جستجوی مقالات مرتبط با کلیدواژه « rapeseed » در نشریات گروه « گیاهپزشکی »

Members of the genus Polerovirus, including Turnip yellows virus (TuYV), are important viruses on field crops. They are being transmitted by aphids in a circulative non-propagative manner. During 2018 and 2019, 32 leaf samples from rapeseed (Brassica napus) and one sample from wild mustard (Sinapis arvensis) were collected in Kermanshah Province, Iran. The samples were tested by a TAS-ELISA kit (DSMZ) that detects four poleroviruses including TuYV, Beet mild yellowing virus (BMYV), Beet western yellows virus (BWYV) and Beet chlorosis virus (BChV). A positive reaction was observed for the wild mustard and seven rapeseed samples. Myzus persicae and Brevicoryne brassicae were used for virus transmission. The virus was successfully transmitted by the aphids to rapeseed and radish but not to sugar beet plants. In IC-RT-PCR using a specific primer pair, a 780 bp fragment was amplified from wild mustard and two rapeseed samples. The two nucleotide sequences from rapeseed and wild mustard had 99.4% identity to each other and showed up to 97.2% similarity to TuYV isolates previously deposited in GenBank from fenugreek, rapeseed, pea and chickpea plants in Australia. In phylogenetic analysis based on the nucleotide sequences of ORF0, two Iranian isolates of TuYV were placed in the same clade with other TuYV isolates and were distinct from other poleroviruses such as BMYV, BWYV and BChV. In this study, for the first time in Kermanshah Province, TuYV was identified in Iranian rapeseed fields based on nucleotide sequencing of the P0 coding region.

Stem rot caused by Sclerotinia sclerotiorum, is one of the important diseases of rapeseed, and fungicides are applied for its control. In Iran, carbendazim and tebuconazole are often used for chemical control of the disease. In order to introduce other effective fungicides against the disease, seven fungicides were studied in laboratory conditions and then six of them were applied in the field. In the laboratory conditions, different concentrations of the fungicides showed significant differences (P<0.01) with control (without fungicide) and caused inhibition of pathogen radial growth on potato dextrose agar medium except chlorothalonil (Daconil®). Effective concentration (EC50) and minimum inhibitory concentration (MIC) of the fungicides including iprodione + carbendazim (Rovral TS®), propiconazole (Tilt®), thiophanate methyle (Topsin M®), trifloxystrobin+ tebuconazole (Nativo®), tebuconazole (Folicure®) and spiroxamine+ tebuconazole+ triadimenol (Falcon®) was calculated. The EC50 values of these fungicides were 0.10, 0.11, 0.12, 0.22, 0.36 and 0.60 ppm, and MIC values were 1, 5, 1, 10, 10 and 10 ppm respectively. In the field conditions, all fungicides, had significant difference (P<0.01) with control  and decreased the rate of the disease infection and increased the crop yield about 300 to 700 Kg/ha. Nativo® was the most effective fungicide. The duration of plant protection in Nativo® treatment was longer and occurrence of disease symptoms after spraying was later than other treatments. Therefore, these fungicides can be used in rotation with common fungicides.

Many species of the family Syrphidae are predators of pests, especially aphids. To study the predacious syrphid species of rapeseed fields of Kermanshah, we assembled a sizable collection of syrphids between 2013-2015. The result showed the existence of 12 species in these fields of which the species Eupeodes corollae F. was found to be the predominant species. The length of growth periods and feeding capability of this species was studied on cabbage aphid (Brevicoryne brassicae) at 3 different temperatures. The growth period means of this fly are 22.45, 18.82 and 15.17 days at 20, 25 and 30oC respectively. The predation rate of E. corollae on third instar nymphs of B. brassicae at 20, 25 and 30°C significantly decreased with increasing temperature with a mean value of 371.07, 283.00 and 253.13, respectively. There were significant differences between daily and total feeding rates of the first, second and third instar larvae of E. corollae at various temperatures. The results suggest that 25ºC was the optimum temperature for both survival and feeding of E. corollae. As the temperature increases of the feeding rate reduces during periods of growth. The lowest mortality rate occurred at 25°C.

