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Warwick, Australia

George-Jaeggli B.,Hermitage Research Facility | Jordan D.R.,University of Queensland | Van Oosterom E.J.,University of Queensland | Broad I.J.,Fisheries and Forestry | Hammer G.L.,University of Queensland
Field Crops Research

Presence of the dw3 sorghum dwarfing gene had negative effects on grain yield in some genetic backgrounds and environments. In a previous study we showed that this was due to a significant reduction in shoot biomass (mainly via reduced stem mass), which in turn negatively affected grain size. The current study examines whether shoot biomass was reduced via effects of dw3 on traits associated with resource capture, such as leaf area index (LAI), light interception (LI), and canopy extinction coefficient (k) or with resource use efficiency, such as radiation use efficiency (RUE). Three pairs of near-isogenic sorghum lines differing only in the presence or absence of the dwarfing allele dw3 (3-dwarfs vs 2-dwarfs) were grown in large field plots. Biomass accumulation and LI were measured for individual canopy layers to examine canopy characteristics of tall and short types. Similar to the previously reported effects on grain yield, the effects of dw3 on RUE, LI and k varied among genetic backgrounds and environments. Interactions between dw3 and genetic background, but also interactions with environment are likely to have modulated the extent to which RUE, LI, or k contributed to biomass differences between tall and short sorghum. © 2013 . Source

Mace E.S.,Hermitage Research Facility | Singh V.,University of Queensland | van Oosterom E.J.,University of Queensland | Hammer G.L.,University of Queensland | And 3 more authors.
Theoretical and Applied Genetics

Nodal root angle in sorghum influences vertical and horizontal root distribution in the soil profile and is thus relevant to drought adaptation. In this study, we report for the first time on the mapping of four QTL for nodal root angle (qRA) in sorghum, in addition to three QTL for root dry weight, two for shoot dry weight, and three for plant leaf area. Phenotyping was done at the six leaf stage for a mapping population (n = 141) developed by crossing two inbred sorghum lines with contrasting root angle. Nodal root angle QTL explained 58.2% of the phenotypic variance and were validated across a range of diverse inbred lines. Three of the four nodal root angle QTL showed homology to previously identified root angle QTL in rice and maize, whereas all four QTL co-located with previously identified QTL for stay-green in sorghum. A putative association between nodal root angle QTL and grain yield was identified through single marker analysis on field testing data from a subset of the mapping population grown in hybrid combination with three different tester lines. Furthermore, a putative association between nodal root angle QTL and stay-green was identified using data sets from selected sorghum nested association mapping populations segregating for root angle. The identification of nodal root angle QTL presents new opportunities for improving drought adaptation mechanisms via molecular breeding to manipulate a trait for which selection has previously been very difficult. © 2011 Her Majesty the Queen in Rights of Australia as represented by The State of Queensland. Source

Solomon K.F.,Hermitage Research Facility | Zeppa A.,Hermitage Research Facility | Mulugeta S.D.,North West University South Africa
Plant Breeding

The objectives of this study were to evaluate the importance of heterosis for agronomic and quality traits in shrunken (sh2) sweet corn, assess the usefulness of combining ability to predict the value of parents and their crosses for further genetic improvement and examine whether genetic divergence can predict heterosis or F 1 performance. Ten genetically diverse shrunken (sh2) sweet corn inbred lines were used to generate 45 F 1s. F 1s and parents were evaluated for agronomic and quality traits across environments. Heterosis was more important for yield-related traits than it was for ear aspects and eating quality. Heterosis for most traits was mostly dependent on dominance genetic effects of parental lines. Parents and F 1per se performance were highly correlated with general combining ability effects and mid-parent values, respectively, for most traits. Hybrid performance for flavour and plant height was significantly but weakly related to simple sequence repeat (SSR)-based genetic distance (GD). Phenotypic distance (PD), estimated from phenotypic traits was correlated with heterosis for total soluble solids, ear length and flavour. © 2012 State of Queensland. Source

Gilding E.K.,University of Queensland | Frere C.H.,University of Exeter | Cruickshank A.,Hermitage Research Facility | Rada A.K.,University of Gottingen | And 5 more authors.
Nature Communications

The production of adequate agricultural outputs to support the growing human population places great demands on agriculture, especially in light of ever-greater restrictions on input resources. Sorghum is a drought-adapted cereal capable of reliable production where other cereals fail, and thus represents a good candidate to address food security as agricultural inputs of water and arable land grow scarce. A long-standing issue with sorghum grain is that it has an inherently lower digestibility. Here we show that a low-frequency allele type in the starch metabolic gene, pullulanase, is associated with increased digestibility, regardless of genotypic background. We also provide evidence that the beneficial allele type is not associated with deleterious pleiotropic effects in the modern field environment. We argue that increasing the digestibility of an adapted crop is a viable way forward towards addressing food security while maximizing water and land-use efficiency. © 2013 Macmillan Publishers Limited. Source

George-Jaeggli B.,Hermitage Research Facility | Jordan D.R.,Hermitage Research Facility | Jordan D.R.,University of Queensland | van Oosterom E.J.,University of Queensland | Hammer G.L.,University of Queensland
Field Crops Research

Positive correlations between plant height and grain yield have been reported for sorghum. The introduction of stay-green in sorghum, and the associated reduction in lodging, has opened the possibility to exploit this positive association. The aim of this study was to analyse the direct effects of the dwarfing gene dw3 (and therefore plant height) on shoot biomass, grain yield, and yield components in pairs of 3-dwarf genotypes and their isogenic 2-dwarf tall mutants. Isogenic pairs with different genetic backgrounds were grown in three field experiments under nutrient and water non-limiting conditions. Tall mutants were significantly taller and produced more shoot and stem biomass than their shorter counterparts. Generally, tall types yielded more grain than short types, but significant interactions between experiment, genetic background and stature affected the consistency of the results. dw3 only affected grain size and not grain number. Increased grain mass of tall types was associated with significantly greater stem mass per grain at anthesis and greater shoot biomass per grain accumulated between anthesis and maturity. The increased biomass of tall plants was therefore important for increased grain yield under optimum conditions. Potential implications of increased biomass production for drought adaptation are discussed. © 2011. Source

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