Drought is the most drastic abiotic stress that limits crop production
in sub-Sahara Africa. Sorghum ( Sorghum bicolor (L.) Moench) is among
the most climate resilient cereals of the future due to its tolerance
to drought and heat. Thus, identification of tolerant genotypes and
plant characteristics that contribute to drought adaptation is timely.
The objective of this study was to evaluate the response of 12
genotypes, including seven Stay-green (Stg) QTL introgression sorghum
lines and their two donor; and three recurrent parents, to induced
post-flowering drought stress. The recurrent parents were varieties
released for drought prone lowlands of the country, and the donor
parents were lines known to have stay-green properties. The study was
conducted at Werer, in the Great Rift-valley of Ethiopia, during the
off-season of 2014 under well-watered and water limited conditions.
Significant differences (P<0.05) were observed among genotypes under
water deficit regimes, for all measured physiological, biochemical
(proline content), yield and yield related traits. Three Stg QTL
introgression lines showed better tolerance to drought than their
recurrent parents, as reflected by yield and maintenance of green leaf
area. Three Stg QTL introgression lines, Teshale/E36-1, Gambella/B35-5
and Meko/B35-12, gave the highest grain yield under post-flowering
drought stress, and B35 and Teshale/B35 gave the poorest yield under
similar conditions. Therefore, these improved lines bear potential for
use as alternatives in breeding programmes and for possible release in
parts of the country where post-flowering drought stress is frequent.
Proline content, weight of hundred seeds (HSW) and CO2 assimilation are
effective screening tools for Stg property due to their high
correlation with other parameters.La s\ue8cheresse est le stress abiotique le plus drastique qui limite
la production agricole en Afrique Sub-saharienne. Le sorgho ( Sorghum
bicolor (L.) Moench) est parmi les c\ue9r\ue9ales les plus
r\ue9silientes au climat pour le futur d\ufb \ue0 sa
tol\ue9rance \ue0 la s\ue9cheresse et \ue0 la chaleur. Donc,
l\u2019identification des g\ue9notypes tol\ue9rants et les
caract\ue9ristiques des plants qui contribuent \ue0
l\u2019adaptation \ue0 la s\ue9cheresse est opportune.
L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer la
r\ue9ponse de 12 g\ue9notypes, comportant sept lign\ue9es de
sorgho conf\ue9rant l\u2019introgression des QTL des attributs verts
(Stg), leurs deux donneurs\ua0; et les trois parents r\ue9currents,
au stress de la s\ue9cheresse post floraison induite. Les parents
r\ue9currents ont \ue9t\ue9 les vari\ue9t\ue9s
lib\ue9r\ue9es sensibles \ue0 la s\ue9cheresse dans les plaines
du pays, et les donneurs ont \ue9t\ue9 les lign\ue9es connues
pour leurs propri\ue9t\ue9s relatives aux attributs verts.
L\u2019\ue9tude a \ue9t\ue9 conduite \ue0 Werer, dans la
grande vall\ue9e du Rift d\u2019Ethiopie, pendant la contre saison
de 2014 dans des conditions d\u2019irrigation abondante et
d\u2019irrigation limit\ue9e. De diff\ue9rences significatives
(P<0.05) ont \ue9t\ue9 observ\ue9es entre les g\ue9notypes
sous des r\ue9gimes de d\ue9ficit hydriques, pour tous les traits
physiologiques, biochimiques (teneur en proline), le rendement et les
composantes de rendement. Trois lign\ue9es d\u2019introgression de
Stg QTL ont montr\ue9 de meilleure tol\ue9rance \ue0 la
s\ue9cheresse que leurs parents r\ue9currents, comme
refl\ue9t\ue9 par le rendement et la maintenance de la surface
verte de la feuille. Trois lign\ue9es d\u2019introgression de Stg
QTL, Teshale/E36-1, Gambella/B35-5 et Meko/B35-12, ont donn\ue9 le
plus haut rendement sous le stress de s\ue9cheresse de post
floraison, et B35 et Teshale/B35 ont donn\ue9 le plus faible
rendement dans des conditions similaires. En cons\ue9quence, ces
lign\ue9es am\ue9lior\ue9es d\ue9tiennent tout le potentiel
pour leur usage comme alternatives dans des programmes
d\u2019am\ue9lioration g\ue9n\ue9tiques et pour une
lib\ue9ration possible dans les r\ue9gions du pays o\uf9 le
stress de la s\ue9cheresse post floraison est fr\ue9quent. La
teneur en proline, le poids de 100 graines (HSW) et
l\u2019assimilation du CO2 sont des outils effectifs de criblage pour
la propri\ue9t\ue9 de Stg due \ue0 leur forte corr\ue9lation
avec les autres param\ue8tres