حبیب الله حمزه زرقانی

Protection of forests, rangelands and other natural ecosystems in Iran is facing challenges and currently the natural areas of the country are not in favorable conditions. Some of the problems and mega global challenges that affect various natural areas in the world. This group of challenges include climate change, desertification, land degradation, global warming, deficiency of fresh water and increasing demand for energy. The second group of challenges that are specific to Iran at the national level and have affected the natural environments include lakes drying up, land subsidence, salinity and alkalinity of underground water, desertification and consequently the particulate matter air pollution. Also, the breakdown of the natural hydrology systems of the watersheds and changes in the usage of the natural areas are two man-made super challenges affecting the natural environments of Iran. In this article, the major challenges related to Iran's natural areas and the relevant national and regional challenges at the level of natural ecosystems are discussed. Finally, in order to deal with the challenges raised, the necessary solutions to protect and support Iran's natural areas as better as possible are presented. This includes paying attention to these challenges as one of the basic requirements for applying and implementing ecosystem-based management in the natural areas.

Legumes are one of the primary protein sources in human and livestock diets worldwide. There are five different types of legumes (i.e., beans, peas, peanuts, lentils, and lupines), with beans as the most important. Fusarium root rot (FRR) is among the most challenging diseases of common beans (Phaseolus vulgaris). While soil-borne diseases are difficult to control, resistant bean cultivars significantly help reduce the losses caused by the disease. This study was conducted in a greenhouse to investigate the susceptibility of different bean cultivars to FRR caused by the F. solani species complex (FSSC).

Several bean fields in Fars, Kohgilouyeh and Boyer-Ahmad, Chaharmahaal and Bakhtiari, Hamdan, Lorestan, Markazi, Qazvin, Zanjan, East Azerbaijan, and Mazandaran provinces were explored during summer from 2017 to 2019. Infected plants were sampled, and the fungi were isolated in the laboratory. Once appeared on the culture medium, the fungal isolates were purified using single-spore isolation or hyphal tip methods. Fungal DNA extraction was performed using Doyle and Doyle’s method for molecular identification of the isolates. A part of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene and a translation elongation factor 1-alpha (EF-1α) were amplified from the polymerase chain reaction (PCR). PCR-amplified fragments were sent to the Cardiogenetics Department of Rajaie Cardiovascular, Medical and Research Center (Tehran, Iran) for sequence analysis. After editing, the Basic Local Alignment Search Tool (BLAST) was applied to ITS and EF-1α sequences of the isolates in the GenBank data set in the National Center for Biotechnology Information (NCBI) database. A preliminary pathogenicity test was performed on the Sadri bean cultivar-pathogenicity tests were fulfilled in 400ml plastic pots. An inoculum was prepared by pooling the isolates in a pot experiment utilizing Bilgi et al.’s (2008) method to evaluate bean cultivars. Ten representative isolates of F. solani with the highest pathogenicity were selected from different regions. The cultivar susceptibility was assessed in 3-liter pots as described in the preliminary pathogenicity test. Saleh, Sadri and Koosha chiti (pinto) bean cultivars, Akhtar, Goli and Sayyad red bean cultivars, Dorsa, Shekoofa white bean cultivars, and Valentino and Sanri green bean cultivars were compared based on disease severity and yield correlates (shoot/root fresh and dry weight).

Fusarium isolates from the sampled provinces were identified using authentic scientific sources and Fusarium identification keys based on morphological properties. A Blast search of ITS and EF-1α sequences in GenBank yielded 100% nucleotide identity with the sequences of strains of FSSC. In the preliminary pathogenicity test, leaf yellowing and falling symptoms appeared on the Sadri cultivar in the greenhouse three weeks after inoculation. All FSSC isolates caused root rot on the tested bean cultivar. To evaluate the susceptibility of bean cultivars to the selected isolates, the plants were carefully removed from the 3-liter pots two months after inoculation. The results showed statistically significant differences (p=0.01) among the cultivars. Koosha chiti bean, green Sanri and Valentino cultivars with the lowest root rot severity (19.5%, 22.62% and 23.81%, respectively) and red Goli and Dorsa white bean cultivars with the highest root rot severity (66.67% and 70.24%, respectively) were the least and most susceptible bean cultivars to the pooled FSSC isolates, respectively. The results also indicated relatively significant differences in yield correlates (shoot/root fresh and dry weight) among the cultivars. Besides, the Koosha cultivar was shown to be the most resistant to the disease, followed by Akhtar, Sanri, Valentino and Saleh cultivars. Dorsa white bean and Goli red bean cultivars were demonstrated to be the most susceptible to the disease. This study identified several cultivars with low susceptibility to bean root rot caused by FSSC isolates. A good variation was observed in the spectrum of bean plant responses to the disease. Koosha, Akhtar, Valentino, Sanri and Saleh cultivars with low susceptibility to the selected FSSC isolates may be considered for further studies. Proper soil management with cultivating resistant cultivars is an integral part of any disease management program for FRR.

