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To evaluate the effects of potassium and nitrogen fertilizers on yield and lodging characteristics of Gilaneh rice cultivar under two irrigation regimes (permanent flooding and irrigation with to 10 days interval) a field split split plot experiment based on complete randomized block design with 3 replications in Rasht. Nitrogen and potassium fertilizers used were at the 0, 60 and 120 kg.ha-1 and 0, 80 and 160 kg.ha-1 as sub and sub sub factor, respectively. The results showed that the highest seed yield obtained about 3713 kg.ha-1 from permanent flooding with the application of 120 kg.ha-1 of nitrogen fertilizer and 80 kg.ha-1 of potassium fertilizer and the lowest yield 634 kg.ha-1 from 10 days irrigation interval, without using of potassium and nitrogen fertilizers. The 10-day irrigation interval reduced the bending moment of the internode 4 by 40%. With increasing the rate of potassium fertilizer, the lodging index of intermediate 4 decreased, which was due to the increase of cellulose content by 60% in this intermediate. Increasing nitrogen and potassium fertilizers decreased the lodging index at internodes 3 and 4. Irrigation at 10 days intervals decreased plant height, internode bending moment, cellulose and hemicellulose and seed yield It increased lodging index of intermediate, butincreasing fertilizer levels in both irrigation regimes had adverse effect on the traits under study.

This study was conducted to evaluate the response of hybrid varieties of maize (single cross 260) under drip irrigation treatments in the Fars province in 2012 and 2013 at the Experimental Field of Islamic Azad University of Shiraz. Irrigation levels were 20, 40, 60 and 80% deplection of moisture contents and experiment was conducted in a randomized complete block design. The triats measured were leaf area index, dry matter yield and total biomass in 2012 and the measurements were repeated in 2013 to validate the use of SWAP model. The results showed that simulated yield changes by the use of model, at different levels of irrigation levels in the farm, corresponded with the yield changes in the field. Statistical indices including correlation coefficient (greater than 0.9), t-test (greater than 0.05), the root mean square error and normalized root mean square error (RMSEn) equal to 1.9-6.9, indicate good performance for grain yield and total biomass by using the SWAP model.

Due to the dependency of direct seeding of rice on the application of herbicide and possibility of weed resistance to herbicides, the use of mixtures of herbicides is of considerable importance. To evaluate the effectiveness of consecutive applications of some herbicides with lower concentrations, including Thiobencarb, Pretilachlor, Bensulfuronmethyl, Ethoxysulfuron + Anilofos, Butachlor, and Propanil, on weed density, yield and yield components of rice (Oryza sativa L. cv. Hashemi) an experiment based on a randomized complete block design with eight treatments and three replications was conducted at the Research Farm of Faculty of Agricultural Sciences, University of Guilan in 2014. The results showed that plant height, seed yield, dry matter yield, harvest index, number of tillers and number fertile florets per panicle were affected by these treatments. Tandem use of Thiobencarb (9 day before sowing), Bensulfuronmethyl (9 day after sowing) and Propanil (30 day after sowing) affected weed dry matter and weed density by 92 and 98 %, respectively. The highest number of fertile floret per panicle (71 pcs) and tillers number per plant (14 pcs) were observed in plots where Thiobencarb, Bensulfuronmethyl and Propanil were used consecutively. In this treatment, seed yield and biological yield increased by 72 and 73 percent respectively as compared with that of control. Application of Pretilachlor caused phytotoxicity, where by reduced plant height and seed yield. The highest grain yield of rice (3092 kg.ha-1) was produced by consecutive use of Thiobencarb, Bensulfuronmethyl and Propanil. This treatment was more effective in reducing density of weeds and their dry matters than of two times hand weeding. The use of Thiobencarb followed by Bensulfuronmethyl and Propanil was the most effective treatment in this expriement.