Growing vegetables
F. Ghaemizadeh; F. Dashti
Abstract
Introduction
At present, garlic (Allium sativum L.) production is completely dependent on asexual propagation, but a wide diversity of bolting and scape formation is observed in garlic. Based on their ability to produce flowering stem (scape), garlic clones are classified into non-bolting, semi-bolting, ...
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Introduction
At present, garlic (Allium sativum L.) production is completely dependent on asexual propagation, but a wide diversity of bolting and scape formation is observed in garlic. Based on their ability to produce flowering stem (scape), garlic clones are classified into non-bolting, semi-bolting, and bolting clones. In non-bolting clones, scape is not formed or abort at early stages. In semi-bolting clones, cessation of scape development often results in the formation of very short scape between the leaves and development of the elongated leaf-like bracts in the center of the inflorescence. In bolting clones after exposure to low temperature during autumn and winter (vernalization) and long day during spring, long and thick scape is formed which contains inflorescence with flowers. Transition from vegetative to reproductive phase and formation of scape, inflorescences and flowers in plants includes a series of continuous stages which control by several gene groups. Vernalization reduces the expression of the flowering inhibitors like FLOWERING LOCUC C (FLC), resulting in increased flowering integrators expression like SUPPRESSOR OF OVER EXPRESSON OF CONSTANT 1 (SOC1), APETALA 1 (AP1) and APETALA 1 (AP2). So, a correct understanding of the vernalization control genes expression pattern will improve garlic flowering and breeding programs. The aim of this study was to investigate the relative expression of AsFLC, AsSOC1, AsAP1 and AsAP2 before and after vernalization in Iranian bolting, semi-bolting and non-bolting garlic clones.
Materials and Methods
In this study, three garlic clones including, bolting (Mazand Zabol), semi-bolting (Langrud), and non-bolting (Hamedan) garlic clones were selected from vegetable collection of Bu-Ali Sina university (Hamedan, Iran). At first, RNA extracted from meristems of three clones monthly, from 4 to 20 weeks after planting (for AsFLC, AsSOC1, AsAP1 and AsAP2 expression analysis) and from inflorescence of semi-bolting and bolting clones at 24 weeks after planting (for AsSOC1, AsAP1 and AsAP2 expression analysis) at 2 biological replicates. Then, cDNA synthesized using Oligo d(T) primer and relative expression pattern of the mentioned genes were analyzed using quantitative Real time- PCR.
Results and discussion
The highest expression of the AsFLC in all three clones were observed at 4 weeks after culture (before vernalization). Its expression in non-bolting clone at 4 weeks after planting was 2.03 and 1.13 times more than bolting and semi-bolting garlic, respectively. After vernalization AsFLC expression decreased in the meristem of the all three clones. The decrease in the relative expression of AsFLC in bolting garlic occurred at a faster rate compared to the other two garlic clones. Then the relative expression of the AsSOC1 was increased in the meristem during vegetative to reproductive transition phase (12 weeks after planting). The highest AsSOC1 expression was observed in the meristem of bolting garlic at 12 weeks after planting which was 10.98 and 18.41 times more than the meristem of semi-bolting and non-bolting garlic, respectively. AsAP1 was expressed in the meristem of three clones in the vegetative to reproductive phase, but its highest expression was in bolting clone at 12 weeks after planting and was 1.22 and 3.64 times more than the meristem of semi-bolting and non-bolting clone respectively. AsAP2 was just expressed in the meristem of semi-bolting and bolting clones and after reproductive transition. The highest expression of the AsAP2 was observed at 16 weeks after planting in the meristem of semi-bolting and bolting garlic, which was higher in bolting garlic (2.33 times) in comparison to semi–bolting garlic. Decreases in the expression of the AsFLC during vernalization and increases in the expression of the AsSOC1 and AsAP1 during vegetative to reproductive phase in the meristem may lead to scape formation in bolting garlic. However, the higher AsFLC and the lower AsSOC1 and AsAP1 expression in the meristems of non- and semi bolting garlics in comparison to bolting garlic inhibit scape formation. In non-bolting garlic scape aborts and in semi-bolting garlic short and thin scape formed in the middle of leaves. According to the results AsSOC1 and AsAP1 were expressed in the inflorescence of semi-bolting and bolting garlic. AsSOC1 and AsAP1 relative expression in the inflorescence of bolting garlic were 4.28 and 11.25 times more than semi-bolting garlic, respectively. AsAP2 was just expressed in the inflorescence of the bolting clone but wasn’t expressed in the inflorescence of semi-bolting garlic. The differences in the expression pattern of AsSOC1, AsAP1 and AsAP2 in the inflorescence of the garlic clones could be the reason of the abnormal inflorescence in semi-bolting garlic.
Conclusions
Finally, it seems that AsFLC is a flowering inhibitor and AsSOC1 and AsAP1 are flowering integrators in bolting garlic. As AsFLC expression decreased after vernalization and AsSOC1 and AsAP2 were expressed highly in the time of vegetative to reproductive transition in the meristem of all clones, and there was difference in the bolting of clones, it is suggested that these genes may influence flower induction but their low relative expression cause incomplete bolting in semi-bolting garlic and forbid bolting in non-bolting garlic.
Growing vegetables
S. Parsajoo; F. Dashti
Abstract
Introduction
Plants are sometimes exposed to several stresses during their growth and development. Salinity stress is one of the most common abiotic stresses that significantly reduces the growth and yield of most plant species. A large part of the soils and a significant volume of all water resources ...