Aflatoxins are toxic secondary metabolites produced by speices of Aspergillus including A. flavus and A. parasiticus. Mycotoxins are potential carcinogens and reduce global trade of agricultural products. Soil and peanuts were sampled across fields located in seven important peanut production villages of Astaneh Ashrafieh to investigate the frequency of toxigenic and atoxigenic strains of A. flavus and A. parasiticus. Toxigenicity of the Flavi section strains was evaluated according to change in color of the back of colonies on coconut agar in contact with ammonium hydroxide vapor. 48 isolates of Flavi section were identified, including 20 isolates of A. flavus and 28 isolates of A. parasiticus with nine atoxigenic and 39 toxigenic isolates. Risk maps were developed based on mean toxigenicity where Lakujdeh, Mohsenabad, and Noghredeh respectively with mean toxigenicity of 2.50, 2.25 and 2.10 had the highest risk scores for peanut cultivation while parkaposht, Nubijarmahale and Nabi dehka with mean toxigenicity of 1.00, had the lowest risk scores. Peanut fields located in Dehsar with a mean toxigenicity of 1.50 were classified with moderate risk scores. The outlook of this study was based on identification of atoxigenic isolates of the fungus with potential future application in biological control of toxigenic strains of Flavi section and emphasize on their competitive ability to colonize peanuts as well as developing risk maps to plan for reducing the risk of aflatoxin production on peanuts, an important product of Guilan province, and to pave the way for increased production and export of this product.

Heterodera schachtii is the most important nematode of sugar beet worldwide. Application of organic matter can reduce populations of plant-parasitic nematodes. In this study, the inhibitory effects of creeping thistle, tall sisymbrium, liquorice, narrow-leaf plantain, wild lettuce, castor bean, French marigold, cornflower, wild safflower and arugula on sugar beet cv. Sharif and H. schachtii were investigated in two microplot experiments. The first experiment was conducted in pasteurized mixed field soil and river sand, and the second in field soil, both with an initial population of 4200 eggs/plant. Also, the effects of the treatments on nematode egg hatching and root penetration were studied in a glasshouse experiment. The results showed that adding plant powders to pasteurized soil had no significant effect on the infected sugar beet growth indices. However, except marigold, the other treatments caused a relative increase in taproot weight of 5% to 241% compared to the control. Cornflower, wild lettuce and wild safflower increased taproot weight more than twofold compared to the control. Moreover, creeping thistle, castor bean and plantain caused a relative decrease in nematode final population and reproduction factor. In field soil, castor bean, marigold, wild lettuce, cornflower and sisymbrium increased taproot weight by at least twofold, and arugula increased sugar content by 1.2-fold. The treatments had no significant effect on the nematode indices. Plantain and wild lettuce caused a relative decrease in the nematode reproduction factor. In glasshouse experiment, wild lettuce caused the greatest reduction in egg hatching and safflower reduced nematode penetration into the roots.

Fusarium rot is one of the most important diseases of beans (Phaseolus vulgaris). In order to identify Fusaria that cause bean root rot in Markazi Province (Iran), in the summer of 2018 and 2019, several bean fields were visited and infected plants with root rot were sampled and the fungi were isolated in the laboratory. Based on morphological and sequencing characteristics of internal transcribed spacers of rDNA (ITS) and translation elongation factor 1-α (EF-1α) gene regions, 37 Fusarium isolates, including Fusarium oxysporum species complex, F. solani species complex, and F. lateritium species complex, as well as F. equiseti, F. acuminatum and F. redolens were identified. All isolates caused root rot on Sadry bean cultivar. Since F. solani isolates were the most common, twelve isolates of this group were selected and their phylogenetic relationships were studied. Of the three Clades of F. solani species complex, the isolates were placed in Clade 2 and 3. Only one isolate was found in Clade 2 whose properties matched those of F. brasiliense. The other isolates were classified in Clade 3 divided into two subgroups. In host range tests of F. solani isolates, none of the isolates was pathogenic on lentils, vetch and cowpea. A number of isolates caused root rot in chickpeas, soybeans, and potato tubers. F. lateritium, F. redolens and F. brasiliense are reported for the first time from Iran.