Ascospore dimensions of eight populations of Leptosphaeria maculans and L. biglobosa, causal agents of rapeseed blackleg disease, isolated from debris of rapeseed (Brassica napus) and wild mustard (Sinapis arvensis) were evaluated in Mazandaran and Golestan provinces. Results of ANOVA indicated significant differences in the dimensions of ascospores of the different populations. The greatest length and width of sexual spores were 87.5 and 12.5 micrometer, respectively. Variations in the range of Length and width of ascospores in the studied populations was measured, 46.25 and 7.5 micrometer, respectively also these variations were 6.25 and 2.5 micrometers greater than the dimensions of ascospores reported by other studies in the world. The length of sexual spores isolated from stem debris of mustard was much bigger than those of canola. Germination percentage of most studied populations was more than reported in other studies, so likely the most of studied populations of different regions belong to non aggressive group. Sexual spores of aggressive types have greater number of germ tubes, shorter in length, twisted and originate from the middle cells. While in the nonaggressive type the germ tubes grow out of end cells and are not twisted. With regard to morphological characteristics of sexual spore germ tube and also cotyledon test characteristics, field symptoms, pigment production and colony growth rate it was determined that ascospores of the studied populations from Dasht-e-Naz of Sari, Kohikheil and Fazel Abad were of the aggressive type (L. maculans) and most of population in Lala, Mazarustaq and Talookola areas belonged to nonaggressive type (L. biglobosa). There was no correlation between germ tube characteristics of fungus populations on mustard and their pathogenicity.

Herbicides are the most widely used of chemical pesticides for agricultural production and landscape management. The environmental risk of herbicides should be evaluated near sites of application, even though basic ecotoxicological tests have been conducted before they can be registered for marketing. For example, triazine herbicides, which are photosynthetic PSII herbicide that considered only slightly or moderately toxic to many susceptible plants, soil microorganisms, mammals and humans, however, concerns have arisen because this herbicide are members of a class claimed to be carcinogenic, or may affect the development as reproductive toxins. For this reason, most reliable evidence is needed to test these claims and investigate their ecological effects. Prometryn is a herbicide belongs to triazine family that may leave residual activity in the soil for extended periods, causing injury and yield reduction of susceptible soil microorganisms and crops in rotation. Compared with other methods, the rapidity of response, sensitivity, high level of precision, simple process and easy operation are the advantages of bioassay methods for the routine monitoring of biologically available photosynthesis-inhibiting herbicides present in agricultural soils.
A pot experiment was conducted under greenhouse conditions in order to study the sensitivity of 4 different crops to prometryn soil residue at the College of Agricultural Sciences, Ilam University, Ilam, Iran in 2014. Experimental type was completely randomized design in a factorial arrangement with three replications. Treatments included 4 different crops (lettuce, barley, rapeseed and beet) and prometryn simulated concentrations residues in soil (0.0033, 0.0166, 0.033, 0.066, 0.1 and 0.166 mg. kg-1soil). 15 cm diameter pots were filled with a modified soil and 10 of seeds of crops were planted in 5 regular positions. The plants were thinned to five plants per pot after germination. The pots were kept for 30 days under controlled conditions. Shoot and root biomass production was measured 30 days after emergence. At harvest, growth parameters including the dry weight of shoots and roots were determined. The data were subjected to analysis of variance by computer facilities, using Mstatc software. Plant response to prometryn residues was fitted with sigmoidal 3 and 4 parametric equations to the shoot biomass data as a function of the herbicide residue concentrations and was used to calculate the doses for 50% inhibition of shoot growth (ED50). In another experiment the effect of prometryn concentrations (0, 0.0033, 0.0166, 0.033, 0.066, 0.1 and 0.166 mg. kg-1soil) on soil microbial activity was determined using titration method in controlled conditions.
Plant response to increasing concentration of prometryn, in general, followed a classical dose response relationship. The logistic model fitted well to the root and shoot plants response herbicide concentrations. Results showed that the shoot and root dry matter were significantly affected by increasing prometryn soil residue in all crops (plettuce>beet>barely. Based on the mechanism of action of prometryn and its best efficiency on board leaf plants control, the least biomass reduction obtained for barley is understandable. In general, this is safe to plant a susceptible species if the plant-available residue were less than the species ED10 value, and there would be a great risk for different levels of crop damage if the plant-available residue were higher than ED50 values of the species. Comparisons between species allow the safe selection of a crop that has a critical ED50 level lower than the residue level in the soil. Alternatively, planting a sensitive species could be delayed until the residue level in the soil is less than the critical level. In the Southwest areas of Iran, these crops are often sown few months after the application of a residual herbicide in the preceding crop. This large variation in plant sensitivity to prometryn residues indicates that there is potential for considerable damage to some of the rotational crops. In second experiment the results clearly indicating that in initial days of prometryn application used drastically reduced the C, N and total microbial in treated soil compared with the untreated (Control) soil.
According to the results of this studyt the study crops are very suitable for use in bioassays for the side-effects of prometryn at low concentration rates. In this study prometryn herbicide provided symptoms of phytotoxicity to the crops, whereas seed germination of crops was not adversely affected. In the other words, this condition indicating that the application of prometryn in agricultural soil leads to decrease the total biomass of soil microorganisms at initial period. By possibly knowing the level of prometryn residual in the soil, producers could have some flexibility in crop rotations if sensitive crops such as rapeseed are to be planted following triazine herbicide use on crops.

