نشریه دانش علفهای هرز
سال هجدهم شماره 1 (بهار و تابستان 1401)

To study the possibility of decreasing weed seed bank of artichoke (Cynara scolymus L.) by mycorrhizal inoculation and mulches, a three replicated split plot design based on randomized complete block design was conducted during 2017 and 2018 at the research farm of the Faculty of Agriculture, University of Zanjan. Two levels of inoculation (inoculation with mycorrhiza and non- inoculation) were considered as the main plots and a variety of living mulches (Trifolium alexandrinum and Lathyrus sativus), polyethylene film (silver-black color), wheat straw, consistently hand weeding throughout the growing season, once hand weeding and no-weeding were considered as sub plots. Results revealed that the highest density of weeds seed (4453 seeds) was recorded in no-weeding treatment under non-mycorrhizal inoculation conditions in 2018. The lowest weeds seed density was recorded in silver-black plastic mulch treatment under mycorrhizal inoculation conditions in 2017. Seed frequency showed significant positive correlations with seedling frequencies (R2=0.85); therefore, mycorrhizal inoculation and living and non-living mulches application can be suggested as a solution to decrease the seed bank density.

Forty-six suspected herbicide-resistant winter wild oat populations collected from wheat fields of Khuzestan province were screened in a whole plant bioassay using the recommended field dose of mesosulfuron methyl+idosulfuron methyl (Atlantis %1.2 OD) and mesosulfuron methyl+idosulfuron methyl+diflofenican (Othello %6 OD). The resistance index of two populations, with the highest percentage of herbicide resistance recorded at the screening tests, to the mentioned herbicides was tested in a dose-response experiment. Thirteen and six populations showed resistance to Atlantis based on Adkins and Moss methods, respectively. Also, 18 and three populations were classified as Othello resistant populations based on Adkins and Moss methods, respectively. This is the first report of resistance to Othello in winter wild oat populations collected from Khuzestan province. A distribution map of winter wild oat populations resistant and susceptible to herbicides was prepared based on the results of the screening test. Herbicide resistance index to Atlantis in two dose-response experiments for the studied populations was ranged between 8.9 and 15.1. Herbicide resistance index to Othello was ranged between 3.3 and 15.0. Due to an increase in herbicide-resistant populations to ALS inhibitors in Khuzestan province, herbicide-resistant winter wild oat management programs should be pursued more seriously.

In order to investigate the effect of different chemical and non-chemical weed control approaches in strawberry fields, this study was conducted as a randomized complete block design with three replications in a perennial strawberry field in Sanandaj in 2019. Treatments included some pre (indaziflam and trifluralin) and post-emergence (tribenuron methyl and clodinafop propargyl) emergence herbicides and non-chemical methods including hand weeding, vinegar, mulches (transparent and black poly ethylene, straw and sawdust), flaming and check. The results showed that different treatments had significant effects on most of the studied traits of strawberry and weeds.  Weed biomass had a significant decrease (97%) after indaziflam application compared to weed infested treatment. Tribenuron methyl and sawdust mulch had no differences from hand weeding and reduced weed biomass by 86% compared to weed infested. Also, sawdust and indaziflam resulted in the highest strawberry yield (703.02 and 686.51 g.m-2) compared to the other methods. In general, indaziflam and sawdust not only had not negative effect on strawberry fruit, but also due to the proper weed control effects, they increase the strawberry yield (126 and 131%, respectively, compared to the weed-infested check) and can be used as recommended weed control method in these fields.

To investigate the resistance of wild oat (Avena ludoviciana) accessions collected from wheat fields of Kerman province to clodinafop-propargyl herbicide, whole-plant bioassay pot experiment was performed on 16 winter wild oat accessions (15 suspected and one sensitive accessions) in a research greenhouse in Jiroft, Kerman during 2019-2020. First, the screening test was performed with the recommended dose (1 L/ha) of clodinafop-propargyl (EC 8%) herbicide in a randomized complete block design with four replications. Then, in a dose-response experiment, wild oat accessions were sprayed at 2- to 4-leaf stage with 9 doses of clodinafop-propargyl including 0, 0.25, 0.5, 1, 2, 4, 8, 16, and 32 times of recommended dose for resistant accessions and 0, 0.0625, 0.0125, 0.25, 5) 0, 1, 2 and 4 times of recommended dose for the susceptible accessions. Four weeks after spraying, fresh and dry weights and survival percentage of the plants were measured. According to the results, the resistance of 14 accessions to clodinafop-propargyl was confirmed according to the Adkins and Moss methods. The results of the dose-response test based on the fresh weight showed that F3 (14.3) and R4 (3.9) had the highest and lowest resistance index, respectively. Furthermore, based on the survival, M3 and M4 accessions with 14.1 and 2.4 resistance index showed the highest and lowest resistance level to the herbicide, respectively. Therefore, the first case of wild oat resistant to clodinafop-propargyl was recorded in Kerman province.