Rose is the most important cut flower in the world. Dieback is one of the most devastating rose diseases in greenhouses. The main symptom of the disease is dryness of the branch tips and lack of flower formation. The disease causal agents are Coniothyrium fuckelii, Botryodiplodia theobromae, Botrytis cinerea, Trichothecium roseum, Acremonium sclerotigenum, Diplodia rosarum, Lasiodiplodia pseudotheobromae, Phomopsis sp., and Pestalotia funereal. Disease management methods include cutting the top of the knot at an angle with the least remaining of the deadwood tissue to accelerate the formation of callus tissue, chemical protection of pruning wounds with fungicides, disinfection of the garden knife after each cut, avoiding wounds on the stems and compliance with greenhouse sanitation are described in this article.

Identifying resistance related metabolites as biomarker for screening wheat germplasms resistant to leaf rust (Puccinia triticina) is a useful approach to increase the speed, accuracy and cost effectiveness of screening disease resistance. The relatively polar metabolites were extracted in a mixture of methanol-water from near isogenic line (NILs) of wheat susceptible (Thatcher Lr22b) or resistant (Thatcher Lr25) to leaf rust in the two leaf stage, 24 h after inoculation with the pathogen, talcum powder or sterilized distilled water, in three replications. Metabolites were analyzed using a GC/MS. ANOVA showed that abundance of 26 metabolites had significant differences among experimental factors including near isogenic lines (NILs), inoculation (I) and NILs ×I interaction. Abundance of 26 significant metabolites was subjected to canonical discriminant analysis and hierarchical cluster analysis to group observations of metabolite profiles based on similarities and differences in the investigated metabolic space. Finally 13 resistance related metabolites (RR) and 13 Pathogenesis related metabolites (PR) were identified that the majority of RR metabolites involved in induced resistance and constitutive resistance. Significant metabolites included metabolites with potential signaling and/or antimicrobial activity as well as molecules used as precursors for cell wall reinforcement, phenolic and alkaloids compounds, and accumulation of amino acids and proteins associated with resistance. Up-regulation of the number pathways upon infection of wheat to leaf rust fungus is discussed.Key words: metabolic profiling, Wheat leaf rust, screening resistance, gas chromatography/mass spectrometry.

Reducing the damage of the cyst nematode Heterodera schachtii is one of the research fields in sugar beet producing countries. Using chemical fertilizers can improve soil fertility and reduce damages of plant parasitic nematodes. In this study, the effects of ammonium sulfate, calcium sulfate, zinc sulfate, potassium sulfate, potassium nitrate, sodium silicate, triple superphosphate, iron sequesterine and sulfur on H. schachtii and growth parameters of susceptible sugar beet cultivar (cv Sharif) were investigated in two experiments. The first experiment was performed in plastic pots containing 6 kg of pasteurized field soil and river sand (1:1), and the second one in pots filled with 9 kg of field soil for four and five months, respectively, both under microplot conditions. Fertilizers were mixed with pots soils before sowing and the nematode was inoculated by adding 200 g of infested soil containing 18 cysts with 4200 eggs. The results showed that chemical fertilizers and sulfur did not have significant effects on growth of the infected sugar beet plants in pasteurized mixed or field soils, and some of them reduced it. In the pasteurized soil, zinc sulfate 50 kg/ha, iron sequestrene 5 kg/ha, sodium silicate 10 kg/ha and triple superphosphate 100 kg/ha caused a relative decrease of more than 67% in the nematode final population and reproduction factor. In the field soil, these indices in triple superphosphate 100 kg/ha and sulfur 100 and 200 kg/ha were lower than other treatments, but were at the same statistical level with the control. The third experiment was performed in small containers filled with infested soil to investigate the effects of treatments on nematode egg hatching in greenhouse. The results showed that the highest hatching was happened in the treatment of ammonium sulfate 200 kg/ha, which was statistically at the same level with triple superphosphate 100 kg/ha.

