مجله پژوهش علف های هرز
سال پانزدهم شماره 1 (بهار و تابستان 1402)

Purple nutsedge (Cyperus rotundus L.) is a problematic weed in tropical regions particularly in Jiroft, Kahnooj and Birjand, so that farmers annually suffer severe damage to their vegetable and cucurbit crops. Currently, very little research on the biological basis of this noxious weed has been don.This study was conducted to evaluate the effect of burial depth on tubes germination and emergence of different purple nutsedge ecotypes. Purple nutsedge tubers were collected from birjand, kahnooj and jiroft regions. A factorial experiment was conducted based on randomized complete block design in University of Birjand with three replications. To investigate the viability of tubers before being used for bioassays, their germination potentials were examined in a growth chamber set at 25/15°C. Then, ten tubers of each ecotype with almost equal weight (3.6gr) and size were planted in polyethylene tubes with 25 cm in diameter and 50 cm in height. Ten tubers of each purple nutsedge ecotype were sown at 8 different depths, including 0, 2.5, 5, 10, 20, 30, 40 and 50 cm. At the termination of experiment, number of tubers and pre tubers, underground tuber dry weight, shoot number and above ground dry weight were recorded. Results showed that purple nutsedge tubers were able to emerge from very deep burial depths (up to a depth of 50 cm), and in this regard, there were some differences among the three ecotypes. Generally, as depth increases, the number and weight of tubers, and shoots decreased; whereas the burial depth showed no effect on the shoot height and pre-tuber production. Therefore, in addition to deep plowing, other control methods such as cultural control and chemical methods should be used in an integrated management.

In recent years, the use of allelopathy in weed management has received great attention. In this study, the effect of allelopathy of a double haploid population of barley on the growth characteristics of wild rye and hedge mustard was studied in the Laboratory of Agriculture and Plant Breeding, Faculty of Agriculture, Zanjan University. Some germination traits (root and shoot length, fresh and dry weight of seedlings) and their heritability were measured in barley, rye and hedge mustard. The results showed that the double haploid lines, rye and hedge mustard are significantly different in terms of all four traits of fresh weight, dry weight, root length and stem length. Lines 25 and 34 showed the lowest allelopathy and lines 17 showed the highest allelopathy on rye. Lines 39, 48, 55, 65, 66, 68, 70, 75, 76, 77 and 82 of barley were also affected by rye allelopathy. Lines 73 and 17 had the highest rate of allelopathy on hedge mustard plant, as well. Except for the dry weight of barley control, the length of roots and stems of hedge mustard, which had low private heritability, showed moderate other heritability traits.

In order to study the effects of nitrogen and irrigation interval on Broomrape (Orbanche aegyptiaca) damage reduction in cucumber (Cucumis sativa L.), an experiment with two factors, nitrogen (urea in three levels 100,200 and 300 Kg/ha) and irrigation interval (with three levels 3,6 and 9 day) in three replications was performed in the greenhouse of Northern Khorasan Agricultural and Natural Resource Research Center. The results showed that the growing velocity was maximum in the treatment of 200 Kg N/ha. However, height and the number of cucumbers were lower. The effect of irrigation interval on the number of flowering days was significant, whereas nitrogen fertilizer did not have a significant influence on this parameter. Hence, irrigation level rising caused reduction in the number of flowering days. Maximum length and diameter of cucumber was observed in the treatment of highest nitrogen level and minimum irrigation interval or the treatment of lowest nitrogen level and medium irrigation interval. The maximum number of cucumbers and weight was obtained in maximum nitrogen and irrigation interval. In addition, rising irrigation interval caused the number of cucumber increase and decrease in cucumber weight. The maximum wet weight of shoot and root was observed in the highest nitrogen treatment. On the other hand, the maximum wet weight of shoot and root was derived from the highest nitrogen and medium irrigation treatment and the highest nitrogen and minimum irrigation interval treatment, respectively. The comparison of water percent in wet and dry weight of shoot showed that the highest value was observed in 300 and 100 Kg N/ha treatments respectively. Maximum shoot/root ratio was observed in the treatment of 100 Kg N/ha and a six-day irrigation interval.