The efficacy of pretilachlor from chloroacetamide herbicides inhibiting lipid synthesis and bensulfuron from sulfonylureas urea inhibiting the synthesis of enzyme acetolactate synthase in the control of barnyardgrass and bulrush were investigated in sole and mixed applications at 0, 25, 50, 75, 100 and 125% of the recommended doses. The results showed that weed control in response to different doses of two herbicides could be expressed by logistic dose-response model (R2≥95%). The required dose for 50% reduction of barnyard grass biomass (ED50) in the treatment with pretilachlor and bensulfuron was 17.1% and 24.7% of the recommended dose, respectively, and 32.3% and 26.4% of the recommended dose for bulrush respectively, indicating higher efficiency of pretilachlor in barnyardgrass and bensulfuron in bulrush controls. While pretilachler provided complete control of barnyardgrass, none of the herbicides were able to completely control bulrush up to 125% of the recommended dose. According to the fitted dose response logistic model (R2≥95%), mixing the recommended doses of bensulfuron with 75% of recommended dose of pretilachlor or the recommended dose of pretilachlor with 25% of recommended dose of bensulfuron resulted in 100% control of bulrush. Today, sedges are the most abundant and diverse weeds in rice fields, and according to the results of this study, to control the most prevalent weed of this group, bulrush, mixing of herbicides is necessary. By mixing the pretilachlor and bensulfuron herbicides, it is possible to control bulrush and barnyardgrass, the two key weeds of paddy, with lower doses of these herbicides, which require further studies in field conditions to determine the appropriate dose.

Purple nutsedge causes severe damages to vegetable crops in Jiroft, Kahnooj and Birjand. In order to evaluate the effects of high temperature and time of exposure to high temperatures on various ecotypes of purple nutsedge tubers, a factorial experiment was conducted based on randomized complete block design with 3 replications in the Research greenhouse of Birjand University, Iran, in 2016. Experimental factors consisted of 3 ecotypes (Jiroft, Kahnooj and Birjand), different temperatures from 40 to 60°C with 5°C increments, and exposure time including 1, 2, 4, 8, 16, 32 and 64 hours. Results indicated that at all exposure times, 40°C temperature did not affect the growth characteristics of purple nutsedge, while at 45 °C, increasing the exposure time decreased the growth characteristics of purple nutsedge. Three-parameter logistic model estimation showed that  tuber viability (T50) at 45 °C in Jiroft ecotype was 14.64 hours, it decreased to 5.01 hours  at 50 °C. T50 was about 66% lower than for 45 ° C, but it was 19.76 hours in Kahnooj ecotype at 45 °C, while at 50 °C, this parameter decreased to 2.73 hours (86.2%). T50 of Birjand ecotype at 45 °C was 12.90 hours, but at 50 °C, the tubers viability reduced and T50 was 8.91 hours (31% decrease). Results of this research could have an important role in controlling purple nutsedge in vegetable fields.

To evaluate the effect of Corn and Cowpea living mulch planting pattern on forage yield and weeds suppression after harvesting of corn, an experiment was conducted in a randomized complete block design with nine treatments and three replications in Shush during 2019 growing season. Experimental treatments were included single-row corn on furrow, double-row corn on furrow, single-row corn in furrow, single-row corn on furrow+ single-row cowpea in furrow, single-row corn on furrow+ double-row cowpea in furrow, double-row corn on furrow+ single-row cowpea in furrow, double-row corn on furrow+ double-row cowpea in furrow, single-row cornin furrow+ single-row cowpea on furrow; single-row cornin furrow+ double-row cowpea on furrow. According to results, the best treatment in terms of corn forage yield and weed control after harvesting was single-row cornin furrow+ double-row cowpea on furrow pattern. The highest corn forage yield (30998 kg.ha-1), the lowest weed dry matter (26/3 g.m-2) and the highest weed smothering efficiency index (85%) gained from this planting pattern. Based on the results, application of single-row cornin furrow+ double-row cowpea on furrow planting pattern can be recommended to increase corn forage yield and weed control.

