Pol. J. Environ. Stud. Vol. XX, No.

X (XXXX), 1-10
DOI: 10.15244/pjoes/191981 ONLINE PUBLICATION DATE:

Original Research
Germination Ecology of Red Sprangletop:
a Problematic Weed of Direct-Seeded Rice

Muhammad Ehsan Safdar1, Muhammad Sikander Hayyat1,

Hussam F. Najeeb Alawadi2, Muhammad Mansoor Javaid1**, Athar Mahmood3*,
Basharat Ali4, Muhammad Nawaz4, Muhammad Ather Nadeem1, Amjed Ali1,
Rashad Mukhtar Balal5, Abeer Hashem6, Alanoud Alfagham6,
Javid A. Parray7, Elsayed Fathi Abd_Allah8

Department of Agronomy, College of Agriculture, University of Sargodha, Sargodha, Pakistan

1

2
Al-Qadisiyah University, College of Agriculture, Iraq
3
Department of Agronomy, University of Agriculture Faisalabad, Faisalabad, Pakistan
4
Department of Agricultural Engineering, Khwaja Fareed University of Engineering and information Technology,
Rahim yar Khan, Pakistan
5
Department of Horticulture, College of Agriculture, University of Sargodha, Sargodha, Pakistan
6
Botany and Microbiology Department, College of Science, King Saud University,
P.O. Box. 2460, Riyadh 11451, Saudi Arabia
7
Department of Higher Education, GDC Eidgah Srinagar India -190017
8
Plant Production Department, College of Food and Agricultural Sciences, King Saud University,
P.O. Box. 2460, Riyadh 11451, Saudi Arabia

Received: 28 December 2023

Accepted: 3 August 2024

Abstract

Leptochloa chinensis L. commonly called red sprangletop is a new problematic weed of rice
(Oryza sativa L.) sown under dry conditions in Pakistan and caused a drastic reduction in its yield and
quality. Scientific inquiry was conducted concerning the germination ecology of this weed in direct-
seeded rice. A series of laboratory experiments were conducted to determine the effect of pH, salinity,
temperature, seed burial depth, and water ponding conditions on the germination of L. chinensis.
In five different experiments, six variable pHs ranging from 5 to 10; six salinity levels viz. 0 (Distilled
water), 50 mM, 100 mM, 150 mM, 200 mM, 250 mM and 300 mM; six variable temperatures viz.
20oC, 25oC, 30oC, 35oC, 40oC and 45oC; seven different burial depths viz. 0 cm (on soil surface),
1 cm, 2 cm, 3 cm, 4 cm, 5 cm and 6 cm; and different water ponding depths viz. 0 cm, 2 cm, 3 cm,
4 cm, 5 cm and 6 cm were kept as experimental treatments. The results revealed that within the pH
range of 6-7 and 35oC temperature, L. chinensis seeds attained the highest germination percentages
(78% and 92%, respectively). A gradual significant decline in germination of L. chinensis was noted by
the increase in NaCl concentration from 0 to 200 mM, sowing depth from 1 to 5 cm, and flooding

* e-mail: athar.mahmood@uaf.edu.pk
**e-mail: mmansoorjavaid@gmail.com
2 Muhammad Ehsan Safdar, et al.

depth from 0 to 4 cm. However, beyond 200 mM NaCl concentration, 5 cm sowing depth, and 4 cm
flooding depth, no L. chinensis seed could germinate/emerge. According to the 3-parameters logistic
model estimation, 50% germination of the maximum germination of L. chinensis occurred at 102 mM
NaCl concentration, 1.56 cm burial depth, and 2.2 cm flooding depth.