The cabbage aphid, Brevicoryne brassicae (L.) is the most important pest of canola (Brassica napus L.) in Iran. Two same field trials (control and infested) were conducted to study the effect of macroelements (NPK) fertilizer on cabbage aphid population on rapeseed SLM046 at Borujerd agricultural research station during 2002-2003. The RCBD with factorial arrangement was used with three factors, N (N1=0, N2=190, N3=270, N4=350 Kg/ha), P (P1=0, P2=150 Kg/ha) and K (K1=0, K2=100 Kg/ha). Result showed that, at the beginning of stem stage (in late March), when the urea was applicated at the second time, aphid infestation at fertilizer level N4 significantly decreased. But after the blooming stage (in late April), when the urea was applicated at the third time, aphid infestation in N4 was increased. According to this research, Nitrogen (N) alone and its interaction with Phosphorus (P) and Potassium (K), significantly decreased the damage of B. brassicae in the canola fields.

Ascospore dimensions of eight populations of Leptosphaeria maculans and L. biglobosa, causal agents of rapeseed blackleg disease, isolated from debris of rapeseed (Brassica napus) and wild mustard (Sinapis arvensis) were evaluated in Mazandaran and Golestan provinces. Results of ANOVA indicated significant differences in the dimensions of ascospores of the different populations. The greatest length and width of sexual spores were 87.5 and 12.5 micrometer, respectively. Variations in the range of Length and width of ascospores in the studied populations was measured, 46.25 and 7.5 micrometer, respectively also these variations were 6.25 and 2.5 micrometers greater than the dimensions of ascospores reported by other studies in the world. The length of sexual spores isolated from stem debris of mustard was much bigger than those of canola. Germination percentage of most studied populations was more than reported in other studies, so likely the most of studied populations of different regions belong to non aggressive group. Sexual spores of aggressive types have greater number of germ tubes, shorter in length, twisted and originate from the middle cells. While in the nonaggressive type the germ tubes grow out of end cells and are not twisted. With regard to morphological characteristics of sexual spore germ tube and also cotyledon test characteristics, field symptoms, pigment production and colony growth rate it was determined that ascospores of the studied populations from Dasht-e-Naz of Sari, Kohikheil and Fazel Abad were of the aggressive type (L. maculans) and most of population in Lala, Mazarustaq and Talookola areas belonged to nonaggressive type (L. biglobosa). There was no correlation between germ tube characteristics of fungus populations on mustard and their pathogenicity.

