فهرست مطالب mehranoosh emamian tabarestani

Seed germination and emergence are the most sensitive stages of growth and development of rice plants. In this regard, the use of growth-promoting fungi in the form of seed biological pretreatment (bio-priming) for germination and optimal growth of seedlings can be feasible. Therefore, this study aimed to investigate the effect of isolated root symbiotic fungi on the improvement of germination and growth components of two traditional and bred rice (Oryza sativa L.) cultivars.

This experiment was done as a factorial-based completely randomized design with three replicates at Sari Agricultural Sciences and Natural Resources University in the summer of 2021. Experimental treatments included 22 isolates of root symbiotic fungi (isolated and identified from previous experiments) and control (without inoculation) and two native (Hashemi) and bred (Roshan) rice cultivars. After the end of the germination period, the number of normal seedlings was counted and five normal seedlings were randomly selected to measure the length of the root, stem, and seedling as well as the fresh and dry weight of the root, stem, and seedling.

Based on the results of cluster analysis the fungi were divided into four and three groups in Roshan and Hashemi cultivars, respectively. In both cultivars, group I was selected as the best group. In this group, the highest positive effect on vegetative traits varied from 5 to 59% compared to the control in fungal treatments was related to Bjerkandera adusta (ST1), Trichoderma atroviride (SF1), Monosporascus cannonballus (B3) and Trichoderma atroviride (SN1) in Roshan cultivar and Bjerkand adusta (ST1) in Hashemi cultivar. The best fungal treatments in germination traits of Roshan and Hashemi cultivars were Chaetomium globosum (SE2) and Bjerkandera adusta (ST1), respectively.

Overall, the results indicated the positive effect of most symbiotic fungi on the growth and germination characteristics of rice in both Roshan and Hashemi cultivars. These results show that symbiotic fungi use different mechanisms to increase growth and improve germination indicators in plants.

Highlights:

1- Growth-promoting fungi in the form of seed biological pretreatment were used (bio-priming) for optimal growth and germination and of rice seedlings.
2- The effect of native fungi isolated was investigated for the first time in two native (Hashemi) and bred (Roshan) rice cultivars.

 Drought is one of the most important environmental stressors that adversely affects agricultural products, especially in arid and semi-arid regions. Using Trichoderma fungus along with biopolymers such as chitosan is one of the ways to reduce drought stress. Trichoderma fungus as plant growth-promoting fungus is the most common fungal and soil-modifying species that are able to directly with plant roots in the rhizosphere and improve growth as well as biological control of living stresses such as pathogenic fungi and non-living stresses such as drought, salinity and heavy metals. On the other hand, one of the effective ways to protect the plant in conditions of low irrigation is the use of anti-transpirants, including the biostimulant of chitosan, which markedly limits transpiration from the plant surface. The anti-transipirants action of chitosan can be attributed to the involvement of chitosan in the abscisic acid pathways, which closes the stomata and thus reduces transpiration. Chitosan is readily soluble in water and organic acids. Therefore, it can be used in various methods such as mixing with soil, foliar spraying and impregnation with seeds in agriculture.

 This research was conducted in a split factorial arrangement based on randomized complete block design. The main plot factor was irrigation interval in three levels (two days as normal irrigation and three and four days as deficit irrigation conditions) and sub-plots were inoculated with T. longibrachiatum at two levels (inoculation and uninoculated control) and chitosan at three levels (0, 0.2 and 0.4 g/L). Each experimental plot consisted of three planting lines two and a half meters long and one meter wide .T. longibrachiatum was obtained from Tabarestan Agricultural Genetics and Biotechnology Research Institute. The first irrigation was done simultaneously with planting basil. Up to one month after sowing the seeds (six to eight leaf stage of plants), the plots were irrigated evenly with tubes and from this stage onwards, irrigation treatments were applied. Pesticides and herbicides were not used during the experiment and weed control was done manually. Chitosan was prepared from Sarina Teb store and prepared in three levels of zero, 0.2 and 0.4 g/l and sprayed in three stages: vegetative, before flowering and 50% flowering.