Keywords: rice, germination, salinity stress, ecology, soil pH

Introduction process, thus considered the major environmental factor

affecting seed germination [13, 14]. Sowing depth also
Leptochloa chinensis L. commonly called red influences the germination and seedling emergence by
sprangletop. It is a grassy weed belonging to the family mediating the supply of light, moisture, and temperature
Poaceae. Its physiological characteristics classify it to to germinating seed. Water ponding conditions in
be a C4 plant [1]. It is native to tropical Asia and widely the seed germination medium reduce germination by
distributed in South and Southeast Asia, Australia, and restricting the supply of O2 to germinating seed [15].
Africa. Geographically, it is distributed in China, Korea, Salinity inhibits germination by imposing osmotic
Japan, Bangladesh, Philippines, Pakistan, Cambodia, effects and ionic effects on germinating seed. However,
India, Malaysia, Myanmar, Sri Lanka, Vietnam and the effect of salinity varies according to plant species,
Thailand [2]. It is summer annual or perennial tufted genotypes and environmental conditions. Salinity
grass that can attain up to 120 cm height, having hollow, adversely affects the germination and growth process
cylindrical, erect stems, and linear smooth 10-30 cm long through its osmotic effect by retarding the imbibition
leaves. Inflorescence is a narrowly ovate, loose panicle process and its specific ionic effect by imposing toxicity
with two rows of 2-3 mm long spikelets that are purplish of undesirable ions. The lowering of the osmotic
or green and 4-6 flowered. It reproduces both sexually potential of the germination medium imposes a more
and asexually [3]. Leptochloa chinensis is known to be dominant influence on germination compared with
an invasive weed in Southeast Asia [4]. It has abundant specific ion effects. The seedling growth is mostly
seed-producing ability, thus widespread in almost all suppressed due to specific ionic stress, depending
crops including rice. The other characteristics that make on the amount and distribution of rainfall [16, 17].
it a successful invasive weed are strong allelopathicity, The disastrous influences of salt stress are altered by
adaptability to variable soil conditions, and aggressive intermingling with other environmental attributes
growth habits. Two plants of L. chinensis cause a 55% like temperature and light. The ecological optima of
yield reduction in rice [5]. Due to its hydrophytic nature germination and early seedling growth of an invasive
and amphibious adaptation, it can thrive best under weed species determines its chances of success in a new
alternate soil flooding conditions. It has dominated all region. Therefore, knowledge about the ecology of the
the weeds of rice [6, 7]. That is why; it has now become germination of a weed can act as a tool for its better
a serious weed of transplanted as well as direct-seeded management [18].
rice. The allelopathic effect of red sprangletop on rice
In Pakistan, rice is mostly cultivated through and the effect of different agronomic practices on its
transplanting the nursery-grown seedlings to flooded growth in rice have been widely studied. However, very
field conditions. However, to save labor and time, little research has yet been done on the germination
farmers are widely adopting direct seeding technology ecology (temperature, salinity, pH, burial depth and
in which rice seed is directly sown in dry soil conditions. ponding conditions) of L. chinensis [19]. Knowledge
This shift from traditional transplanting to direct about the optimum and sub-optimum levels of all these
seeding has resulted in a change in weed flora [8, 9]. environmental factors on germination of L. chinensis
The weeds that were previously considered minor weeds can contribute to the development of an effective
have now become major weeds. L. chinensis is also one management program for this weed in direct-seeded rice.
of the examples of a dominant weed in direct-seeded A study was therefore being planned to investigate the
rice (DSR). The importance of this weed has increased ecology of L. chinensis so that facts could be established
due to the fact that contrary to other DSR weeds, about how it has flourished very much in direct-seeded
L. chinensis is very difficult to control even by the use rice conditions in Pakistan [20].
of all existing herbicides [10, 11]. To launch a successful
management program against a weed, knowledge of
its germination ecology is of utmost importance. Seed Materials and Methods
germination is affected by a number of factors (Fig. 1)
including soil pH, temperature, seeding depth, water To know about the effect of pH, salinity, temperature,
ponding conditions, and soil salinity [12]. Soil pH has a seed burial depth and water ponding conditions on the
minute role in germination, yet it affects the germination germination of L. chinensis, 5 individual experiments
process by mediating the availability of nutrients. were carried out, respectively. In experiment 1,
Temperature is directly linked with the germination treatments consisted of six variable pHs ranging from 5
Germination Ecology of Red Sprangletop... 3

Fig. 1. Ecological factors affecting germination of red sprangletop.

