JOURNAL OF PLANT ENVIRONMENTAL PHYSIOLOGY
Year:2019 | Volume:14 | Issue:55 |Papers Count:8

Draught stress is the most important abiotic stress significantly affecting plants’ growth, development, and performance. This study was carried out to determine the effect of perlite, as a modifying element of soil, on growth and physiological responses of Queues castanifolia seedlings under water deficit stress. A factorial experiment was conducted as randomized complete block design under greenhouse condition of the Agricultural and Natural Resources Research Center in Gorgan, 2015. Perlite treatments at 4 levels (0, 15, , and 35% (V/V)) were added in soil and water stress at 3 levels (40, 70, and 100% irrigation at field capacity) were applied in the pot experiment for 5 months. Some parameters including gas exchange (photosynthesis, stomatal conduction, and transpiration), leaf water potential of seedlings, diameter and height growth, and dry weight of root, stem, leaf, and seedlings were measured in different treatments at the end of the experiment period. Results showed that all parameters were affected by different levels of irrigation and perlite. Water deficit by 40% FC reduced 51% and 68% of photosynthesis and stomatal conductance, respectively. The highest diameter and height growth and dry weight of the seedlings were observed in 25% and 35% (V/V) perlite application under normal and stress conditions, respectively. The use of perlite alleviated the negative effects of water deficit and ameliorated seedling growth. The findings suggest that perlite application in soil is suitable for the production of desirable seedlings under water deficit condition.

In order to investigate the effect of different levels of IBA and strains of Pseudomonas fluorescens bacteria, an experiment was conducted as factorial with completely randomized design containing two factors and three replications. In the first factor, the effect of three levels of IBA (0, 2000, and 4000 mg/ ml) and in the second one, the effect of two strains of P. fluorescens (R5 and R64) were investigated on olive (Olea europaea cv. conservaliya). Results showed that bacterial inoculation with R5 strains increased shoot and root dry weight, total dry weight, nitrogen concentration, and phosphorus uptake compared to control, but there was no significant difference between R5 and R64 strains in terms of total chlorophyll. The 2000 mg/ml IBA also increased shoot and root dry weight, nitrogen concentration, total chlorophyll, and total dry weight compared to control while the maximum phosphorus uptake was obtained at 4000 mg/ml IBA. The interaction of effects of IBA and bacteria in morphological characteristics and uptake and concentration of elements showed that maximum average were obtained at 2000 mg/ml IBA and R5 strain treatment. According to the obtained results, the application of both of 2000 mg/ml IBA and R5 strain for improvement in rooting is recommended.

In order to investigate the effects of foliar application of calcium (Ca), potassium (K), and Volck oil separately or in combination on budburst and cold tolerance-related physiological indices in Bidaneh-Sefid grapevine, a randomized complete block design with four replications was conducted in 2017 in a commercial vineyard located in Abasabad village, Khondab in Markazi province. Treatments included control, Volck oil, Volck oil + Ca, Volck oil + K, K, Ca, Ca + K, and Volck oil + Ca + K. The vines were sprayed with Volck (1%), calcium (2%), and potassium (3%) in mid April at the wooly stage and one week later. The traits included days to budburst, ion leakage, peroxidation of membrane lipids, chlorophyll a and b, relative water content, soluble carbohydrates, proline, soluble proteins, and phenol. The combined treatment of Volch + Ca + K resulted in 5 day retardation in budburst compared to control vines. The highest concentrations of carbohydrate, phenol, and protein were obtained with Ca + K combined treatment, and the lowest ones were observed in both control and Volck oil-treated vines. The highest amounts of chlorophyll a, b, carotenoids, and total chlorophyll were obtained from Ca and K treatment and the lowest was observed in Volck oil treatment. The highest concentrations of proline, carbohydrate, and soluble protein were related to Ca + K treatment, and the lowest ones were obtained for control treatment. The highest relative water content, ion leakage, and membrane lipid peroxidation were detected in control vines. Therefore, in order to avoid late spring frost in vineyards, the combination of Volck oil + Ca + K was found to be appropriate in vineyards.

In order to investigate the combined effect of organic and chemical fertilizers on vegetative and yield characteristics of sweet pepper (Caspsicum annuum, Var: Traviata), an experiment was conducted on a randomized complete block design with three replications at Ferdowsi University Research Station Mashhad, in 2017. Treatments included control (without adding any fertilizer), NPK fertilizer, manure, vermicompost, vermicompost + chemical fertilizer, manure + chemical fertilizer, manure + vermicompost, and manure + vermicompost + chemical fertilizer. Results showed that the application of combined animal and chemical fertilizers significantly increased the morphological and yield components of the plant. The highest plant height, leaf number, leaf area, shoot dry weight, SPAD index, fruit length, number of fruits per plant, and fruit fresh weight per plant were obtained from combined treatment of manure and chemical fertilizers. Applying combined manure and chemical fertilizers increased the amount of stomata conductance about 45% in comparison with the control. The highest number of stomata in fruit was obtained from vermicompost treatment and the highest fruit diameter was recorded from combined vermicompost and chemical fertilizer. In general, the results showed that the combined application of manure and chemical fertilizer due to the effect of improving physical and chemical structure of soil, stimulation of some microorganisms, and availability of nutrients, led to increases in the morphological traits, yield components, and yield of sweet pepper.

