Root development of Thuja plicata in peat-substitute rooting media

In this study we investigated the potential usefulness of different substrates produced from gorse (Ulex europaeus L.) for propagating cuttings of Thuja plicata ‘Atrovirens’. The gorse was composted by different methods, to produce four types of compost. These composts were then used as such (100% compost) or in mixes with coarse sand and pine bark compost (25% compost, 25% coarse sand and 50% pine bark compost, v/v/v) to prepare eight different substrates. The substrates were compared in cutting propagation trials carried out in a greenhouse, with a standard rooting medium consisting of 25% Sphagnum peat moss, 25% coarse sand and 50% pine bark compost (v/v/v). Cuttings were taken from a garden hedge in March 2003, and comprised shoots of the previous year's growth. The bases of the cuttings were treated with a 0.4% solution of IBA rooting hormone, then inserted into cells filled with the corresponding substrate and placed on a propagation bench. Rooting percentage and visual rooting score were determined in July. The quality of roots was evaluated, as total root length and number of root tips, in July, September and November 2003, by use of a Delta-T Scan system. The rooting success of the cuttings ranged from 75% to 90%, except when the substrate comprised the pure composted gorse, obtained after the shorter period in an enclosed composting system with addition of fertilizer and reuse of leachates. Most of the cuttings in this substrate died and only 4% of the cuttings rooted successfully. Physicochemical characteristics of this rooting medium included very high electrical conductivity, low C/N ratio and high water retention. Addition of coarse sand and pine bark compost to the composted gorse significantly increased the rooting success. The root quality variables differed depending on the substrate considered and date of harvest. The results showed that substrates made from gorse compost are of potential use as a peat substitute for propagating cuttings of T. plicata ‘Atrovirens’. The physicochemical properties of the composted gorse should be determined before its use to establish whether it can be used pure as a substrate for rooting or whether it should be mixed with other substances.     

Growth of Viburnum tinus in peat-based and peat-substitute growing media

To assess the growth of ornamental shrubs in peat alternative substrates, one ornamental species, Viburnum tinus L., was cultivated in a number of different substrates in two climates: a French oceanic (Oce) and a Spanish Mediterranean (Med). In Oce, three mixtures (1/1, v/v) of Finnish peat/yard compost, yard compost/raw coir and Finnish peat/raw coir were used while the expanded perlite/composted manure (1/1), forest compost/composted bark (1/1) and forest compost/cattle manure compost (2/3) were tested in Med. A mixture (1/1) of Finnish peat/pine bark compost was used in both climates as a control. Plants were cultivated at a density of six plants/m² in 4 l containers with drip irrigation. Plant height, dry mass, and leaf area were measured at intervals during cultivation. In Oce, substrates with yard compost or raw coir produced plants of similar size to those in the control substrate. In Med, forest compost/cattle manure compost mixture produced plants with the same height as those in the control mixture and the two other mixtures produced shorter plants. In both climates, substrates ranked the same whether height, dry mass or leaf area were considered. Using those parameters, significant effects of different substrates were revealed. Those effects are related to the substrate characteristics, mainly physical ones. As peat is used in a large range of situations, the experiment showed that substrate performance varies with its use, so alternative substrates can show better performance than those using peat.     

Comparison of composted hardwood and peat-based media for the production of seedlings,foliage and flowering plants

The germination and growth of Brassica oleraceae var. capitata, Lactuca sativa and Matthiola incana were not significantly affected by replacing peat in their growing-media with sawdust (Eucalyptus and Tristania) composted with urea (2.6 kg/m³) and other fertilizers for 6 weeks. Two thirds of the peat in the media could be replaced with sawdust before the germination or growth rates of Papaver orientale or Senecio × hybridus were significantly affected, while half of the peat could be replaced with sawdust before Viola × wittrockiana was significantly affected.The growth rates of Adiantum raddianum, Asplenium nidus, Coleus blumei, Dieffenbachia picta, Nephrolepis elata, Peperomia scandens, Philodendron sellonium × specciosum, Pilea cadleri, Saintpaulia and Schefflera actinophylla in media containing 50–80% composted hardwood sawdust were equivalent to, or significantly better than, growth in media containing an equal percentage of sphagnum peat and receiving the same level of liquid or slow-release fertilizer. Substitution of sphagnum peat with composted sawdust reduced the leaf area and dry weight of Impatiens walleriana, possibly due to a small decrease in the available water in the media. It did not, however, have a significant effect on either their number of flowers or their surface area. The growth of Pilea and Saintpaulia was best where the media contained equal percentages of sawdust and peat than where either was used alone.     