to 10. The pH of different buffer solutions was maintained at 35oC temperature. The germination/emergence data
by using hydrochloric acid (HCL) and sodium hydro- were collected on a daily basis for the period of 20 days.
oxide (NaOH) with MES, HEPES, and tricine were The seed was supposed to be germinated when radicle
used as buffers. In experiment 2, treatments comprised and plumule attained 2 mm length and the sprouted seed
of 6 increasing salinity levels maintained by variable was poured out of the petri dish / pot after counting.
NaCl solution concentrations viz. 0 (Distilled water), Soil used in pots was collected from the site without any
50 mM, 100 mM, 150 mM, 200 mM, 250 mM and vegetation at Agronomic research farm. Collected soil
300 mM. Different levels of salinity were generated by was sieved and then filled in plastic pots.
using sodium chloride (NaCl) solution. In experiment 3, Following parameter was recorded in all
treatments were six variable temperatures viz. 20oC, experiments:
25oC, 30oC, 35oC, 40oC and 45oC. The experiment 1. Germination /emergence percentage (GP/EP)
4 comprised of 7 different burial depths viz., 0 cm (on Based upon final germination / emergence count,
surface of soil), 1 cm, 2 cm, 3 cm, 4 cm, 5 cm and 6 cm. germination / emergence percentage was calculated
In 5th experiment, different ponding conditions viz. 0 cm, according to formula of The Association of Official Seed
2 cm, 3 cm, 4 cm, 5 cm, and 6 cm were maintained as Analysts [21].
experimental treatments. In the first three experiments,
25 seeds of L. chinensis were spread in a petri plate
(9 cm in diameter) with having double layer of filter (1)
papers. In the pH experiment, 5 ml buffer solutions of
different pH levels, in the salinity experiment, 5 ml of 2. Time to start germination / emergence (Ti)
solutions with different salinity levels, whereas in the It is the time in days when seeds start germinating /
temperature experiment, 5 ml of distilled water were emerging.
applied to petri plates and petri plates were enclosed 3. Germination/emergence index (GI/EI)
with parafilm to avoid moisture loss. Petri plates in The Germination Index was determined as portrayed
the first two experiments were put into the germinator by the Association of Official Seed Analysts, (1990) by
at 35oC while in the third experiment, at different the following Equation (2):
temperatures as per the treatment plan. In the fourth
and fifth experiments, 25 seeds of L. chinensis were
sown in pots (9 cm diameter) filled with soil. In sowing
depth experiment, seeds of L. chinensis were sown
in soil saturated with distilled water at a prescribed
depth according to the treatment plan and then pots (2)
were irrigated with distilled water as per requirement.
However, in the water ponding experiment, seeds of 4. Mean germination/emergence time (MGT/MET)
L. chinensis were sown on the surface of the soil and Mean germination/emergence time was determined
then pots were irrigated with distilled water to maintain by the situation of [22].
the proposed ponding conditions throughout the study as
per the treatment plan. Pots were kept in the germinator
4 Muhammad Ehsan Safdar, et al.

Where E is the total emergence at x sowing and

(3) flooding depth, x50 is the sowing and flooding depth
for 50% inhibition of the maximum emergence and e
Where indicates the slope.
n = Number of seeds that had germinated on day “D”
D = Number of days counted from the beginning of
germination. Results and Discussion
5. Time to 50% germination/emergence (T50)
The time to obtain 50% germination/emergence (T50) Effect of pH
was determined by the equation of [23] as adjusted by
[24] The pH value expresses the acidity or alkalinity
of the solution on a logarithmic scale. Germination of
L. chinensis was significantly influenced at various
(4) pH levels (Fig. 2, Table 1). The pHs 6 and 7 attained
the highest germination percentages (77 and 78%,
Where respectively) (Fig. 2). The earliest time to germination
N = Last number of germinated / emerged seeds initiation (Ti) (3.75 days) was recorded with a pH 8
ni & nj = Accumulative number of seeds germinated by (Table 1). The maximum germination index (19.54)
contiguous counts at times ti and tj, individually, where was recorded with Petri plates that were supplied with
ni <N/2 < nj. a solution having pH 9 which was statistically similar
6. Seedling vigor index (SVI) to pH 8 (Table 1). The maximum germination speed of
Germination percentage and seedling length were L. chinensis seeds was observed with pH 8 as the lowest
used to calculate seedling vigor index (SVI) by the values of MGT (5.09 days) and T50 (5.63 days) were
succeeding method as designated by [25] noted with it. However, pH 9 also gave significant at par
values of MGT and T50.
The better germination performance of L. chinensis
seeds at slightly acidic to alkaline pHs seems to be
(5) the result of enhanced activity of enzymes involved
in the germination process enzymes are directly
affected by the H+ ion concentration in the germination
Statistical Analysis medium. Our outcomes are in accordance with the
outcomes of [26] who described that pH may not be
All the experiments were arranged as completely a restricting component for the emergence of turnip
randomized designs with each treatment having weed. Correspondingly, higher than 45% emergence
four replications. All the experiments were repeated was observed over a pH range from 4-10. [27]
twice. Data were subjected to a one-way analysis described that germination of seed was pragmatic over
of variance (ANOVA) and all possible comparisons a broad range of pH however maximum germination
among treatment means were made through the least percentage of L. chinensis was recorded at pH 7 while
significant difference test. Germination percentage data E. glabrescens was proved to be more sensitive to given
in response to increasing NaCl concentrations, sowing range of pH. Our consequences are also in agreement
depths and flooding depth were fitted to a functional
three-parameter logistic model using Sigma Plot
2008 (Version 11.0, SyStat Software GmbH,
Schimmelbuschstrasse 25 D-40699 Erkrath Germany).
The model equation fitted for NaCl concentration
experiment was:

