AJCS 18(07):395-400 (2024) ISSN:1835-2707
https://doi.org/10.21475/ajcs.24.18.07.pne-43
Trade-offs between grain number, grain weight and fruiting efficiency
of different bread wheat genotypes in response to anthesis drought
stress
Hanane Ouhemi
1,*
and Ali Amamou
2
1
Laboratory of Agronomy, Regional Center of Agricultural Research of
Settat, National Institute of Agricultural Research, Avenue Ennasr, BP
415 Rabat Principale, 10090, Morocco
2
Laboratory of Wheat Breeding, Regional Center of Agricultural
Research of Settat, National Institute of Agricultural Research, Avenue
Ennasr, BP 415 Rabat Principale, 10090, Morocco
Abstract: Cereal crops in Morocco are mainly
cultivated under rainfed conditions of dryland
regions. Under these conditions, they are mostly
exposed to drought stress that affects different yield
components. We studied the effect of anthesis
drought stress on the relationships among the
components of grain number (GN), thousand grains
weight (TGW), fruiting efficiency (FE) and yield. And
we examined fruiting efficiency (FE= grains set per g
of spike dry weight at anthesis) as promising trait for
further increasing yield without compromising yield
components. Greenhouse experiments were
Submitted:
07/11/2023
Revised:
26/01/2024
Accepted:
24/04/2024
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conducted on 2019/2020, 2020/2021 and
2021/2022 cropping seasons. Two contrasting water
regimes, irrigated and stressed treatments at anthesis
growth stage were assessed. Results showed that
anthesis drought stress affects negatively all
components studied. Substantial decrease of 10%,
16%, 9% and 34% were recorded for GN, TGW, FE, and
yield, respectively, under water stress compared to
irrigated treatments. Two genotypes, namely 15/42
and Achtar, were found to be the most adapted to
both stressed and irrigated conditions. Under
stressed conditions yield becomes less correlated
with GN (r = 0.36) and FE (r = 0.37) and more
correlated with TGW (r = 0.56*). GN becomes less
correlated with FE (r = 0.02) and TGW (r = -0.14).
While, FE becomes more correlated with TGW (r =
0.73*). To the extent of this study, FE was found as
promising selection criterion under stress conditions
without compromising TGW component.
Keywords: wheat; water stress; anthesis; fruiting efficiency; grain
number; thousand grain weight.
Abbreviations: GN_Grain number; TGW_thousand grains weight;
FE_fruiting efficiency; ns_no-significant; p_P
value
;
r, coefficient of
correlation.
Introduction
Water is the main factor limiting crop production of arid and semi-arid
regions. The amount of rain and its distribution, affect the crop
growth and productivity (Alqudah et al., 2011; Khakwani et al., 2012).
Previews studies reported several effects of anthesis drought stress on
metabolic, morpho-physiologic, and agronomic traits of wheat
(Qaseem et al., 2019; Fan et al., 2022; Ru et al., 2022). However, the
amount of these effects varied with genotypes and across
environments (Elía et al., 2016; Ferrante et al., 2017; Terrile et al.,
2017; Pretini et al., 2020).
Concerning agronomic traits; number of grains per unit area and
average grain weight are the main components of yield. The grains
number is determined during flowering time (Alqudah et al., 2011; Liu
et al., 2015). It recognizes a decrease under water stress due to pollen
abortion in the young microscope stage of pollen development, and
spikelets and florets abortion in the floral development stage (Ji et al.,
2010; Mahrookashani et al., 2017; Slafer et al., 2023). Other causes of
grain loss may be related to reduced spike dry weight at anthesis
(SDWa) (Terrile et al., 2017; Rivera-Amado et al., 2019; Pretini et al.,
2021), or reduced duration of the late reproductive phase (Gonzalez-
Navarro et al., 2016). Similarly, grain size started its construction just
before anthesis which make it vulnerable to anthesis drought stress
and to the lack of sufficient assimilate to fill the grain during grain
filling growth stage (Ji et al., 2010; Weldearegay et al., 2012).
However, longer phase from terminal spikelet to anthesis, results in
later grain filling conditions and consequently smaller grains
(Gonzalez-Navarro et al., 2016).
One of the alternatives for further increasing yield is increasing
fruiting efficiency (grains set per unit of spike dry weight at anthesis).
Increasing FE may be achieved by an accelerated rate of floret
development, an enhanced partitioning of spike assimilates, a long
stem elongation duration, or by reducing the abortion of grains
(Gonzalez-Navarro et al., 2016; Terrile et al., 2017; Slafer et al.,
2023). The fruiting efficiency has been used recently in breeding
program as a promising trait to enhance grain number and therefore
grain yield of wheat crop (Ferrante et al., 2015;
Table 1. Year of release and the pedigree of the genotypes studied.
Genotypes Year of release Pedigree
15/42
2020
-
8
44/10/17
-
MINO
132-88 - UP2338*2/KKTS*2//YANAC
132-93 - BAJ #1/KISKADEE #1
Achtar
1988
HORK/YMH//KAL/BB
Amal
1993
Bow’s’/Buc’s’
Table 2. Means of treatments, mean squares and significance of ANOVA.
