Nabila S. Karam

Growth and rosmarinic acid accumulation in callus, cell suspension, and root cultures of wild Salvia fruticosa

The accumulation of rosmarinic acid (RA) in Salvia fruticosa callus, cell suspension, and root cultures was studied. For callus induction, leaves excised from microshoots were cultured on MS medium containing thidiazuron (TDZ) (0, 2.3, 4.6, 6.9, 9.2, or 11.5 μM) and indole-3-acetic acid (IAA) (0 or 3 μM). For root culture, hairy roots were cultured in B5 medium containing 2.7 μM α-naphthaleneacetic acid (NAA) and different concentrations of sucrose or phenylalanine. Induction of callus was completely inhibited in the absence of both TDZ and IAA and the largest callus (0.79 g) was obtained with a combination of 6.9 μM TDZ and 3 μM IAA. Culture duration of 5 weeks resulted in maximum callus growth and RA yield (2.12 mg/ 100 mg dry weight). Cell suspension growth and RA yield (5.1 mg/ 100 mg dry weight) were maximum after 20 days of culture. The highest root growth and RA yield (2.62 mg/ 100 mg dry weight) was obtained with 4% (w/ v) sucrose. Incorporation of 10 mg l−1 phenylalanine in the medium increased RA yield in the roots to 4.68 mg/ 100 mg dry weight after 4 weeks of culture. Amounts of RA extracted from in vivo leaves and roots were 0.21 and 0.72 mg/ 100 mg dry weight, respectively.

CRYOPRESERVATION OF AFRICAN VIOLET (SAINTPAULIA IONANTHA WENDL.) SHOOT TIPS

SummaryCryopreservation of African violet via encapsulation-dehydration, vitrification, and encapsulation-vitrification of shoot tips was evaluated. Encapsulation-dehydration, pretreatment of shoot tips with 0.3 M sucrose for 2 d followed by air dehydration for 2 and 4 h resulted in complete survival and 75% regrowth, respectively. Dehydration of encapsulated shoot tips with silica gel for 1 h resulted in 80% survival but only 30% regrowth. Higher viability of shoot tips was obtained when using a step-wise dehydration of the material rather than direct exposure to 100% plant vitrification solution (PVS2). Complete survival and 90% regrowth were achieved with a four-step dehydration with PVS2 at 25°C for 20 min prior to freezing. The use of 2M glycerol plus 0.4M sucrose or 10% dimethyl sulfoxide (DMSO) plus 0.5M sucrose as a cryoprotectant resulted in 55% survival of shoots. The greatest survival (80–100%) and regrowth (80%) was obtained when shoot tips were cryoprotected with 10% DMSO plus 0.5M sucrose or 5% DMSO plus 0.75M sucrose followed by dehydration with 100% PVS2. Shoot tips cryoprotected with 2M glycerol plus 0.4M sucrose for 20 min exhibited complete survival (100%) and the highest regrowth (55%). In encapsulation-vitrification, dehydration of encapsulated and cryoprotected shoot tips with 100% PVS2 at 25°C for 5 min resulted in 85% survival and 80% regrowth.

Metal concentrations, growth, and yield of potato produced from In Vitro plantlets or microtubers and grown in municipal solid‐waste‐amended substrates

Abstract In vitro plantlets or microtubers (in vitro produced tubers) of ‘Spunta’ potato (Solanum tuberosum L.) were planted in a 3 soil: 2 peat moss: 1 sand substrate (by volume) amended with municipal solid waste (MS W) compost at 0, 10, 20, or 30 g 4‐1 L pot. Three months later, plant growth and tuber yield were evaluated and concentrations of shoot and tuber tin (Sn), arsenic (As), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), manganese (Mn), cadmium (Cd), and iron (Fe) were determined. Amending with MSW resulted in significant increases in concentrations of all tested metals in the substrate. Number of proliferated shoots of plants started from rooted plantlets was greatest at 10 g pot‐1 MSW, whereas shoot weight of plants started from microtubers was greatest at 10 and 20 g pot‐1 MSW. Tuber yield of plants started from rooted plantlets or microtubers was greatest at 10 or 30 g pot‐1 MSW, respectively. In all instances, amending with MSW at 30 g pot‐1 resulted in significant increases in concentrat...