Improvement of soil properties using compost for optimum parsley production in sandy soils

In the warm and wet north Florida climate, growing Italian parsley (Petroselinum crispum [Mill.]) is gaining popularity with small producers as a short duration crop on sandy soil. Application of compost to agricultural land can benefit the low fertile sandy soils in Florida and subsequent crop production, while providing an outlet for recycling municipal solid wastes (MSW) and biosolids. A field study was laid out in a randomized complete block design with four replications to evaluate the effects of compost (75% MSW:25% biosolids) application in comparison to fertilizer, fertilizer + compost (50:50), and control treatments on: (a) parsley fresh weight (FW), (b) soil and plant tissue nutrient concentrations, and (c) soil bulk density and moisture retention in winter and spring seasons. Soil amended with fertilizer or compost + fertilizer doubled parsley FW from 15.02 Mg ha⁻¹ in the non-amended control plot to 30.75 and 32.67 Mg ha⁻¹ in soils that received fertilizer + compost or fertilizer alone, respectively. Significantly higher total soil carbon (C) levels of 2.16% and 1.95% and nitrogen (N) levels of 0.19% and 0.16% were recorded in compost and fertilizer + compost treatments, respectively. Addition of compost reduced soil bulk density significantly to 1.03 Mg m⁻³ and increased soil moisture retention in simulated drier conditions at 1500 kPa to 0.12 m³ m⁻³ in plots that received only compost at the end of winter growing season. Overall, addition of compost resulted in improvement of both physical and chemical properties as well as increased parsley yields.     

Hydraulic characteristics of composted pig manure,perlite, and mixtures of them,and their impact on cucumber grown on bags

Composted pig manure (CPM), unmixed or in mixture with perlite, was evaluated as growing medium based on both physical characteristics and agronomic performance. The physical properties were determined in CPM, perlite (0.5–2.5 mm), and their 75:25, 50:50 and 25:75 mixtures by volume. It was found that unmixed CPM has a higher bulk density (BD) than perlite, a slightly lower air space at a suction of 10 cm, and a markedly higher content in easily available water (EAW), although the water content at a suction of 10 cm is the same in the two media. Mixing CPM with perlite by 50:50 seems to increase the actual water content and decrease the actual air content at container capacity, while the BD and the EAW score intermediate to those in the unmixed constituents. Simulation of the relative hydraulic conductivity (K_r) indicates a sharp decrease in the unsaturated hydraulic conductivity (K) of CPM, perlite and their mixtures as the media suction increases. The differences in the decrease rate of K_r between the tested substrates are rather small, with the most and least steep decrease being observed in perlite and the mixture by 50:50, respectively. The agronomic performance of CPM was assessed by growing greenhouse cucumber in bags filled with perlite up to 20 cm in height, CPM up to 10 or 20 cm in height, and their mixture by 50:50 up to the same heights as CPM. A media height of 10 cm in the bag resulted in appreciably higher yields than a height of 20 cm, regardless of the type of the substrate, while the latter had no significant effect on yield. This effect of media height was ascribed to the steep decrease in K, which was minimized in all media at higher suction levels than 10 cm, thereby severely restricting water availability in their upper layers (10–20 cm) when their height in the bag was 20 cm.     

Effects of light,macronutrients, and sucrose on germination and development of the endangered fern Adiantum reniforme var. sinense (Adiantaceae)

Effects of light, macronutrients strength of Murashige and Skoog (MS) (1962), and sucrose in the culture medium on spore germination and gametophyte development of the endangered fern Adiantum reniforme var. sinense were investigated. The presence of light was found to be essential for both spore germination and gametophyte growth. Moreover, a medium consisting of 1/4 MS with 15 g/l sucrose was optimal for spore germination and early gametophyte development; whereas, MS medium with 30 g/l sucrose was optimal for further gametophyte development. Increasing amounts of sucrose (45–60 g/l) in the medium delayed gametophyte growth and development. Additionally, sporophyte formation and early growth of gametophytes in a medium consisting of clay and peat (v/v = 1:2) was higher than those in a medium consisting of pure river sand. These findings indicated that requirements for nutrients for spore germination and early gametophyte development of A. reniforme var. sinese were relatively low, but these increased with further gametophyte development, formation and growth of sporophytes.     