To investigate the amount of yield losses caused by Iranian  isolates of tomato yellow leaf curl virus (TYLCV-[Ab]) and tomato leaf curl Karnataka virus (ToLCKV-IR) in Rio Grande (RG) and Grosse Lisse (GL) tomato cultivars, tomato seedlingswere separately agroinoculated with  an infectious clone of either virus and disease development was monitored over four time intervals. After the emergence of symptoms, disease severity (DS) was evaluated visually using an ordinal rating scale and the data was converted to a ratio scale. Losses caused by the viruses were estimated by measuring vegetative indices including wet and dry weight and height of the aerial and underground parts of the plants. Initial DS in plants infected by ToLCKV-IR was less than those infected by TYLCV-[Ab]. Descending order of rates of disease increase for the studied pathosystems was as follows: ToLCKV-IR-infected GL>TYLCV-Ab-infected GL> TYLCV-[Ab]-infected GL> ToLCKV-IR-infected RG. With delayed inoculation, DS was reduced in both cultivars inoculated with either of the two viruses. A segmented linear model showed a very good fit to the data of relative biomass and duration of exposure of all pathosystems. The estimated parameters of the model were used to evaluate different aspects of the damage curve. The highest crop loss disease threshold was observed for GL cultivar irrespective of the inoculated virus. Similar results were achieved when the desensitization disease level was evaluated. Curvilinear tolerance or slope did not show any significant difference between the infected-GL plants to either virus and also TOLCKV-IR-RG, while TYLCV-[Ab]-RG showed the highest curvilinear tolerance. Findings of this study can be applied in screening for tolerant tomato plants.

Potato is one of the most important crops produced in Kurdistan province, western Iran. Although several species of plant-parasitic nematodes have been reported in association with these potato fields, no comprehensive nematode community structure has been investigated. The present study reports the frequency, abundance and prominence value of all nematode groups from 40 potato fields across Ghurveh and Dehgolan regions. Bacterivorous nematodes showed the highest frequency, abundance and predominance in the region, followed by herbivorous (plant-parasitic nematodes), fungivorous and omnivorous nematodes. Predatory nematodes (carnivores) were not recovered probably because field soils were highly disturbed. Root-lesion nematodes were the most predominant among the identified plant-parasitic nematodes. The calculation of the indices of ecosystem function, as well as the plotting colonizer-persister (c-p) triangle, food web faunal analysis and metabolic footprint of the potato fields revealed that most of the studied fields had high proportions of c-p1 and c-p2 nematodes, but nematode individuals of c-p3-5 counted fewer in the population. According to the present study, 50% of the sampled fields represent either stressed and enriched, 30% could be considered as stable and enriched, and 20% may be described as stressed and depleted in terms of their soil nematode food webs. The current study provides the first known study in Iran on nematode assemblages and their implication in soil health.

To evaluate the effect of residue of sulfonylurea herbicides and  wheat residues on the growth and yield of sunflower, a split factorial experiment was conducted based on a randomized complete block design (RCBD) with four replications at the College of Agriculture, Shiraz University, Shiraz, Iran. The treatments included with and without wheat residues from the tested farm as the main plots, and a combination of three herbicides (Total, Apirus and Atlantis) and their concentrations (recommended and 30% overdose) which were considered as subplots. No herbicide treatment was used as control. The results showed that application of all herbicides reduced sunflower height, seed number and seed weight as well as seed yield of sunflower. The highest reduction in seed yield was recorded when Total  followed by Apirus residues were applied, which caused 95% and 80.6% yield reductions, respectively. Also, the minimum reduction of seed yield (32.7%) observed in Atlantis treatment. Moreover, 30% increase in herbicides dose caused increasing adverse effects and decreasing grain and biological yield compared to the recommended dose. Wheat residues incorporated to the soil increased damage of Atlantis by maintaining it in the soil (reduced seed yield from 3932.3 to 3556.9 kg/ha) and reduced damage of Total and Apirus by further degradation of these herbicides (increased seed yield from 235.4 to 311.6 kg/ha in Total treatment, and from 996.6 to 1161.3 kg/ha in Apirus treatment). But overall, wheat residues increased seed yield (2.1%) in comparison to the removal of plant residue. Therefore, addition of wheat residues as organic matter in the soil can affect the biological changes of herbicides.