 The results showed that with increasing the irrigation period from two to four days, the morphological traits of basil, such as root length and stem length, leaf dry weight, root, stem and dry matter yield decreased. Also, physiological traits of basil such as carotenoids and chlorophyll meter increased while chlorophyll a, b and total chlorophyll decreased. Application of 0.2 g/L of chitosan inoculated plants increased chlorophyll b content by 68%. The highest percentage and yield of essential oil in both normal and irrigation deficit conditions were obtained when plants inoculated with Trichoderma and foliary sprayed by chitosan. The highest percentage and yield of essential oil were observed with an average of 0.88 and 42.87% in normal irrigation conditions, application of Trichoderma and zero level of chitosan, respectively. According to the results, increasing the irrigation cycle along with chitosan application and fungal inoculation increased the percentage and yield of essential oil. However, by increasing the irrigation cycle, chitosan alone decreased the percentage and yield of essential oil and only in the three-day irrigation cycle, it increased the percentage of essential oil compared to the control.

 Overall, the findings showed the positive effect of concomitant use of Trichoderma fungus and chitosan on improving the growth of sweet basil and increasing drought resistance.

Water deficit is one of the most important factors limiting the crops performance like basil. Using growth-promoting bacteria along with silica could improve them. Accordingly, the present research was conducted to investigate the effect of Enterobacter sp. and foliar application of silica on vegetative and physiological characteristics of basil under water deficit irrigation.

Methods & Materials:

 This research was conducted in a split factorial arrangement based on randomized complete block design. The main plot was irrigation levels (two, three and four days) and sub-plots were Enterobacter (inoculation and control) and silica concentrations (0, 6C, 6X and 12X).

Results showed that irrigation with three- and four-days intervals reduced vegetative and some physiological traits alone. However, SPAD in irrigation with three and four days intervals and essential oil percentage (EOP) and yield in four days intervals showed an increase at the range of 11 and 29%. 12X silica was very useful in some of these traits with increasing irrigation intervals. Although using bacteria inoculation with 12X silica was able to produce the highest amount of chlorophyll a and a+b in complete irrigation and dry matter yield in water deficit irrigation. However, when plants grown under water deficit irrigation, using 12X silica was maximally improved the EOP and yield.

In conclusion, the positive effect of silica was more pronounced than Enterobacter on improving the vegetative and physiological traits of basil. In addition, silica with high concentration (X) showed better results than low (C) concentration.

In order to quantify the response of canola (Brassica napus L.) plant to lead different levels, an experiment was conducted in completely randomized design with three replications. Treatments were twelve lead concentrations from lead nitrate source (0, 10, 50, 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000 mg/kg soil). Results showed that decrease in vegetative traits fitted with segmented model when lead concentration increased. Also, chlorophyll a, b, a+b contents and SPAD index value declined about 23, 47, 30 and 22%, respectively. Chlorophyll a/b ratio (a/b) and carotenoid, however, showed increasing trend by 46 and 39% in 4000 mg/kg of soil as compared to the control. In addition, the activity of catalase, peroxidase and ascorbate enzymes increased until about 10, 447 and 18 mg/kg of soil, respectively and then decreased when lead concentration was increased. Superoxide dismutase activity in 4000 mg/kg of soil was about 2.3 times greater than the control. Also, malon-di-aldehyde (MDA) and H2O2 concentrations in 4000 mg/kg of soil were about two times and proline concentration was about 12% greater than the control. In conclusion, up to 100 mg/kg of soil vegetative traits and photosynthetic pigments particularly showed the highest sensitivity. Among photosynthetic pigments, the sensitivity of chlorophyll b was higher than chlorophyll a. Also, the higher activity of superoxide dismutase enzyme than the other enzymes and proline can be a possible reason for ameliorating the damage of high levels of lead in canola.

Agricultural soils in many parts of the world are slightly to moderately are contaminated by heavy metals elements. Among them, Pb has an effect on growth and metabolism of plants with a wide range of adverse effects like decrease in root elongation and biomass, accelerated leaf senescence, inhibition of chlorophyll biosynthesis and seed germination, interferes with nutrient uptake, influence the net photosynthetic rate and respiration and alternate permeability of cell membrane. So, the usage of a fast and safe method is necessary to remove pollutants with the lowest cost and impact on the environment. One of the best methods is phytoremediation that the Brassicaceae family plants such as canola (Brassica napus L.) have a special ability to refine contaminated soils due to their much biomass production. On the other hand, bioremediation is one of the methods that has been considered in recent years to remove contaminants. In this context, it is important to use a variety of microorganisms like algae, fungi and bacteria in order to improve phytoremediation efficiency. Therefore, the purpose of this research was to evaluate the effect of Piriformospora indica and Trichoderma longibrachiatum on improving the growth and some physiological traits of canola under lead stress.

