نشریه دانش علفهای هرز
سال هجدهم شماره 2 (پاییز و زمستان 1401)

Whitefly is one of the polyphagous and most important pests of greenhouse crops, which reduces the quantitative and qualitative yield of crops. To study th resistance of some weeds and green house plants as trap crop in controlling whitefly, an experiment was conducted in a completely randomized design with eight treatments and 10 replications in the greenhouse of flower garden in Aligudarz city, 2018. The effect of trap plants on all traits of antixenosis and antibiosis mechanisms of whitefly was significant at 1%. The highest number of adsorbed insects and whitefly eggs were observed in cucumber (Cucumis sativus) and prickly lettuce (Lactuca scariola) and the lowest in cock seggs (Cestrum nocturnum). Although black nightshade (Solanum nigrum) was not attractive treatment for feeding adult whitefly, but after cucumber it was the most attractive treatment for spawning and the observed the highest percentage of egg and nymph mortality percentage (79%) in this treat. Also, the highest growth length of whitefly was observed in jerusalem chery (Pseudocapsieum solaum) (47 days) and black nightshade (46 days) treatments, and the lowest in cock seggs. Therefore, cucumber and prickly lettuce due to the attractiveness of feeding and laying for insects (low antixenosis resistance and jerusalem chery and black nightshade, due to higher egg and nymph mortality percentage and growth length (high antibiosis resistance): can be used as a trap plant to reduce the number of generations and control of whitefly and increasing of production of greenhouse crops.

This study was conducted to determine the resistance, as well as the effect of temperature, drought and acidity on the relative fitness of wild mustard ecotypes. Sampling was performed from 313 rain-fed wheat farms in Eslamabad-Gharb located in Kermanshah. After sowing the seeds in the greenhouse, the seedlings were treated by the recommended dose (15 g.a.i.ha-1) of Tribenuron methyl (granstrar) 75% WP in the 2-4 leaf stage and sensitive and resistant ecotypes of wild mustard were identified. The results of dose-response test (Tribenuron methyl concentrations: zero, 3.75, 7.5, 15, 30, 60, 120, 240, 480 g.a.i.ha-1) showed that the amount of LD50 in the susceptible and the resistant ecotype were 22.2 7 and 39.85 g.a.i.ha-1, respectively and the resistance index was 5.52 resistant ecotype. Susceptible ecotype at 20 and 25 ° C had higher germination percentage and vigor than resistant ecotype. In general, wild mustard was sensitive to reduction of soil osmotic potential, but the sensitivity of the resistant mass was higher than the susceptible ecotype. The highest germination percentage in both susceptible and resistant ecotypes was observed in slightly acidic to neutral pH (6 to 7) that the germination percentage of resistant ecotypes in this range was significantly higher than the susceptible ecotype. Considering the temperature conditions, drought stress of rain-fed fields and also the alkalinity of the soil in the study area, it seems that if the pressure caused by herbicide application is relieved, the susceptible ecotype will have more fitness to environment condition of studied region.

Weeds reduce crop growth and yield through interference and competition with the crop. Polygonum convolvulus L. is an annual weed from the Polygonaceae family. In order to investigate the effect of different treatments in breaking the P. convolvulus seed dormancy, a study was conducted in the weed research laboratory of Gorgan University of Agricultural Sciences and Natural Resources in 2020. The treatments included after-ripening (for seven months), different concentrations of gibberellic acid and potassium nitrate, hot water treatment, mechanical scarification with sandpaper, sulfuric acid (98%), chilling at 4 °C and cutting the seed coat. The results showed that after-ripening, gibberellic acid and potassium nitrate, immersion of seeds in hot water and scarification with sandpaper had no effect on seed germination. Treatment of P. convolvulus seeds with sulfuric acid as well as chilling caused germination in the seeds. Also, scarification the P. convolvulus seed coat around the embryo caused maximum seed germination (87%). The highest germination percentage of P. convolvulus seeds was observed in combined treatment of sulfuric acid treatment (20 minutes) and chilling (15 day) (91.66%) and scarified the seed coat (87%), which were not significantly different. According to the obtained results, it can be stated that the mechanical resistance of seed coat against embryonic growth is the main cause of dormancy in P. convolvulus seeds.

