Morphological characteristics and yield components associated with accumulation and loss of dry mass in the internodes of wheat

Stored stem reserves serve as a source of carbon for grain filling in wheat , particularly during stress conditions. However, the influence of these su bstances on yield formation in tropical environments has been poorly addres sed. In the present study, yield components, morphological traits and dry m atter content of the peduncle and the two subtending internodes were measur ed in wheat cultivars having contrasting morphological characteristics. Cor relation analysis was performed to assess the possible link characteristics of particular internodes with morphological traits. The maximum mass of th e three uppermost internodes of main stems differed between cultivars and s owing dates. Dry matter loss from the second internode during grain filling positively correlated with yield, mass per grain: number and mass of grain s per ear, and harvest index. By contrast, dry matter loss was negatively c orrelated with relative growth rate of main shoots during grain filling and mean temperature from solving to anthesis Thp result indicate that thp sec ond internode from thr top supplied a larger amount nf non-structural to th e grains than the other two internodes and that source-sink status does hav e a role in the mobilization of stored carbohydrates. The differences betwe en internodes, as well as genotypic variability in amounts of reserve stora ge, should be important in further analysis of the contribution of stem res erves to grain filling. (C) 2000 Published by Elsevier Science B.V. All rig hts reserved.