Seyyedeh Mahdiyeh Kharrazi; Ali Tehranifar; Ahmad Sharifi
Abstract
Introduction: Success in tissue culture technique, especially in bulbous plants, depends on the microbial contamination control during in vitro culture. Applying different treatments, such as heat treatment and usage of fungicides, can control the microbial contamination and consequently increase the ...
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Introduction: Success in tissue culture technique, especially in bulbous plants, depends on the microbial contamination control during in vitro culture. Applying different treatments, such as heat treatment and usage of fungicides, can control the microbial contamination and consequently increase the percentage of explant survival.
Materials and Methods: This study aimed to investigate the effect of heat treatment and fungicide on reducing the contamination during in vitro culture of narcissus. So, an experiment was done as a factorial experiment in a completely randomized design with two factors, including benomyl concentration in the medium (1 and 2 g/l) and heat treatments (two levels, with and without heat treatment), with 10 replications. In order to sterilizing the plant materials, damaged and infected scales were removed firstly and then bulbs were washed for 30 minutes with running tab water and a few drops of dishwashing liquid. For applying heat treatment, bulbs were divided into two groups. In the first group, heat treatment was not applied and in the second group heat treatment 54 °C was applied for one hour using water bath. After this step, bulbs surface were sterilized by dipping in 70% ethanol for one minute and rinsed with sterile distilled water, followed by immersing in 1.5% sodium hypochlorite solution for 30 min. After sterilization with sodium hypochlorite solution, bulbs were washed three times with sterile distilled water under laminar air flow hood. After sterilization step, bulbs were cut into 32 twin scales explants and cultured in MS medium supplemented with 1 mg/l BA and 0.2 mg/l NAA + benomyl (1 or 2 g/l). After 30 days, the response of explants (number of produced bulbs, percentage of explant survival, percentage of bacterial contamination, percentage of fungal contamination, percentage of browning) was evaluated. Data preparation was done in the Excel program and data analysis was done using JMP-8 software. Mean comparison of the treatments was done by LSD test and finally the charts were drawn using the Excel program.
Results and Discussion: The results showed that increasing the concentration of benomyl in the medium and applying heat treatment had negative effect on regeneration potential of explants, so that the maximum regeneration mean were observed when heat treatment was not applied for explants and medium contains 1 g/l benomyl. Using the heat treatment and application of 2 g/l benomyl in the medium leads to the lowest regeneration amount. On the other hand, evaluating the browning percentage of explants showed that the effect of treatments was significant in this trait. Applying the heat treatment and using 2 g/l benomyl in the medium had severe effect on the increasing of explant browning and the maximum mean was observed in this treatment. But reducing the benomyl concentration in the medium and none application of heat treatment caused the lowest amount of explant browning. Contamination percentage that includes bacterial and fungal contamination is an important parameter in this study. Explants that cultured in the medium containing 1 g/l benomyl and applying heat treatment showed the highest contamination percentage, which contains 21% fungal and 14% bacterial contamination. The lowest percentage of contamination was observed when heat treatment applied and medium contains 2 g/l benomyl. However, this treatment caused the highest percentage of explant browning that lead to reduction of explants regeneration potential. Researches showed that the use of fungicides can help to control tissue culture contamination and according to previous studies, benomyl is the most effective treatment against fungal infection. As benomyl is considered as a systemic fungicide, so it is useful to eliminate the internal fungus. On the other hand, there are some reports about the positive effect of heat treatment on the control of tissue culture contamination. As regards this investigations were done in 1914 to 1997 and then stopped, so it seems that application of this treatment had no sufficient efficiency for contamination control during in vitro condition.
Conclusion: Therefore, by considering the browning, regeneration and contamination percentage, non-application of heat treatment and usage of 1g/l benomyl fungicide in the medium for in vitro culture of Narcissus twin scales explants is recommended.
Fereshteh Kamiab; Hamid Mohammadi
Abstract
Introduction: Narcissus is one of the most important ornamental plants in the world. The deficiency of microelements is a major problem limiting the production of ornamental plants under high-pH soils in most regions of Iran. Cu and Mn are essential microelements for the growth and development of plants ...
