Biological and Clinical Sciences Research
Journal
Biol. Clin. Sci.
Res. J. Volume, 2020: e020
GENETIC
VARIABILITY AND ASSOCIATION AMONG SEEDLING TRAITS OF ZEA MAYS UNDER DROUGHT STRESS CONDITIONS
HASEEB A, NAWAZ A, RAO MQA, *ALI Q,
MALIK A
Institute of
Molecular Biology and Biotechnology, The University of
Lahore, Lahore, Pakistan
Corresponding
author: saim1692@gmail.com
Abstract
Maize
is an important food crop for human and feed for animals or livestock. It is
highly sensitive for abiotic and biotic stress
conditions. An experiment was conducted in the greenhouse of Institute of
Molecular Biology and Biotechnology, The University of Lahore for the
determination of effects of drought on maize growth related seedling traits.
Four maize genotypes/varieties viz., B-316, Raka-poshi,
Pak-Afghoi and EV-1097Q were grown to evaluate the
effects of drought stress. Four drought treatments were used including 20% irrigation water, 40% irrigation water, 60% irrigation water, 80%
irrigation water, 90% irrigation water and control or 100% irrigation water. It was found
that the genotypes B-316 and Raka-poshi showed better
performance for all studied traits especial shoot and root length as compared
with other two genotypes EV-109Q and Pak-Afghoi. The
minimum effects of drought were reported at control and 90% irrigation water.
The effects of drought were increased with the increase in concentration of
drought stress. The adverse drought effects were reported under the treatment
of drought at 20% and 40% irrigation water. The higher genetic advance and
heritability was recorded for root length, shoot length, dry shoot weight and
dry root weight. The significant correlation was recorded between root length,
shoot length and dry shoot weight. The higher contribution for shoot length was
reported for root length, dry shoot weight and number of roots per plant. It
was concluded from study that the selection of maize genotypes on the basis of
root length, shoot length and dry shoot weight may be fruitful to produce
drought stress tolerance maize hybrids and synthetic varieties.
Keywords:
maize, drought, genetic advance, heritability, root length, shoot length
Introduction
Maize is also known as corn in
western countries. All grains were known as corn in trade and maize was very
famous grain in trade. The corn or maize has been considered as an imperative
cereal crop however, with course of the time, the needs of maize has been going
to enhance, therefore the need of maize to grow hastily during the short
duration for overcoming the malnutrition in human population (Ali
et al., 2013). Maize
contains oil, sugar, ash, fibres and proteins (Ali
et al., 2014; Chaudhary, 1983). The
production of grain yield of maize in Pakistan has been low as compared with
developed countries due to low seed quality; therefore, a large number of abiotic and biotic environmental factors are there which
affect the crop productivity and yield during crop growth periods (Ali
et al., 2016; Ali et al., 2012; Buckler
et al., 2009). There
are significant losses in grain yield
of corn or maize has been projected due to drought because of increase in
global climate changes among major maize production areas of the world. Maize
plant is highly sensitive to drought stress conditions which mainly caused
damages at silking, anthesis
and grain filling phases of maize crop plants. Maize has been suffered from
water deficit or drought between the anthesis as well
the grain filling stages of crop plants which caused up to 40-80% grain yield
los, therefore, the drought has been considered as a main or major limiting
factor which affects plant development, growth and grain yield of maize (Edreira and Otegui, 2012; Masood et al., 2015; Mupangwa et
al., 2007; Mustafa et al., 2013). The need is for the development of such new
techniques and varieties to overcome the grain yield losses due to changing
global environmental conditions which are included salt, heat, alkalinity,
flood and drought stresses (Barnabás et al., 2008; Cakir, 2004; Zubair et al., 2016) also cold, heat and salinity caused losses in corn
grain production and mainly affects at anthesis stage
(Boomsma et al., 2009; Chai et al., 2016; Farre and Faci,
2006).
Materials and methods
For
evaluating maize for drought stress, we have conducted an experiment in the
greenhouse of Institute of Molecular Biology and Biotechnology, The University
of Lahore, Lahore. Four maize genotypes were selected for our research work, viz., B-316, EV-1097Q, Raka-poshi and Pak-afghoi. The
seeds of selected wheat genotypes were sown in 56 pots. Each of the pot was in
triplicate for each of the maize genotype. The treatments of drought stress
were kept as 20% irrigation water, 40% irrigation water, 60% irrigation water,
80% irrigation water, 90% irrigation water and control or 100% irrigation water.