Cryopreservation of sour orange (Citrus aurantium L.) shoot tips

SummaryThe objective of this study was to establish a cryopreservation protocol for sour orange (Citrus aurantium L.). Cryopreservation was carried out via encapsulation-dehydration, vitrification, and encapsulation-vitrification on shoot tips excised from in vitro cultures. Results indicated that a maximum of 83% survival and 47% regrowth of encapsulated-dehydrated and cryopreserved shoot tips was obtained with 0.5M sucrose in the preculture medium and further dehydration for 6 h to attain 18% moisture content. Dehydration of encapsulated shoot tips with silica gel for 2h resulted in 93% survival but only 37% regrowth of cryopreserved shoot tips. After preculturing with 0.5M sucrose, 80% of the vitrified cryopreserved shoots survived when 2M sucrose plus 10% dimethyl sulfoxide (DMSO) was used as a cryoprotectant for 20 min at 25°C. Survival and regrowth of vitrified cryopreserved shoot tips were 67% and 43%, respectively, when 0.4M sucrose plus 2M glycerol was used as a loading solution followed by application of 100% plant vitrification solution (PVS2) for 20 min. Increased duration of exposure to the loading solution up to 60 min increased survival (83%) and regrowth (47%) of cryopreserved shoot tips. With encapsulation-vitrification, dehydration with 100% PVS2 for 2 or 3 h at 0°C resulted in 50 or 57% survival and 30 or 40% regrowth, respectively, of cryopreserved shoot tips.

Cryopreservation of bitter almond (Amygdalus communis L.) shoot tips by encapsulation-dehydration and vitrification

This study was directed towards cryopreservation of shoot tips of bitter almond (Amygdalus communis) using encapsulation-dehydration and plant vitrification solution (PVS2) techniques. For encapsulation-dehydration, microshoots were precultured on a medium containing 0.3 M sucrose and exposed to cold acclimation (5°C) for 0, 3 or 5 weeks. Shoot tips were then excised and treated with a medium containing 0.5 or 0.75 M sucrose for one day before dehydration for 4 or 6 hr. Highest survival (77 or 80%) or regrowth (50 or 60%) rates were obtained with cryopreserved shoot tips that were dehydrated for 4 or 6 hr, respectively, and pretreated with 0.75 M sucrose after 5 weeks of cold acclimation. Other microshoots were cold acclimated at 5°C for 0, 2 or 4 weeks on media supplemented with 0.3 M sucrose. Shoot tips were then treated with PVS2 for 60, 90 or 120 min at 0°C before liquid N 2 . Highest survival (93 or 1110%) and regrowth (57 or 67%) rates were obtained for shoot tips that were cold acclimated for 2 or 4 weeks, respectively, and treated with PVS2 for 120 min.

Response of Croton Grown in a Zeolite-Containing Substrate to Different Concentrations of Fertilizer Solution

Abstract Utilization of minerals such as zeolites as substrates for horticultural crop production has been receiving considerable attention. A growth chamber experiment was conducted to determine the response of croton grown in a substrate composed of a mixture of zeolitic tuff, peatmoss, and perlite at a ratio of 1:1.5:1.5 by volume, respectively, to different concentrations of a fertilizer solution. Before application of the fertilizer solution, the substrate was allowed to dry via evapotranspiration (ET) to a pre-irrigation moisture content equivalent to 55% of available water. The plants were then fertigated with a complete fertilizer solution containing different concentrations of nitrogen (N) (0, 75, 150, or 225 mg L−1), phosphorus (P) (0, 32.75, 65.5, or 98.25 mg L−1), and potassium (K) (0, 62.5, 125, or 187.5 mg L−1) to render the substrate to its container capacity and allow for 0.2 leaching fraction. The results indicated that there was no significant effect of the concentration of the fertilizer solution on plant growth. The highest concentration of the fertilizer solution resulted in the highest protein and N contents in the plant. Nonfertilized plants accumulated the highest amount of sodium (Na). At the end of the growing period, the concentrations of N, P, and K were the lowest in the nonfertilized substrates. The highest pH values were recorded for leachates collected from nonfertilized substrates at the end of the experiment. Substrate and leachate salinity and concentration of mineral N were the highest when the highest concentration of fertilizer solution was used. It was concluded that the use of this substrate as a growth medium for croton can provide the plant with adequate amounts of N, P, and K for the given growth period investigated. This will favorably reflect on the effort for lowering the cost of production of container-grown plants in greenhouse and nursery industries.

Response of in vitro cultures of potato, tomato, apple rootstock, and bitter almond to a culture medium supplemented with municipal solid waste

Abstract In vitro cultures of Spunta’ potato (Solanum tuberosum L.), ‘Fiona F1’ tomato (Lycopersicon esculentum Mill.), ‘MM 106’ apple rootstock (Malus domestica Borkh), bitter almond (Amygdalus communis L.) were grown on Murashige and Skoog (MS) medium supplemented with municipal solid waste (MSW) compost at 0,3,6, or 9 g L−1. Thirty‐five days later, cultures were evaluated for number and length of proliferated shoots and roots, callus size, and visual quality. (Concentrations of tin (Sn), arsenic (As), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), manganese (Mn), cadmium (Cd), and iron (Fe) in the culture medium and in potato microshoots were determined. As the percentage of MSW in the medium was increased, concentrations of all elements increased. Concentrations of As, Cu, Zn, and Ni in potato microshoots increased consistently and significantly as the MSW percentage in the medium was increased. Municipal solid waste had no effect on number or length of potato roots. The highest number of potato shoo...

