Effects of high-humidity storage on quality,decay and storage life of cherry,lemon and peach fruits

Sweet cherries (Prunus avium (L.) ‘Lambert’ and ‘Blackboy’), lemons (Citrus limon (L.) Burm. f. ‘Lisbon’) and peaches (Prunus persica (L.) Batsch, ‘Summerset’) were stored at 77–83, 90–94 and 95–99% RH (high humidity) at near-optimal storage temperatures after harvest and treatment with fungicides. High-humidity storage did not increase the storage life of peaches held at 0°C, but the life expectancy of cherries (both cultivars) was extended by 7–10 days at 0°C, and of lemons by at least 4 weeks at 10°C when fruit were stored at 95–99% RH compared with levels below 95%. The beneficial effects of high humidity were attributed to retardation of peel desiccation and associated reductions in fruit deformation, peel de-greening, chilling-injury and decay in lemons and to the maintenance of a fresher stalk and a firmer, less shrivelled fruit in cherries. High humidity had no effect on decay in cherries or peaches, but it significantly reduced weight loss and delayed the appearance of shrivel in peaches stored at 0°C. However, after storage at high humidity for 4 weeks, peaches ripened with low rates of C₂H₄ evolution and showed severe low-temperature injury, slight peeling-injury and a poor flavour ex-store.     

Storage conditions and ripening of papaya ‘Bentong’ and ‘Taiping’

The optimum storage and ripening temperature for the 2 cultivars was approximately 20°C. Both cultivars ripened earlier after exogenous application of C₂H₄ combined with the removal of CO₂. The storage life of the fruits could be extended by maintaining them in an atmosphere devoid of C₂H₄ but containing 5% (v/v) CO₂ and with a high relative humidity. Chilling-injuries occurred at temperatures below 15°C when the papayas were stored for more than 7 days. The nutritional value of ripe fruit decreased rapidly with prolonged storage. At the “eating-ripe” stage, the glucose, protein and ascorbic acid contents were 2.23 g, 209 mg and 33 mg per 100 g pulp in ‘Bentong’, and 2.15 g, 196 mg and 30 mg per 100 g pulp in ‘Taiping’, respectively.     

Fungicide evaluation for control of dry bubble,caused by Verticillium fungicola, on commercial mushroom strains

Twelve fungicides were compared with chlorothalonil, thiabendazole and benomyl for activity against Verticillium fungicola on mushroom crops. Triforine, dimethirimol and tridemorph were phytotoxic, but prochloraz, tridemorph and a carbendazim/maneb mixture (“Delsene M”) gave significantly higher yields of healthy mushrooms than untreated controls. Healthy yields from prochloraz and “Delsene M” treatment were greater than from chlorothalonil, but some formulations of prochloraz were phytotoxic and “Delsene M” discoloured treated mushrooms.     

Storage of some local and introduced mango cultivars grown in Trinidad

The fruit characteristics and storage potential of some local and introduced mango cultivars grown in Trinidad were compared. At ambient temperature (28–32°C), fruit could be stored satisfactorily for between 3 and 8 days, after which ripening rapidly occurred. At 14°C, storage life was increased to as much as 18 days (cultivar ‘Graham’). Enclosure of fruits individually in polythene bags increased storage life at either ambient or 14°C temperature, while treatment with 3% Sta-fresh wax increased storage at ambient but not at 14°C. In the case of ‘Doodooth’, which was highly susceptible to anthracnose, treatment of fruit with hot water (52 ± 2°C) containing 500 or 1000 mg l^?4 benomyl for 5 min reduced the incidence of disease. Results are discussed in relation to the export potential of mangoes.     

Plantlet regeneration and stability from callus cultures of Freesia × hybrida Bailey cultivar ‘Royal’

True-to-type plantlets of Freesia × hybrida Bailey cultivar ‘Royal’ were generated from callus after 27 months of sub-culture in liquid medium. Callus was initiated from young flower pedicels cultured on semi-solid Linsmaier—Skoog (LS) medium supplemented with 5 mg/l of 2,4-D and 0.5 mg/l kinetin, and transferred to the same medium in liquid form without hormones and thereafter sub-cultured every 7–10 days. Liquid cultures with 2.4–4.3 g of callus per 25 ml medium produced largest increases in callus fresh weight. Callus generated the most shoots when cultured on LS medium supplemented with 5 mg/l of kinetin and incubated in the light, while fewer plantlets were produced when no growth regulator or GA₃ or PBA were used. Callus cultures incubated in continuous darkness did not form shoots.     

