WEED RESEARCH JOURNAL
Year:2016 | Volume:8 | Issue:2|Papers Count:6

The study of weed flora changes under different crop management system is an important key to achieve successful weed management in every agroecosystem. This study was conducted in order to evaluate the effect of potato monoculture continuing on weed density and diversity in the conventional agroecosystems of Jiroft region-at 2015-16 in University of Jiroft, Iran. Agroecosystems, which was assessed in this study, were potato monoculture systems included continues monoculture period less than 3 years (S1), 3-6 years (S2), 6-9 years (S3) and more than 9 years (S4) and long-term fallow (F). Sampling was performed using systematic-randomized method in three stages (before sowing, 60 days after planting and 30 days after harvest) with 1×1 m2plot. Base on results 28 weed species were observed which 17 species of them were common in all five agroecosystems. ANOVAs' result showed there were significant effect of continuing in potato monoculture on density weeds as Cyperus rotendus L., Cyperus esculentus L., Trifolium repens L., Chenopodium album L., Cynodon doctylon L., Amamrantus retrofloxios L. and Digitaria sanguilanis L. Increase of potato monoculture period from 3years in agroecosystem of S1 up to 9years in S4 agroecosystem caused to significant increasing in weed density so maximum weed density was observed in S4. Evaluating of diversity indices showed continuing in potato monoculture period had significant effect on diversity indices includes of Simpson, Shannon, Margalef, Menhinik and Evenness, so highest value of these indices (Simpson: 0.97, Shannon: 3.65, Margalef: 5.24, Menhinik: 2.99) and lowest value (Simpson: 0.87, Shannon: 2.22, Margalef: 3.88, Menhinik: 2.00) were observed respectively in agroecosystems of S4 and F. In summary continuing in period of potato monoculture caused to significant increase in weed flora density and diversity indices.

In order to study the effect of drought stress and salt stress and temperature on Germination and Seedling vigour of resistant and susceptible biotypes of wild mustard (Sinapis arvensis L.) to Acetolactate Synthase Inhibitors from three provinces Golestan, Kermanshah and Khoozestan, three experiments were conducted as factorial based on completely randomized design in four replications. Different salt and drought stresses levels were 0, -3, -6, -9 and -12 bar that created by NaCl and PEG respectively. Examined temperatures were 0, 5, 10, 15, 20, 25, 30 and 35oC. In each three experiments second factors was Biotypes of Wild Mustard include three susceptible (Ker-1, Kh3 and G9) and three resistant biotypes (Ker-2, Kh5 and G3). Studied traits were germination percent and rate, seedling length and seedling vigor index. Result showed salt and drought stresses reduced vigor and early growth of all biotypes but this reduction was different in biotypes. Optimum temperature for all biotypes were observed in 15 and 20oC. In almost conditions, different of resistant and susceptible biotypes of Golestan were not significant but in Khuzestan province, vigour of resistant biotype was lower than susceptible biotype but about Kermanshah biotypes, resistant biotype in many conditions had higher vigour than susceptible biotype. Results showed that resistant biotype of Golestan and Kermanshah caused to high vigor, in competition with susceptible biotypes and crop had better and faster germination and have to find other herbicide or nonchemical methods to control these biotypes.

Access to weed distribution maps can be very useful in planning their management. Locating areas prone to infection with new entrant weeds is needy to knowledge of ecological characteristics of these plants such as cardinal temperatures, EC and pH. In order to investigate the effects of temperature on germination and determine the main germination temperatures (base temperature, optimum and ceiling for germination) of ivy-leaved morning glory, seeds incubated at 10, 15, 17, 20, 25, 30, 35 and 40oC. To determine the cardinal temperatures, Original beta, Modified beta, segmented and dent like models were used. The results indicated that the original beta model was superior than the other models and base, optimum and ceiling temperatures for seed germination were 10, 25.91 and 41.22oC respectively. The results showed that ivy-leaved morning glory has high tolerance ability to soil salinity. So, germination percent of this plant can be reduced by 50% in salinity of 45dS.m-1. In addition, germination present of these plants in acidic pH was higher than the alkaline pH. Distribution maps indicated that there were no limitations regarding temperatures and EC for germination and establishment of this weed through the Golestan Province. But regarding pH, there is a major in increasing distribution extent in the province. So that only a small section of Kalaleh and Galikesh lands are suitable in this regard.

