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In order to investigate the possibility of improvement of yield, yield components and the concentration of some nutrients in rice leaves (Tarom variety) by using rice straw and its biochar, a factorial experiment was conducted in the form of a randomized complete block design in nine treatments and three replications in the farm of Sari Agricultural Sciences and Natural Resources University, Sari, north of Iran, in 2021. The first factor was rice straw (S) at three levels of zero, 2 and 4 tons/ha and the second factor was rice straw biochar (B) at three levels of zero, 1 and 2 tons/ha. The maximum concentration of potassium (1.22%), nitrogen (4.73%) and iron (208 mg/kg) in the flag leaf was observed when rice was grown in the high levels of rice straw and particularly its biochar. Also, the concentration of silicon, manganese and zinc in the flag leaf increased with the increase in the levels of rice straw and its biochar. By increasing the use of rice straw and its biochar, the number of tillers, plant height, panicle length, weight of 1000 seeds and the number of filled seeds increased significantly. The combined use of rice straw and its biochar increased the rice grain yield, indicating a 1.78 times increase in the treatment of 2 tons/ha of rice straw biochar + 4 tons/ha of rice straw (S2B2) compared to the control. Therefore, it can be concluded that the application of 2 tons/ha of biochar and 4 tons/ha of rice straw can lead to the maximum grain yield by increasing the concentration of nutrients in the flag leaf and improving the growth and yield components of rice. [ABSTRACT FROM AUTHOR]

In order to determine the effect of weeds interference and nitrogen on the sugar beet growth and yield, a field study was performed in the 2010 growing season as a split plot design based on RCBD with three replications in Hana region (Semirom, Esfahan). Treatments were four levels of nitrogen from urea source as the main factor (0, 70, 150 and 210 kg ha-1) and weed interference at five levels (6-leaf, 8-leaf, 10-leaf, 12-leaf, and throughout the growth stages) growth stages in sugar beet as the sub factor. The results indicated that nitrogen and weed interaction had significant effects on the quantitative and qualitative traits of sugar beet (root yield and sugar). With increasing the nitrogen levels from 150 to 210 kg ha-1, the percentages of sugar molasses, sodium, and α-amino nitrogen were increased by 7.48, 24.26 and 21.09%, respectively, while the impurity percentage of sugar, alkalinity coefficient, and extractable sugar content were reduced by 3.09, 8.18, and 4.78% , respectively. The highest total fresh weight, root fresh weight, root dry weight, total biomass and root yield (2.1, 2.18, 1.55, 1.73 and 1.33-times, respectively) were achieved under high levels of nitrogen (210 kg ha-1) and weed interference at the 6-leaf growth of sugar beet in comparison to the use of no nitrogen. Reduced duration of weed competition and /or weed free till 6- leaf growth stage of sugar beet along with application of 150 kg ha-1 N led to reduction in weed interference, detrimental effect of nitrogen on quality characteristics, and increase in the root yield of sugar beet. [ABSTRACT FROM AUTHOR]