JOURNAL OF PLANT ENVIRONMENTAL PHYSIOLOGY
Year:2014 | Volume:9 | Issue:3 (35)|Papers Count:8

Environmental parameters are the most important factors affecting morphological characteristics and expression of biosynthetic genes of secondary metabolites in medicinal plants. In this study the effects of altitude on some morphological and biochemical characteristics of nettle were examined in Mazandaran and Golestan provinces. Sampling from different regions was done at the flowering stage of the plant. The data were analyzed in a CRD as nested by SAS software. The result of the analysis of variance showed a significant effect of altitude and ecotype on morphological and biochemical characteristics of nettle. The results revealed that with an increase in altitude above sea level, the length and width of the leaves and plant height were minimum while the chlorophyll content was maximum in Lehkooh region of Mazandaran at the altitude of 2250 meters. The results also indicated that the amount of phenolic and flavonoid compounds such as chlorogenic acid, caffeic acid, and rutin increased in leaf of nettle as the altitude increased so that the highest amount of compounds under study were observed in Lehkooh region of Mazandaran at altitude of 2250 meters.

In this study, in order to investigate the effect of seasonal changes on some physiological and biochemical characteristics of Populus deltoids, leaf and root samples were collected with four replicates in spring, summer, and autumn in Langroud region in 2010. Results showed that during the summer, with an increase in temperature and decrease in relative humidity, the amounts of chlorophyll a and b, soluble sugars, and activity of catalase and polyphenol oxidase enzymes in leaves were significantly increased compared to the spring leaves, whereas increment in the activity of peroxidase enzyme was not significant. On the other hand, the amount of soluble sugars, activity of catalase and peroxidase enzymes in roots did not show any significant change in the summer compared to the spring roots. However, the activity of polyphenol oxidase enzyme increased significantly. The amount of proline in leaves and roots increased significantly in the spring when the temperature was minimum compared to the other two seasons. The amount of Fe, Cu, and Mn increased significantly both in leaves and roots in spring compared to the other two seasons. Accumulation of Fe and Mn in roots was higher than those of leaves and the accumulation of Cu in leaves was higher than that of the roots in spring and summer.

Measuring natural compounds is one of the useful indexes for reducing the postharvest decays of agricultural products. In this research effects of different concentrations of salicylic acid(SA) 0, 0.7, 1.4, and 2 mM and storage duration of 1, 2, 3, 4, and 5 weeks on quality and survival of Vitic vivifera cv Askary were studied. The results showed that with an increase in SA concentration from 0 to 2 mM, pH and soluble solids decreased 1 and 2.3%, respectively, whereas titratable acidity increased 20%. At the same time, the highest vitamin C content was obtained at 1.4 mM SA which showed 7.7% increase compared to the control. During storage period pH, soluble solids, and titratable acidity increased 1.9, 15.6, and 22.8%, respectively, but vitamin C decreased 52.8%. At the concentration of 2 mM SA, the percentage of decay, abscission, and weight loss decreased 53.2, 13.3, and 12.2 %, respectively while firmness increased 17.5% compared to control (0 mM SA).Therefore, it seems that SA which is a natural phenolic compound has high potential in controlling postharvest loss of horticulture products including Askary grape vine cultivar.

Grazing is one of the ways of exploiting lands and is considered an environmental factor that influences ecosystems and the plant growth causing physiological and morphological changes in the plants. In this research to study the effect of grazing on morphological traits and also soluble sugar contents and antioxidant activities, two species, Stachys lavandulifolia and Stachys turcomanica were selected from grazed and ungrazed sites of the rangeland vegetation in Sisab, situated 35 Km away from Bojnoord, North Khorasan province. The two regions were relatively similar regarding physical parameters such as geographic location, altitude, precipitation, and soil pH and they were separated by a wire fence. The results showed that the grazing intensity did not have any significant effect on trichome density, leaf characters (leaf length and width of the leaves at 1.2, 1.3 and 2.3 of the leaf length and leaf area), size and form of pollen grain whereas the amount of soluble sugars and antioxidant activity increased significantly in the grazed sites. Based on the results of the present study, it seems that increase in soluble sugar and antioxidant compounds may have a compensation role and may imply the high plasticity of these species.