(6)

Where G is the total germination at x NaCl

concentration, x50 is the NaCl concentration for 50%
inhibition of the maximum germination and g indicates
the slope. The model equation fitted for sowing and
flooding depths experiments was:

(7)
Fig. 2. Effect of pH on germination of L. chinensis.
Germination Ecology of Red Sprangletop... 5

Table 1. Influence of variable pHs, salinity levels and temperatures on germination of Leptochloa chinensis L.
Treatments Ti (days) GI T50 (days) MGT (days)
pH
5 5.75 a 11.0 c 7.18 a 8.08 a
6 5.75 a 11.8 c 7.38 a 8.25 a
7 5.00 a 13.2 bc 7.39 a 8.06 a
8 3.75 b 19.4 a 5.09 b 5.63 b
9 5.00 a 19.5 a 5.66 b 6.32 b
10 5.50 a 15.2 b 7.05 a 7.65 a
LSD 1.174 2.95 1.350 1.311
Salinity level
Control 4.25 d 20.6 a 6.62 d 6.06 d
50 mM 4.50 cd 13.9 b 7.14 d 6.92 c
100 mM 5.25 c 8.80 c 7.93 c 7.01 c
150 mM 7.25 b 3.42 d 8.72 b 7.89 b
200 mM 9.25 a 1.29 e 10.37 a 9.70 a
250 mM NG NG NG NG
300 mM NG NG NG NG
LSD 0.786 1.477 0.564 0.368
Temperature
20 C
o
5.00 b 9.86 c 7.23 bc 7.50 d
25 C
o
4.75 b 15.0 a 6.65 c 7.72 d
30oC 5.00 b 14.4 ab 7.66 abc 8.23 c
35oC 5.50 b 14.1 ab 7.94 ab 8.59 b
40 C
o
6.00 ab 13.6 ab 8.65 a 9.34 a
45 C
o
7.00 a 11.8 bc 8.77 a 9.21 a
LSD 1.298 2.9782 1.1885 0.3457
In columns, values with different letters show significant difference (p≤0.05) as determined by least significant difference (LSD) test.

with the observations of [28] who observed that the L. chinensis occurred at 102 mM NaCl concentration
highest germination of L. fusca (92%) was recorded at (Fig. 3). The earliest germination initiation (4.25 days)
pH 7 while the lowest value of germination (54%) was and T50 (6.62 days) of L. chinensis occurred at 0 mM
observed at pH 10. NaCl concentration that was not significantly delayed up
to 50 mM NaCl concentration beyond which these were
Effect of Salt Stress significantly increased (Table 1). The GI and MGT of
L. chinensis followed the same trend as the highest
The term salinity refers to the quantity of dissolved value of GI (20.6) and the lowest value of MGT (6.06
salts that are present in water. Data given in Table 1 days) were recorded with control. However, a significant
indicated that different levels of salinity significantly delay in germination in terms of these parameters
reduced the germination of L. chinensis. Results revealed occurred at and beyond 50 mM NaCl concentration.
that germination of L. chinensis was significantly Higher soil saltiness hinders seed germination because
reduced by the increase in NaCl concentration from of the low osmotic potential of water created around
0 to 200 mM whereas no L. chinensis seed germinated the seed, which hinders water imbibition by seed [29].
beyond 200 mM NaCl concentration. According Moreover, a higher concentration of Na and Cl in the
to the 3-parameters logistic model estimation, germination medium might itself prove poisonous to
50% germination of the maximum germination of seeds [30].
6 Muhammad Ehsan Safdar, et al.

