Farnoosh Malekshahi; Ali Ashraf Mehrabi; Elahe Tavakol; Khosro Mehdikhanlo; Vahid Shariati
Abstract
Introduction: Basil genus (Ocimum) contains 30 to 150 species which grown in tropical and subtropical regions of Asia, Africa, Central and South America and found as a wild plant in these areas. In India, around 25,000 ha is under cultivation of Ocimum spp., with an annual production of about 250–300 ...
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Introduction: Basil genus (Ocimum) contains 30 to 150 species which grown in tropical and subtropical regions of Asia, Africa, Central and South America and found as a wild plant in these areas. In India, around 25,000 ha is under cultivation of Ocimum spp., with an annual production of about 250–300 tonnes of essential oil. Ocimum gratissimum L., a dicotyledonous shrub plant, which belongs to the Lamiaceae family, stands out for the quality, quantity and chemical diversity of the essential oils. These oils have been used in the pharmaceutical, cosmetic and food industries. Some of the essential oil compounds have antibacterial, insecticidal and antioxidant properties with high demand on the international market of the fine perfumery industry. It is also popularly used in herbal medicine for treating several diseases, such as upper respiratory tract infection, fever, cough, diarrhea and pneumonia. Being a short-duration economically viable medicinal and aromatic crop, clove basil has huge potential for large scale cultivation. Plant genetic has an important role in determining the type and amount of secondary metabolites of medicinal plants. Moreover, the recognition of species and genotypes with high genetic capability in the production of desired metabolites has been at the top of the plant breeding plans of medicinal plants. In addition, essential oil composition of plants may be affected by harvest time which is due to the impact of weather conditions on plant growth and development. The present study was aimed to evaluate the oil composition of two genotypes in two harvests. Materials and Methods: The research was conducted in the research farm of the college of agriculture, shahid Chamran University, Ahvaz, Iran during 2019. Two valuable genotypes of Ocimum gratissimum L. (278 and 296), with two different essential oil profiles, were investigated in two harvests; spring and autumn seasons. The aboveground parts of the plants were collected on June and November and dried on shade at room temperature. The essential oils of the plants were extracted by water distillation through Clevenger apparatus and the quantity and quality of the essential oils were analyzed by GC and GC-MS. Results and Discussion: The results of present study showed that the essential oil content of two genotypes was not affected by the harvest season while its amount was different in two genotypes. The essential oil content of genotype 296 was 2-fold of 278. According to the qualitative analysis of the essential oils, fifty compounds were identified in the essential oils of 278 and 296 genotypes. More than 98% of the identified compounds (in the essential oils of these two genotypes) were classified into five chemical classes; including hydrocarbon and oxygenated monoterpens, and hydrocarbon and oxygenated sesquiterpene and phenylpropanoids. The major constituent of the essential oil of genotype 278 was oxygenated monoterpene, thymol, on June (35.48 %) and November (45.85 %), which was not found in genotype 296. Gamma-terpinene was also significantly increased from June (13.15 %) to November (25.80 %). P-cymene (11.31-3.56 %), alpha- thujone (4.76-2.94 %), Germacrene D (3.73-2.76 %), caryophyllene E (3.66-1.51 %), myrcene (2.93-3.01 %), alpha-terpinene (2.63-3.38 %) and bourneol (2.28-0.71 %) were the remains of oil composition. Dihydro eugenol, which belongs to the chemical class of phenylpropanoids, was identified as the main essential oil components of genotype 296 which its amount was not affected by the harvest time. The other oil constituents were Beta (Z)-Ocimene (11.89-3.40 %), Germacrene D (3.58-2.80 %), and caryophyllene E (0.52-2.68 %). Conclusion: Terpenoids such as thymol are synthesized via the mevalonic acid pathway, and phenylpropanoid compounds such as dihydroeugenol and eugenol are synthesized via the shikimic acid pathway. The metabolite diversity across different species could be explained by the differential gene expression pattern. According to the results of the present study, thymol was identified as the main oil components of genotype 278. This may be due to the increased expression of mevalonate enzymes. The monoterpene was replaced by phenylpropanoid; dihydrogenugenol, in the oil of genotype 296 which might be due to more expression of the enzymes of the phenylpropanoid pathway. In the other hand, Thymol, P-cymene and gamma-terpinene in genotype 278 varied significantly in different harvesting times, indicating the effect of temperature on the activity of enzymes involved in the synthesis of essential oil components. On the contrary, the amount of dihydrogenugenol in genotype 278 on June and November is not affected by the environmental conditions in two seasons. With regard to the conclusions to the proper growth of genotype 278 and 296, as well several harvests annually, essential oil content and thymol and dihydrogenugenol, therefore, it is suggested that further research should be carried out for developing plant cultivation in Khuzestan and southern provinces which is not suitable for basil growth.
