Grain, sugar and biomass accumulation in tropical sorghums. I. Trade-offs and effects of phenological plasticity

Gutjahr, S. and Vaksmann, M. and Dingkuhn, M. and et al, . (2013) Grain, sugar and biomass accumulation in tropical sorghums. I. Trade-offs and effects of phenological plasticity. Functional Plant Biology, 40 (4). pp. 342-354.

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Grain and sweet sorghum (Sorghum bicolor (L.) Moench) differ in their ability to produce either high grain yield or high sugar concentration in the stems. Some cultivars of sorghum may yield both grains and sugar. This paper investigates the trade-offs among biomass, grain and sugar production. Fourteen tropical sorghum genotypes with contrasted sweetness and PP sensitivity were evaluated in the field near Bamako (Mali) at three sowing dates under favourable rainfed conditions. Plant phenology, morphology, dry matter of different organs and stem sugar content were measured at anthesis and grain maturity. A panicle pruning treatment was implemented after anthesis. Late sowing (shorter days) led to a decrease in total leaf number, dry mass and sugar yield even in PP-insensitive genotypes because of an increased phyllochron. Dry matter production and soluble sugar accumulation were strongly correlated with leaf number. Sugar concentration varied little among sowing dates or between anthesis and maturity. This indicates that sugar accumulation happened mainly before anthesis, thus largely escaping from competition with grain filling. This was confirmed by the low impact of panicle pruning on sugar concentration. Changes in sugar concentration from anthesis to maturity were negatively correlated with harvest index but not with grain yield. Physiological trade-offs among sugar, biomass and grain production under favourable rainfall are small in late-maturing and PP-sensitive sweet sorghums cultivated under sudano-sahelian conditions. The results differ from earlier reports that focussed on early maturing, PP-insensitive germplasm. Further research is needed on the interactions of these traits with agricultural practices and drought.

Item Type: Article
Additional Information: This work was supported by the European Commission through the Frame Work Programmed 7 project ‘SWEETFUEL’ (Grant Agreement no. 227422).
Uncontrolled Keywords: grain filling, phenology, photoperiod sensitivity, sink competition, Sorghum bicolor (L.) Moench, sugar storage.
Author Affiliation: CIRAD, UMR AGAP, F-34398 Montpellier, France
Subjects: Plant Production
Crop Improvement
Plant Physiology and Biochemistry > Plant Physiology
Divisions: Sorghum
Depositing User: Mr Balakrishna Garadasu
Date Deposited: 05 Jun 2013 12:53
Last Modified: 05 Jun 2013 12:53
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