GN/S
TGW (g)
FE (grains.g
spike
-
1
)
Yield (g/pot)
Mean irrigated treatments
25.14
±0.83
29.19
±0.88
35.22
±1.53
9.42
±0.34
Mean stressed treatments
22.59
±0.90
24.40
±1.35
31.91
±1.35
6.26
±0.36
Source of variation (
mean square
ns, *, **, *
**
)
Water regime (WR) 176.46
**
619.44
**
296.08
ns
269.611
***
Genotype (G) 121.44
***
65.42
ns
184.82
ns
3.885
ns
Year (Y)
4734.07
***
1353.48
***
3400.35
***
129.961
***
WR x G
12.64
ns
35.84
ns
29.82
ns
2.438
ns
WR x Y 84.79
*
390.31
**
1052.22
***
34.336
**
G x Y 78.33
**
72.141
ns
140.36
ns
7.978
ns
WR x G x Y
18.76
ns
9.32
ns
82.36
ns
4.356
ns
± standard error. ns: no-significant; *: significant at p<0.05; **: highly significant at p<0.01; ***: very highly significant at p<0.001.
Joudi et al., 2016; Gerard et al., 2019; Curin et al., 2021; Pretini et al.,
2021). The eco-physiological model defined above encompasses the
grain number as the result of the spike dry weight and fruiting
efficiency at anthesis (Pretini et al., 2021). However, the trade-off
recorded between FE and grain weight may limit its usefulness
(Gonzalez-Navarro et al., 2016; Terrile et al., 2017; Slafer et al.,
2023). In response to that, the objectives of this study were to identify
the best-performant genotypes among six bread wheat genotypes
exposed to anthesis drought stress, to underly the resulting
relationship among yield, grain number, grain weight and fruiting
efficiency, and to discuss the resulting trade-offs between these
traits.
Results
Effect of anthesis drought stress on grain number, grain weight,
fruiting efficiency and yield
Analysis of variance revealed significant difference (p<0.05) between
water regimes (WR) for GN/S, TGW and yield. Average decrease of
10%, 16%, 9%, 34% were observed for GN, TGW, FE and yield,
respectively, under water stress compared to control treatment (Table
2). Highly significant difference (p<0.001) between genotypes was
recorded for NG/S. In fact, all genotypes recorded substantial
decrease due to water stress in GN/S, TGW, FE and yield. However,
15/42 and Achtar genotypes recorded small amount of decrease
between water regimes for GN/S and FE components. Amal variety
recorded the same value of TGW (25 g) under both water regimes. And
the three genotypes, Amal, Achtar and 15/42 recorded small amount
of decrease in yield between both water regimes (Fig. 1).
The range of variation in GN/S among genotypes oscillated between
20 and 29 grains under irrigated regimes (9 grains of difference),
while this range lowered to 6 grains of difference when it is exposed
to stress (Fig. 1a). Likewise, TGW showed a range of 9 g of difference
between genotypes (from 26 to 35 g) when it was irrigated, while this
range was lowered to 3 g when it was exposed to water stress (Fig.
1b). Similarly, FE ranged between 28 and 41 (13 grains/g.
spike
of
difference) when it was irrigated, while this range was lowered to 7
grains/g.
spike
(from 29 to 36) when it was subjected to water stress
(Fig. 1c). Finally, grain yield recorded a range from 9 to 11 g/pot when
it was irrigated, while it ranges around 6 g/pot when it was stressed
(Fig. 1d).
Genotypes ranking under stressed and irrigated environments
The results of the centered scatter plot revealed that the six
genotypes studied varied noticeably in reaction to stressed or irrigated
environment for each trait. 15/42 and Achtar genotypes showed the
best performance under stressed environments for grain number
component (GN/S) (Fig. 2a). For thousand-grain weight (TGW), all
genotypes except 132-93 performed better in stressed environment
(Fig. 2b). Whereas, for the fruiting efficiency trait (FE), 132-93, 15/42,
and Achtar genotypes showed the best performance under stressed
conditions (Fig. 2c). Finally, for grain yield, 15/42, Amal, and Achtar
genotypes performed better in stressed environment (Fig. 2d).
Trade-offs: grain number, grain weight, fruiting efficiency and yield
As shown in Table 3, Grain number (GN) recorded significant and
positive correlation with FE (r = 0.48*) under irrigated conditions. This
trend was changed under stressed conditions by reducing the positive
correlation to r = 0.02. On the other side, significant negative
correlation between GN and TGW (r = - 0.66*) was recorded under
irrigated conditions. While under stressed conditions, this negative
correlation becomes much lower (r = - 0.14). Additionally, FE
recorded a negative correlation with TGW (r = - 0.11) under irrigated
conditions. This trend was changed under stressed conditions by
favoriting the positive correlation between FE and TGW (r = 0.73*).
Finally, yield recorded significant (<0.001) and positive correlation
with GN (r = 0.76*) and FE (r = 0.61*), and significant and negative
correlation with TGW (r = - 0.50*) under irrigated conditions. While
under stressed conditions it records less positive correlation with
Fig 1. Means of genotypes under stressed and irrigated treatments for a) grain number per spike (GN/S); b) thousand-grain weight
(TGW); c) fruiting efficiency (FE); and d) yield. Different small letters indicate significant difference according to Tukey’s test.
Table 3. Pearson’s correlation coefficients of different traits under irrigated (above) and stressed (below) conditions
Correlations Irrigated
Stressed
- NG/S TGW FE Yield
NG/S
-
-
0.66*
0.48