Hybridization and in vitro culture of an orchid hybrid Ascocenda ‘Kangla’

The present study focuses on hybridization program involving two species belonging to two different vandaceous genera, viz., Ascocentrum ampullaceum (Roxb.) Schltr. var. auranticum, a narrow endemic orchid of Manipur and Vanda coerulea Griff., an endangered orchid of Appendix I of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), to synthesize the primary hybrid genus with intermediate and improved characters in the F₁ generation. Observations on the crossability in the present bigeneric cross between V. coerulea and A. auranticum had been achieved with 60% success when V. coerulea was taken as female parent. Murashige and Skoog (MS) basal medium at half-strength was effective for the development of the hybrid seedlings of V. coerulea × A. auranticum followed by Vacin and Went (VW) and Knudson C (KC) media. The best response of seedling growth was observed on MS medium at half-strength supplemented with 2.3 μM kinetin + 0.5 μM α-naphthalene acetic acid with maximum shoot height (2.7 cm), leaf number (4.6) and root number (4.1) after 150 days of inoculation. The survival percentage and growth performance of the seedlings were found to be higher (80% survival) in potting substrate consisting of brick:charcoal in the ratio 2:1 mulched with moss (Sphagnum sp.) than in potting substrate consisting of brick:charcoal:tree fern in the ratio 2:1:1. The first flowering was observed in the hybrid seedlings of V. coerulea × A. auranticum after 2 years of transfer to the ex vitro environment. Morphologically, the flowers differed from that of the parents clearly showing the success of the hybridization experiment. Registration of the hybrid has been made with the Royal Horticultural Society with the nomenclature Ascocenda ‘Kangla’ (No. T128725).     

Use of organic agricultural wastes as growing media for the production of Anthurium andraeanum ‘Pink Lady’

Summary

The conventional organic growing medium used for anthurium (Anthurium andraeanum) production is peat. Quality peat, however, is costly and is a non-renewable natural resource. The current study compared the suitability of using charred and composted organic agricultural wastes (OAW) vs. sphagnum peat as components of various growth media for the ornamental plant, anthurium (A. andraeanum ‘Pink Lady’). Ten different media were prepared from composted corn cobs (C), charred corn cobs (CC), charred garden waste (CG), and Pindstrup? sphagnum peat moss (P) in various proportions. The media contained [on a % (v/v) basis]: C (100%), CC (100%), CG (100%), C (70%) + CG (30%), CC (70%) + CG (30%), C (35%) + CG (15%) + P (50%), CC (50%) + P (50%), CC (35%) + CG (15%) + P (50%), C (50%) + P (50%), or P (100%) as a control. After 15 months in a greenhouse, the growth and flowering of transplanted anthurium plants were optimal using P, CC+P, or CC+CG+P.These results indicate that mixing charred OAW with peat could provide a suitable medium for anthurium production, thereby reducing the need for peat and converting agricultural waste material into useful products.     

Plant regeneration of pansy (Viola wittrockiana) ‘Caidie’ via petiole-derived callus

An in vitro plant regeneration protocol for pansy (Viola wittrockiana) cultivar ‘Caidie’ from petioles was established as following: callus induction on a half-strength MS medium supplemented with 0.45 μmol l⁻¹ 2,4-d plus 8.9 μmol l⁻¹ BA, callus subculture on medium F (1/2MS with 4.5 μmol l⁻¹ 2,4-d, 2.7 μmol l⁻¹ NAA and 0.44 μmol l⁻¹ BA) and then on medium T (1/2MS with 4.5 μmol l⁻¹ 2,4-d, 2.7 μmol l⁻¹ NAA and 2.2 μmol l⁻¹ BA), shoot regeneration on medium D3 (MS media supplemented with 2.9 μmol l⁻¹GA₃, 23.6 μmol l⁻¹ AgNO₃, 0.02% active charcoal and 4.5 μmol l⁻¹ TDZ), shoot multiplication on medium M (half-strength MS medium containing NAA 1.1 μmol l⁻¹, TDZ 9.1 μmol l⁻¹ and GA₃ 8.7 μmol l⁻¹), and then shoot elongation and rooting on medium R (MS medium supplemented with 1.1 μmol l⁻¹ NAA and 1.1 μmol l⁻¹ BA). Subculture on appropriate medium was found to be important for successful shoot regeneration.     