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Introduction: Narcissus is one of the most important ornamental plants in the world. The deficiency of microelements is a major problem limiting the production of ornamental plants under high-pH soils in most regions of Iran. Cu and Mn are essential microelements for the growth and development of plants as they are involved in many physiological reactions. Fe is involved in the synthesis of chlorophyll and many enzymes, respiration, and nucleic acid metabolism. Cu is a cofactor for numerous enzymes and is also involved in ethylene biosynthesis and activity, respiration, photosynthesis, regulatory proteins, cell membrane metabolism, and hormone signals. The deficiency of microelements, especially Fe, influences productive and reproductive growth of ornamental plants. Thus, this experiment aimed to evaluate the uptake rate of Cu and Mn nano-chelates and their effects on some morphological and physiological Characteristics of ‘jonquil’ narcissus.
Materials and Methods: This study was carried out in the research garden of Agriculture Faculty of Rafsanjan University in 2015 in factorial experiment based on randomized complete block design with two factors of Fe at four levels of 0, 1, 2 and 3 (g/l) and Cu at three levels of 0, 1 and 2 (g/l) in three replications. The weight of the cultivated bulbs were about 8-10 g. They were planted in eight rows spaced 20 cm with on-row spacing of five cm at the depth of 15 cm in each plot in August. According to soil analysis, 40 tons of manure and 100 tons of urea per ha were applied. The nano fertilizer was purchased from Nano-research Biozar Company. Foliar application was done three times: 1- when the plants had three leaves, 2- before flowering and 3- after flowering at 45-day intervals. Different parameters were recorded including plant height, number of leaves, width and length of leaves , number of main bulb, main bulb weight and diameter, , bulblet diameter and weight, flowering stem height and diameter, number of florets, florets diameter, fresh and dry weight of florets, flower vase life, Cu and Fe concentration, protein, chlorophyll and total soluble solids. Foliar spraying was done three times at the intervals of 45 days.
Results and Discussion: The results showed that the concentration of Cu and Fe in the leaves were enhanced with increase in the rate of each nano-chelate, implying high uptake rate of these nano-chelate by leaves in this plant. The application of Fe (2g/l) and Cu (0.5 g/l) resulted in the highest vegetative growth such as plant height, number of leaves, leaf width and length, number of main bulb, main bulb weight and diameter , and bulblet diameter and weight. High pH in experimental soil caused low absorption of micro elements in this condition. This deficiency was compensated with foliar application of nano-chelates and as a result, the Fe and Cu involved processes were improved in them. On the other hand, enhanced Fe and Cu concentrations in leaves could cause more photosynthesis and higher level of assimilation in plants. Likewise, these elements influence some enzymatic activity such as peroxidase, catalase and cytochrome oxidase; consequently, more vegetative growth was observed. Reproductive growth such as flowering stem height and diameter, number of florets, floret diameter and fresh and dry weight and flower vase life were improved in this experiment. The control of abiotic stress is one of the most important roles of Cu and also it is cofactor of superoxide dismutase that has been known as a free radical scavenger in plants that could increase quantitative and qualitative traits of flower. This treatment resulted in the highest amount of protein, chlorophyll and total soluble solids in the leaves of narcissus. Fe is one of the essential elements for chlorophyll synthesis. It also has an important role in activating nitrate reducates enzyme that uses ammonium to synthesize proteins. Cu is involved in the synthesis of proteins and enzymes that have major roles in such processes as respiration, photosynthesis, phenol metabolism, lignifications and ouxin regulation in plants. Thus, the results of this experiment showed that these nano-chelates were absorbed considerably by leaves of narcissus and they are suitable for foliar application. It should be noted that higher concentration of this fertilizer in this experiment has toxic effects. It is suggested that 2g/l Fe plus 0.5 g/l Cu were used to improve vegetative and reproductive growth of ‘jonquil’ narcissus, especially in high-pH soils.
