مجله پژوهش علف های هرز
سال چهاردهم شماره 2 (پاییز و زمستان 1401)

In order to investigate the effect of different sources of nitrogen fertilizer on the relative frequency, density and biomass of safflower, a factorial experiment was conducted in a randomized complete block design with three replications located in the research farm of faculty of agriculture university of Jiroft in 2018-2019 year. The first factor at two levels included the use of manure and non-use of manure, the second factor included different nitrogen fertilizer sources at five levels of control, urea fertilizer, urea fertilizer with sulfur coating, ammonium nitrate, nitroxin and nano nitrogen. The results showed that in all three stages of sampling weeds, Clover (Trifolium repens L.) and Umbrella sedge (Cyperus rotundus L.) weeds had the highest and Bermudagrass (Cynodon dactylon) and Sorrel (Rumex crispus L.) had the lowest relative abundance. Different sources of fertilizer had a significant effect on biomass weeds of clover, umbrella sedge, common mallow and other weeds during three sampling stages. Based on the results of mean comparison, the highest biomass was obtained of clover weed in the first stage in the treatment of manure with chemical fertilizers urea (17.04 g). The lowest biomass was obtained in no manure in control (6.47 g) and nano nitrogen fertilizer (4.63 g). Shannon and Margalef indices in the first stage of sampling 0.96 and 0.94, the second stage of sampling 0.79 and 1.06 and the third stage of sampling 0.63 and 1.11 respectively in the treatment of manure was more than to non-use manure. Sources of urea and urea fertilizers with sulfur coating had higher weed diversity index than other treatments. According to the results of this study, it is suggested to use biological sources of nitrogen in order to prevent weed infestation and competition with the target plant.

AbstractThe use of soil fungi such as Fusarium is one of the strategies for controlling and managing parasitic plants. Accordingly, in order to evaluate the pathogenic potential, Fusariumoxysporum was isolated from the stems of infected plants of Phelipancheaegyptiaca and after identification, it was tested in a greenhouse using two treatments inoculated with fungal suspension. F. oxysporum and control treatment (no inoculation) were performed. In the inoculated treatment, fungal suspension with a concentration of 107 × 5 spores per ml, at a rate of 50 ml per pot and in the control treatment, tap water was used. Studied traits were including total number of parasite stems, number of parasite stems removed, number of diseased and dead parasite stems, number of healthy parasite stems, and number of flowering stems, number of parasite stems per plant, stem height of the parasite and the dry weight of Egyptian broomrape and tomato plants. The results of comparing the mean of the two treatments with t-test showed a significant difference in the dry weight of broomrape and tomato so that the mean dry weight of broomrape in the treatment inoculated with F. oxysporum (6 g), compared to the control treatment (16.84 g), was 2.8 times lower. Also, the highest dry weight of tomato (36.43 g) was observed in the inoculated treatment with F. oxysporum, which increased by 44.27% compared to the control with 25.25 g. In the host range test, none of the tested plants showed signs of persistent infection, including permanent wilting and necrosis. In general, the use of this fungus in the biological control of Egyptian broomrape could have an effect on all studied traits, reduce the dry weight of Egyptian broomrape and increase the dry matter of tomato.

The present study was conducted in 2018 at research farm of Dashte-Naz, Sari to evaluate the effect of weed management methods on yield and yield components of Aerobic and Neda cultivars of rice under seeding and transplanting conditions. This experiment was conducted as combined analysis in places with three replications. The factors included planting method (seeding, transplanting), genotype including aerobic line and Neda and weed management (as the place) including 1-hand weeding (weed-free), 2-control (weed-infested), 3-bispyribac sodium, 4-pendimethalin, 5-traifamone, 6-bispyribac sodium+pendimethalin and 7-triafamone+pendimethalin. The results showed that the highest number of fertile tillers compared to control was associated with the hand weeding treatment and panicle length in the aerobic genotype was higher compared to Neda. The most filled grain number was obtained in hand weeding under seeding conditions followed by bispyribacsodium+pendimethalin and triafamone+pendimethalin. The amount of empty grains were higher under transplanting method compared to seeding. Also, the highest yield in both Neda and the aerobic genotype was observed in hand weeding followed by bispyribacsodium+pendimethalin and triafamone+pendimethalin. Considering labor costs and time consuming nature of hand weeding, applying the combination of the studied herbicides is recommended to improve agronomic traits of rice.

