Abstract: For a citrus grower to choose the right clementine cultivar for a given region or market, it is very important to know the characteristics of that cultivar particularly in terms of the development of its internal as well as external quality attributes. In particular, it is very important to know when the maturity index is attained along with the rate of color change, sugar accumulation, acid dissipation, firmness loss, etc. This paper describes the results obtained for several quality attributes (rind color, firmness, juice content, juice titratable acidity and soluble solids content) of seven clementine cultivars sampled at different stages of maturity. All of the cultivars reached minimum maturity index (sugar / acid ratio greater than 7.0) by early November. The rate of rind color change is significantly influenced by picking period and is the main attribute that differs among most of the clementine cultivars. In addition, 'Guerdane', the new clementine cultivar, is the only cultivar that matures much later (January-February) and has the characteristics of a late-maturing cultivar both internally (juice quality) and externally (rind color).
Oyetunji, O.J. Kabeya, M, Shiwachi, H.
Department of Botany and Microbiology, University of Ibadan, Nigeria. International Institute of tropical Agriculture (IITA), Ibadan, Nigeria.
Key words: D. alata, D. rotundata Poir, cultivars, IBA, mini tuber, root formation, vine cuttings, survival, white yams.
Abstract: The multiplication ratio for seed yam production is very low compared to other tuberous crops. Seven clones of Dioscorea rotundata Poir (white yam) were evaluated for production of mini tubers from their vine cuttings. Three to four nodes leafy vine cuttings were prepared from the middle portion of the lateral branches collected from mother plants 127, 134 and 141 days after planting (DAP). The lower portion of these nodes were wounded with a clean razor blade and then dusted with 1.0% Indole-3 butyric acid (IBA) powder in order to promote rooting. The mini tubers were harvested 115 DAP. The developed mini tubers varied in sizes among the tested cultivars from 1.9 to 4.2g. The weights were found to be genotype dependent. The survival rate of the planted vine cuttings ranged from 31.1 to 77.1% while the average total number of roots per vine ranged from 5.1 to 5.8. The average number of tubers per vine was 1.8 ?0.8. If these number and weights of mini tubers can be obtained from propagation of vine cuttings, there will be tremendous increase in propagating material thereby making yam cultivation less expensive and also allowing the ware yam only for consumption and other uses.
A. Moreira, L.A.C. Moraes, J.C.R. Pereira and C. Castro
'Embrapa Cattle Southeast, Rodovia Washington Luiz, Km 234, C.P. 339, 13560-970, Sao Carlos, Sao Paulo State, Brazil; 2Embrapa Western Amazon, C.P. 3'9, 69011-970, Manaus, Amazonas State, Brazil; 3Embrapa Soybean, C.P. 23', 8600'-970
Abstract: Banana cultivation is ranked as one of the agricultural activities of greatest economic importance and social significance in Brazil. The area under banana cultivation in Brazil (516,000 ha) is larger than India and Ecuador, leading countires in production, but with rather lower productivity due to lack of adequate crop management, particularly fertilizer application. The objective of this work was to investigate the rate of nutrient retranslocation and the effect of fertilization on the yield and uniformity of banana bunches cultivated in central Amazon region. Two field experiments were conducted in a xanthic Ferralsol (dystrophic Yellow Latosol) - predominant soil of the region, examining: a) the nutrient translocation rate in twelve plants; and b) the efficiency of zinc use, in a completely randomized blocks in split plot design with four rates of ZnSO4 (0, 30, 60 and 120 g plant1 cycle1) and two application times (in the hole together with the seedling or applied in the fifth month after planting), with four replicates. Under the local edaphoclimatic conditions, the results show that N, P, K, Mg and Cu have a high retranslocation rate. The plant yield was influenced by the rates of ZnSO4, with the most efficient application method being in the planting hole. Results indicated that at high concentrations, zinc had mobility in the phloem from the leaves to the fruits. The proposed critical leaf zinc concentration at the start of inflorescence was 12.9 mg kg-1 for the third leaf.
Miguel A. del Amor and Francisco M. del Amor
Consejeria de Agricultura y Agua de la Region de Murcia. Plaza Juan XXIII. 30008 Murcia, Spain. Instituto Murciano de Investigacion y Desarrollo Agrario y Alimentario. C/Mayor s/n. 30150 La Alberca. Murcia. Spain.