In order to study efficacy of prosulfuron+dicamba for control of wheat broadleaf weeds, an experiment was conducted in randomized complete block design with four replications at Zarghan, Dezful, Karaj and Mashhad regions during 2018-2019 cropping season. The treatments were included of bromoxynil+MCPA (1.5 l ha-1 of Bromicide-MA® 40%), bromoxynil + 2,4-D (1.25 l ha-1 Buctril Universal 56%), bazagran+dicloprop ( 2 l ha-1 Basagaran-DP® 6.56%), triasulfuron+dicamba (165 g ha-1 Lintur® 70%), and the new herbicide prosulfuron+dicamba (300, 400 and 500 g ha-1 alone or mixed with adjuvants). The results showed that prosulfuron+dicamba in all doses, alone or mixed with adjuvants, caused a decrease in the dry weight of the dominant weeds in Karaj (75 to 100%), Zarghan (85 to 93%), Dezful (70 to 100%) and Mashhad (42 to 97 percent), but compared to other herbicides, there was no significant difference in saving wheat yield in most areas. Lintur® was the most inefficient (50%-75%) and Buctril Universal® was the most efficient (more than 85%) herbicide in our experiment. The most important weeds include Descuriania sophia, Fumaria vailantii, Galium tricornutum, Centaurea depressa, Carduus sp., Rapistrum rugosum, Veronica persica, Malva neglecta and Sinapis arvensis. As a recommendation, prosulfuron+dicamba can be used in the dose of 300 g ha-1, alone or mixed with adjuvants (0.5% v/v of Cytogate). No visual damages were observed from prosulfuron+dicamba application on wheat.

To evaluate the application of the image processing method (RGB and Lab methods) compared to the visual evaluation method for determining the seed viability or stainability of wheat (Triticum aestivum) and hairy vetch (Vicia villosa) using tetrazolium test, a factorial experiment based on a completely randomized design with three replications was conducted in the laboratory of Department of Mechanical and Biosystems Engineering of the Faculty of Agriculture, Tarbiat Modares University in 2019. The experimental factors included methods for determining seed stainability (visual assessment, RGB, and Lab methods), two plant species (wheat and winter vetch), physical stratification (cross cutting, longitudinal cutting, sanding, needling, and control), and duration of exposure to tetrazolium (10 and 24 hours). The results showed that the stainability of seeds exposed to tetrazolium for 24 hours was higher than those exposed for 10 hours. The highest stainability of seeds was observed in the longitudinal cutting treatment for both wheat and hairy vetch species in the all three determining seed stainability methods. The RGB and Lab methods showed the highest stainability percentage for wheat and hairy vetch seeds, respectively, where the seeds were cut longitudinally. Therefore, the RGB and Lab image processing technique can be used as a fast, precise, and new method for determining the seed viability of crops and weeds through the tetrazolium test.

Butomus is an aquatic weed belonging to the butomaceae family, which has invaded the paddy field ecosystem in recent years. This study was carried out in order to investigate some eco-physiological aspects and chemical management of butomus in paddy field. In the field studies; the emergence time, height, tillering, flowering, and life cycle of butomus in the paddy field ecosystem and the germination rate of bulblets in the laboratory and the effectiveness of pre-emergence and post-emergence soil-applied herbicides in pot experiments, and also foliar-applied herbicides were investigated. The results revealed that waterlogged lands are the main habitat of butomus, and the bulblets are the main reproductive organs of this weed. While puddling, about 100% bulblets are separated from the rhizomes which floated on the water and dispersed. Both rhizomes and bulblets of butomus were submergence tolerant and germinated from 15 cm or more of submergence. Flowering of butomus preceded about one week the initiation of rice panicle. Each plant produced dozens of flowering tillers taller than rice stalk, hundreds of spindle-shaped bulblets up to 25 mm long, with more than 95% emergence rate. In pre-emergence application, soil-applied herbicides including clomazone+pendimethalin, oxadiargyl, pretilachlor, pendimethalin, and thiobencarb, controlled butomus less than 65% and sulfonylureas herbicides; pyrazosulfuron, metazosulfuron, flucetosulfuron, and bensulfuron methyl provided more than 85% control of butomus. The effectiveness of sulfonylureas in the post-emergence application was around 10% lower compared with pre-emergence application. Foliar applied herbicides; penoxsulam and propanil controlled butomus 62% and 70% and its control by bispyribac sodium, penoxsulam+cyhalofop-butyl, bentazon+MCPA, and pyribenzoxim were 80, 86, 89, and 99%, respectively. Therefore, it is recommended to apply a soil-applied sulfonylurea or a foliar-applied herbicide in the paddy fields infested with butomus in addition to the specific herbicide for barnyardgrass control.