High-frequency embryogenesis,regeneration of broccoli (Brassica oleracea var. italica) and analysis of genetic stability by RAPD

High-frequency somatic embryogenesis and shoot regeneration of broccoli (Brassica oleracea var. italica) were achieved. Cotyledon and hypocotyl explants from four varieties of broccoli were cultured on MS and modified MS media (mMS, supplemented with PG-96 organic components) with different combinations of growth regulator. The effects of genotypes, different explants, growth regulator combinations, organic components and AgNO₃ on induction of calli and shoots were evaluated. The optimal media for inducting calli/shoots and roots were mMS medium containing 3% (w/v) sucrose and 0.8% (w/v) agar supplemented with NAA at 0.5 mg l⁻¹, 6-BA at 3.0 mg l⁻¹, AgNO₃ at 4.0 mg l⁻¹ and MS medium containing 3% sucrose and 0.8% (w/v) agar supplemented with NAA at 0.2 mg l⁻¹, respectively. The callus induction percentages were over 90% in all four varieties; shoot induction percentage was 92.5% and the average number of shoot per explant was 4.1 from cotyledon explant in variety Bishan. In this study, we established high-efficient embryogenesis and shoot regeneration system of broccoli and analyzed genetic stability of regenerants at DNA level using RAPD molecular marker. Out of 62 arbitrary primers screened using PCR amplification, 79 polymorphic bands were amplified from 20 primers. The results demonstrated the genetic stability of regenerants from the same variety.     

Comparison of traditional and improved methods for estimating the stability of organic growing media

Organic growing media employed in hydroponic crops could change their characteristics due to organic matter degradation during culture growing season. Traditional methods for measuring the stability of growing media (Biochemical Stability Index, Lemaire) do not take into account the activity of crop roots, nutrients in the growing media or microorganism presence. Three experiments were performed to determine the stability of six organic substrates. Stability was measured as the percentage of organic matter remaining in substrates. In experiment one (short duration and small scale without plant) 500 ml samples were incubated for 180 days following original methodology proposed by Lemaire (L) and with three modifications: (1) Inoculation with compost (I), (2) watered with nutrient solution (NS), and (3) both combined (I + NS). In experiment two (Long duration, medium scale) 10 l samples were incubated with and without a lolium crop for 720 days in a greenhouse. In experiment 3 stability of each substrate was real measured in 20 l hydroponic bags after use in four cycles of tomato production in a commercial greenhouse (2 years). All incubations were triplicated. Physicochemical properties of substrates were measured. Correlations between stability estimated in experiment one and two and real determinations in experiment three were analyzed. Lemaire methodology modified by adding and inoculum an nutrients (I + NS) was the best method to estimate the stability of organic growing media measured in real conditions in experiment 3. This new method greatly improves the estimation performed with original Lemaire methodology. Long term incubations with lolium also reproduce well the real stability of growing media but this methodology is not feasible because it requires four times longer and the amount of substrate required is 20 times larger for each sample.     

Effect of application methods of organic fertilizer on growth,soil chemical properties and microbial densities in organic bulb onion production