Wastewater Re-Use for Croton in Substrates Amended with Zeolitic Tuff

ABSTRACT Treated wastewater was compared with tap water for irrigation of croton (Codiaeum variegatum Blume cv. ‘Petra’) in substrates consisting of 1 peat moss: 1 perlite (PP) or 1 soil: 1 sand (SS), alone or supplemented with zeolitic tuff at a ratio of 3:1 (PPZ and SSZ). Substrates were allowed to reach 80% of available water before the plants were irrigated with wastewater or tap water. Results indicated that neither water quality nor substrate affected plant width, leaf area, shoot fresh weight, or root length or weight. Wastewater increased stem diameter; node and leaf number; tissue nitrogen (N); sodium (Na); and chloride (Cl); substrate electrical conductivity (EC); phosphorus (P); Na, Cl, and leachate EC; and concentrations of Na, Cl, NO3 −, and NH4 +. Root count, tissue Na, substrate potassium (K) and Na, and leachate pH were higher for zeolite-containing substrates. Shoot dry weight and tissue contents of N and P were the highest for wastewater-irrigated PP and PPZ. Wastewater-irrigated plants in PP and tap water-irrigated plants in PPZ exhibited the highest K content. The highest level of tissue Cl was recorded for SS. Tap water-irrigated PPZ had the highest pH and K concentration. Wastewater-irrigated PP, PPZ, and SS exhibited the highest contents of N, Na, and Cl, respectively. Based on the results, amendment of the substrate with zeolitic tuff is recommended to offset the adverse effect of salinity associated with wastewater.

Slow Growth in vitro Preservation of African Violet

In vitro preservation of African violet (Saintpaulia ionantha Wendl.) via slow growth was evaluated using different osmotic agents and temperatures. Microshoots were excised from in vitro plantlets and cultured on a hormone-free MS medium containing different concentrations of sucrose (0, 0.09, 0.18, 0.26 or 0.35 M), mannitol or sorbitol (0, 0.16, 0.33, 0.49 or 0.66 M). Other microshoots were cultured on a hormone-free MS medium supplemented with 0.09 M sucrose and incubated at 2, 10, or 24°C in the dark. Results indicated that preservation of microshoots on a medium containing 0.18 M sucrose or 0.16 M mannitol or sorbitol under 16 hr light was able to decrease shoot growth and maintain explant quality for 12 weeks. Preservation of microshoots at 10°C in the dark was effective in decreasing the growth and maintaining explants in a good condition for six weeks.

Growth and irrigation requirements of croton in substrates amended with pre-charged zeolitic tuff

Abstract Peatmoss-perlite (PP) was mixed with pre-charged zeolitic tuff (Z) at different ratios (Z, 3Z : 1PP, 1Z : 1PP, 1Z : 3PP, and PP) (v/v). Rooted cuttings of “Aceton” croton (Codiaeum variegatum Blume) were planted in the substrates and grown under controlled conditions. During the 4-month experiment, substrates were allowed to dry via evapotranspiration to 80% of container capacity before the plants were irrigated with a nutrient solution to target a 0.2-leaching fraction. In another 4-month experiment, rooted cuttings were planted in 1Z : 3PP and the substrates were allowed to dry via evapotranspiration to 55, 65, 75, or 85% of available water before the plants were irrigated to target a 0.2-leaching fraction. Results indicated that plants grown in 3Z : 1PP or 1Z : 3PP received the least volume of water (3.4–3.5 L) and amount of nitrogen (N) (514–529 mg). Plants grown in 1Z : 3PP were more vigorous than those grown in 3Z : 1PP and comparable to those grown in peatmoss-perlite. The highest tissue content of N (4.8%) was obtained with zeolitic tuff, phosphorous (P) (0.19–0.21%) with zeolitic tuff and peatmoss-perlite and potassium (K) (2.6%) with peatmoss-perlite. The highest concentrations of N (6944 ppm) and P (306 ppm) were detected in peatmoss-perlite substrate and of K (6594 ppm) and sodium (Na) (4385 ppm) in zeolitic tuff. Plants irrigated at a substrate moisture content equivalent to 55% of available water received the least volume of water (2.4 L). Plant growth and tissue contents of N, P, and K were not affected by substrate moisture content. The lowest Na concentration in the tissue (1.6%) and the substrate (3086 ppm) was recorded for the 85% moisture content. Irrigating at 55 or 65% moisture content resulted in the highest substrate content of N (1778–1841 ppm). The highest substrate content of Na (4031 ppm) was recorded for the 55% moisture content. It is apparent that a croton grower will be able to use around 29% less water and fertilizer if zeolitic tuff is incorporated into the commonly used peatmoss-perlite medium.