In order to investigate the variation in germination rate, cardinal temperature and hydrothermal time parameters of wild mustard seed in different water potentials were designed and implemented during the study in gorgan university of agricultural sciences and natural resources, in 2017 as a split plot done in a completely randomized design with three replications of the municipality. In this research, germination modeling was performed well. To describe the germination rate response to temperature in different potentials of water 0, -0.2, -0.4, -0.6, -0.8 MPa were used from the dent-like function. By applying different concentrations of gibberellic acid (100, 300, 500, 1000, 1500 and 2000 ppm), the process of germination changes in the studied temperatures was incremental, so that the highest germination percentage was related to gibberellic acid 2000 ppm. By reducing the potential at each level of gibberellic acid, the base temperature increased and the lower and upper optimum temperature and the ceiling temperature decreased. The hydrotime coefficient in control seeds decreased significantly with increasing temperature and the water potential was increased. The hydrotime coefficient and base water potential increased with decreasing gibberellic acid. The results showed that the coefficients obtained by the hydrothermal time model were of relatively high precision and the constant value of hydrothermal time, base water potential and base temperature in control seeds were 1173.83 MPa ºC h-1, -0.09 MPa and 3.07 °C and for gibberellic acid with concentration of 2000 ppm were 315.57 MPa ºC h-1, -0.50 MPa and -1.22 ºC, respectively. Changes in the base water potential for 50% of germination in gibberellic acid 1500 and 2000 ppm treatments had a two segmented trend up to 20 °C so that it -0.7 to -0.6 MPa and increased above 20 °C the maximum value at 30 °C.

Awareness of the existence of specific weeds in an area can be better decided and planned about their control methods. Otherwise, applying different control methods will not have the desired effect. In this study, in order to identify and prepare maps of weed distribution in canola fields of Sorkhankalateh region of Gorgan county, 50 fields were selected and sampled based on W pattern in two stages. Then, using current formulas, frequency, relative frequency, species uniformity and biodiversity indices were calculated. We were recorded the geographical coordinates and altitude of the sampling location by a GPS, Garmin touch model for each field. The obtained information was processed using Arc GIS software (var. 10.3) and the distribution maps of all weeds in canola fields were prepared. The results showed that 41 weed species (20 species in the pre-spraying stage and 21 species in the post-spraying stage) from 14 plant families were present in surveyed fields of Sorkhankalateh region, which Poaceae, Asteraceae, Fabaceae, Brassicaceae and Polygonaceae were the most important plant family. In the pre-spraying stage, the share of annual, perennial and biennial species was 75, 15 and 10%, and in the post-spraying stage, their share was as 66.66, 23.80 and 9.52, respectively. In terms of growth form, in the pre- and post-spraying stages, 8 and 76.19% species were belonged to dicotyledonous and 20 and 23.80% were as monocotyledonous, respectively. According to the results of biodiversity indices, weeds in the post-spraying stage had more diversity than the pre-spraying stage. Also, the results related to weed distribution maps showed that most of the dominant weeds were distributed in the Eastern and southern parts of the studied region.

Compared to other agricultural sciences, weed science is a new science, but it has been considered as an old tradition and method. Weeding was one of the first method in weed control, but with the over of time and the invention of agricultural tools, new methods for weed control were introduced and have been more or less used until. However, Today, challenges have been created in this science, the most important of which are the emergence of herbicide-resistant biotypes, reduction of the effectiveness of old herbicides, the lack of weed management methods and the reduction of the introduction of herbicides with new modes of action. In the future, according to the need, it is important to introduce natural compounds as a suitable option to discover a new site of action and produce bio-herbicides. Also, genetic engineering will be considered as another tool for adjusting the selective properties of herbicides and creating new management methods. Computer science and robotic, which include electronic eyes, sensors for distinguishing crops from weeds, and other tools related to engineering sciences, are also important and needed in weed management that are being developed and processed. Also, combining old methods with new tools can be considered as a suitable option for sustainable management of weeds.