Pythium oligandrum is known as an important biological agent against plant pathogens. Isolates from different regions of Iran including Bushehr, Bakhtiari, Chaharmahal, Fars, Golestan, Ilam, Kermanshah, Kerman, West Azerbaijan and Yazd were identified based on morphological and molecular characteristics. The highest recovering frequency of isolates was observed in Kermanshah and Fars provinces. The functional diversity of isolates based on their growth temperature and biological control effect under laboratory conditions was evaluated. The antagonistic effects of native P. oligandrum isolates were evaluated against soil–borne fungal pathogens including Rhizoctonia solani, Phytophthora parasitica, Fusarium solani, F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. pisi using nonparametric statistics, and compered with commercial products of various biocontrol agents such as Clonostachys rosea, Fusarium oxysporum, P. oligandrum and Trichoderma spp. The native isolates of P. oligandrum were diverse in their growth temperature and biocontrol activities. The highest mycelial growth inhibition was found in the interaction between P. oligandrum isolates and R. solani. A significant difference between P. oligandrum isolates was found by evaluating their volatile compounds. The isolates of P. oligandrum showed maximum inhibition on P. parasitica and R. solani and minimum inhibition on F. oxysporum f. sp. lycopersici. The non–volatile compounds had the highest significant effect on P. parasitica as well. The result of this study showed that the growth characteristics and the in vitro biocontrol ability of the native isolates of P. oligandrum on various plant pathogens were different. This variety can be employed in biochemical and greenhouse screening of the isolates.

Recent improvements in instrumentation and data mining have made it possible to investigate the effects of various stressors on primary and secondary metabolisms. In this study, in order to study mechanisms of pathogenesis and identify the pathogenesis-related metabolic pathways, changes in metabolic profiles resulting from a compatible interaction between canola cultivar (Hyola 401) and Leptosphaeria maculans (anamorph Phoma lingam) (Phkv102 isolate) were investigated by GC-MS chromatography using the polar fraction of plant extract. Under completely controlled conditions, 14 days after planting, when cotyledons were completely unfolded, the plants were inoculated by 107 spores per ml suspensions and water (control) by drop-wound method, respectively. The tissue samples were taken 48 hours after inoculation and were shock frozen immediately. Metabolites were extracted using methanol as solvent, identified and quantified with GC-MS and subjected to statistical analyses. Results indicated that 70 metabolites showed significant difference over their controls at P≤0.05, which is caused by changes in 28 metabolic pathways. Infection of canola cultivar Hyola 401 to P. lingam resulted in change in pathways related to the host cell wall, phenolic compounds, alkaloids and terpenoids biosyntesis, energy generator, hormone biosynthesis, signal transduction.The abundance of a number of sugars was also decreased, suggesting the crucial role of these carbohydrates in pathogenesis in an incompatible interaction of  P. lingam and a susceptible cultivar.

Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis is an economically important disease of tomato. In this study after isolation and characterization of the pathogen, effects of tomato pre-treatment with DL-β-aminobutyric acid (BABA) on bacterial canker was investigated under laboratory conditions. BABA is known as a powerful chemical resistance inducer in plants against diverse pathogens. In this study, tomato plants were treated with a 0.2 mM concentration of BABA and distilled water served as control. The plants were subsequently challenged with a 1×108 CFU ml−1 bacterial suspension. The results of experiments in different time intervals showed that BABA pre-treatment resulted in a significant reduction of bacterial population and symptoms severity of inoculated plants as compared to their controls. Furthermore, late appearance of disease symptoms indicated longer incubation periods for BABA treated plants. Also, a significant increase was observed in the expression of PR1 and catalase genes in treated plants. Based on our results and regarding the lack of proper management options against the disease, application of BABA as an environmentally safe agent is recommended as a valuable contribution to disease management.

The occurrence of viral co-infection is a common phenomenon in cultivated and native plant species and can alter the dynamics of virus infection. In this study, disease progress was examined in single and mixed infections of Cucumber mosaic virus (CMV) and Bean yellow mosaic virus (BYMV) by measuring the rate of symptom development, disease severity and area under disease progress curve on infected bean and broad bean. Simultaneous infection of bean to CMV and BYMV caused higher disease severity; however, no significant differences in disease severity were found on broad bean. In this study, a novel statistical approach (Abbott's approach) was used to recognize virus joint action in bean and broad bean hosts. Abbott's approach indicated synergistic effect between CMV and BYMV on bean only while the interaction was antagonistic when growth responses were considered on the same host. In broad bean plants inoculated with CMV+BYMV, CMV and BYMV, the two viruses affected disease severity and growth responses in an additive manner. Taken together, Abbott's approach was an appropriate method to determine synergistic interaction in these pathosystems.