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Introduction
Plants are sometimes exposed to several stresses during their growth and development. Salinity stress is one of the most common abiotic stresses that significantly reduces the growth and yield of most plant species. A large part of the soils and a significant volume of all water resources in Iran are affected by salinity to varying degrees. Due to the rapid population growth and the need for more food and the water crisis, the use of unconventional water such as salt water or wells and treated wastewater in agriculture has received more attention. Soil and water salinity is one of the integrative problems in agriculture and is one of the most important barriers to crop production in the world. Salinity stress reduces the ratio of carbon dioxide to oxygen in the leaves by closing the leaves stomata and prevents the stabilization of carbon dioxide. Under these conditions, the formation rate of reactive oxygen species in chloroplasts and mitochondria increases, the electrons produced react with oxygen by photosynthesis and lead to the production of oxygen free radicals. These affects the growth, yield and quality of agricultural products. The use of antioxidant compounds can moderate the effects of this stress. Many compounds have been used to reduce the harmful effects of salinity stress. Ascorbic acid is a water soluble antioxidant and has some effects on plant resistance against environmental stresses by neutralizing free radicals. Researches showed that ascorbic acid increased plant resistance on various stresses such as salinity and drought. It has been widely used to control the effects of salinity stress. The aim of this study was to investigate the effect of ascorbic acid on resistance to salinity stress in bell pepper seedlings.
Materials and Methods
This study was done as a factorial experiment in a completely randomized design including ascorbic acid treatment (0, 1, 3 and 5 mM) and salinity stress of sodium chloride (0 and 100 mM) in 3 replications. The seeds of bell pepper Cv. California Wonder were planted in a seedling tray containing cocopeat. After emergence of cotyledons, they were fertilized with complete fertilizer (N20, P20, K20). At the stage of three true leaves the salinity treatment were started. One week before the beginning of salinity treatment, ascorbic acid was sprayed on plants and repeated two more times by seven days interval. Salinity treatment was applied by irigation for three weeks. After producing 5 leaves, a few growth properties (plant fresh and dry weight, root fresh and dry weight, leaf number and leaf area), biochemical characteristics (amounts of total chlorophyll, proline, soluble proteins, ion leakage and malondialdehyde and activity of Catalase an Proxidase enzymes) and amounts of some elements (K, P, Na, Fe, Zn and Cu) were measured.
Results and Discussion
Based on the results, the simple effect of salinity stress, ascorbic acid and the combined effect of them on ion leakage and amounts of malondialdehyde were significant at the level of 1% probability. Salinity stress increased the amounts of ion leakage and malondialdehyde and application of 5 mM ascorbic acid reduced the amount of these traits to 41.01% and 46.58% compared to the control respectively. The effect of salinity stress, ascorbic acid and the combined effect of them on the concentration of proline and chlorophyll in the leaves of bell pepper were significant at the level of 1% probability. Salinity stress increased the amount of proline but decreased chlorophyll and leaf protein of pepper seedlings and application of 5 mM ascorbic acid increased them to 79.42% and 46.57% compare to control respectively. Under salinity stress the uptake of iron, zinc, copper and phosphorus decreased; using of 5 mM ascorbic acid increasing accumulation of these elements in leaves .On the other hand ascorbic asid could decrease the amounts of sodium accumulation in seedling,s leaves. The results showed that, salinity decreased growth indices (number of leaves, leaf surface, fresh weight of roots and plants) and ascorbic acid reduced the effect of salinity stress on growth parameters. Under salinity stress, 5 mM ascorbic acid treatment increased the leaf surface to 36.30% compared to salinity without ascorbic acid tretment. The effects of salinity stress and the combined effect of salinity stress and ascorbic acid on the amount of catalase and peroxidase enzymes were significant at the level of 1% probability. The effect of ascorbic acid was significant for catalase at 5% probability level and peroxidase at 1% probability level. Although salinity increased the amounts of the antioxidant catalase and peroxidase enzymes but ascorbic acid could increased the activity of them in saline condition.
Conclusion
It seems that application of ascorbic acid as an antioxidant could reduce the effects of salinity stress by increasing the activity of catalase and peroxidase enzymes, reducing sodium uptake and increasing the uptake of phosphorus, potassium, iron, zinc and copper. These could have positive effects on the growth parameters of bell pepper seedlings in salinity conditions. Generally, on based of obtained results, spraying 5 mM Ascorbic acid on bell pepper seedlings modified the resistance of them in salinity stress conditions.
Khosro Parvizi; Farshad Dashti
Abstract
To evaluate the influence of arbuscular mycorrhizal inoculation on growth, yield and minituber production of potato plantlets, a pot experiment was conducted using a factorial based on completely randomized design with four replications. The factors were mycorrizal inoculation (non-inoculated and inoculated ...
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To evaluate the influence of arbuscular mycorrhizal inoculation on growth, yield and minituber production of potato plantlets, a pot experiment was conducted using a factorial based on completely randomized design with four replications. The factors were mycorrizal inoculation (non-inoculated and inoculated with Glomus mosseae, Glomus etunicatum and mixed of them) and two potato cultivars (Agria and Sante). Some growing characteristics and physiological traits such as chlorophyll content, internode length stem diameter, stolon length, leaf area, fresh and dry stem weight, fresh and dry root weight and percentage of colonization were measured. After harvesting, minitubers were separated to different classes according their size and their percentage of dry matter was measured. The results showed that inoculation with mycorrhiza had significant effect on all parameters. In growth characters the interaction of cultivar and mycorrhiza was significant only in stolon diameter and root fresh and dry weigh. The interaction of cultivar and mycorrhiza had significant effect on production of all minituber classes. Highest number of minituber was achieved by inoculating with mixture of fungi. Correlation coefficients demonstrated that most of growth parameters and minituber yield had significant relation with colonization percentage.