Key words: Yield, crop quality, total soluble solids (TSS), drought, stress, Solanum lycopersicon L.
Abstract: Field studies were conducted to compare the yield and fruit quality of processing tomatoes in surface and subsurface drip irrigation, with 100 and 50% of crop evapotranspiration (ETc). The results showed that when irrigation was reduced by 50% ETc the subsurface treatment showed higher water content at root depth compared with the on-surface treatment. At 50% ETc subsurface irrigation yield increased by 66.5% compared with the surface treatment. However at 100% ETc no significant difference in total fruit yield was observed between irrigation methods. The superficial and water-stressed treatment increased the pH and the acidity of the fruits but the subsurface treatment did not show differences with respect to the full-irrigation treatments. Our results show that the subsurface drip irrigation method could be reasonably applied for processing tomato when water resources are limited.
John H. Mirandaand Richard Williams
School of Agronomy and Horticulture Science, The University of Queensland, Gatton, Qld.4343, Australia. Present address: Brisbane South Lifestyle Support Services, 48 Duke Street Kangaroo Point, Q 4169
Key words: Carbon dioxide enrichment, air flow, photo system II, photochemical efficiency of PS II (FV/FM), photosynthetic photon flux (PPF), photoinhibition, dry weight, chlorophyll and nitrogen.
Abstract: The influence of light quality and carbon dioxide concentration on the development of photosynthetic functional structures of strawberry leaves in vitro was examined. We assessed the photochemical quenching parameter of chlorophyll a photochemical efficiency of photo system II (PSII) of strawberry leaves in vitro in a factorial set up. The main effects of light quality; averaged over CO2 enriched, air flow and closed systems, increased the initial chlorophyll fluorescence value from 485 for yellow light developed PS II system of leaves to 1142 for white light (control) developed ones. The photochemical efficiency of PSII significantly increased from 0.64 under white light to 0.80 for yellow light developed leaves. The leaves developed under blue light were similar to that of control white light for many chlorophyll fluorescence parameters except the initial chlorophyll fluorescence level. The increase in photochemical efficiency of PSII of strawberry leaves can be attributed to lower initial fluorescence values. Under blue light the total dry weight and total chlorophyll content were increased. The possible role of high mercury peak of white light and photoinhibition during development in vitro is discussed.
Yu Zhou and Bal Ram Singh
Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747 USA.
Abstract: Cranberry callus was successfully induced from cranberry (Vaccinium macrocarpon Ait, Ericaceae) leaves by using Gamborg's B5 medium containing phytohormones at 25oC in the dark. Anthocyanin-producing cranberry callus was obtained only under conditions of continuous light exposure. Red light and UV light exposure of the callus enhanced anthocyanin content by 41.3 and 29.3%, respectively. The light-dependent anthocyanin production in the callus was regulated by temperature. Anthocyanin content in the callus decreased 81.1% at 42oC, 58.9% at 37oC, 47.0% at 30oC, and increased 10.4% at 4oC, compared to the callus maintained at 25oC after 48 hours of incubation at the given temperature. A temperature decrease of 10oC from 25 to 15oC resulted in a critical increase of the anthocyanin production in the callus, irrespective of differences in pH of culture medium. The growth of the callus cultured in medium at pH 7.0 was 6.2-fold higher than in the same medium at standard pH of 5.8.
Abstract: Response of low-chill peach cultivar 'Premier' to early forcing culture was studied. Three-year-old trees were forced in a glasshouse from 15 November, 1 and 15 December and 1 and 15 January. Symptoms of insufficient chilling were detected when forcing was started from 15 November and 1 December. Bud break was delayed and sporadic. The flower and leaf buds forced from 15 December and 1 and 15 January rapidly burst within 15 days after the onset of the treatments. The final burst rate exceeded 70%. Generally, flowering started 10-15 days after flower bud burst. The size of the flowers from the trees forced from 15 November and 15 January was smaller than that recorded at other forcing times. Earliest harvest started under forcing from 15 December and 1 January. These results suggested that by using this low-chill cultivar, forcing could be initiated from mid-December, more than one month earlier than for high-chill cultivars, with complete dormancy release, in this region.