The seeds were sown and after
germination, the seedlings were given stress treatments after one week of
germination. The salt treatment was carried out through the application of
200ml water to normal or control plants while calculated amount of water was carried
out for stress conditions. The seedling data was recorded for diverse
morphological traits, viz., leaf
area, roots per plant, dry root weight, root length,
shoot length, shoot dry weight. The recorded data was analyzed statistically
through the analysis of variance (ANOVA) techniques through using the SPSS23.1
software.
Results and
discussion
It was found from results shown in
table 1 that all of the maize genotypes were affected by water deficiency or
drought stress conditions. The survival rate of all of the genotypes was 100%
under normal or control conditions, while the survival rate was decreased as
the shortage of water was exposed to the seedlings; the higher survival rate at
lowest irrigation water was recorded for maize genotypes B-316 and Raka-poshi, while the lowest survival rate was recorded for
Pak-afghoi. The higher survival rate of B-316 and Raka-poshi indicated that these genotypes showed tolerance
for drought stress conditions and may be used for the development of higher
yielding maize hybrids and synthetic varieties (Ali et al., 2012; Boomsma et al., 2009).
Table
1. Survival percentage of maize genotypes under different drought
stress conditions
|
Treatments |
B-316 |
Raka-poshi |
EV-1097Q |
Pak-Afghoi |
|
Control |
100 |
100 |
100 |
100 |
|
20% irrigation water (T1) |
75.21 |
74.17 |
73.24 |
72.76 |
|
40% irrigation water (T2) |
78.45 |
76.34 |
77.48 |
74.28 |
|
60% irrigation water (T3) |
81.24 |
80.83 |
76.53 |
76.34 |
|
80% irrigation water (T5) |
87.78 |
86.87 |
78.45 |
79.25 |
|
90% irrigation water (T6) |
89.34 |
90.47 |
80.12 |
81.42 |
It was revealed from results given
in table 2 that significant differences were reported for genotypes,
treatments, and interactions between treatments of drought and genotypes. The
results revealed that the average leaf area (4.1522±0.00112cm2),
number of roots per plant (7.693±0.0114), dry root weight (0.7215±0.0001),
shoot dry weight 0.9763±0.0022g) root length (1.923±2.0923cm) and shoot length
(1.326±1.0223cm) under all of the drought treatments. The coefficient of
variation was found lower for all of the studied traits which revealed the
consistency among the results and showed that the results were reliable for the
selection of maize genotypes for drought stress tolerance to improve grain
yield and productivity of maize crop plants under drought stress environmental
conditions. The genetic advance was found higher for all of the studied traits
while highest were recorded for root length (28.252%) and shoot length
(24.132%). The higher genetic advance for root length and shoot length
indicated the selection of drought tolerance maize genotypes on the basis of
root length and shoot length may be helpful to improve maize grain yield under
drought stress conditions (Farre
and Faci, 2006; Mustafa
et al., 2013). The higher genetic advance also revealed that the shoot
length and root length may be fixed in next generation hence may be used as selection
criteria. The higher heritability was also found for all of the studied traits,
while again higher heritability was recorded for root length (91.298%) and
shoot length (92.145%), the higher heritability indicated that the genes for
traits will be inherited to next generation for improvement of root and shoot
lengths. The selection on the basis of higher heritability may be used for the
development of hybrids and synthetic varieties of maize (Ali et al., 2012; Ali et al., 2011; Boomsma et al., 2009).