Spritzungen mit Calciumchlorid erhöhen die Calcium- und reduzieren die Kaliumkonzentrationen der peripheren Schichten von Apfelfrüchten

Eight year old apple spindle trees (‘Elstar’, ‘Gala’, ‘Karmijn de Sonnaville’, ‘Pinova’, ‘Pilot’) were sprayed 12 times with aqueous CaCl₂ (400?l/ha) from July through September 2004. Controls (Fu) were trees sprayed with fungicides only (Captan 80, Dithane Ultra, Euparen M and Malvin). The treatment (FuCa) was sprayed with fungicides plus CaCl₂ (increasing concentrations from 5 to 25?g/l during the season) and the treatment FuCaTe contained in addition the surfactant Plantacare 1200 UP, which reduced surface tension to 29–30?mN/m. Ca concentration in the first layer (0–5?mm) of the control fruits (Fu) ranged from 7.6 (‘Elstar’) to 9.8?mg/100?g fresh weight (‘Pilot’). Ca concentrations in the second layer (5–10?mm) were lower and ranged from 4.5 (‘Pinova’) to 6.2?mg/100?g (‘Karmijn de Sonnaville’). CaCl₂ applications to fruits (FuCa) increased Ca concentrations in the first layer to 12.7 (‘Elstar’) or 14.2?mg/100?g (‘Pinova’ and ‘Pilot’). Ca concentrations in the second layer were also increased by the treatments. They ranged from 5.4 (‘Karmijn de Sonnaville’) to 9.1?mg/100?g (‘Pinova’). Adding the surfactant (FuCaTe) further increased Ca concentrations (‘Pilot’) up to 17.4 and 10.6?mg/100?g in the first and second layers, respectively. This effect of the surfactant was the result of faster penetration into fruits of CaCl₂ which reduced losses by rain shortly after spraying. Potassium concentrations were about 70?mg/100?g in both layers. Treatments with CaCl₂ leading to higher Ca concentrations in the fruits resulted in a decrease in K concentrations to 21 (first layer) or 50?mg/100?g (second layer). It is not clear if this was caused by a reduced K-influx into fruits or by displacement of K from peripheral into deeper layers of the fruits.     

Callus induction and culture of Rosa

Leaf and stem explants of Rosa manetti Hort. and R. hybrida L. ‘Tropicana’ were placed on Murashige and Skoog (MS), Schenk and Hildebrandt (SH) and Gamborg and Wetter (1-B5C) media, containing growth regulators, casein hydrolysate (CH) or coconut milk (CM), to determine the optimum conditions for callus initiation and maintenance. The explants were cultured either in dark or in light (2 Klux 16 h/day) at 26±2°C. Friable, fast growing callus was evident after 3 weeks for both rose species on MS + 2.0 mg/l 2,4-D, 0.25 mg/l kinetin (K) and 2.0 g/l CH as well as on SH + 0.5 mg/l 2,4-D, 2.0 mg/l p-CPA and 0.1 mg/l K. Callus initiation occurred sooner on SH than on MS. However, during sub-culture of callus arising on SH, rapid oxidation often occurred, resulting in severe browning of the callus, which made it unsatisfactory for further experimental use. Callus initiation occurred faster in dark than in light, but deteriorated when continuously sub-cultured in the dark regardless of media. Although ‘Tropicana’ initiated callus sooner than R. manetti, very fast growing callus of the latter was obtained when leaf callus was transferred to MS + 2.0 mg/l NAA and 0.5 mg/l BA. Unsuccessful attempts to regenerate callus and induce adventitious shoots on the 2 explants are discussed.     

Flowering,vegetative growth and mineral nutrition of pot chrysanthemums in sawdust and peat-life media

Plants of Chrysanthemum morifolium Ramat ‘Mountain Peak’, ‘Goldstar’ and ‘Cir Bronze’ were grown in sawdust, sawdust mixed with Ca(NO₃)₂ 7 weeks before planting and held at 20°C (unheated), or at 43°C (heated), and in a sphagnum-peat/vermiculite mix (peat-lite). C:N ratios for the sawdust media at planting were 265.9, 125.7 and 123.3, respectively. Plants grown in each medium received nutrient irrigation containing macro- and microelements, with N at 150, 200 or 250 mg l^?1.Days to full flower development, and flower diameter at harvest were not influenced by medium or irrigation N concentration. Plants grown in peat-lite produced the thickest and longest stems, although the stature of plants in all media was judged to be commercially acceptable. Plants grown in unheated sawdust pre-mixed with Ca(NO₃)₂ produced the thinnest and shortest stems.Leaf concentrations of N, P, K and Mg at harvest were highest in plants grown in peat-lite. Accumulation of Ca, B, Fe, Mn, Cu and Zn was more variable. With the exception of P, foliar nutrient concentrations in all plants were optimal or above published optimal ranges. The onset of flower senescence occurred an average of 1 day earlier in sawdust-grown plants.     

