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Sustainable development of food production depends on damping the environmental impacts of agricultural production. The aim of this study was to investigate the environmental performance of rice production in single crop and ratooning (main rice + ratoon crop) agro-systems through life cycle assessment (LCA) methodology in Guilan province, Northern Iran, in 2015. The flooding irrigation regime was the dominant irrigation method for single cropping system and main crop rising in ratooning agro-system. The data were gathered through a face to face interview with 215 single crop and 115 ratoon breeder paddy farmers. The environmental risks were determined in six impact categories including global warming, terrestrial eutrophication, acidification, and depletion of fossil fuels, phosphate, and potash resources. The functional unit (FU) was set as 100 kg protein. Results indicated that the CO, NO, and CH emissions of the rice ratooning agro-system (661.44, 1.96, and 5.42 kg 100 kg protein) were less than the corresponding values in the rice single cropping agro-system (1341.63, 2.88, and 9.20 kg 100 kg protein, respectively). Among all the environmental impact categories, the terrestrial eutrophication had the widest negative environmental effect followed by depletion of phosphate resources in single cropping agro-system with weighted indices of 0.51 and 0.41, respectively. Moreover, the terrestrial eutrophication had the largest negative environmental effect followed by acidification in rice ratooning agro-system with weighted indices of 0.48 and 0.29, respectively. Overall, the results highlighted that the rice ratooning ago-system is more environmentally beneficial than the single cropping system, particularly in terms of depletion of fossil fuels, global warming, and depletion of phosphate and potash resources categories. This priority may be improved through adopting proper management of agronomic practices for main and ratoon rice in ratooning agro-system. Graphical abstract ᅟ.

Volumen 33, Nº 4. Páginas 15-21 IDESIA (Chile) Septiembre-Noviembre, 2015 Effects of phosphorus fertilization and Pseudomonas fluorescens strain on the growth and yield of faba bean (Vicia faba L.) ABSTRACTA field experiment was conducted in Lihijan, Iran in 2013 to evaluate the effect of phosphorus fertilization (P) and Pseudomonas fluorescens strain on the growth and yield of the faba bean. The experiment used a randomized complete block design with a factorial treatment arrangement and three replicates. The experimental factors were phosphorus application (0 and 25 kg ha -1 ) and P. fluorescens strains (non-inoculated, strain 136, and strain 168). ANOVA showed a significant interaction effect of P and P. fluorescens strain on plant height, pod number per plant, 100 grain weight, pod length, and pod and grain yield. ANOVA also showed that grain number per pod was significantly affected by P application and P. fluorescens strain, while haulm yield was significantly affected only by P. fluorescens strain. In the absence of P, the grain yield of inoculated plants was not significantly different from that of non-inoculated plants. In the presence of P (25 kg ha -1 ), strain 168 showed an increase in grain yield of 42% and 65% over strain 136 and non-inoculated plants, respectively. The results indicated that application of phosphorus (25 kg ha -1 ) and seed inoculation with P. fluorescens strain 168 can be recommended to increase grain/pod yield significantly.

-To evaluate the effect of planting date and spatial pattern on common bean yield under weed-free and weed-infested conditions, an experiment was conducted in Kelachay, Northern Iran, in 2013. The experimental design was a randomized complete block in a factorial arrangement with three replicates. Factors were planting date (10 August and 20 August), spatial pattern (square and rectangular planting pattern, with a planting distance of 30 x 30 cm and 45 x 20 cm, respectively), and weed management regime (weed-free and weedy conditions, weeded and not weeded throughout the growing season, respectively). Results showed that the main effect of planting date was significant only for pod number per plant and seed number per pod. At the same time, pod number per plant, seed number per pod, pod length, and grain yield were influenced significantly by spatial pattern. Results of ANOVA have also indicated that all traits, except pod length, were influenced significantly by weed-management regimes. Moreover, effect of planting date and spatial pattern were nonsignificant for weed dry weight. Mean comparison has expressed a significant increment in seed yield for square planting arrangement (1,055 kg ha ). Weeding has also presented an overall 12% and 8% improvement in grain and pod yield over control (weedy check), respectively. Based on the results of this study, weed control, as well as square planting pattern, are recommended for obtaining the highest seed yield in common bean. Palavras-chave: feijoeiro comum, competição, época de plantio, sistema de plantio, Phaseolus vulgaris. Keywords

Field experiment was conducted at Agricultural and Natural Resources Research Center of Golestan Province, Iran, to determine the effects of tillage system and weed management regime on yield and weed populations in soybean (Glycin max L.). The experimental design was a split plot where the whole plot portion was a randomized complete block with three replicates. Main plots were tillage system: 1-Notill row crop seeding, 2-No-till seed drilling, 3-Tillage with disc harrow and drill planting, 4-Tillage with chisel packer and drill planting. The subplots were weed management regimes: 1-Weed control with herbicide application, 2-Hand weeding, 3-Herbicide application plus hand weeding, and 4-Non-weeding. Results indicated that the main effects of tillage system and weed management regime were signifi cant for seed yield, pod number per plant, seed number per pod, weed density and biomass, while their interaction were signifi cant only for weed density, weed biomass, and seed number per pod. The highest grain yields (3838 kg ha ).

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Pondweed is a rhizomatous perennial weed of aquatic habitats that has recently been adopted to rice ecosystems in northern Iran. Two field experiments were conducted at the Rice Research Institute of Iran to determine the impact of pondweed on rice yield and identify effective herbicides for pondweed control. The focus of the first study was to evaluate the efficacy of herbicides commonly used in Iranian rice, including butachlor, pretilachlor, oxadiargyl, pendimethalin, thiobencarb, and bensulfuron methyl. None of these herbicides effectively controlled pondweed except bensulfuron, which reduced pondweed biomass by ≥95% and produced 26% higher rough rice grain yield than the weedy check. The second experiment evaluated the efficacy of eight acetolactate synthase-inhibiting herbicides on pondweed control, rough rice yield, and pondweed regrowth. Herbicide efficacy varied from 36% to 100%. Five preemergence soil-applied herbicides, bensulfuron-methyl, metazosulfuron, flucetosulfuron, triafamone + ethoxysulfuron, and metsulfuron-methyl provided excellent control (≥98%) of pondweed. Postemergence herbicides penoxsulam, bispyribac-sodium, and pyribenzoxim provided 36%, 89%, and 93% pondweed control, respectively. Rough rice yields ranged from 107% to 124% in herbicide-treated plots compared with the weedy check. No significant differences were detected between the rough rice yield of hand-weeded control and foliar-applied herbicide treatments, whereas yields in soil-applied herbicide treatments were higher (≥119%) than the hand-weeded control. Pondweed regrowth was affected by herbicides and was variable. Soil-applied residual herbicides metazosulfuron, flucetosulfuron, and metsulfuron provided complete control of pondweed and prevented regrowth. In contrast, pondweed regrowth in other soil and foliar-applied herbicide treatments occurred, indicating that they have less translocation to underground vegetative rhizomes. This study shows that while most sulfonylurea herbicides can control pondweed effectively to achieve high rough rice yield, only a few soil-applied herbicides were able to prevent pondweed regrowth.