In order to investigate the composition and herbicidal activity of yarrow essential oil on barnyard grass (Echinochloa crus-galli (l.) beauv) and common lambsquarter (Chenopodium album L.), two factorial experiments were conducted in a complete randomized design with four replications at Islamic Azad University in 1399. The first factor was the type of essential oil at two levels (ordinary and nano) and the second factor was the concentration at six levels (0, 100, 200, 400, 800 and 1000 µlL-1). The results of essential oil analysis led to the identification of 49 compounds. Among these compounds, camphor (21.1%), 1,8-cineole (19.3%), myrtenol (8.4%), carvacrol (8.3%) and borneol (6.1%) are the main compounds in essential oil. Scanning Electron Microscopy Images showed the particles were 1 and 100 nm in size. There was no significant difference between the concentrations of 100 µlL-1 of the two types of essential oils in germination percentage of barnyard grass. However, with increasing the concentration, this difference became significant, so that at a concentration of 400 µlL-1, the germination percentage of barnyard grass treated with ordinary and nano essential oils reached 30.12 and 10.02%, respectively. Germination completely inhibited with nano essential oil at 1000 at µlL-1 concentration in barnyard seeds. At a concentration of 400 µlL-1 of nano and ordinary essential oils, common lambsquarter germinated at 36.12 and 13.02 percent and nano essential oil at a concentration of 800 µlL-1 completely prevented germination. Common lambsquarter was more sensitive to essential oil of yarrow in comparison with barnyard grass.

A greenhouse study was conducted during the 2019-2020 at the Plant Protection Research Institute in Tehran. A completely randomized design in factorial arrangement with four replications was used evaluate the effects of five adjuvants (first factor), different doses in conjunction with mesosulfuron-methyl+iodosulfuron-methylsodium herbicide(second factor) on the resistantandsensitive populations of wild oat to clodinafop-propargyl herbicide (third factor). At the 2 to 3 leaf stage of the wild oat, spraying was done doses of 1.05, 1.2, 1.35, 1.5 liters per hectare, with five types of additives in the amount of four, two, 0.1, 0.04 and 0.03 liters per hectare. Four weeks after spraying percentage of fresh weight, dry weight and survival of the plants were measured. In all doses, Ino Alg NPK (NG) adjuvant had the greatest effect on reducing the fresh weight of sensitive and resistant wild oat biotypes. Among the four doses of mesosulfuron-methyl+iodosulfuron-methylsodium herbicide, the doses of 1.5 and 1.05 times the recommended dose, had the highest and lowest efficacy in fresh weight loss and dry weight in sensitive and resistant populations of wild oat, respectively. According to the EWRC index data, the effectiveness of all adjuvants was the same on sensitive associations (100%) but different on resistant associations. Also, based on this index, sensitive and resistant populations in almost all doses showed almost the same percentage of control. In general, in this experiment, Ino Alg NPK (NG) adjuvant and 1.5 times the recommended dose showed the highest efficiency in controlling both susceptible and resistant populations of wild oat.

The present experiment was conducted to study the resistance of winter wild oat biotypes in wheat fields and mapping the distribution of its biotypes resistant to clodinafop propargyl, diclofop methyl and fenoxaprop P ethyl in Kalaleh township. Samples included 105 suspected resistance winter wild oat accessions were collected in June of 2014 from 150 wheat fields of Kalaleh township. The coordinates of the sampling points were recorded by a GPS. A susceptible sample was also collected from a region with no spraying history. Screening of accessions was done with discriminating concentration of three herbicides. The results showed that among the suspected resistant accessions, 27.60, 24.76 and 23.81% were resistant to clodinafop propargyl, diclofop methyl, and fenoxaprop P ethyl, respectively. Among the suspected resistant accessions 4, 7 and 11 biotypes were resistant only to clodinafop propargyl, diclofop methyl, and fenoxaprop P ethyl, respectively 3.81, 6.67 and 11.47% out of 105 suspected resistant accessions. Eight biotypes showed cross-resistance to both clodinafop propargyl and diclofop methyl which was equal to 7.62% of suspected resistant accessions. Eleven biotypes equal to 11.47% of total accessions showed cross-resistance to diclofop methyl and fenoxaprop P ethyl, 12 biotypes equal to 11.43% of suspected resistant accessions showed cross-resistance to all three herbicides, and only one biotype was cross-resistant to clodinafop propargyl and fenoxaprop P ethyl which was equal to 0.96% of total accessions. Finally, the distribution map of resistant weed-infested fields was generated using geographic information systems.