The influence of preplanting dips and postplanting temperatures on root growth and development of nonprecooled tulips,daffodils and hyacinths

The effects of preplanting dips and postplanting temperatures were studied, using nonprecooled bulbs of Tulipa gesneriana L. ‘Paul Richter’, Narcissus pseudonarcissus L. ‘Explorer’ and Hyacinthus orientalis L. ‘Pink Pearl’, for 2 consecutive years. Preplanting treatments consisted of a non-dip control, and 30-min dips of either tap water or benomyl—ethazol. After planting, the tulips and daffodils received temperatures of 5, 9, 13, 17 or 21° C for a 5-week period. Hyacinths received temperatures of 9, 13, 17, 21, 25, 29 or 33° C for 5 weeks in the first year and for 25 days in the second year.It was determined that 17° C for 3 weeks and 17° C for 3–4 weeks were the optimal temperatures and periods of time for root development of tulips and daffodils, respectively. For hyacinths, a range of from 17 to 25° C for 10–14 days was optimal. Under these conditions, a minimum root length of 70 mm was obtained and all bulbs of each species had rooted.The benomyl-ethazol and water preplanting dips stimulated root growth for the first 2 weeks for tulips. This effect was not observed for daffodils and hyacinths.     

The influence of irradiance and external CO2-concentration on photosynthesis of different tomato genotypes

With 4 genotypes of tomato, irradiance and CO₂-response curves of net photosynthesis were analysed by means of curve fitting. Estimated values of the light compensation point I_c showed small but significant differences between the genotypes, the overall value being in the order of 8 W m^?2. The photochemical efficiency (α_n) and the maximum net photosynthesis per unit leaf area basis (P_nm) reached the highest values for ‘F6 IVT’ (13.3 μg CO₂ J^?1 resp. 0.549 mg CO₂ m^?2 s^?1), the lowest value of α_n with ‘Bonabel’ (9.9 μg CO₂ J^?1), and the lowest value of P_nm with ‘PI 114969’ (0.424 mg CO₂ m^?2 s^?1). The CO₂-compensation point (C_c) was relatively high (177–245 mg m^?3). ‘F6 IVT’ demonstrated the highest value of C_c, the lowest carboxylation efficiency and the highest maximum rate of net photosynthesis. The results clearly demonstrate that the latter genotype requires a much higher external CO₂-concentration than the other genotypes in order to exhibit the highest rate of net photosynthesis.     

Effect of GA3, Planofix (NAA) and Ethrel on granulation and fruit quality in ‘Kaula’ mandarin

The effect of GA₃ 15 mg l^?1, Planofix (NAA = 1-naphthalene acetic acid) 300 mg l^?1 and Ethrel 250 mg l^?1 on granulation and fruit quality in ‘Kaula’ mandarin (Citrus recticulata Blanco) was studied during 1975–1976. Three sprays of Planofix reduced the incidence of granulation to 30.7% from 62.7% in control. Three sprays of GA₃ were almost equally effective (31.3% granulation). These treatments also improved the fruit quality and gave the highest fruit weight, pulp percentage, juice, T.S.S., reducing and non-reducing sugars and ascorbic acid, and the lowest acidity, peel and rag. In both these treatments (3 sprays of GA₃ or Planofix) the T.S.S. was 9.3% (8.1% in control). The application of 3 sprays of Planofix 300 mg l^?1 or GA₃ 15 mg l^?1 is, therefore, considered to be successful in reducing the granulation in this cultivar of mandarin.     