In order to evaluate germination response of Dinebra weed to alternating temperatures and (40/30, 35/25, 30/20 and 25/15 °C day/night) in two light conditions (light/dark and continuous dark), osmotic stress (0, -0.2, -0.4, -0.6, -0.8, 1-, and -1.2 MPa), salt stress (0, 50, 100, 150, 200, 250, 300, and 350 mM) and seed burial depth (0, 0.5, 1, 2, 4, 6, and 8 cm), four separate experiments were conducted at Agricultural Sciences and Natural Resources University of Khuzestan during 2019 with four repetitions. The highest germination percentage was observed at alternating temperatures 30/20 °C in light/dark (93 percentage) and the lowest at 25/15 °C in continuous dark condition (5 percentage). Also, the germination percentage was higher in light/dark than continuous dark condition. Salinity and drought stresses required to inhibit 50% germination of the maximum germination were 54 mM and -0.49 MPa, respectively. Also, with increasing the seed burial depth, the emergence of Dinebra decreased and stopped completely at depth of 2cm. The results indicated that this weed is sensitive to salinity and drought. It is recommended to use plowing (especially at night) and planting in the temperature range of 25/15 °C in the integrated weed management program to reduce the emergence seedlings.

Among biotic and abiotic stresses, broomrape (Orobanche cernua L.) is the most important factor in reducing the yield of tobacco plant, so it is necessary to determine the genotypes that produce relatively acceptable yield under stress conditions. In order to identify tolerant genotypes to broomrape stress, 92 tobacco genotypes were investigated based on randomized complete block design with three replications in two control (without broomrape) and stressful (along with broomrape) environments at the research farm of Urmia tobacco research Centre during two successive years in terms of flowering date, plant height, leaf number, fresh and dry weight of root, leaf area, fresh and dry weight of leaf, fresh and dry weight of plant aerial parts. Broomrape stress was applied by mixing 0.06 grams of broomrape seeds with pot soil. The results of analysis of variance in the two experimental environments during two years showed that there is not significant difference between the experimental environments for most of the studied traits. There was a significant difference between genotypes for all of the studied traits. Genotype × environment interaction was significant for all of the studied traits indicating the presence of different reaction of genotypes within each environment. Mean comparisons showed that broomrape stress reduced the mean of all morphological traits. So that the fresh weight of shoots except leaf (23.50%) and dry weight of shoots except leaf (23.70%) had the highest decrease percentage; whereas flowering date (-0.7%) and number of leaves (5.02%) had the lowest decrease percentage. In general, based on the results of the percentage reduction of mean of studied traits, it was found that C.H.T.283-8, Kharmanli, Immni 3000, F.K.40-1, Pz17, K.B, L 16a, Rustica, C.H.T.209.12e, C.H.T.283-8, Basma 181-8, SPT 413, T.K.L and Samsun 1 are among the most susceptible genotypes to broomrape stress. While Ploudive 58, Ts 8, Mutant 3, OR-379, P.D.328, Jahrom14 and Lengeh genotypes did not show any decrease in any of the traits and are tolerant genotypes to broomrape stress.

A greenhouse experiment was conducted to investigate Citrullus colocynthis (L.) Schrad. response to some pre-planting and post-emergence herbicides application in Department of Agronomy and Plant Breeding, University of Tehran, in 2015. The experimental design was randomized complete block design (RCBD) with seven treatments and four replications. Treatments were trifluralin, pendimethalin, metribuzin as pre-planting herbicides and imazethapyr, rimsulfuron, bentazon as post-emergence herbicides as well as no herbicide application (control). Fresh weight, dry weight, survival percent and visual evaluation (EWRC) of seedlings (15 and 28 days after spraying) were measured. Results showed that the treatments were significantly different in terms of fresh weight, dry weight and seedling survival percent (P < 0.01). The highest weed fresh weight reduction percent compared to the control belonged to metribuzin application with 92.4%, that there was no significant difference with imazethapyr. Metribuzin with 83.8% had the highest dry weight reduction percent compared to the control. Visual evaluation in both periods of time showed that the post-emergence herbicides had the significant effect on weed seedlings. This study was a primary investigation to select a proper herbicide in chemical management of C. colocynthis, therefore, the results can be used for herbicides screening in supplementary experiments.