نشریه بوم شناسی گیاهان زراعی
سال هشتم شماره 3 (پیاپی 28، پاییز 1391)

Tolerant seeds to drought stress could play significant role in steady seedling establishment and subsequent yield increase. In order to study the germination and initial seedling growth indices of safflower (cv. Sina) seeds with different thousand kernel weights (TKW) of 23, 23.83, 25.13 and 27.27 g, under different drought stress intensities, an experiment was carried out as factorial based on a completely randomized design in Physiology Laboratory of Zanjan University. Drought stress levels comprising 0 (control), -4 and -8 bar were obtained using polyethylene glycol 6000. Increasing drought stress intensity significantly decreased germination percentage from 81.8% in control to 57.8% in -8 bar. Seeds with higher TKW were better in terms of germination percentage and germination coefficient rate. The seeds with 27.27 TKW produced longer radicle and plumule in drought stress condition. Besides, seeds with higher TKW showed higher vigor index and seedling dry and fresh matter. In conclusion, seeds with higher TKW showed higher germination indices and were more tolerant to drought stress.

In order to study the effect of chemical control of Echinochloa crus- galli in different growth stages and determine the best herbicide application time and amount on the yield of oil-seed sunflower cv. Urofloure, an experiment was conducted at Agricultural and Natural Resources Research stations of Khoy region as split-split plot based on a randomized complete block design with three replications in 2006. Factors comprised of herbicide type as main factor (Haloxyfop-ethoxyethyl, Setoxydim and cycloxydim along with a control), herbicide application time as the sub-factor (4-6, 8-0 and 12-14 leaf stages) and herbicide dosage as the sub-sub factor (1 l.haP -1 Pand 2 l.haP -1 P). The measured traits were number of seeds per plant, weigh of thousand seeds, seed yield and oil yield. Results showed that maximum weight of thousand seeds was obtained by application of one litre per hectare Cycloxydim at 4–6 leaf stage. Application of one litre per hectare Haloxy fop-ethoxyethyl at 4–6 leaf stage resulted in maximum seed yield (4961 kg.haP -1 P). Also, the maximum oil yield was obtained with application of 2 litre Haloxy fop-ethoxyethyl at 8–10 leaf stage and one litre Haloxy fop-ethoxyethyl at 4–6 leaf stage (2315 and 2310 kg.ha,P -1 P respectively). Based on the results, Haloxy fop-ethoxyethyl application at 4–6 leaf stage caused maximum number of seeds per plant and the highest oil and seed yield. Haloxyfop ethoxyethyl was also better than other treatments in weed control.

The effect of nitrogen fertilizer levels and row spacing was studied on grain yield and morphological characteristics of rapeseed (Brassica napus L., var. Hyola 308) as second cropping in paddy fields of Rice Research Institute of Iran. experiment was carried out for two years as factorial based on a randomize complete block design with three replications. The first factor was four nitrogen fertilizer levels from urea including 98, 140, 182 and 224 kg.haP -1 P. The second factor was row spacing at three levels of 20, 25 and 30 cm. In this experiment, some important growth characteristics such as plant height, number of siliques per plant, number of seeds per silique, biological yield, harvest index, grain yield, oil yield, initiation of flowering and growth periods were studied. Results of the combined analysis of variance showed that there were no significant difference for grain yield between the two experimental years. Between nitrogen levels, the treatment of 224 kg haP -1 Pproduced maximum grain yield (2189 kg haP -1 P), oil yield (1001 kg.haP -1 P), biological yield (7142 kg.haP -1 P), plant height (111.9 cm) and height of the lowest silique bearing branch from soil surface (34.4 cm). Row spacing of 20 cm showed the highest grain yield (1947 kg.haP -1 P), oil yield (887.4 kg.haP -1 P), biological yield (6652 kg.haP -1 P) and plant height (109.9 cm). Although the interactions between nitrogen levels and row spacing was not significant, maximum grain and oil yields were obtained by application of 224R Rkg.haP -1 P nitrogen fertilizer in 20 cm row spacing.

In order to study the priming effect on germination and seedling characteristics of a single cross corn (S 704), an experiment was carried out as a randomized complete block design (RCBD) with three replications at Agricultural and Natural Resources Research Center, Mazandaran province (Sari) in 2010. Treatments included seed priming with poly ethylene glycol (PEG) at concentration of 10%, potassium nitrate (KNOR3R) 0.5%, potassium chloride (KCl) 2%, normal water and a control (no priming). The results showed that the maximum germination rate was occurred for a pretreatment with poly ethylene glycol 10% and hydropriming (water). The lowest shoot wet weight and germination rate was obtained for osmopriming of potassium chloride 2%. Maximum germination rate index, average germination time and mean daily germination was observed in the control and osmopriming with KCl 2% and the highest ratio of dry weight R/S was obtained in potassium chloride 2% pretreatment. Also the weighted index of seedling vigor was obtained by seed pretreatment with polyethylene glycol 10%. In conclusion, the results of this study revealed that priming procedure improved seed germination of corn hybrid SC704 and increased seed emergence rate could eventually increase its performance. According to the results, priming by polyethylene glycol 6000 (PEG 6000) 10% and hydropriming (pure water) for 24 hours is recommended.