The physiology of hyacinth bulbs. XV. The effect of gibberellic acid and silver nitrate on dormancy release and growth

The effect of gibberellic acid (GA₃), supplied to dormant hyacinth bulbs of cultivars ‘Lady Derby’ and ‘L'Innocence’ by vacuum infiltration, on growth and flowering was investigated. Results showed that GA₃ in all applied concentrations (50, 500, 1000 and 5000 mg/l) accelerated growth and flowering in both cultivars, after chilling for 42 days in a garden frame in natural conditions or chilled dry in cold storage at 5°C. Bulb infiltration with 10 mg/l AgNO₃ resulted in the acceleration of flowering only in ‘L'Innocence’, but stimulated the growth of the inflorescence stalk and leaves in both cultivars regardless of the mode of chilling.The infiltration method was confirmed to be very promising.     

Induction of lateral branches in tree fruit nursery stock with propyl 3-t-butylphenoxy acetate (MB 25, 105) and Promalin (GA4+7 + 6-benzyladenine)

Sprays with 250–2000 mg l^?1 propyl 3-t-butylphenoxy acetate (MB 25,105) and 250 and 500 mg l^?1 GA₄₊₇ + 6-benzyladenine (Promalin) were applied to scion growth of first nursery trees of ‘Bartlett’ pear (Pyrus communis L.), ‘Bing’ cherry (Prunus avium L.) and ‘Oregon Spur II Delicious’ apple (Malus domestica Borkh.) to stimulate lateral branching in the nursery. Most treatments significantly increased branching compared to untreated controls. Combination sprays of the two chemicals were usually better than either used alone. Chemical treatment usually produced greater branching and wider branch angles than mechanical heading. Both chemical and mechanical treatments reduced tree height and caliper, but the decrease was not always statistically significant.     

Effect of exogenous growth regulators on flowering and cytokinin levels in azaleas

‘Alaska’ and ‘Redwing’ azaleas having dormant flower buds were sprayed with gibberellins (GA₃ or GA_{4 + 7}) alone and in combination with thiourea, N⁶ benzyl adenine (BA) or kinetin weekly for 3 or 4 weeks to test the efficacy of these materials in breaking bud dormancy. Additional plants received 6 weeks of cold storage at 4.5°C or glasshouse day temperatures of 21°C and above. The 2000 and 3000 mg l^?1 GA₃ and Ga_{4 + 7} sprays were better than 1000 mg l^?1 in promoting flowering, with ‘Redwing’ responding better than ‘Alaska’. GA-treated plants flowered in fewer days than those receiving cold storage. Flower diameter and pedicel length increased with higher levels of GA, and flower uniformity was comparable to cold-stored plants on most GA-treated ‘Redwing’-plants. Thiourea, BA and kinetin applied alone had no effect and considerable cytokinin activity was highest in GA-treated buds 14–21 days after treatment application. No increase in activity occurred on plants not receiving GA.     

Effect of stratification-temperature,chemical treatments and seed coat on the growth of peach seedlings cultivar ‘Sharbati’

In order to obtain normal seedlings of peach cultivar ‘Sharbati’ before the commencement of winter, treatments with GA₃, thiourea and kinetin were given to seeds before stratification at 7°C, 10°C or 24°C. The seedlings raised from the treated seeds and after-ripened at 24°C were dwarf. The seedling growth was increased when the treated seeds were stratified at 10°C or 7°C and the stratification period was prolonged from 15 days to 75 days. 10°C stratification-temperature was better than 7°C. The seedling growth was improved when the seed coat was removed before the treatments. With respect to both seed types, 1000 mg/l GA₃ produced the tallest seedlings at all the after-ripening temperatures and during each stratification period. The next best treatment was 100 mg/l kinetin.     

In vitro propagation of Lychnis senno Siebold et Zucc., a rare plant with potential ornamental value

Lychnis senno is a rare and valued ornamental plant. Seed propagation is not efficient because of the low germination rate. To grow commercially L. senno in China, a protocol for in vitro germination and propagation of this species was developed. Various germination rates were obtained by treating seeds with GA₃ during 1–6 months storage period. The highest germination rate reached 19.4% when seeds were treated with 250 mg/l GA₃ and stored for 5 months at 4 °C. Axillary shoot proliferation was induced in the nodal segments of the seedlings on medium containing specific concentrations of BA and NAA [Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassays with tobacco tissue culture. Physiol. Plant 15, 473–497]. Maximum number of shoots was developed on a medium supplemented with 5 mg/l BA and 0.5 mg/l NAA, while the higher shoots were observed on a medium supplemented with 0.5 mg/l BA and 0.05 mg/l NAA. Rooting was induced in 91.7% of the regenerated explants on a half-strength MS medium supplemented with 0.5 mg/l NAA. The plantlets grew well and flowered after transfer to the greenhouse. The chromosome numbers of seedlings and propagated plants were also determined to be 2n = 2x = 24.     