H. Kitazawa, T. Asao, T. Ban, Y. Hashimoto, T. Hosoki
United Graduate School of Agricultural Sciences, Tottori University, Koyama-cho Minami, Tottori, Tottori 680-8553, Japan; Faculty of Life and Environmental Science, Shimane University, Kamihonjo, Matsue, Shimane 690-1102, Japan; Department of Soil Science
Abstract: In order to mitigate the autotoxicity in growing plants in closed hydroponic systems, the effects of foliar applications of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthaleneacetic acid (NAA) on the growth of strawberry were investigated. Although the growth of strawberry plantlets was not affected by the auxin treatments in the fresh nutrient solution, the auxin treatments recovered the growth in the used nutrient solution. Benzoic acid, a compound reportedly accumulating in the reused nutrient solution of strawberry hydroponics, resulted in a significant decrease in the growth of strawberry plantlets at 50 uM concentration, compared to the growth in the nutrient solution without benzoic acid. Mitigation of the growth inhibition caused by the previously used nutrient solution or addition of the high concentration of benzoic acid in the fresh solution was demonstrated by immersing strawberry leaves in the auxin solutions (0.45 and 4.5 uM 2,4-D or 5.4 and 54.0 uM NAA) for two seconds before transplanting. The number of flowers and harvested fruits, and the fruit yield of strawberry plants grown in the greenhouse for about 33 weeks were reduced by the non-renewing the nutrient solutions. These values recovered in the 5.4 uM NAA treatment and were not significantly different from the control (renewal of the nutrient solution). These results suggested that reductions in the number of flowers and the yield of strawberry in closed hydroponic systems appear to be related to the allelochemicals exuded by the plant itself. The auxin such as NAA would avoid the growth reduction of strawberry caused by autotoxicity. The 5.4 uM NAA treatment may be the most effective for alleviating autotoxicity of strawberry and increasing the yield.
Yueju Wang, Michael Wisniewski, Richard Meilan, Sandra L. Uratsu, Minggang Cui,Abhaya Dandekar and Leslie Fuchigami
Department of Horticulture, Oregon State University, Corvallis, OR, 97331- 7304, USA; USDA-ARS, 45 Wiltshire Road, Kearneysville, WV, 25430-9606, USA, Forestry & Natural Resource Department, Purdue University, West Lafayette, IN, 47907-2072, USA, Departme
Key words: Superoxide dismutase, oxidative stress, salt stress, transgenic tomato.
Abstract: Production of reactive oxygen species (ROS) is associated with a number of physiological disorders in plants. Superoxide dismutase (SOD) catalyzes the breakdown of superoxide (O2-) into O2 and H2O2 and provides the first line of defense against the toxic effects of elevated levels of ROS. The effect of increased expression of Mn superoxide dismutase (Mn-SOD) on salt stress tolerance was studied using transformed tomato (Lycopersicon esculentum cv. Zhongshu No. 5) plants. Northern blots confirmed expression of the heterologous Mn-SOD in transgenic plants. Strong Mn-SOD enzyme activity was detected by native PAGE in transformed plants. Transgenic plants showed resistance to the superoxide-generating herbicide methyl viologen (MV, 10-4 M). The total SOD activity was one and one half- to two-fold higher, and APX (ascorbate peroxidase) activity was six to seven fold higher in transgenic, than in wild-type (WT) plant under MV stress. Germination of transgenic tomato seeds at a NaCl concentration of 150 mM was greater than wild-type seeds. When exposed to salt stress, roots of transgenic plants were less stunted and leaf injury was lower than that observed in WT plants. Also, the total APX activity of transgenic plants was 4 to 5 fold higher than that of WT under NaCl (200 mM) stress.