Non-pathogenic Pseudomonadsare the main biocontrol agents that are used in plant disease management. In this study, effects of four strains of Pseudomonas fluorescens (Pf1, Pf2, Pf3, Pf4), and P. putida (P13) were studied for their ability to elicit induced systemic resistance against diseases caused by Botrytis cinerea and Alternaria alternata on tomato (Super Majar and Queen cvs) and Arabidopsis. The ability of biocontrol agents to colonize roots of tomato cultivars and Arabidopsis and induce resistance was shown to be highest for P13, and Pf3 strains and P13, and Pf3 were able to reduce the average lesion diameter of diseased leaves to 30% and 25%, compared to that of control, respectively. The ability of biocontrol agents for direct control the pathogens was also evaluated. The results revealed that P. putida (P13) was the best biocontrol agent as measured by the reduction in disease severity. P13 reduced the average lesion diameter of diseased tomato leaves by about 45%. Finally, Pf3 and P13 were identified as more powerful strains. Moreover, these strains could induce some level of resistance against various pathogens and they had the ability to enhance plant growth.

The critical period of weed control is a part of crop life cycle during which weeds must be kept weed-free to avoid yield losses due to competition. In order to evaluate the effect of deficit irrigation on critical period of redroot pigweed (Amaranthus retroflexus L.) in sunflower (Helianthus annuus L.), an experiment was carried out  as split plot based on randomized complete block design with three replications at the experimental farm of  College of Agriculture, Shiraz University, during 2010 and 2011 growing seasons. Factors were water deficit at three levels (100%, 75% and 50% of field capacity) as main plots and weed interference periods in weedy and weed-free plots at five sunflower growth stages (8-leaf, 12-leaf, head emergence, flowering and maturity) as subplots. Results showed that water deficit decreased grain yield and grain yield components in both years. Critical period of redroot pigweed in normal irrigation with accepting 5% yield loss in sunflower was 35-86 DAP (days after planting) in the first year and 49-94 DAP in the second year. By decreasing irrigation water to 75%FC and 50%FC, the length of critical period increased to 34-100 and 32-105 DAP in the first year and 50-101 DAP and 44-98 DAP in the second year of the study, respectively. Generally, our results showed water deficit extended the length of critical period of redroot pigweed in sunflower. Nomenclature: Redroot pigweed, Amaranthus retroflexus L.; Sunflower, Helianthus annuus L.

In this research the effect of mixed infection of witches’ broom disease of lime (WBDL) (16SrII-B) and lettuce phyllody (LP) (16SrIX-D) phytoplasmas on symptom expression and phytoplasma density in periwinkle plants (Catharanthus roseus (L.) G. Don) were investigated. Four healthy periwinkle plants of the same age were first inoculated with LP phytoplasma and after three weeks with WBDL phytoplasma using detached fragments of inoculative dodder (Cuscuta campestris Yank.). Disease symptoms and phytoplasma population in plants inoculated with both phytoplasmas were compared with those in plants inoculated with either WBDL or LP phytoplasma. In doubly inoculated periwinkle plants the disease symptoms mitigated to mild reduction of leaf size and internodes which strongly differed from those in periwinkle plants singly inoculated with either WBDL or LP phytoplasma. Plants with mixed infection lived longer than those inoculated singly with either phytoplasma. Both WBDL and LP phytoplasmas could be detected in singly and doubly infected plants by conventional and real time PCR assays using specific primer pairs. Analysis of the data obtained by real-time PCR showed that the population of both WBDL and LP phytoplasmas in the mixed infection was significantly lower than that in plants singly inoculated with WBDL or LP phytoplasma. It seems that interaction of WBDL and LP phytoplasmas in mixed infection of periwinkle is of the mutual suppression type.

The effects of inoculum density and temperature on the disease intensity of Phytophthoraparsiana on almond seedlings were investigated. Almond seeds (Rabie and Kaghazi cultivars) were placed in moist vermiculite at 4°C for 45 days. Germinated seeds were sown in a soil: sand mixture (2:1 v/v) and grown in greenhouse (18°C-25°C). One-month-old seedlings were transferred from the greenhouse to the growth chambers set at 15, 18, 20, 25,30 and 32°C. The seedlings were subsequently inoculated either with mycelium of P. parsiana grown for 4-6 weeks on vermiculite amended with hemp seed extract or with zoospore (103, 104, 105 and 106 ml-1) by root dip method. The effect of temperature, inoculum density and their interaction on seedling mortality was measured. The results indicated that all three factors had significant effects on seedling mortality. While the highest disease incidence (100% mortality in almond seedlings) occurred at 30°C and 32°C, no mortality was observed at 15°C and18°C. Increasing temperature from 20°C to 30°C and inoculum rate from 103 to 106 zoospores ml-1 increased disease incidence significantly. Higher temperatures and inoculum densities also caused significant increases in the colonization level of the crown, main and lateral roots as well as reductions in the fresh and dry root weights of the seedlings.