Table 2. Genetic components for morphological traits of
maize seedlings
|
Source |
LA |
RPP |
DRW |
DSW |
RL |
SL |
|
Replication |
0.0002 |
0.0318 |
0.00063 |
0.0023 |
0.0342 |
0.0134 |
|
Genotypes |
6.0023* |
1.6371* |
0.00053* |
0.0036* |
64.002* |
26.246* |
|
Treatments |
8.436* |
1.3084* |
0.01873* |
0.01672* |
6.8624* |
7.4317* |
|
Genotypes × treatments |
21.543* |
1.4464* |
0.00478* |
0.00148* |
0.0871* |
0.017* |
|
Error |
0.0213 |
0.00897 |
0.00003 |
0.0003 |
0.0197 |
0.0342 |
|
Grand Mean |
4.1522 |
7.693 |
0.7215 |
0.9763 |
19.923 |
19.326 |
|
Coefficient of variance (%) |
7.464 |
8.231 |
9.26 |
7.242 |
10.23 |
5.32 |
|
Standard Error |
0.00112 |
0.0114 |
0.0001 |
0.0022 |
2.0923 |
1.0223 |
|
Genetic advance |
21.234 |
15.891 |
17.245 |
23.981 |
28.252 |
24.132 |
|
Broad sense heritability |
87.242 |
83.109 |
89.435 |
90.131 |
91.298 |
92.145 |
* = Significant at 5% probability level, DRW = dry
root weight, FRW = fresh root weight, RL= root length, SL = shoot length, RPP =
roots per plant, LA = leaf area
The table 3 showed that the all of
the genotype B-316, Raka-poshi, EV-1097Q and Pak-afghoi showed varying behavior under all treatments of
drought stress on maize seedlings, the results indicated that the genotypes
B-316 and Raka-poshi showed higher root length and
shoot length under lowest irrigation water treatment of 20% irrigation water as
compared with other genotypes. The higher root and shoot lengths of both of the
genotypes indicated that the selection of these two genotypes may be effective
for developing drought tolerant maize varieties and hybrids (Ali et al., 2014; Mazhar et al., 2020; Saif-ul-malook et
al., 2014; Zameer
et al., 2015).
Table
3. Mean comparison
for maize genotypes under different salt concentrations
|
Genotypes |
Treatments |
SL |
RL |
LA |
NR |
SDW |
RDW |
|
B-316 |
|||||||
|
Control (T0) |
18.760b |
17.560c |
5.170b |
7.560a |
0.980a |
0.775a |
|
|
20% irrigation water
(T1) |
19.950a |
19.100a |
5.280a |
5.160e |
0.875d |
0.676d |
|
|
40% irrigation water
(T2) |
18.758b |
17.560c |
5.360a |
5.360d |
0.878d |
0.680c |
|
|
60% irrigation water
(T3) |
18.760b |
18.160b |
4.570d |
6.260b |
0.990b |
0.681c |
|
|
80% irrigation water
(T5) |
18.759b |
18.260b |
4.250d |
6.160b |
0.990b |
0.669e |
|
|
90% irrigation water
(T6) |
18.302c |
17.347c |
4.989c |
6.012c |
0.942c |
0.692b |
|
|
Raka-poshi |
|||||||
|
Control (T0) |
17.579c |
18.440c |
5.710c |
7.210a |
0.950c |
0.729c |
|
|
20% irrigation water
(T1) |
19.010a |
17.140d |
5.901b |
5.243e |
0.860e |
0.650d |
|
|
40% irrigation water
(T2) |
18.606b |
17.540d |
5.410e |
6.310c |
0.858f |
0.648e |
|
|
60% irrigation water
(T3) |
18.609b |
17.520d |
5.633d |
6.210d |
0.960b |
0.649e |
|
|
80% irrigation water
(T5) |
17.579c |
21.140a |
6.150a |
6.410b |
0.938d |
0.741a |
|
|
90% irrigation water
(T6) |
17.341d |
19.23b |
5.231f |
6.135d |
0.974a |
0.734b |
|
|
EV-1097Q |
|||||||
|
Control (T0) |
19.567a |
18.320c |
5.24d |
7.960a |
0.928b |
0.739a |
|
|
20% irrigation water
(T1) |
18.56b |
18.32c |
5.26c |
7.86a |
0.833d |
0.613d |
|
|
40% irrigation water
(T2) |
17.54c |
19.54a |
6.35a |
6.96b |
0.809e |
0.731b |
|
|
60% irrigation water
(T3) |
17.541c |
19.31a |
6.35a |
6.86b |
0.908c |
0.733b |
|
|
80% irrigation water
(T5) |
18.562b |
19.13b |
5.36c |
6.86b |
0.933a |
0.732b |
|
|
90% irrigation water
(T6) |
18.23d |
18.34c |
6.214b |
6.90b |
0.903c |
0.721c |
|
|
Pak-afghoi |
|||||||
|
Control (T0) |
17.422d |
17.74c |
7.426a |
7.652a |
0.932a |
0.722a |
|
|
20% irrigation water
(T1) |
18.522a |
18.624b |
6.351d |
5.124f |
0.821d |
0.614d |
|
|
40% irrigation water
(T2) |
19.512b |