James T. Cole and Janet C. Cole
Department of Horticulture and Landscape Architecture, Oklahoma State University, Stillwater, OK 74078-6027, USA
Abstract: Tolerance of field- and container-grown lilyturf (Liriope muscari (Decne.)), (Liliaceae) and four species of ornamental grasses (Poaceae), perennial quaking grass (Briza media L.), Japanese bloodgrass (Imperata cylindrica (L.) Beauv. 'Red Baron'), river oats (Chasmanthium latifolium (Michx.) Yates) and dwarf fountain grass (Pennisetum alopecuroides (L.) Spreng. 'Hameln'), to five preemergent herbicides (isoxaben, oryzalin, oxadiazon, oxyfluorfen, and prodiamine) was evaluated. Grasses were planted in the fall of 1997 and in the spring of 1998. Herbicides were applied to the fall planting in the spring of 1998. The April, 1998 plantings received herbicide applications within two or 45 days after planting. Herbicides were applied within two days of planting in May and June of 1998. All species in the field and containers were damaged most by oxyfluorfen, followed by oxadiazon; however, injury was not as severe with oxadiazon as with oxyfluorfen. The oxadiazon-treated plants recovered more quickly than oxyfluorfen-treated plants. Plants were least damaged by prodiamine, oryzalin, and isoxaben. Field-grown Japanese bloodgrass, dwarf fountain grass and lilyturf were generally less damaged when herbicide was applied in June, regardless of planting date or herbicide applied than by the April herbicide application. Prodiamine, oryzalin, or isoxaben caused few phototoxicity symptoms in the species tested, but oxyfluorfen and oxadiazon caused unacceptable injury.
Faculty of Agriculture, Shahid Chamran, University, Ahwaz, Iran.
Key words: Allium cepa, Aspergillus niger, cultivars, life storage, onion
Abstract: In Khuzestan (South Iran), onion bulbs are usually formed and harvested in spring and consumed either in the same season or during summer while some of these are kept for seed production. In order to study the losses in onion bulbs under hot store conditions, an experiment was conducted in autumn 2002 and spring 2003. The data were collected on five cultivars being produced at Shahid Chamran University, two local cultivars and three of those under commercial cultivation. The collected bulbs were kept in 30 x 50cm boxes, 15 cm in height. The experiment was replicated three times in completely randomized design. Data on change in number, weight of the healthy bulbs and decayed bulbs were recorded every 15 days. No bulb root was produced during the storage when maximum, average and minimum temperature were 48, 33 and 25oC, respectively with the average relative humidity (RH) of 30%. As far as storage life was concerned, there was a significant difference among the varieties. Compared to both the local and market bulbs, those produced at Shahid Chamran University showed more storage life. Another important finding of this research was that 50% of the local and university bulbs remained unspoiled after 120 days, whereas the Taxes Yellow Grano, Taxes Early Grano and G1 had the short storage life; 50% of the stock were destroyed after 60 days. In the present study, Aspergillus niger was found to be the most important factor responsible for onion decay in hot stores of Khuzestan.
Maria Remedios Cigales Rivero and Octavio Perez Zamora
Centro Universitario de Investigacion y Desarrollo Agropecuario Universidad de Colima. Km 40Autopista Colima-Manza-nilloTecomdn, Col. 28100Mexico.InstitutoNacionaldeInvestigacionesForestales, Agricolas y Pecuarias. Campo Experimental Tecomdn.
Abstract: In cantaloupe farming (Cucumis melo L.), the production of export quality fruit require nutritional indicators that allow an adequate management of nitrogen fertilization and irrigation water supply. This study with cantaloupe muskmelon was carried out to test four nitrogen fertilization treatments and three levels of soil moisture tension under field conditions. Nitrate content (N-NO3) in the cellular extract was evaluated as an indicator of nutritional status. Significant correlation was found between the lowest nitrate concentrations in the petiole sap and the N fertilization doses in three different sample periods. The effect of soil moisture tension on nitrate concentration varied in both years; this was attributed to soil temperature differences. Results showed that it is feasible to establish outcome predictions of yield and quality of the fruit based on the nitrate concentration in petiole sap, concluding that this is an adequate indicator of the nutritional status of the cantaloupe plant. However, its use as a guide for managing fertilization and irrigation must include a permanent follow up of the crop that evaluates the effects of environmental factors in plant growth and uptake of the nutrients.
P.l. Garriz, H.L. Alvarez, G.M. Colavita and M.S. Gajdos
Faculty of Agriculture, Comahue National University, c.c. 85, 8303 Cinco Saltos, R.N., Argentina.
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.
G. Talluto, V. Farina and R. Lo Bianco
Dipartimento S.En.Fi.Mi.Zo., Sezione di Frutticoltura Mediterranea, Tropicale e Subtropicale, Universitd degli Studi di Palermo, Viale delle Scienze 11, 90128Palermo, Italy.
Key words: Canopy size, crop load, deficit irrigation, fruit growth, fruit quality, leaf area, shoot length, stomatal conductance, yield.
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
Key words: Bell pepper, fertigation, hydraulics, stomata, canopy, leaf potential, water uptake
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.