Research Institute of Forests and Rangelands Iranian Journal of Wood and Paper Science Research 1735-0913 34 3 2019 11 22 Morphological characteristics and chemical components of sunflower stalk (Helianthus annus. Var. cheernianka 66) cultivated in Astara Morphological characteristics and chemical components of sunflower stalk (Helianthus annus. Var. cheernianka 66) cultivated in Astara 372 386 119793 10.22092/ijwpr.2019.127139.1562 FA Mona Otarod M.Sc., Graduate, Department of Wood and Paper Science and Technology, Astara Branch, Islamic Azad University, Astara, Iran Asghar Tabei Scientific member- Islamic Azad University, Astar Branch Journal Article 2019 07 20 This study was conducted to determine morphological characteristics and chemical components of sunflower stalks (Helianthus annus. Var, cheernianka 66) cultivated in Astara area. After collecting number of stalks, 6 stalks of the same size were selected to determine for morphological characteristics and remaining stalks were used to determine the chemical components. Morphological tests were performed to determine fibers dimensions and biometric coefficients by sampling from 3 heights of stalks (5%, 50% and 75%).Maceration of fibers was done by Franklin method . Measurement of chemical components was performed on the basis of TAPPI standard in 2 modes such with bark and without bark. The total average of fiber length, fiber diameter, lumen diameter and fiber wall thickness were measured for this stalk as 663µm , 29.848 µm, 25.182 µm and 2.336 µm respectively. The total average of slenderness coefficient, flexibility coefficient and Runkel index of fibers were calculated as 22.681, 84.259 and 0.188 respectively. Average percentage of cellulose, lignin, acetone extractives, alcohol extractives, hot water extractives and ash for this stalk were measured as 40.066, 22.758, 3.953, 1.86, 2.186 and 3.208, respectively. The results showed that fibers length increased with increasing of stalk height, but this increasing was not significant. Fibers diameter, lumen diameter and fibers wall thickness decreased with increasing of stalk height, this decreasing was significant for fibers diameter and lumen diameter in the height of 75%, but it was not significant for fibers wall thickness. Also, the results showed that bark has significant effect on all of the chemical components, so that, the stalk with bark has lower cellulose and more lignin, extractives and ash in compare with the stalk without bark. This study was conducted to determine morphological characteristics and chemical components of sunflower stalks (Helianthus annus. Var, cheernianka 66) cultivated in Astara area. After collecting number of stalks, 6 stalks of the same size were selected to determine for morphological characteristics and remaining stalks were used to determine the chemical components. Morphological tests were performed to determine fibers dimensions and biometric coefficients by sampling from 3 heights of stalks (5%, 50% and 75%).Maceration of fibers was done by Franklin method . Measurement of chemical components was performed on the basis of TAPPI standard in 2 modes such with bark and without bark. The total average of fiber length, fiber diameter, lumen diameter and fiber wall thickness were measured for this stalk as 663µm , 29.848 µm, 25.182 µm and 2.336 µm respectively. The total average of slenderness coefficient, flexibility coefficient and Runkel index of fibers were calculated as 22.681, 84.259 and 0.188 respectively. Average percentage of cellulose, lignin, acetone extractives, alcohol extractives, hot water extractives and ash for this stalk were measured as 40.066, 22.758, 3.953, 1.86, 2.186 and 3.208, respectively. The results showed that fibers length increased with increasing of stalk height, but this increasing was not significant. Fibers diameter, lumen diameter and fibers wall thickness decreased with increasing of stalk height, this decreasing was significant for fibers diameter and lumen diameter in the height of 75%, but it was not significant for fibers wall thickness. Also, the results showed that bark has significant effect on all of the chemical components, so that, the stalk with bark has lower cellulose and more lignin, extractives and ash in compare with the stalk without bark. https://ijwpr.areeo.ac.ir/article_119793_48b212fe6dca377c363c4d74bfd91a85.pdf