Journal of Ornamental Plants
Volume:6 Issue: 3, Summer 2016

The effects of root temperatures (25, 35 and 45°C) and temperature duration (30, 60 and 90 min) on net photosynthesis rate, stomatal conductance and transpiration rate in Tradescantia pallida were investigated. The experiment was conducted under controlled conditions with factorial arrangement based on a completely randomized design (CRD) and four replications. Result showed that, net photosynthesis rate was not significantly different between plants treated with 25 and 35°C. However, aperture area and width increased at 35°C and declined sharply at 45 °C as compared with that at 25 °C. Net photosynthesis rate and stomata1 conductance of plants treated with 45°C decreased to 76 and 68%, respectively, as compared with those at 35°C. Stomatal aperture area of plants treated with 35°C was 27% and 320% higher than those treated with 25 and 45°C, respectively. Stomatal resistance of plants treated with high temperature (45°C) were higher (174%) than those treated with 35°C. In 35 °C, aperture area of plants after 30 min was 61% and 45% higher than those after 60 and 90 min exposure, respectively. The results revealed that, a heat shock of roots at 45°C could lead to a significant decrease in stomatal conductance (by 81%) and transpiration rate (by 60%) as compared with those at 35°C. Overall, the results suggest that the root temperature affects leaf gas exchange and stomatal behavior and has to be taken into account in plant production system, in particular, hydroponics.

In recent years, the symptoms of viral diseases such as dwarfism, mosaic, discoloration, necrosis, and circular spots have been prevalent in ornamental plants in parks, gardens, and streets in North Khorasan Province. Tomato ring spot virus (ToRSV) belongs to the Nepovirus genus of Secoviridae family. This virus is a major cause of the infection of ornamental plants in the world. In this study, to evaluate the percentage of infection to ToRSV, in the early autumn of 2014, 400 samples of ornamental plants were collected based on the suspicious viral symptoms from parks, gardens, and streets of North Khorasan province (Bojnord and Shirvan Cities) and were transported to the laboratory in cold conditions. In the laboratory, DAS-ELISA serological test was performed to evaluate the presence of virus in the suspected samples. Then, the infected samples identified by ELISA test were inoculated to the test plants of Cucumis sativus L. (Cucumber), Vigna unguiculata L. (Cowpea) and Nicotiana glutinosa L. (Tobacco). After the appearance of symptoms, in order­ to verify the infection, they were tested again using DAS-ELISA. The molecular identification of the infected samples was done by Qiagene RNA extraction kit. Using specific primers in RT-PCR reaction, a fragment was amplified in the band of 449bp. The results of DAS-ELISA and RT-PCR tests proved the presence of the virus on ornamental plants in North Khorasan Province. In the mechanical inoculation of the virus, three above-mentioned plants showed the symptoms of the disease.

In this paper, we present a machine vision system that was developed on the basis of neural networks to identify twelve houseplants. Image processing system was used to extract 41 features of color, texture and shape from the images taken from front and back of the leaves. The features were fed into the neural network system as the recognition criteria and inputs. Multilayer perceptron (MLP) neural network with Declining Learning-Rate Factor algorithm (BDLRF) training algorithm was used as a classifier. Classification was done in three stages based on eligibility and strength of characteristics in identifying the plants. Eligibility criteria were assessed at each stage using plants class resolution power. In this classification method, each step requires a small number of attributes and for this reason its speed and accuracy can be very high. The results showed that the accuracy of classification of plants in three steps reaches 100%. Also, the optimal features for classification included three inputting steps of morphological features, HSI color features extracted from back of the leaves, and HSI texture features of the back of the leaves.

Stem and peduncle bending by the weight of the flower is one of the main postharvest problems in gerbera (Gerbera jamesonii Bolus.) and sometimes caused stem crushing or water loss. In this research, silicon and salicylic acid were applied to enhance the mechanical strength of inflorescence stem, and the results revealed that stem curving was decreased by silicon and salicylic acid treatments. Shear strength and lignin content were increased by SA treatments at both upper and lower parts of the stem. It seems that lignin content was associated with shear strength at upper part of stem. Additionally, silicon content of flower stem was significantly increased under silicon application and mechanical strength of the lower part of stem has correlation with silicon content in stem tissue. These results suggested that silicon and salicylic acid application could enhance the mechanical strength of inflorescence stem and improve the cut flower quality in gerbera.

