min), and were stored in a cold storage at 1?1?C with 85-95% RH for 6 months. At the end of storage, irradiated fruits for 15 min had lower pH and total soluble solids/titratable acids ratio and higher titratable acids and firmness than irradiated fruits for 5 min and control fruits. A significant difference was observed among total soluble solids of irradiated 'Red Delicious' fruits for 15 min, irradiated fruits for 5 min and control fruits at the end of storage. 'Red Delicious' apples had lower total soluble solids and total soluble solids/titratable acids ratio and higher firmness than 'Golden Delicious' apples after 6 months. Our results showed that UV-C irradiation can be used to reduce loss of fruit quality during long period storage of apples.