Isa Keramatlou; Saeid Navabpour; Khalil Zainilnejad; Elahe Tavakol; Seyyed Mehdi Hosseini Mazinani
Abstract
Introduction
Low temperature is one of the major abiotic stresses which can cause a significant reduction in olive growth and productivity mainly at late autumn, winter and early spring. Although olive is moderately freezing tolerant, temperatures below a certain threshold -7oC can damage the plant, ...
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Introduction
Low temperature is one of the major abiotic stresses which can cause a significant reduction in olive growth and productivity mainly at late autumn, winter and early spring. Although olive is moderately freezing tolerant, temperatures below a certain threshold -7oC can damage the plant, while at -12oC damage may be serious enough to threaten the life of the tree. Different cultivars of olives have diverse reactions to cold stress and so, the selection of cold resistant cultivars is the most effective method to avoid frost damages. First step to achieve this goal, is indentifying tolerant cultivar and genotypes in olive area growing. Due to extensive and high freezing damage in November 2016, the objective of the present study was to evaluate morphological characteristics and selection of single -tolerant cold trees.
Materials and Methods
The present study was carried out in some cold tolerant olives after freezing event in December 2016 in Eastern region of Golestan province of Iran. After freezing stress Healthy olive trees were identified in tow major olive cultivation regions and then were evaluated in four stages. Thus, this study included: 1- Meteorological data analysis, 2- Evaluation of freezing stress symptoms in olive orchards and identification of single tolerant trees, 3-stugy of single tolerant cold trees in 4 stages. For each genotype, studies on morphological traits (Tree age, location altitude, dip direction and its percentage, previous yield, tree height, canopy height, average of canopy diameter, canopy volume, canopy surface area, trunk perimeter, trunk diameter, trunk cross section area, length of internodes, growth habit, canopy density, canopy defoliation, barksplit ranging, flowering and fruit set) based on CFC / IOOC / 03 and Lodolini et al. (2016) results.
Results and Discussion
History of cold climate in the last two decades showed freezing event several times cause damage to olive orchards. The last freezing stress occurred with the entrance of the cold air to the Golestan province and a sudden drop in temperature to less than 0 degrees Celsius and stability of these conditions for 5-days in the late of November, 2016. The temperature drops below 0 ° C began on November 23 and lasts for 4-days. However, the main damage to the olive orchards is on November 25, when temperature is - 7 ° C. The minimum temperature recorded in the studied regions in November 25, Maravehtapeh, Gonbad, Kalaleh and Minoudasht are -14.2, -12.7, -12.3 and -8.5 ° C, respectively. Symptoms of freezing damage on olive tree can range from shoot tip burns and defoliation up to bark split on branches or trunk. After 4 stages visiting olive orchards, Finally, from 218 primary individual trees, 58 trees were introduced for further evaluation. Location altitude (meters above sea level) of the idividual trees are 81-411 in the CTO-17 and CTO-5 genotypes, respectively. Generally, 93% of all trees identified in sloping land orchards, and the Percentage variation for this trait is 48. 99. Fruit production of selected olives before freezing event in 2016 showed except of 13 trees, 44 of olives was of 2-60 kg/tree. Tree height was 2-6.82 in CTO-35 and CTO-17 genotypes, respectively. However, average of canopy diameter in all genotypes was 2.68. Also, trunk diameter (TD) and trunk cross section area (TCSA) was maximum in CTO-29 and minimum in CTO-9. But the average of this trait was 17.13 cm. Variation between genotype in internode length changed between 1.05 in CTO-20 and 16.2 in the CTO-49. Reduction of internode spaces and shoot growth, even though the total node number is normal resistance of the olive tree to cold is reduced. Leaf defoliation is one of the most important symptoms of freezing event. The study of selected trees showed that 48 trees (83%) did not showed symptoms of leaf loss, and only 10 trees showed less than 50% leaf loss. Except for the CTO-54 genotype, which showed symptoms of bark spliting on one-year shoots, no evidence of bark spliting observed in other selected olives.
Conclusions
Although olive is the most cold-hardy of the subtropical fruit trees, some varieties can withstand low temperatures better than the other. Although temperatures at which olive trees can be damaged vary, depending on climatic conditions, temperatures at or below -7°C are often critical. The most important symptoms were leaf defoliation, bark split, and limb dieback. Finally, because of different influence of environmental factor in different regions, evaluation of location, yield and morphological traits showed some of cold tolerant olive in different region had a similar behavior, thus by supplementary molecular studies, it can be hoped that among recognized trees, cold resistant cultivars with acceptable yields were introduced.
