Effects of leaf infections of Drechslera tritici-repentis on the carbohydrate and nitrogen metabolism of wheat plants
1993
Kremer, M. (Technische Univ. Muenchen, Freising-Weihenstephan (Germany). Lehrstuhl fuer Phytopathologie) | Hoffmann, G.M.
Samples taken from wheat grown in pots under controlled growth conditions were analyzed for carbohydrate and nitrogen content at different growth stages after inoculation with Drechslera tritici-repentis. Results were compared with healthy plants. Two spring wheat cultivars ("Star", "Sokrates") were infected between growth stages EC and EC 73 with different spore densities applied as a single or series of doses. The accumulation of assimilates, their storage, remobilisation and translocation to the ears was traced by the identification of glucose, fructose, sucrose, fructans and starch content. Analysis of total nitrogen provided an indication of uptake and distribution. Carbohydrate analyses were conducted between 7 and 21 days afte inoculation and again at full marurity. The nitrogen determinations were conducted only with fractions from fully mature plants. The negative effect on the phtosynthetic efficiency resulting from a single inoculation at EC 32 (which was seen as a reduction in grain number) was compensated by the activity from the later formed leaves (higher grain weight). Infections between growth stage 37 and shortly before flowering resulted in a particularly high reduction in the storage of sucrose and fructans in the lower part of the plant. This lead to a reduction in grain number as described above. In this case, there was no compensation (no increase in grain weight). Infections during grain filling resulted in a reduction in assimilation which, in turn, caused a premature mobilisation of carbohydrate reserve. Translocation ceased prematurely due to infection-induced ripening. The undisturbed storage of carbohydrate reserves in wheat is seen as an important pre-requisite for a high grain yield
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