This study was carried out to maximize the fertilization efficiency of mixed organic fertilizer (OF) for organically managed onion (Allium cepa L.) production during the one growing season of 2005–2006. The organic fertilizer was made of organic materials like sesame oil cake, rice bran and molasses and minerals like illite and mountainous soil. Four organic topdressing treatments, which all followed the same basal fertilization with solid OF, consisted of solid OF without mulch (OF/OFnM), liquid organic fertilizer without mulch (OF/LOFnM), liquid organic fertilizer under mulch (OF/LOFuM) and liquid organic fertilizer over mulch (OF/LOFoM). Chemical fertilizer (CF) and no fertilizer (NF) were treated as controls. The solid organic fertilization base was 2.0 ton ha⁻¹, and 4.57 ton ha⁻¹ and was used for topdressing. The total amount of liquid organic fertilization was 133.2 ton ha⁻¹, which was divided into 6 applications from February through March. The OF/LOFuM and OF/LOFoM topdressings did not reduce onion height, leaf number or bulb diameter as compared to chemical fertilizer, whereas no mulch treatments made onion growth significantly poorer. Onion top weight in CF was significantly higher than that in OF groups at the peak growth stage, while there was not much difference in bulb weight between the CF and OF/LOFoM treatment. Finally, the onion marketable yield was 45.9 ton ha⁻¹ in the OF/LOFoM treatment, which exceeded that in the CF treatment by up to 1.9 ton. Furthermore, OF/LOFoM was the most effective among all the treatments in transferring the nutrients from sink to source. CF made the soil pH more acidic than OF did, and the electrical conductivity (EC) remained higher with CF than OF as well. While organic fertilizer helped to keep the NO₃-N content stable throughout the growing season, the concentration rapidly oscillated up and down according to CF fertilization. Organic fertilizer increased population number of soil microorganisms like aerobes, actinomycetes in the field.     

Mineral nutrient requirements and effects of CO2 enrichment on Gerbera microcuttings

Summary

The effects of CO2 concentration (350 and 1200 μmol mol^-1), growing media (peat + perlite, 3:1, peat + coco dust, 1:1; and coco dust alone), and concentration of nutrient solution (EC 2.1 and 2.8 mS cm^-1) on growth of gerbera microcuttings, leaf nutrient content, and the chemical properties of the growing media were investigated. Plants grown in peat + coco dust had the highest dry weights of leaves and roots. There were no significant differences in the fresh and dry weights of leaves and roots due to concentration of nutrient solution. CO₂ enrichment increased all growth variables, except leaf number. Leaf nutrient content of gerbera cuttings and chemical properties of growing media after eight weeks of growth, with reference to all treatments, are discussed and presented as tables.     

Comparison of three pea cultivars (Pisum sativum) regarding their responses to direct and bicarbonate-induced iron deficiency

The aim of this work was to explore leaf characteristics underlining the difference in the sensitivity of pea cultivars (cv. Kelvedon, Douce and Lincoln) to Fe deficiency. Plants were grown in a greenhouse under controlled conditions in continuously aerated solution. Three treatments were used: 30 μM Fe (+Fe), 0 μM Fe (−Fe); direct deficiency and 30 μM Fe + 10 mM NaHCO₃ (+Fe+Bic); indirect deficiency for 12 days. Growth parameters, iron status, potassium content, chlorophyll fluorescence and photosynthetic capacity were studied. Our results showed that Fe deficiency led to a significant decrease of chlorophyll index (SPAD readings) and bivalent iron content in all Pisum sativum cultivars. The lower reduction was observed in Fe-deficient plants of Kelvedon and Douce. In addition, shoot length and whole plant dry weight were not affected by Fe deficiency in the latter cultivars. Both tolerant cultivars showed higher accumulation of potassium content in their leaves compared with the sensitive one. Moreover, both chlorophyll fluorescence ratios (F_v/F_m and F_v/F₀) were significantly decreased in all cultivars under both Fe deficiency treatments. The photosynthetic electron transport activity was reduced in the sensitive cultivar, especially in the absence of iron. The adverse effect of bicarbonate-induced Fe deficiency on the above mentioned parameters were more pronounced than that of the direct one. The capacity of both tolerant cultivars to preserve adequate chlorophyll synthesis, photosynthetic capacity and plant growth under iron-limiting conditions is related to the suitable nutrition of their leaves in ferrous iron, due to (at least partially) their higher potassium content.     