To investigate the effects of silicon on the growth characteristics and the reduction of the powdery mildew damage to Zinnia (Zinnia elegans Jacq. ʻMagellanʼ), an experiment was carried out as a factorial experiment in the form of a randomized complete block design with two factors including eight treatments and three replications. The first factor included silicon concentrations at four levels (0, 50, 100, 150 mg L-1 Si) and the second factor consisted of the Si application methods (foliar spray and medium drenching). Depending on the concentration and method of silicon supplied, several horticultural traits were improved as a result of Si supplementation. Silicon content of Si-treated plants (100 and 150 mg L-1 Si foliar spray) significantly increased as compared with untreated controls. Disease severity of powdery mildew was reduced by sodium silicate. The results of our study demonstrated that foliar spray treatments were more effective in managing disease than drenches treatments.

Cut gerbera (Gerbera jamesonii) flowers are sensitive to microbial contamination and have short vase life. The effect of salicylic acid, citric acid and ascorbic acid (50, 100 and 200 mg l-1) was evaluated on vase life of gerbera flowers. Changes in vase life, water absorption, and bacterial population in stem and vase solution, also biochemical characteristics such as protein concentration, lipid peroxidation level and enzymes activity such as superoxide dismutase and peroxidase were measured and compared with the control. Results showed that the maximum vase life (11.31 and 11.21 days) was achieved in 100 mg l-1 of both citric acid and salicylic acid, respectively. The vase life of control cut flowers was 5.80 days. Most solution uptake (0.907 ml g-1 F.W) was obtained in 100 mg l-1 of citric acid, too. The least bacterial colonies in stem end (151.00) and vase solution (66.33) was obtained in 100 mg l-1 citric acid. Differences between the content of bacterial colonies in vase solution containing 200 mg l-1 citric acid and 100 and 200 mg l-1 salicylic acid was not significant with 100 mg l-1 citric acid. The lowest content (46.04 and 46.21 nmol g-1 F.W.) of lipid peroxidation or MDA content was obtained from cut flowers treated with 200 mg l-1 of citric acid and 100 mg l-1 salicylic acid, respectively. Maximum activity of the peroxidase (0.063 mmol g-1 F.W.) and superoxide dismutase (40.80 nmol g-1 F.W.) enzymes was observed in 200 mg l-1 of citric acid.

Pelargonium odoratissimum is a perennial evergreen used as a fragrant ornamental plant. Leaves, green branches and fresh flowers contain essential oils, that have been shown to possess antibacterial, antifungal, antiviral, insecticidal and antioxidant properties. In order to study the effect of foliar spray of ZnSO4 (0, 1000, 2000, 3000 and 4000 mg L-1) on vegetative growth and some physiological characteristics of Pelargonium odoratissimum L. plants, a pot experiment was carried out during 2015 at the Research Greenhouse of Azarbaijan Shahid Madani University, Iran. Vegetative growth (plant height, fresh and dry weight) was significantly affected by the application of ZnSO4. Foliar application of ZnSO4 promoted plant height especially at 2000 mg L-1. Chlorophyll a, b, total chlorophyll and carotenoid contents were affected with ZnSO4 treatment as well. The content of essential oil was not significantly influenced with ZnSO4 spray. ZnSO4 application had significant effect on total phenolic and anthocyanins (at 1000 and 2000 mg L-1) and total flavonoids (at 2000 mg L-1) content.

Due to the lack of scientific knowledge for the use of substrate and best fertilizing method in the growth of Araucaria excelsa, it is crucially important to find the most appropriate planting substrate and fertilizing method. The effect of conventional fertilizing method and the application of Fe nanofertilizer were studied on the growth of A. excelsa in which six fertilizing methods and three substrates were examined in a factorial experiment based on a Randomized Complete Design with three replications. The seedlings of A. excelsa were transferred to 4-L pots after the selection of substrate type and were placed in greenhouse at day/night temperature of 21-23/17-19°C. Some growth indices were recorded including plant height, lateral shoot length, stem diameter, root length, shoot and root fresh weight, shoot and root dry weight, total fresh and dry weight, and the concentrations of some nutrients in leaves. It was found that the substrate A3 (25% cocopeat 25% vermicompost 25% light soil 25% perlite) was the most appropriate substrate for this plant in terms of most estimated traits (lateral shoot length, root fresh weight, root dry weight, total dry weight, and shoot P and Fe content). Among fertilizing compounds, the treatment B3 (Ferrilene NPK (20-20-20) diammonium phosphate potassium sulfate ammonium sulfate) was found to be superior for some traits like lateral shoot length, shoot fresh weight, total fresh weight, shoot dry weight and total dry weight. It was revealed that the treatment A3B2 (25% cocopeat 25% vermicompost 25% light soil 25% perlite) diammonium phosphate, potassium sulfate and ammonium sulfate was the most appropriate treatment in terms of shoot and root fresh weight, total fresh weight and total dry weight. So, it is recommended to apply this treatment in the production of Araucaria excelsa.