Afield experiment was conducted in 2014 at the Research Station of Agricultural Faculty, Bu-Ali University to evaluate the effect of water stress and replacement itercropping patterns of soybeen and millet on weed population and species diversity. A split plot design with three replication was used for the experiment. Main plots consisted of three levels of water stress. The subplots consisted of five levels of replacement intercropping as soybean monoculture, millet monoculture, 75% soybean+25% millet, 50% soybean+50% millet, and 25% soybean+75% millet. The results showed that the intercropping patterns of 50S: 50M and 25S: 75M were successful in reducing weed plant density and diversity in comparison with soybean monoculture. The highest plant density (27 plant Square meters), shannon-wiener diversity index (1.46) and margalef index (1.29) were obtained in soybean monoculture. Moderate water stress has no effect on plant density and diversity indices of weeds. Severe water stress (Irrigation after 120 mm evaporation from pan), reduced plant density, Shannon- Wiener index and species richness of weeds compared to non-water stress, about 68.71, 48.36 and 38.80 percent, respectively. The highest Simpson dominance index (0.61) was obtained in severe stress.

Dodders are parasitic flowering plants and accurate identification is very important. Using a software programming with VB.net named as "Dodders of Iran" was designed and developed. This application provides information in text, numerical and descriptive 34 ID contains 18 species, two subspecies and 14 varieties along with their distribution points were set based on interactive identification keys. The common operating systems such as Windows for this software is applicable and learn more and download a provisional version especially since the results of this paper are introduced. Thus, given the importance of the diversity and distribution of dodders, such as the ability to update information facilities, the possibility of use in field conditions, applicable even for non-experts, the possibility of combining morphological and molecular characteristics, technical reports, extension and localization of technical knowledge for weed identification and can be extended to identify even for quarantine species, is noteworthy in this application.

In order to control weeds in transplanting onions in Hormozgan province, an experiment was conducted based on randomized complete block design with eight treatments and three replications in research farm of Agriculture Shamil district of Bandar Abbas city functions during 2015-2016. The treatments were: Control (no control), Oxyfluorfen (Goal) (EC%24) at 0.48 Kg a.i.ha-1, Sethoxydim (Nabu-s) (EC%12.5) at 0.375 kg ai.ha-1, Haloxyfop-R methyl ester (Gallant Super) (EC%10.8) at 0.81 Kg a.i.ha-1, Oxadiazon (Ronstar) (EC%48) at 1.44 Kg a.i.ha-1, Chlorthal dimethyl (dacthal) (WP%75) at 6 Kg a.i.ha-1, Ioxynil (Totril) (EC%22.5) at 0.45 Kg a.i.ha-1 and weeding (control weeds growing in all periods). The results showed that the density, dry weight of weeds and yield of onion was affected by treatments. Mechanical methods (weeding) in between treatments the highest effect on the density, dry weight of weeds and yield of onion was. So that the yield of onion increased at a rate of 5.50 tons.ha-1. Among the herbicides, herbicide oxyfluorfen (2 to 4 leaf stage of weeds) after mechanical method have the greatest impact on the density, dry weight of weeds and yield of onion accounted. As weed density and dry weight, by 65.2, 63.1% respectively, and yield of onion as much as by 509% increased performance. In total, herbicide efficacy in controlling weeds oxyflorfen and Ioxynil, C. album L., A. retroflexus, P. oleracea, M. sylvestris L. and C. rotundus L. was good. Chlorthal dimethyl on A. retroflexus and C. rotundus L., Oxadiazon on M. sylvestris L., A. retroflexus, and C. rotundus L. weed control and herbicide Haloxyfop-R methyl ester, P. oleracea and C. album L. and C. rotundus L. was good. In first grade mechanical methods (weeding) with good control of weeds and the highest yield of onion best treatment was experimental and oxyflorfen in the second grade herbicide and another herbicide Oxadiazon and Ioxynil is recommended in the Hormozgan province.