Wheat (Triticum aestivum L.) is one of the most important crops among cereals. Many factors could be responsible for low yield in wheat, but one of the major causes is weed infestation. The efficacy of any herbicide primarily depends on selectivity and the dose of application. Use of herbicides is an effective and efficient means of weed management. In many cases, there are no practical alternatives to chemical weed control methods. However, not only all kinds of weeds do not control by one type of herbicide and continuous use of that, but also lead to increase weed resistance to herbicides over the time (Hall et al. 1999). Of the many weeds that infest wheat fields across southern Iran, wild barley (Hordeum spontaneum L.), foxtail (Setaria viridis L.) and wild oat (Avena fatua L.) are the major weeds causing economic losses .Baghestani et al. (2007) reported that sulfosulfuron at 19.95 and 24.90 g a.i. ha-1 were proper application rates for broadleaf and grass weed control in wheat fields. Sij et al. (2016) reported that sulfonylurea herbicides were more efficient in terms of weed control. Lair and Redente (2004) reported that sulfonylurea herbicide application increased stability and biomass of crop as much as 43% over auxin herbicide and simultaneously reduced the grass weeds up to 71%. Golparvar et al. (2012) reported that limited doses of herbicides provided the same yield as weed free plots, therefore, this could be recommended to the farmers. The present study initiated to investigate the effect of some sulfonylurea herbicides on weed control and grain and biological yield of winter wheat under with/without wheat residue treatments. A field experiment was carried out in split-plot arrangement based on randomized complete block design with four replicates at College of Agriculture, Shiraz University, in 2014 growing season. Treatments included wheat residue at two levels (0 and 1850 kg/ha) as main plot in combination with each of the three of herbicides (Total, Apyrus and Atlantis) in two concentrations (recommended dose and 30% over the recommended dose) as Subplots. A weed infest plot (no herbicide application) was used as control. Wheat (Shiraz cultivar) planted on 5th November 2014, by Pneumatic planter at the rate of 200 kg ha-1 and maintaining 20 cm distance between crop rows. The plot size was 5m × 5m. Measurement of the effects included weed dry weight, weed density, wheat height, grain yield and its components. The data were subjected to the analysis of variance using SAS statistical software and means were compared by Duncan multiple range test (DMRT) at the 0.05 level of significance. Investigation on the effects of different application doses of Total, Apyrus and Atlantis to control weeds in wheat fields under applied wheat residue showed that the wheat residue had negative effect on the efficiency of three types of herbicides and increased weed dry weight by 41.4 percent, as compared to without wheat residue. Wheat residue incorporated to soil, reduced biological yield (from 14865.60 to 12340.40 kg ha-1) in comparison to without residue treatment. Three herbicides reduced weed biomass and the highest (43.56%) and lowest (18.7%) weed control recorded compared to weedy check. In comparison to weed infest control, Total increased wheat grain yield (from 3329.88 to 5283.19 kg ha-1), followed by Apyrus and Atlantis with 46 and 21 % increase in wheat grain yield, respectively. Application of Total, Apyrus and Atlantis herbicides, had increased wheat biological yield in comparison with weed infest control by 30.7, 26.8 and 13.6 %, respectively. Additive dose of herbicides application had better effect on weeds control and increased wheat grain and biological yield more than the recommended dose. Baghestani et al. (2007) reported that the wheat yield increased with increasing application dose of herbicide without any crop injury. Wheat grain yield for Total applied at the recommended dose was 5090.99 kg ha-1 but no significant effect was observed when an additive dose of the Apyrus herbicide was applied. This could be due to strong weed control effect of the Total herbicide at this dose. Interaction effect of herbicides and application dose indicated that Total at additive dose resulted in highest seed yield and weed control. Wheat residue had negative effect on weed control and the highest weed dry weight (~48.5%) observed when Total was applied under no residue conditions. All herbicide treatments increased wheat biological and grain yield as compared with the weed infested control. Application of Atlantis did not provide acceptable weed control in wheat. It is concluded that the most effective herbicide treatment was Total that provided maximum reduction in overall weed dry matter and obtained maximum grain yield. Atlantis had the lowest effect on weed control compared with the other herbicides (Total and Apyrus) and this could be due to poor weed control of the herbicide at both doses.

