Nitrogen and dry matter dynamics in linseed as affected by the nitrogen level and genotype in a Mediterranean environment Christos A. Dordas* Aristotle University of Thessaloniki, Faculty of Agriculture, Laboratory of Agronomy, 54124 Thessaloniki, Greece article info Article history: Received 18 May 2010 Received in revised form 20 March 2012 Accepted 2 April 2012 Available online 4 May 2012 Keywords: Linseed Linum usitatissimum L. Partitioning Retranslocation Variation Harvest index abstract Linseed or oilseed flax (Linum usitatissimum L.) is an important source of edible and industrial vegetable oil and is grown widely in temperate regions around the world. Nitrogen, one of the most important nutrients for linseed, is often applied for higher yield and better quality. However, the effects of N level on dry matter and N accumu- lation, partitioning, and retranslocation have not yet been identified in linseed. A two- year field study was therefore conducted to determine the effects of N level on dry matter, N accumulation, partitioning, and retranslocation of three linseed cultivars (Livia, Lirina, Creola) grown in a Mediterranean environment under rain-fed conditions. It was found that N fertilization increased biomass at anthesis by an average of 47% and at maturity by an average of 38%, compared with the control. N fertilization increased the dry matter partitioning in leaves þ flowers and stems at anthesis, and also in leaves þ capsule vegetative components, stems, and seeds at maturity. Dry matter translocation was affected by N fertilization, growing season, and by the interaction between growing season and N treatment. In addition, N fertilization increased N retranslocation from the vegetative parts of the plant to the seed. Moreover, the N uptake by seeds was more affected by the seed yield and less affected by the seed N concentration. The present study indicates that N fertilization affects dry matter and N translocation in linseed. ª 2012 Elsevier Ltd. All rights reserved. 1. Introduction Linseed or oilseed flax (Linum usitatissimum L.) is an oilseed crop that is grown in many temperate climates throughout the world, with Canada, Argentina, and India being among the largest producers [1]. Linseed is an important source of essential fatty acids for human diets and has several human health benefits [2]. Thus, there is growing interest in linseed for food, feed, and industrial products, and more attention is now being given to meeting the growing demand for this crop. However, the great variability of seed yields has been one of the major limiting factors to the increase of linseed area [3]. Therefore, it is important for scientists to develop a better understanding of the factors that can affect seed yield. One of the most important crop management techniques for linseed production is N fertilization. Linseed requires less N and other nutrients than many other annual crops [4,5]; however, the application of N fertilizer is needed to optimize seed yield [6e10]. Grant et al. [10] reported that seed yield * Tel.: þ30 2310998602; fax: þ30 2310998634. E-mail address: chdordas@agro.auth.gr. Available online at www.sciencedirect.com http://www.elsevier.com/locate/biombioe biomass and bioenergy 43 (2012) 1 e11 0961-9534/$ e see front matter ª 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.biombioe.2012.04.001