WEED RESEARCH JOURNAL
Year:2017 | Volume:9 | Issue:2 |Papers Count:6

This study was conducted to evaluate the effect of temperature and moisture on germination of Eryngium caeruleum seeds as factorial experiment in a completely randomized design with three replications at weed science laboratory, college of agriculture and natural resources, university of Tehran. Factors were seven temperatures (5, 10, 15, 20, 25, 30 and 35° c) and seven levels of moisture (0,-2,-4,-6,-8,-10 and-12 bar) and hydro thermal time model used for description of Eryngium caeruleum germination. Germination parameters including base temperature (Tb), optimum temperature (To), the minimum moisture needed for start of germination (Wpb), decreasing coefficient (b) and standard deviation (Sigma) were obtained 2. 39, 23. 52,-0. 93, 0. 13 and 0. 34 respectively, affected by different levels of temperature and moisture by using hydro thermal time model. The results also showed that germination percentage and rate increased up to-4 bar in base temperature and these germination characteristics reached to their highest level in optimum temperature. According to the results of this study, it can be said that the seeds of Eryngium caeruleum do not have resistance to the water stress at very low and very high temperatures, and have the maximum resistance at 20° c.

In order to investigate the changes in cardinal temperatures of wild mustard seed germination during the dormancy elimination, a split plot experiment was conducted as completely randomized design in three replications in the Seed Research Laboratory of Agricultural and Resource University Natural Gorgan in 2017. The main factor was different temperatures (5, 10, 15, 20, 25 and 30° C) and sub-factor was different concentrations of gibberellic acid (GA: 0, 100, 300, 500, 1000, 1500, 2000 ppm). A dent-like function was used to describe the response of the germination rate to temperature. For different germination stages, the base temperature decreased from 2. 9 to 3. 4 ° C in GA0 towards-1. 2 to-2/0 ° C in GA2000; the ceiling temperature was 25 ° C at GA0 and increased to 33. 3 ° C in GA2000; the temperature tolerance range from 21. 6 to 22. 1 ° C in GA0 reached 32. 4 to 35. 1 ° C in GA2000. Due to cardinal temperature changes, the dormancy of wild mustard is a non-deep physiological dormancy type 1. Seeds with dormancy initially have the highest germination at low temperatures, and when they come out of dormancy, they germinate at high temperatures and the temperature range of germination increase. The estimated parameters in the present study can be useful in simulation models of seed bank and for further studies on the biology and ecology of wild mustard.

In order to evaluate mixture of rimsulfuron (Titus) and metribuzin (Sencor) herbicides on weed control, yield of potato (Solanum tuberosum L. ) a factorial experiment conducted on the base of Randomized Complete Block Design in 3 replications and use of Agria cultivar of potato in Research Field of Mohaghegh Ardabili University at 2016. The treatments consist of rimsulfuron herbicide in 0, 12. 5, 25, 37. 5 and 50 gr ai/ha and metribuzin in 0, 153. 25, 306. 50, 459. 75 and 613 gr ai/ha for 5 herbicide mixture percentage (as: 0: 613, 12. 5: 459. 75, 25: 306. 50, 37. 5: 153. 25 and 50: 0) and the second factor was different time of application of this herbicides include (pre-plant and potato emergence). In order to results of experiment, use of rimsulfuron + metribuzin herbicide mixture improved the efficacy of each one of herbicides in weed control by means of lowering weed density. The results of stem yield and total yield of potato tuber showed that use of 306. 50 gr ai/ha metribuzin + 25 gr ai/ha rimsulfuron in emergence stage induced 10. 53% and 61. 83% yield of stem and total yield in comparison to weedy.

In order to evaluate fungal colonization of roots of canola and some weed species eight separated trails were carried out as completely randomized design with 5 replications in 2017 and 2018. Experimental factores were fungal inoculation of Piriformospora indica and non inoculatrdcontrol on nine plant species of Brassica napus, Cardaria draba L., Sisymbrium irio L., Descuaraiana Sophia L., Capsella bursa pastoris Medik., Sinapis arvensis L., Avena ludoiviciana Dureu. and Phaiaris minor Retz. After filling out pots with 0. 6 lit of autoclaved soil, germinated seed were transferred in to the pots and were thinned after wards, leaving two seedlings per pot. Plants were harvested 10 weeks after transplanting. Total biomass, root length colonized and P. indica growth responses were analyzed. The results showed the effects of different fungi on canola and weed species growth were varied. The percentage of colonized roots was different among plant species. The highest root colonization by fungi was observed in canola by 50. 49 percent and the lowest one was observed in S. arvensis L. Total dry weight of in species C. bursa-pastoris, C. draba, S. arvensis and P. minor was decreased by colonization of fungi. Fungi growth response of weeds was different from-16. 33 to +50. 49.

In order to study to evaluate the tolerance of some tomato (Lycopersicon esculentum L. ) cultivars and landraces to Egyptian broomrape (Orobanche aegyptiaca pers. ) an experiment was conducted as completely randomized design with 3 replications in greenhouse conditions. In this experiment, 23 cultivars and 4 landraces of tomato were planted in two series of treatments (infected and uninfected (control) with broomrape). Results showed that tomato cultivars and landraces had a significant difference in their biomass and broomrape reduced fresh and dry weight of all all tomato cultivars and landraces significantly. Urbana, GS15, Marconi cultivars and all landraces of tomato were the most susceptible hosts to broomrape. In contrast Cal-jN3, Primo, Hyb. Petopride V, Hyb. Xaman and Hyb. Super Set showed lowest loss percent of shoot and root dry weight in present of broomrape compared to other cultivars. Also, comparison of tomato landraces and cultivars showed that despite higher biomass production of the landraces in control treatments, they were more susceptible and suffered more severe damage in infected treatments.

Evolution of resistance in weeds leads to induction of fitness cost. Five winter wild oat biotypesresistant to haloxyfop R methyl ester collected from Kalaleh Township located in Golestan province were evaluated along with the susceptible biotype in terms of variation in cardinal temperatures in the following study. The experiment was conducted at laboratories of Gorgan University of Agricultural Sciences and Natural Resources as completely randomized design with 4 replications each consisting of 25 seeds. Petri dishes containing seeds were incubated and monitored continuously at temperatures 5-40 ° C (at 5° C intervals) following a 72 hours vernalization at 4° C. Non-linear regression models were used to quantify germination response to temperature. No notable difference was observed between winter wild oat biotypes and beta model at 50 percentile was the most suitable model to describe cardinal temperatures. Base, optimum and ceiling temperatures were estimated between-4. 21 to-5. 91, 23. 37-23. 94 and 36. 99-37. 54 ° C, respectively. Thermal tolerance range of susceptible and resistant biotypes were not significantly different. Susceptible and resistant biotypes showed similar response. Lack of fitness cost regarding cardinal temperatures demonstrates that similar non-chemical management practices including early sowing may be implemented to control resistant and susceptible biotypes germination and emergence.