Regeneration of different Cyclamen species via somatic embryogenesis from callus,suspension cultures and protoplasts

The present study is the first report of the establishment of embryogenic callus cultures from seedling tissue, the regeneration of plants via somatic embryogenesis and the development of a regeneration system from protoplast to plant, using three wild species of Cyclamen, Cyclamen graecum Link, Cyclamen mirabile Hildebrand, Cyclamen trochopteranthum Schwarz (syn. Cyclamen alpinum hort. Dammann ex Sprenger). The ability to form embryogenic callus and to regenerate via somatic embryogenesis was strongly genotype-dependent for each species. From 0.5 g callus, up to 1461 somatic embryos were formed in the case of C. mirabile. Culture media with different concentrations of plant growth regulators, CaCl₂ and activated charcoal significantly influenced embryo formation in this species. Up to 1.4 × 10⁶ protoplasts were isolated from 1 g of C. graecum cell suspension. Diverse growth responses of the protoplasts in two embedding agents, agarose and alginate, were observed for the different Cyclamen species. These specific growth characteristics could be used as a selection marker for future fusion experiments. From both protoplast culture systems, somatic embryos were regenerated, grown to plantlets and acclimatised to greenhouse conditions.     

Testing the ability of vivianite to prevent iron deficiency in pot-grown grapevine

Synthetic vivianite (ferrous phosphate octahydrate) has been reported to reduce the iron (Fe) deficiency symptoms in different crops growing on calcareous soils. We investigated the effectiveness of vivianite in grapevine by means of a 3-year (2002–2004) pot experiment with a Fe chlorosis-susceptible rootstock (‘110 Richter’) grown on a calcareous soil poor in available Fe. There was one treatment in which a suspension of vivianite was injected into the soil at the beginning of the experiment, one treatment with Fe chelate (FeEDDHA) applied yearly, one treatment with one initial application of both vivianite and FeEDDHA, and one control (no Fe fertilizer added) treatment. The concentration of chlorophyll per unit leaf area was estimated with a portable chlorophyll meter (readings in SPAD units). The vines fertilized with vivianite had longer shoots and higher number of leaves, and exhibited higher SPAD values than the control vines. The differences in SPAD value and pruning wood weight between the vines fertilized with Fe and the control were significant through the 3 years. There were no significant differences in SPAD value and pruning wood weight between the vines fertilized with Fe chelate and vivianite. Our results suggest in summary that vivianite is an interesting alternative to other Fe fertilizers used to prevent Fe chlorosis in grapevine judging by its effectiveness and long-term fertilizing effect. Moreover, it is not easily leached from the soil, easy to prepare, and environmentally safe.     

The use of green waste compost in peat-based potting mixtures: Fertilization and suppressiveness against soilborne diseases

Twelve commercially produced Dutch green waste composts were evaluated for their suitability to replace 20% (v/v) peat substrate in the cultivation of ornamentals. Salt concentrations were determined in water extracts of the composts and disease suppressive effects were assessed against various soilborne diseases. The Cl-concentration of the compost extract appeared to be the limiting factor for use of the composts in potting mixtures. The Cl-concentrations in 7 and 1 composts, respectively, were too high to replace 20% of peat for growing salt sensitive and moderately salt sensitive plants, according to guidelines set for these groups of plants. The suppressive effects of the composts were tested in peat-based potting mixtures using three bioassays: Phytophthora cinnamomi—lupin, Cylindrocladium spathiphylli—Spathiphyllum and Rhizoctonia solani AG2-1—cauliflower. Disease levels in compost-amended mixtures were compared with the non-amended controls. None of the composts induced suppressiveness against P. cinnamomi; 3 and 9 composts significantly induced suppressiveness against C. spathiphylli and R. solani, respectively. No significant disease enhancement was observed in any of the bioassays. The pH of the potting mixture showed a negative correlation with suppression of the Rhizoctonia disease (R² = 0.56). The effect of pH (pH 4–6) on suppression of R. solani and P. cinnamomi was further studied in non-amended peat. Disease suppression of R. solani in cauliflower decreased with increasing pH in two different kinds of peat, while there was no effect on P. cinnamomi. The suppressive effect of 3 composts was assessed in two experiments against Fusarium wilt in Cyclamen persicum (caused by F. oxysporum f. sp. cyclamini) and Begonia eliator (caused by F. foetens) under near-commercial conditions. None of the composts had a significant effect on Fusarium wilt in Cyclamen. Two and 3 composts significantly induced suppressiveness against Fusarium wilt in Begonia in the first and second experiments, respectively. No significant differences were observed in growth characteristics between Begonia plants grown in compost-amended and non-amended potting mixture in both experiments. In the second experiment, Cyclamen plants grown in compost-amended potting mixture had significant lower number of flowers than plants grown in non-amended potting mixture, which may have been due to lower concentrations of N in the compost-amended potting mixtures. In conclusion, most composts of the origin and composition tested can replace 20% peat in potting mixtures for moderately salt sensitive and salt tolerant plants. Amendment of these composts can contribute to control of Fusarium wilt in Begonia plants.     