In order to evaluate the impact of time of weed control on yield and yield components of two rapeseed cultivars (Zarfam and Opra) two separate experiments based on each cultivar conducted at Shahryar (Karaj). The experiment was carried out based on RCBD with three replications and six treatments for each cultivar. Treatments were exerted on the different phenological growth stages including the emergence of 4th and 8th leaf, branching, flowering as well as weed-free and weed-infested stages in whole plant growth cycle. In current study some weed species including wild mustard (Sinapis arvensis L.), wild oats (Avena ludoviciana Dur.), lambsquarter (Chenopodium album L.), and Hoary cress (Cardaria draba (L.) Desv.) were selected as main weed species based on their higher dry matter. In both cultivares extended weed interference resulted in increased weed total dry matter. weed interference in four-leafed, eight-leafed, branching, flowering, weed- free and total infestation sages in comparison with weed-free period led to 20، 33، 38، 50 and 55 percent reduction in grain yield respectively in Zarfam cultivar whilst these figures were about 14, 25, 29, 48 and 56 percent in Opra cultivar respectively. The results of mean comparisons revealed that in weed-free treatment, the highest number of sub-branches were 8 and 5/33 in both Zarfam and Opra respectively. Among the weed-interference treatments the highest number of pods in Zarfam cultivar was achieved at the four-leafed stage with 133 pods per plant but in Opra cultivar the four-leafed, eight-leafed and branching stages have the highest number of pod per plant as67/110, 67/109 and 33/108 receptively, which proved no significant difference. In both Zarfam and Opra varieties the highest number of grain per pod was observed in weed-free treatments which was equals to 26. 67 and 21. 33, respectively.

In order to identify the plant parasitic nematodes (suborder Tylenchina & Aphelenchina) of rapeseed fields in North Khorasan province، 40 soils and root samples were collected، during years 2007-2008. Nematodes were extracted by centrifugal flotation technique and transferred to glycerine. The permanent slides were prepared from the extracted nematodes. The nematodes were identified by light microscopy based on morphological and morphometrical characters. In this study، 17 species belonging to 12 genera of the suborder Tylenchina & Aphelenchina were identified. Two species Helicotylenchus egyptiensis and Paratylenchus perlatus are reported for the first time from Iran. Helicotylenchus egyptiensis is recognizable from related species by the truncate lip region with five annulations، non functional spermatheca in female، lateral field with four lines، longitudinal inner together on the tail in a U or V shaped pattern، tail shape and its terminal projection. Paratylenchus perlatus is recognizable by short measurement (200-245 µm)، long stylet (26-27 µm) and functional، spherical and small spermatheca.

In order to identify the plant parasitic nematodes of rapeseed fields in North Khorasan province، during 2007-2008، 40 soils and root samples were collected. Nematodes were extracted by centrifugal flotation technique and transferred to glycerine according to the modified De Grisse method (1969). The permanent slides were prepared from the extracted nematodes. The nematodes were identified by light microscopy based on morphological and morphometrical characters. In this study، from genus Geocenamus، three species G. quadrifer، G. tessellates، G. rugosus and genus Merlinius four species M. brevidens، M. microdorus، M. nanus، and M. nothus were identified. G. tessellates، is reported for the first time from Iran.

The rapeseed (Brassica napus) is one of the most important oilseed crops throughout the world. This crop is being attacked by several pests and diseases. This studies were conducted for the identification of some fungal diseases under laboratory and glass-house conditions on rape plants in Isfahan areas including; Braan, Koohpayeh, Mahabad, Mobarakeh, Dehaghan, Kabootarabad and Fraydan, where the infected plants were collected from the infected fields. The studies indicated that there are certain fungal pathogens infecting the areal and underground of rape plants. Isolation and growing cultures for identification of Fusarium species were with consistent and proper preparation of cultures on SA, WA, PDA, SNA, CLA, NASH & NYDER. Obtained isolates were identified by using morphological and various keys. All isolates were categorized in 5 species of Fusarium including: F. culmorum,F. heterosporum, F. lateritium, F. oxysporum,F. solani and one species of Rhizoctonia (R. solani). Disease severity was calculated under laboratory condition and compared with control using scoring scales (0-24). Results showed that, the highest level of infection was recorded by F. culmorum, F. lateritium, F. oxysporum,F. solani and R. solani, whereas the least infection was noticed by F. lateritium and F. heterosporum. It was also tested the isolated species on growth of plant and symptoms of disease. On the base of analyzing the data using DMRT (P=0.01%, 0.05%) on shoot length, fresh and dry weight of plants by different isolated pathogen, it was noticed significant effect compared to control.