17.528d |
6.504c |
6.043e |
0.811d |
0.625c |
|
|
60% irrigation water
(T3) |
17.421d |
18.516b |
6.503c |
6.164d |
0.921b |
0.727a |
|
|
80% irrigation water
(T5) |
18.432c |
17.452d |
7.143b |
6.405b |
0.901c |
0.711b |
|
|
90% irrigation water
(T6) |
17.241e |
19.234a |
6.342e |
6.325c |
0.930a |
0.712b |
|
From correlation analysis (Table 4) it was found that a positive and
significant correlation was recorded for shoot length with all of the studied
traits including root length, leaf area, number of roots per plant, dry root weight
and dry shoot weight. The root length was significantly correlated with leaf
area, shoot length while negative and significant correlation of root length
was recorded with dry root weight. The positive correlation of root length and
shoot length indicated that under water deficit conditions the seedlings may
withstand for long time and can survive even under harsh environmental
conditions. The election on the basis of root length and shoot length may be
helpful to improve drought stress tolerance in maize and also help to develop
drought tolerant maize genotypes (Ali et al., 2016; Ali et al., 2014).
Table
4. Correlation
among morphological traits of maize
|
Traits |
LA |
RPP |
DRW |
DSW |
RL |
|
RPP |
0.6324* |
||||
|
DRW |
-0.0243 |
0.0942 |
|||
|
DSW |
-0.1354 |
0.2045 |
0.3562* |
||
|
RL |
0.5362* |
0.2845 |
-0.3565* |
-0.3023 |
|
|
SL |
0.4822* |
0.5353* |
0.7632* |
0.8753* |
0.6872* |
* = Significant at 5% probability level, DRW = dry
root weight, FRW = fresh root weight, RL= root length, SL = shoot length, RPP =
roots per plant, LA = leaf area
Regression
analysis was performed to evaluate the contribution of each studied trait for
improving shoot length under drought stress conditions. It was found from our
results (Table 5) that the root length contributed higher towards increasing
shoot length as compared with other traits (Ali
et al., 2016; Cakir, 2004; Mustafa
et al., 2018), the leaf area and dry shoot
weight also contributed positively towards shoot length while the dry root
weight and number of roots per plant contributed negatively towards shoot
length of maize seedlings. The predicted regression equation was as following:
Y = 1.217+8.126(RL) + 3.714(LA) - 2.420(DRW) + 5.4123(DSW) - 1.324(RPP)
Table
5. Regression
analysis for shoot length among morphological traits of maize
|
Traits |
Coefficients |
Standard
Error |
t Stat |
Partial R2 |
Lower 95% |
Upper 95% |
|
RL |
8.126 |
0.052 |
-0.0152 |
0.7623 |
0.0363 |
0.0136 |
|
LA |
3.714 |
0.1102 |
0.0314 |
0.4162 |
0.0117 |
0.3104 |
|
DRW |
-2.420 |
0.0042 |
2.0013 |
0.1556 |
-0.0315 |
0.3055 |
|
DSW |
5.4123 |
0.0212 |
-5.3336 |
0.0323 |
2.1146 |
1.3012 |
|
RPP |
-1.324 |
0.0114 |
0.2103 |
0.4332 |
-0.0135 |
0.0136 |
Y = 1.217, Multiple R2= 0.8534, R2 =
0.6823, Adjusted R2 = 0.6424, Standard Error = 0.0231 DRW = dry root
weight, FRW = fresh root weight, RL= root length, RPP = roots per plant, LA =
leaf area
Conclusions
It
was found that the genotypes B-316 and Raka-poshi
showed better performance for all studied traits especial shoot and root length
as compared with other two genotypes EV-109Q and Pak-Afghoi.
The minimum effects of drought were reported at control and 90% irrigation
water. The effects of drought were increased with the increase in concentration
of drought stress. It was concluded from study that the selection of maize
genotypes on the basis of root length, shoot length and dry shoot weight may be
fruitful to produce drought stress tolerance maize hybrids and synthetic
varieties.
Conflict of
interest
The authors declare absence of any conflict of
interest.
References