Effect of Shading on Nonstructural Carbohydrates and their Turnover in Culms and Leaves during the Grain Filling Period of Spring Wheat¹

Abstract

The effect of light intensity on the content of nonstructural carbohydrates in leaves and culms and on grain yield of spring wheat (Triticum aestivum L., ‘Kolibri’) was studied during the grain filling period. Light intensity was reduced by shading the plants with muslin after the onset of anthesis. At this time, the nonstructural carbohydrate present in highest quantity in the vegetative plant material was sucrose. Later the fructosans showed the highest concentrations in leaves and culms. In both treatments an accumulation of polysaccharides, particularly of fructosans, occurred in the culms during the first 2 to 3 weeks after anthesis, suggesting that at this stage of grain filling, net photosynthesis was higher than assimilate consumption for grain filling. The depletion of nonstructural carbohydrates at maturity was of a much higher order in the culms and leaves of the shaded plants while these parts in the control plants still contained a quantity of nonstructural carbohydrates which amounted to about 10% of the grain weight. Grain yield was about 20% lower in the shaded plants as compared with the control plants. The results conclusively show that fructosans are the most important storage carbohydrates in leaves and culms during grain filling. Mobilization of storage carbohydrates such as fructosans and starch is a major process which may limit grain production.

CN-Wheat, a functional–structural model of carbon and nitrogen metabolism in wheat culms after anthesis. II. Model evaluation

“…Besides, the overall predicted concentrations of metabolites and their relative abundances are in good agreement with the literature. Nevertheless, the predicted concentrations of sucrose appeared to be significantly overestimated compared with published work on various wheat cultivars and growing conditions (Judel and Mengel, 1982;Araus et al, 1987;Trevanion, 2000;Xue et al, 2008). This discrepancy with the literature may result from: (1) an overestimation of C assimilation, in particular for stem and chaff, for which few data are available and which were not measured in the experiment used to calibrate the model; and (2) taking no account of pathways that also use triose phosphates as substrates and/or those related to sucrose consumption (lipid or secondary metabolism).…”

“…Sucrose concentration ranged from 100 to 600 mmol g À1 and showed high diurnal variations ( Caputo and Barneix, 1999). The simulated concentrations of sucrose appeared to be overestimated compared with the literature, where usual values in wheat leaves ranged from 200 to 400 mmol g À1 (Judel and Mengel, 1982;Araus et al, 1987;Trevanion, 2000;Xue et al, 2008). This potential discrepancy could result from an overestimation of photosynthesis, but may also reflect that some metabolic pathways, which were neglected in the model, could affect sucrose concentration (e.g.…”

Effects of Drought and Shading on Non-structural Carbohydrate Stored in the Stem of Potato (Solanum tuberosumL.)

“…In wheat and rice crops, NSC stored in the stem acts as a buffer to maintain a steady rate of grain fi lling, especially when photosynthesis is seriously impaired due to drought or shading (Judel and Mengel 1982;Blacklow et al 1984). Under normal conditions, the amount of stem NSC is more than 40% of the stem DW, and the contribution of these stored reserves is 5−20% of the grain yield (Shakiba et al, 1996).…”

Évolution et rôle des réserves glucidiques et azotées des tiges chez 21 génotypes de blé

“…La connaissance de la contribution de chacune de ces 2 sources est nécessaire pour modéliser En revanche, l'évolution saisonnière des ré-serves, même si elle a été mise en évidence dans des nombreuses études (Pollock et Jones, 1979;Judel et Mengel, 1982;Blacklow et al, 1984;Kuhbauch et Thome, 1989) n'a pas été souvent quantifiée en terme de flux d'entrée et de sortie (Simpson et al, 1983). Les (Judel et Mengel, 1982;Blacklow et al, 1984), nous n'avons analysé que les glucides solubles sans tenir compte de l'amidon présent en quantité insignifiante (Kuhbauch et Thome, 1989 (Triboi et al, 1985a(Triboi et al, , 1985bTriboi, 1990 (Triboi, 1986 (Fischer, 1985).…”

“…Les (Judel et Mengel, 1982;Blacklow et al, 1984), nous n'avons analysé que les glucides solubles sans tenir compte de l'amidon présent en quantité insignifiante (Kuhbauch et Thome, 1989 (Triboi et al, 1985a(Triboi et al, , 1985bTriboi, 1990 (Triboi, 1986 (Fischer, 1985). Ainsi, un (Ollier et (Triboi et al, 1985b …”