This research was done as factorial layout based on a completely randomized design with three replications. Treatments were four levels of lead from lead nitrate source (0. 500, 1000 and 1500 mg kg-1 of soil) and three treatments of fungi (control, Piriformospora indica and Trichoderma longibrachiatum). After 60 days of (Hyola 401 cultivar) planting time, coinciding with the end of vegetative growth and before flowering, Vegetative and some physiological traits were measured. To quantify the effect of lead stress regression analysis and linear and segmental models were used.

The results showed that node and leaf number, stem diameter, leaf fresh weight and stem dry weight (between 20 and 58%) were reduced as linearly and segmental model where lead levels increased from zero to 1500 mg. Also, inoculation of Piriformospora and Trichoderma fungi increased stem diameter and dry weight. Using the mentioned fungi had a positive effect on vegetative traits at different levels of lead. Accordingly, plant height, leaf area, stem and shoot fresh weight and leaf and shoot dry weight reduced from 27, 74, 68, 65, 69 and 70% in control to 12, 44, 35, 36, 52 and 52% in symbiosis with Piriformospora and 31, 48, 58, 53, 52 and 53% after applying Trichoderma at in 1500 mg as compared to the zero levels, as well. Also, the electrolyte leakage rate showed an increasing trend with 0.000084 slope Up to 500 mg and then with a 0.0018 slope. But plant inoculation with Piriformospora and Trichoderma reduced the electrolyte leakage with about two percent. In addition, the interaction between lead and fungi was significant on SPAD reading, chlorophyll a+b, relative water content (RWC) of leaves and proline. SPAD reading and chlorophyll a+b declined from nearly 18 and 35% in non-inoculation treatment to about 7 and 27% in Piriformospora, and 13 and 5% in Trichoderma in 1500 mg as compared to the control, respectively. Among morphological and physiological traits, the highest correlation (r=0.80; P<0.01) was between leaf area and RWC.

In conclusion, results indicated that vegetative traits showed more sensitivity to lead toxicity. Among these traits, the highest sensitivity was recorded in stem and shoot dry weights. Inoculation of canola seed with Piriformospora and Trichoderma fungi ameliorated this sensitivity in some traits. Accordingly, it seems that these fungi can improve slightly the adverse effect of lead toxicity and increase canola tolerance to lead stress.

In order to evaluate the joint effects of cold and light stresses on chlorophyll fluorescence parameters in stevia (Stevia rebaudiana Bertoni), an experiment was done in a factorial arrangement based on a completely randomized design with three replicates. Treatments were five levels of cold stress (0, 4, 8, 12 and 16 days) at 6±2 ᵒC and three light intensity levels of normal light, 50 and 10 % of normal light (240, 120 and 24 µm.m-2.s-1, respectively). Plants were kept in controlled conditions for 30 days then chlorophyll fluorescence parameters were measured. Results showed that Fv/Fm and Fv/Fo in response to cold stress changed in reduce trend and was described by a segmented model. Accordingly, these parameters increased linearly until twelfth day with a soft slope (0.0007 and 0.0149, respectively) and then decreased with a sharp slope (0.0074 and 0.1098, respectively). Also, Fm, Fv, Ft, Fm' only linearly respond to cold stress when stevia plant grown at 240 and 120 µm.m-2.s-1, while in 24 µm.m-2.s-1 the response of plant was fitted by a segmented model in which linearly decreased and then increased. Furthermore, Y(II) adversely affected by cold stress in all light intensity levels while Y(NPQ) and Y(NO) increased particularly in 240 µm.m-2.s-1. In conclusion, the results suggest that chlorophyll fluorescence parameters are sensitive to cold stress particularly when stevia plant exposed for a prolonged period of time and higher light intensity.