In the present study, the effects of pretreatment of time (24 and 96 hours) and pH (7 and 9) at extremely limited carbon dioxide concentration were studied on the exponential growth phase, photosynthetic pigments per cell, absorption shift of chlorophyll, structure and function of phycobilisome, the ratio of light harvesting to reaction center pigment, and the ratio of photosystem 1 to photosystem 2 in stigonematalean cyanobacterium Fischerella sp. FS 18. Results showed that pretreatments kept the exponential growth phase at both 24 and 96 hours and also under pHs 7 and 9. Contrary to the absorption peak of chlorophyll, cellular pigments showed no stable pattern regarding pretreatments. Phycobilisomes were the main point of treatment affects. The pattern of the rode part of phycobilisomes was the same at pretreatment reactions. The shift of phycocyanin was about 1 and phycoerythrin about 3. The highest rate of photosystem 1 to photosystem 2 ratio was observed at 24 hours and under neutral condition. This changed by the time and led to decreased efficiency of energy transport in photosynthesis system. The change in the phycobilisome operation may be a compensation mechanism to mitigate the degree of such a decrease.

Pollution with heavy metals, especially those combined with petroleum, is one of the major environmental problems. These pollutants contaminate soil, water, and related ecosystems and cause problems for the flora and even humans. Considering the potential of microalgae for elimination of petroleum pollution and reduction of various heavy metals contaminations, this study was carried out using Calothrix sp., isolated from polluted areas with the aim of investigating the reduction of nickel as well as studying some physiological behaviors of microalgae. Experiments were designed using the Design Expert software and factors such as PH (pH4-9), nickel concentration (5-100 mg/L), and time (30-120 min) were considered. Results showed that at pH 8, 80. 74 mg/L nickel concentration, and 48. 24 min the highest nickel uptake (69%) was observed. Treatment of algal biomass with different chemical and physical factors in various forms, such as immobilization or use of its metabolites could improve and facilitate the absorption process and paves the way for the potential application of these microalgae in subsequent purification systems.

Ferula ovina Boiss. (Apiaceae) is a perennial rangeland medicinal plant found in the mountainous area of Iran. Due to overexploitation, climate changes in the area, and seed dormancy at time of maturity, the population of this species is being reduced. Accordingly, in the present study the effects of smoke treatments (aerosol smoke and two methods of smoke extract preparation) were investigated on seed germination characteristics of this plant after varying periods of cold stratification including 0, 7, 15, and 30 days. Findings suggested that cold stratification changed significantly the level of seed dormancy and increased the rate and percentage of seed germination. Furthermore, aerosol smoke applied after cold stratification increased the rate and percentage of seed germination. The greatest increase in germination percentage compared to control (20%) was observed in seeds that had been cold-stratified for 7 days and were exposed to aerosol smoke for two minutes. Smoke extracts with concentrations (0. 001-0. 01 v/v) prepared by the two methods also increased the germination of cold stratified seeds so that the maximum percentage of germination (80%) was obtained for seeds cold stratified for 30 days and treated with 0. 001 dilution of charred straw solution. However, undiluted smoke water decreased the percentage of seed germination after 0 and 30 days of cold stratification and led to abnormal seedling development. In general, the results of this study demonstrated that smoke treatments improve seed germination percentage and speed of cold stratified Ferula ovina seeds.

In order to effect of spermidine and polyethylene glycol pretreatment on germination and some physiological and morphological activity durum wheat under salinity stress a experiment with 20 treatments, three replications was conducted in 60 experimental units. Treatments included five levels of spermidine (0/ 02, 0/ 05, 0/ 1 and 0/15 mM) and four levels of polyethylene glycol (0-2,-4 and-5 bar). The results showed that the use of spermidine increased the relative weight contact of leaf (RWC), leaf area ratio, chlorophyll s and phenolic compounds. In this study, carotenoids content and leaf antioxidant activity decreased with increasing spermidine level and also had no statistically significant effect on germination. With increase of polyetylen glycol antioxidant activity, carbohydrates and total phenolics increased but decreased germination. Therefore, according to the above results, application of spermidine and polyethylene glycol as seed pre-treatments can have significant effects on physiological and morphological activities in stress conditions and increase plant potency under stress conditions.