Most of the symbiotic fungi can improve the growth of host plants by increasing the potential for water and nutrient uptake. Among them, Piriformospora indica shows specific potential. To study the effect of this fungus on the qualitative characteristics of peach fruit, an experiment was conducted in a randomized complete block design with 10 replications comparing inoculated and non-inoculated plants with Piriformospora in an orchard near Ali-Abad, Golestan province. To study the qualitative changes and to determine the phytochemical characteristics such as total soluble solids, pH, malic acid, total sugar, glucose, sucrose, and the contents of phenolic and flavonoid compounds, after harvesting fruits were transferred to the laboratory of Department of Horticulture at Gorgan University of Agricultural Sciences and Natural Resources. The results showed that some qualitative indexes of fruits were significantly different from those of the control. Total sugar contents of inoculated fruits were significantly higher than those of the control fruits. The same results were observed for sucrose and glucose. Total phenol content of fruits at ripening showed a significant increasing trend and the content of flavonoid increased, even though nonsignificantly, compared with that of the control.

Gum tragacanth is a natural dried secretion produced by some species of Astragalus which is considered as a high quality hydrocolloid used extensively in food industry, pharmacology, medicine, and textile industry. Gum tragacanth producing species of Astragalus are mainly spiny and xerophyte that are spread in mountainous and destroyed rangelands. Density and yield of these species in different slope aspects vary due to significant changes of rainfall and humidity, grazing intensity, erosion and soil structure. In order to investigate these variations in gum tragacanth of Astragalus hypsogeton in Mount Bahar exploitation program in North Khorasan, the gum tragacanth yields were sampled in four cardinal directions of slopes. Analysis of variance of the data and comparisons of the means based on Duncan Multiple Range test, showed that gum tragacanth yield in southern aspects was more than that of other aspects because of increasing density and vegetative cover of Astragalus due to moisture shortage of soil in this aspect in comparison with the other aspects, in particular Northern aspect, and as a consequence elimination of main and key species of the rangeland and substitution of the invasive Astragalus.

The use of nanofertilizers to precisely control nutrient release can be an effective step in achieving sustainable and environmentally friendly agriculture. In this research, the effects of nano-potassium fertilizer on growth parameters such as number of leaves and nodes, and fresh and dry weight of root and shoot, root and shoot length, and physiological parameters including amount of chlorophyll a, b, soluble sugars, and protein in wheat) Triticum aestivum cv N8019) were studied. To achieve this aim, wheat plants were grown under field conditions according to a randomized complete block design. At the early reproductive stages, foliar nano-potassium fertilizer was applied at 0 (control), 0.15, 0.3, and 0.6% concentrations. The results indicated that the number of leaves in plants sprayed with nano-potassium fertilizer at the concentration of 0.3% and length of roots and shoots at the concentration of 0.15 % significantly increased compared to the other treatments, while spraying of the fertilizer had no significant effect on node number and dry weight of roots. The results also revealed that different concentrations of nano-potassium fertilizer significantly increased the content of chlorophyll a, b, soluble sugars, and proteins in the leaf and root of wheat plants N8019 cultivar as compared to the control.

In order to study the impact of using superabsorbent polymer for reducing the effects of drought stress on some physiological traits of Marigold, this research was conducted in a factorial arrangement based on a randomized complete block design with three replications. There were three levels of superabsorbance, i.e., 0, 30, and 60 grams and three levels of irrigation intervals of 2, 4, and 6 days. Results of analysis of variance showed that parameters such as chlorophyll a and total chlorophyll had significant difference (P£.01) under the effect of irrigation interval and superabsorbance and the interaction between irrigation interval and superabsorbance. Also, significant difference (P£0.05) was found for chlorophyll b content under the effect of irrigation interval and superabsorbance, while no significant difference was observed under the effect of the interactions between irrigation interval and superabsorbance. Carotenoids content showed significant difference (P£0.05) under the effect of superabsorbance and the interactions between irrigation interval and superabsorbance, but it showed no significant difference under the effect of irrigation interval. Moreover, in studying the interaction between irrigation interval and superabsorbance, it was observed that the amount of chlorophyll a and b in 60 grams of superabsorbent polymer and irrigation interval of 4 days had the maximum increase which yet showed no significant difference with other treatments with 60 grams of superabsorbent, because superabsorbent polymer minimized the drought stress. Maximum amount of proline and minimum amount of relative humidity were observed in irrigation interval of 6 days and 60 grams of superabsorbent polymer and 6 days and 0 gram of superabsorbent polymer (control), respectively. The maximum amount of relative humidity had no significant difference with other periods containing superabsorbent polymer.