Seasonal fluctuations of starch in root and stem tissues of coppiced Salix viminalis plants grown under two nitrogen regimes.

Seasonal changes in starch were studied at the tissue and cellular levels in roots and stems of Salix viminalis L. cuttings. Cuttings were planted in pots containing sand and grown in a controlled environment chamber in which seasons were artificially induced by changes in temperature and photoperiod. Nitrogen was supplied at optimum and low rates, and during dormancy, one-half of the plants were decapitated. Starch concentrations in root and stem tissues were determined regularly during shoot extension growth, dormancy and resprouting after dormancy. We used light microscopy (LM) combined with image analysis (IA) to determine the cellular localization and amount of starch in different cell types of stem and root tissues. Chemical analysis confirmed that starch concentrations were lower in plants receiving a high-N supply rate than in plants receiving a low-N supply rate. In all plants, the highest concentration of starch was in the roots. Light microscopy and IA showed that starch accumulated mainly in the phloem and cortical cells of both root and stem tissues. Starch grains were also regularly found in ray parenchyma cells. The amount of starch as well as the size of the grains showed strong seasonal fluctuations. In both roots and stems, starch concentrations were highest during predormancy and lowest during periods of shoot extension growth. At the time of resprouting, root cells of decapitated plants were more depleted of starch than root cells of intact plants, supporting the hypothesis that starch reserves in roots are important during the early phase of resprouting in coppice systems.

[1]  P. Wargo.  Estimating Starch Content in Roots of Deciduous Trees--A Visual Technique , 1975 .

[2]  T. Tschaplinski,et al.  Carbohydrate mobilization following shoot defoliation and decapitation in hybrid poplar. , 1994, Tree physiology.

[3]  J. Sauter.  Temperature-induced Changes in Starch and Sugars in the Stem of Populus × canadensis «robusta» , 1988 .

[4]  P. Kramer,et al.  Responses of Plants to Environmental Stresses , 1973 .

[5]  L. Sennerby-Forsse.  Seasonal variation in the ultrastructure of the cambium in young stems of willow (Salix viminalis) in relation to phenology , 1986 .

[6]  A. McDonald,et al.  Dependence of starch storage on nutrient availability and photon flux density in small birch Betula pendula Roth) , 1986 .

[7]  W. Loescher,et al.  Nonstructural Carbohydrate Partitioning in Perennial Parts of Sweet Cherry , 1989, Journal of the American Society for Horticultural Science.

[8]  K. Miyanishi,et al.  The role of root nutrient reserves in regrowth of two savanna shrubs , 1986 .

[9]  Ute Harms,et al.  Changes in Content of Starch, Protein, Fat and Sugars in the Branchwood of Betula pendula Roth during Fall , 1992 .

[10]  Richard E. Dickson,et al.  Accumulation of food reserves in cottonwood stems during dormancy induction , 1981 .

[11]  Kjell Larsson,et al.  CARBOHYDRATES IN ROOTS AND RHIZOMES OF PERENNIAL GRASSES , 1986 .

[12]  T. Ingestad,et al.  Theory and techniques for steady state mineral nutrition and growth of plants , 1986 .

[13]  C. B. Davey,et al.  Accumulation of starch in roots and foliage of loblolly pine (Pinus taeda L.): effects of season, site and fertilization. , 1986, Tree physiology.

[14]  Walter Eschrich,et al.  Changes of Starch Content in the Storage Tissues of Deciduous Trees During Winter and Spring , 1985 .

[15]  L. Rytter,et al.  Leaf nutrient analysis in Salix viminalis (L.) energy forest stands growing on agricultural land. , 1993 .

[16]  Kurt S. Pregitzer,et al.  Late-season changes in allocation of starch and sugar to shoots, coarse roots, and fine roots in two hybrid poplar clones. , 1990, Tree physiology.

[17]  K. Ryugo.  Fruit Culture: Its Science and Art , 1988 .

[18]  S. Wetzel,et al.  Storage compounds in Populus cuttings in response to two different nitrogen regimes , 1995 .

[19]  T. Ericsson.  Growth and nutrition of three Salix clones in low conductivity solutions , 1981 .

[20]  Paul J. Kramer,et al.  Physiology of Woody Plants , 1983 .

[21]  Tord Johansson,et al.  Seasonal changes in contents of root starch and soluble carbohydrates in 4–6‐year old Betula pubescens and Popuius tremula , 1993 .

[22]  Jörg J. Sauter,et al.  Biochemical and Ultrastructural Results during Starch-Sugar-Conversion in Ray Parenchyma Cells of Populus during Cold Adaptation , 1991 .