Changes in Ripening Behaviors of 1-MCP-Treated ‘d’Anjou' Pears After Storage

Abstract

1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, was applied to ‘d’Anjou' pears (Pyrus communis L.) at 20°C between 2 and 5 days after harvest. Scald of ‘d’Anjou' pears was completely controlled by 1-MCP at a concentration between 0.05 and 0.3 µl l1 after a prolonged cold storage plus 7 days of exposure to an environment with or without 500 µl l1 ethylene at a temperature of 20°C or 25°C. 1-MCP inhibited the biosyntheses of α-farnesene and its oxidative products (conjugated trienes) and thus controlled scald. However, fruit treated with the above concentrations of 1-MCP did not ripen normally in an environment with or without ethylene. Ethylene production and fruit softening of 1-MCP-treated ‘d’Anjou' pears were inhibited during 7 and 15 days at 20°C. ‘d’Anjou' fruit treated with 0.01 and 0.02 µl l¹ 1-MCP ripened normally on day 7 at 20°C after 3 months of cold storage at ? 1°C, and ripened fruit did not develop any incidence of scald. Untreated fruit developed substantial scald. After 4 months of storage or longer, both untreated fruit and fruit treated with 0.01 and 0.02 µl l 1 1-MCP developed an unacceptable incidence of scald upon ripening. Thus, use of other scald control methods may be necessary in addition to treatment with a low dosage of 1-MCP to insure both normal ripening and scald control for d'Anjou pear fruit from the Mid-Columbia district.     

Effects of nitrogen and phosphorus on root and shoot growth of Cotoneaster divaricata Rehd. & Wils.

Root and shoot growth rates of Cotoneaster divaricata were determined using a growing system of polyvinyl chloride pipe cylinders in which longitudinal sections could be removed for periodic root observations. Plants were fertilized with nitrogen (N), phosphorus (P), and potassium (K). N, as NH₄NO₃, was applied weekly at levels of 0, 250 or 500 mg/l and P, as H₃PO₄, was incorporated in the medium at levels of 0, 5 or 50 mg/l. K, as KCl, was maintained in the medium at a 150 mg/l level by soil tests conducted weekly. Shoot growth was increased after N application. However, no difference was observed between N levels. P increased shoot growth only at the highest N level applied. Although root growth was not increased by either N or P, high N levels inhibited root growth, whereas P stimulated root growth. No correlation (r = 0.19) was observed between shoot and root growth.     

In vitro germination of apple pollens

In order to characterize pollen viability and germinability by biochemical parameters, an introductory investigation was made of the germinability in vitro of pollen of 2 apple cultivars, ‘Golden Delicious’ and ‘Starkrimson’, partially self-incompatible and totally self-incompatible, respectively. Best results of percent germination were obtained for both cultivars after 120 min incubation in Petri dishes at 30°C in a medium containing 0.2 M sucrose, 20 μg/ml H₃BO₃, 300 μg/ml Ca(NO₃)₂ · 4H₂O. Optimum pH was 6.0 for ‘Starkrimson’ and 7.0 for ‘Golden Delicious’.     

Adventitious shoot formation from sections of sweet potato grown in vitro

Sweet potato (Ipomoea batatas Lam.) root sections were obtained from the cultivars ‘Centennial’, ‘Redmar’ and ‘Jewel’ with a No. 6 cork borer. These sections were cut into 2–3-mm discs and explanted on to modified Murashige and Skoog (MS) medium consisting of MS high mineral salts, myo-inositol (100 mg l^?1), Staba vitamins, 6-benzyl-aminopurine (2.0 mg l^?1), naphthaleneacetic acid (0.1 mg l^?1), sucrose (30 g l^?1) and agar (10 g l^?1). Root discs from internal regions of the tuberous roots gave rise to calli and meristematic bud-like centers (MBLC's). A small percentage of ‘Centennial’ MBLC's burst open to reveal plantlets which grew and rooted well on the medium. Some of the ‘Jewel’ MBLC's contained only roots, while those of ‘Redmar’ did not differentiate. MBLC-formation occurred most often on discs taken from fresh (unstored) roots of ‘Centennial’. Petiole sections taken from in vitro-cultured plants of all 3 cultivars developed plants quite readily on the medium. Shoots of all 3 cultivars grew rapidly, to yield whole rooted plants which could easily be moved to soil and grown in the greenhouse and field.