8TIn order to8T 8Tselect8T 8Thigh yielding8T 8Tand8T 8Tadapted8T 8Twheat8T 8Tlines for rainfed condition, 165 inbred lines of wheat with four controls were examined in a 13 × 138T 8Tsquare lattice8T 8Tdesign8T 8Twith8T 8Ttwo8T 8Treplications in the Agricultural Research Station of Zanjan University during 2010-2011. Number of effective tillers, 8Tplant height, spike length, 8Tawn length8T, 8Tnumber8T 8Tof grains per spike8T, 8Tseed number8T 8Tper plant8T, 1000 grain weight,8T grain yield,8T 8Tbiomass8T and 8Tharvest index8T 8Twere evaluated.8T 8TThe studied lines8T14T 8T14Tshowed significant differences and cluster analysis8T 8Tby8T 8TWard method categorized 1698T 8Tlines8T 8Tinto8T 8Tthree8T 8Tdistinct8T 8Tgroups. The results of8T principal component analysis 8Tand8T 8Tbiplot were relatively8T 8Tconsistent with8T 8Tgrouping8T 8Tof8T 8Tcluster analysis. According to the8T 8Tresults8T 8Tof8T 8Tgrouping8T 8Tand importance of traits in8T 8Tdrought resistance8T 8Tand8T 8Tyield8T 8Tunder8T 8Tstress conditions, third group lines were recognized as8T 8Tthe best8T 8Tlines8T 8Twith higher plant height and8T 8Tfavorable8T 8Tyield8T 8Tcharacteristics and are recommended for8T 8Tfuture8T 8Tbreeding8T 8Tprograms8T.

Fusarium oxysporum f. sp. sesami, the causal agent of sesame yellows and wilt is one of important and destructive pathogens of Sesame indicum. Management methods are mainly based on chemical control with sever environmental problems, because resistance cultivars are not introduced for this disease. In this study, to reach to sustainable agriculture goals, extract and eugenol of clove were used as a biological materials to control of the pathogen. Based on the results, application of 25, 50, 75 and 100 percentage concentrations of clove extract reduced the pathogen growth rate by 10.33%, 11.36%, 13.75% and 51.1%, respectively. Also, eugenol application at above mentioned concentrations reduced the pathogen growth rate up to 75%, 76.47%, 79.83% and 81.85%, respectively. It seems that eugenol is the major and effective components of clove to control of pathogen. The biological material used in this study did not have any negative effect on sesame seed germination and all treatment were placed in one statistical group with the control. This study is the first research for world on control of F. oxysporum. sp. sesami by biological compounds from clove and so more studies are recommended on their effect on the pathogen in greenhouses and fields.

Geopedology allows a systematic approach in geomorphic analysis for soil mapping that extrapolates the results obtained in sample areas up to similar units in the field operations. Due to the unknown accuracy of the maps created by geopedologiy approach in the large scales, this paper examines the location of sample area in order to determine the amount of credibility for generalization of geopedological approach results for similar landforms in Miyaneh region, Azarbayejan-e-Sharghi province. After the initial interpretation of the study area on aerial photos with scale of 1:20000, a geomorphic unit that encompassed the maximum surface of the sample area (and also the study area namely Pi122) was selected and was surveyed. The sample area was designed in three different locations and five soil profile intervals of approximately 150 m in this unit (a total of 15 profiles), were excavated, described and sampled. The credibility of generalization for geopedological approach results for the studied unit was tested by comparison with three profiles in a similar unit (a total of nine profiles) outside the sample area, named the validation area. This soil map completed in the framework of second-order soil surveys. The results showed that change of sample area location resulted in differences in taxonomic levels (order, subgroup, and soil family) and map unit types (complex and consociation) for HPu211 unit. Therefore, in order to increase the accuracy of the geopedological results, the use of landform phases and also phases of soil families and/or series for each landform phases is recommended.

Many decisions and policies in water management are made in a spatial scale larger than farm scale. In this study, the distributed SWAP model was evaluated to simulate wheat yield production in the Doroudzan irrigation and drainage network (Fars province, Iran) in wet, normal and dry years. The study area was divided into 86 simulation units and yield production was determined in each spatial unit with the distributed SWAP. MATLAB program was used for regionalizing the SWAP model and making relationship between this model and input data in each simulation unit. The goodness-of-fit measures, such as correlation coefficient and maximum error were calculated as 88% and 0.94 ton/ha, respectively. In addition, the determined mean square error was less than standard deviation and the modeling efficiency was estimated satisfactorily. In this research, yield production in the simulation period was evaluated higher than the observed values. In farms located at the end of the network, the error percentage of the simulated performance was higher than other spatial units due to water deficit and soil salinity. In general, since there was a good consistency between simulated and observed crop production in Doroudzan network, distributed SWAP model can be used with a good accuracy to simulate and predict yield production and to manage irrigation network.