Seed germination and tissue culture of Cymbidium giganteum Wall. ex Lindl.

Efficient protocols were established for in vitro seed germination, neo-formation of secondary (2°) protocorms from primary (1°) protocorms and multiple shoot buds and protocorm-like body (PLB) induction from pseudo-stem segments of in vitro-raised seedlings of Cymbidium giganteum. Four nutrient media, namely Murashige and Skoog (MS), Phytamax (PM), Mitra et al. (M), and Knudson ‘C’ (KC) were evaluated for seed germination and early protocorm development. In addition, the effects of peptone, activated charcoal (AC) and two plant growth regulators [6-benzylaminopurine (BAP) and 2,4-dichlorophenoxyacetic acid (2,4-D)] were also studied. Both M and PM supplemented with 2.0 g l⁻¹ peptone or 1.0 mg l⁻¹ BAP resulted in ∼100% seed germination. Media supplemented with 2.0 g l⁻¹ AC could effectively induce large protocorms (1.6 ± 0.1 mm in diameter). Neo-formation of 2° protocorms from 1° protocorms was achieved in liquid and agar-solidified PM medium fortified with different concentrations and combinations of auxins (α-naphthalene acetic acid (NAA) and 2,4-D) and cytokinins [BAP and kinetin (KN)]. The highest number of 2° protocorms was obtained in liquid medium (10.7 ± 0.9/1° protocorm) supplemented with 2.0 mg l⁻¹ BAP + 1.0 mg l⁻¹ NAA. Although protocorms proliferated profusely in liquid medium, these did not develop further unless transferred to agar-solidified medium within 6–8 weeks. Multiple shoot buds and PLBs were induced from pseudo-stem segments on agar-solidified PM medium fortified with different concentrations and combinations of BAP and NAA and the maximum number of PLBs (6.00 ± 0.20) was recorded when BAP and NAA were applied at 2.0 mg l⁻¹ each. A solid root system was induced from PLBs and shoot buds when these were transferred to half-strength PM or M media fortified with 0.5 mg l⁻¹ indole-3-acetic acid. Well-rooted plants were transferred to the greenhouse with 95% survival.     

Productivity and quality of statice (Limonium sinuatum cv. Soiree Mix) and cockscomb (Celosia argentea cv. Chief Mix) under organic and inorganic fertilization regiments

Very little information is available on organic specialty cut flower production, especially fertilization requirements. In order to better understand organic fertilization requirements of two specialty cut flower crops, Limonium sinuatum and Celosia argentea, we initiated a field and greenhouse experiment to study the effect of compost (organic) and conventional (inorganic) fertilization treatments on the growth and productivity of these crops. Optimum yields in the field, expressed as fresh weight per plot, were achieved at compost applications of 98.8 t ha⁻¹ for both Limonium and Celosia. However, when number of stems, height of the stems, and the environmental impacts of such compost applications are considered we concluded that the optimal organic fertilizer amounts were 12.4 and 24.7 t ha⁻¹, for Limonium and Celosia, respectively. Limonium and Celosia plants in the greenhouse experiment were fertilized with 100, 200, 300, and 400 mg L⁻¹ nitrogen, combined with 0, 5, 10, 20, 40, and 60 mg L⁻¹ phosphorus. The generation of response surfaces for total weight per pot, number of stems per pot, average weight per stem, and average stem length were attempted for each species. The results showed that nitrogen did not significantly contribute to any of the models, except for Celosia average weight and length per stem models. Total weights per pot on the other hand showed both a linear and quadratic relationship over the range of phosphorus applications we tested. Maximum number of stems and total weight per pot were observed between 30 and 46 mg L⁻¹ P in both Limonium and Celosia. Our results suggest that organic fertilizer recommendations, in the form of animal manure composts should be based on phosphorus content of the compost rather than nitrogen content especially for soils high in initial phosphorous content.