Tomato leaf curl disease (TLCD) is one of the most destructive diseases of tomato caused by a number of begomoviruses including Tomato yellow leaf curl virus (TYLCV) belonging to the genus Begomovirus (family Geminiviridae). TYLCV is transmitted by the whitefly Bemisia tabaci. In order to investigate changes in occurrence and severity of TLCD and evaluate the viral vector population on three tomato cultivars namely Yellow Round Multiple Truss (YRMT), PANDA F1 and Black Russian ST 175 (BRST) in a greenhouse in College of Agriculture, Shiraz University, 45 plants (15 plants from each cultivar) were randomly selected. Specific primers of an Iranian isolate of TYLCV (TYLCV[Ab])were used to detect plants naturally infected with TYLCV by PCR. After symptom emergence, both disease incidence (DI) and severity (DS) were evaluated visually using an ordinal rating scale. To estimate vector’s population, 50 whitefly puparia were collected from two leaves of each cultivar and based on the vasiforme and outward specifications of puparia, B. tabaci distinguished from Trialeurodes vaporariorum. The data analysis by SAS software indicated significant differences in DI, DS and vector population dynamics between three tomato cultivars. The DI was estimated to be 6.6% to 86.6%, at 40 and 100 days after planting date, respectively. The incidence and severity of disease and insect vector populations in YRMT and PANDA-F1 cultivars showed a higher trend and rose more sharply compare to those in the BRST cultivar. BRST was comparatively more resistant than the two other cultivars (YRMT and PANDA) which were susceptible to TYLCV.

Beet necrotic yellow vein virus (BNYVV), the causal agent of rhizomania, is one of the most important viruses influencing sugar beet root in Iran and other parts of the world. A high number of studies has been done on this disease and several resistant cultivars were introduced. In the present study, the physiological changes in two resistant and two susceptible sugar beet cultivars in interaction with this virus was studied. ELISA test results showed that susceptible cultivars had significantly higher virus concentration compared with resistant cultivars. Resistant cultivars showed significantly lower variation in fresh and dry root weight, chlorophyll and antioxidant content. Resistant cultivars showed higher variation in carbohydrate content, total phenol and protein compared with control. In general, BNYVV stimulates a prompt response and more physiological changes in resitant cultivars compared with susceptible ones.

Bermudagrass southern mosaic virus (BgSMV)and Maize dwarf mosaic virus (MDMV) are closely related potyviruses varying in geographical distribution and the existence of an additional 90- nucleotide stretch in the 5 'region of coat protein gene. .In the present study, the effect of temperature on disease severity of both viruses was assessed. A factorial experiment was conducted laid out in a completely randomized design with two factors, temperature at three levels (25, 30 and 35°C) and inoculation at three levels (MDMV, BgSMV and buffer) each in six replications. Eleusine compressa, a common host of both viruses, was inoculated mechanically and disease severity, length of incubation period, plant height, and plant weight were measured 30 days post inoculation. Disease severity of MDMV was not significantly affected by temperature change but that of BgSMV increased with increasing temperature. Incubation period of MDMV inoculated plants decreased with increasing temperature. Bioinformatics analysis showed presence of a coiled-coil region in CP of both viruses. This region was longer in BgSMV extending into extra amino acids in amino terminal region. Extra amino acid stretch may contribute to the adaptation of this virus to higher temperatures.

Root-knot nematodes (Meloidogyne spp.) are one of the main pests of cucumber production in greenhouses and farms. Applications of chemical and organic fertilizers are effective in reducing the damages caused by these nematodes. For this purpose, during 2013-2014, in an experiment, effects of 25, 50 and 100 mg/kg of elemental sulfur at planting time and 45 days before planting, in sterilized and non-sterilized soil were studied in two turns in greenhouse. First, two eggs or second stage juveniles of the nematode/g of soil and sulfur levels were mixed with the soil. Then cucumber seeds cv. Negin were sown immediately in the half of the pots and in the other half after 45 days. In order to evaluate the effect of sulfur evaporates on the initial nematode population, one half of 45 days pots were placed in plastic bags. The results of two trails showed that sulfur 50 mg/kg of soil in 45 days pots, filled with non-sterilized soil and placed inside plastic bags caused 36% increase in the shoot dry weight and 114% in the yield, on average. In addition, sulfur 100 mg/kg of soil caused 70% and 69% decreases in the final population and reproduction factor of the nematode, respectively.