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The challenge
Drought during grain filling is a common
challenge for sorghum production in north-
eastern Australia, central-western India, and
sub-Saharan Africa. We show that the stay-
green drought adaptation trait enhances
sorghum grain yield under post-anthesis drought
in these three regions.
ABOVE : Sorghum plants of near-isogenic lines (NILs) differing for the
parental allele at the stay-green2 (Stg2) QTL. Lines stg2/stg2 NIL (left) and
Stg2/Stg2 NIL (right) were grown in the same conditions and were exposed to
terminal water deficit.
Shifting water use from pre-
to post-anthesis
Physiological studies in Australia found that
introgressing four individual stay-green (Stg1–4)
quantitative trait loci (QTLs) into a senescent
background reduced water demand before
flowering and hence increased water supply
during grain filling, resulting in higher grain yield
relative to the senescent control (1).
Stay-green Drought Adaptation Trait Enhances
Sorghum Production in Sub-tropical Australia,
Central-Western India and Sub-Saharan Africa
A Borrell
1
, B George-Jaeggli
1
, E van Oosterom
2
, G Hammer
2
, E Mace
3
, V Vadez
4
, J Kholova
4
, H Talwar
5
, S Deshpande
4
, S Coulibaly
6
, N
Teme
6
, C Barro-Kondombo
7
, S Souley
8
, A Tirfessa
9
, A Adugna
9
, C Kamau
10
, A Mohamed
11
, D Jordan
1
| a.borrell@uq.edu.au
Stay-green positively
correlated with grain yield
A positive relationship between stay-green and
yield was generally found in breeding trials in
north-eastern Australia that sampled 1668
unique hybrid combinations and 23
environments (2).
ABOVE: Grain yield of Stg NILs is enhanced relative to RTx7000 under post-
anthesis drought in a rain-out shelter study; data are mean±2SE.
Central-western India
Studies in India found that various Stg QTLs
affected both transpiration and transpiration
efficiency, although these effects depended on
the interaction between genetic background
(S35 and R16) and individual QTLs.
The yield variation unexplained by harvest index
was related to transpiration efficiency in S35 (R
2
= 0.29) and R16 (R
2
= 0.72), and was related to
total water extracted in S35 (R
2
= 0.41) but not in
R16 (3).
Sub-Saharan Africa
Sixty-eight stay-green enriched lines were
evaluated in six countries in sub-Saharan Africa
during the 2013/14 season.
Analysis of the data from Kenya indicates
that stay-green and grain size were
positively correlated at two sites: Kiboko
(high yielding, r
2
=0.25) and Masongaleni
(low yielding, r
2
=0.37).
Together, these studies suggest that stay-green
is a beneficial trait for sorghum production in the
semi-arid tropics and is a consequence of traits
altering the plant water budget.
References
–Borrell AK, Mullet JE, George-Jaeggl, B, van Oosterom EJ, Hammer GL,
Klein PE and Jordan DR (2014). Journal of Experimental Botany, 65, 6251–
6263 (doi:10.1093/jxb/eru232).
–Jordan DR, Hunt CH, Cruickshank AW, Borrell AK, and Henzell RG (2012).
Crop Science 52:1153-1161.
–Vadez V, Deshpande SP, Kholova J, Hammer GL, Borrell AK, Talwar HS
and Hash CT (2011). Functional Plant Biology, 2011, 38, 553–566.
Author affiliations
1 The University of Queensland, Queensland Alliance for Agriculture and
Food Innovation, Hermitage Research Facility, Warwick, Australia; 2 The
University of Queensland, Queensland Alliance for Agriculture and Food
Innovation, St Lucia, Australia; 3 Department of Agriculture and Fisheries,
Hermitage Research Facility, Warwick, Australia: 4 International Crops
Research Institute for the Semi-Arid Tropics, Patancheru, India; 5 Indian
Institute for Millet Research, Hyderabad, India; 6 Institut d’Economie Rurale,
Mali; 7 Institut de l'Environnement et de Recherches Agricoles of Burkina
Faso, Burkina Faso; 8 Institut National de la Recherche Agronomique du
Niger, Niger; 9 Ethiopian Institute of Agricultural Research, Adama, Ethiopia;
10 Kenya Agricultural Research Institute, Katumani, Kenya; 11 ARC, Mad
Mwedani, Sudan
-50
0
50
100
150
200
250
300
350
400
0 20 40 60 80 100 120 140
Cumulative water use (mm)
Days after emergence
Stg3
RTx7000
Water conserved Water utilised
Rain-out Shelter
ABOVE: The lysimetry facility at the International Crops Research Institute
for the Semi-Arid Tropics (ICRISAT) in Hyderabad, India, was used to
evaluate transpiration and TE in two populations varying in Stg QTLs.
ABOVE: Stay-green enriched lines were evaluated in West Africa (1, Mali; 2,
Burkina Faso; 3, Niger) and East Africa (4, Sudan; 5, Ethiopia; 6, Kenya).
ABOVE: Dr Niaba Teme, a sorghum breeder, inspects his field trial in Mali.
ABOVE: Stg3 uses less water than RTx7000 before anthesis and
more water after anthesis. The temporal pattern of cumulative crop
water use for RTx7000 (open squares) and Stg3 (filled squares)
grown under a low water high-density treatment in a rain-out shelter
study. The black vertical arrow marks anthesis.