This research was conducted to study of diversity and weed population structure of wheat agroecosystems of Bandar-e-Torkeman county in 2018-2019 year. Diversity indices such as Shannon-Wiener and Simpson for fields and frequency, relative frequency, relative uniformity and relative density indices for all weed species were calculated and measured in two time stages, before and after chemical treatment with herbicides. Obtained data from diversity indices were moved in the GIS media and weed species maps of wheat fields were prepared. In this study, we were identified 18 species from 9 plant families. The checking of plant species showed that 66.67% and 33.33% were belonged to annual and perennial, also, about 27.77% and 72.23% were narrow-leaved and broad-leaved, respectively. Gramineae species include Avena ludoviciana, Lolium temulentum, Phalaris minor, Alopecurus myosuroides and Polygon monspeliensis, Fabaceae species include Medicago scutellata, Polygonom avicular, Vicia villosa and Oxalis corniculata and Compositea species such as Helianthus annuus and Cirsium arvense, had about 27.77, 22.22 and 11.11 percent of the available plant species, that were recognized as the most important plant families in wheat fields of county, respectively. In this study, weed distribution maps in wheat fields of the county before and after chemical control were prepared in three frequency groups of 50-100, 30-50 and less than 30% and showed an almost uniform distribution of weeds in surveyed region.

In order to identify the best method and time of herbicide application in bromus (Bromus japonicus) control, a factorial experiment was conducted in a form of a randomized complete block design with 3 replications. The experimental treatments include (1) the application of 3 post-emergence herbicides metsulfuron methyl + sulfosulfuron (45 grams of active substance per hectare), (2) sulfosulfuron (26.6 grams of effective substance per hectare) and pinoxaden (450 mg of effective substance per hectare) and (3) three times of herbicide application were before tillering, during tillering and after tillering of wheat. The dry weight of bromus and wheat was measured during all three stages of spraying, 30 and 60 days after spraying and during harvest along with grain yield. Metsulfuron methyl + sulfosulfuron and sulfosulfuron treatments showed the highest reduction in bromus biomass and increase in wheat grain yield both before tillering and during wheat tillering. With the application of herbicides after tillering of wheat, the use of the mentioned herbicides in the control of bromus was observed to decrease in a similar way, and by delaying the spraying time, the yield of wheat was also reduced. Based on the results of this study, two herbicides, methsulfuron methyl + sulfosulfuron and sulfosulfuron, are suggested for the effective control of bromus in the early stages of wheat and weed growth.

Among pulses, chickpea and lentil have important characteristics such as resistance to drought and tolerance to cold dtress; It is very important and in terms of cultivated area in Iran, they rank first and third respectively. Since thet are weak competitors with weeds, especially in the early stages of growth, weeds are one of the serious problems in their production and yield gap. So their damage has been reported more than 90%. Therefore, weed control is one of the most important programs in chickpea and lentil management. In this regard, the review of the researchs conducted in order to adopt a suitable approach for weed management and control, can play an important role in reducing yield gap and provide a perspective for future researches in Iran. This study was conducted with the aim of investigating the research conducted in weed control of chickpea and lentil in Iran. According to the reports, Iran's chickpea and lentil fields are infected with a wide range of broad and narrow leaf weeds, especially from the plant families Asteraceae, Fabaceae, Brassicaceae and Poaceae. Considering the critical period of weed control in lentil and chickpea in Iran (30 to 60 days after planting), their control (mechanical, agronomical and chemical) in this period is necessary to obtain an acceptable yield. The most important limitation in the entezari planting of chickpea and lentil weeds are weeds, which due to the decrease in rainfall in the Iran and the importance of changing the growing season from spring to autumn, it is necessary to pay attention to the control of weeds in this planting system. Considering the existence of grass killer herbicides in the Iran, chemical control of grassy weeds in chickpea and lentil is less difficult, and for chemical control of broad leaf weeds, pyridite, trifluralin, fumsafen, isoxaflotel and piroxasulfone and the mixture of sulfentrazone + flumioxazin herbicides have been reported to be acceptable in chickpea and pendimetalin for lentil.