Fig. 3. Effect of NaCl concentration on germination (%) of L. chinensis. The bold line represents a three-parameter logistic model
(G (%) = Gmax/[ 1 + (x/x50)g]) fitted to the data. The vertical dashed line represents X-axis value at 50% of the maximum germination.
The dotted lines show 95% confidence intervals. Vertical bars represent±standard error of the mean.

Plant emergence and growth are significantly highest values of GI (13.6 to 15) recorded within this
hampered in saline soil owing to peripheral osmotic temperature range.
potential to avert water uptake or the poisonous effect Germination of L. chinensis was better at moderate
of sodium and chlorine on germinated seed [31]. to high temperatures. This is because this weed
These outcomes are similar to the observations of is native to tropical regions characterized by high
[32] who pointed out that germination of E. colona temperatures. Similar results were also found by
was reduced linearly by the escalation in NaCl [35] who described that maximum germination of
concentration. The germination of barnyard grass was L. chinensis (95%) was recorded at a temperature range
substantially reduced due to the influence of salinity. from 25-35 oC, indicating high-temperature requisite
Present findings are also similar to those of [33] who for germination of red sprangletop. The judgments of
documented that the germination index was linearly the present experiment are alike with the observation of
decreased by the increase in NaCl concentration. Our [28] who indicated that germination of E. glabrescens,
observations are also in accordance with those of [34] L. chinensis, and D. aegyptiumwas started at 35oC.
who documented that MGT was increased with the However, contrasted results were described by [36]
increase in salt concentrations. At high levels of salinity, who pointed out that emergence of L. chinensis
seeds of different weeds significantly delayed their 50%
germination.

Effect of Temperature

The data regarding germination of L. chinensis at

different temperatures indicated that germination of
L. chinensis was significantly influenced at various
temperature regimes (Fig, 4, Table 1). Significantly,
the highest germination percentage (92%) was noted
at 35oC temperature (Fig. 3). The germination by
L. chinensis seeds was started earlier (4 to 6 days)
within the temperature range of 20oC to 40oC, while
the temperature above 40oC significantly delayed it.
The earliest germination completion in terms of T50
(6 to 7 days) and MGT (7.50 to 7.72 days) of L. chinensis
occurred within 20oC to 25oC temperature range.
However, the overall germination speed of L. chinensis
was the highest at 25oC to 40oC as indicated by the Fig. 4. Effect of temperature on germination of L. chinensis.
Germination Ecology of Red Sprangletop... 7

Table 2. Influence of variable burial depths and ponding conditions in germination of Leptochloa chinensis L.
Treatments Ti (days) EI T50 (days) MET (days)
Burial depth
1 cm 4.25 c 21.5 a 5.92 d 6.60 e
2 cm 4.50 c 12.5 b 7.08 c 7.52 d
3 cm 5.00 c 6.20 c 7.45 c 7.99 c
4 cm 8.00 b 1.61 d 8.12 b 9.89 b
5 cm 11.75 a 0.22 e 10.4 a 11.8 a
6 cm NG NG NG NG
7 cm NG NG NG NG
LSD 0.935 0.945 0.598 0.237
Flooding depth
Control 4.25 c 19.9 a 6.28 d 6.74 d
2 cm 5.00 c 10.1 b 7.19 c 7.85 c
3 cm 6.75 b 1.79 c 8.65 b 8.87 b
4 cm 11.50 a 0.32 d 11.2 a 11.7 a
5 cm NG NG NG NG
6 cm NG NG NG NG
LSD 1.134 0.459 0.430 0.935
In columns, values with different letters show significant difference (p≤0.05) as determined by least significant difference (LSD) test.

were non-significant at various temperature regimes. of [39] who documented that no seedling of L. chinensis
Similarly, the temperature requirement of L. chinensis emerged from a burial depth of 0.5 cm or more. Obtained
was even higher than those of other aquatic weed findings are comparable with the outcomes of [40] who
species, as reported by [37]. described that sowing depth caused an expansion in
MET which rose from 2.5 days in the case of surface
Effect of Burial Depth sowing (1 cm) to 7 days in the case of deep sowing.
Generally, germination of L. chinensis gradually was
Data related to the effect of different burial depths reduced with the increase in each cm of burial depth.
in soil on the emergence of L. chinensis seed have been [41] stated that seeds sown under 2 mm depth usually
given in Table 2. Results indicated that the emergence of received a restricted extent of light, which isn’t sufficient
L. chinensis seed was significantly reduced as its sowing to start germination of seed. At deeper depths, small-
depth was increased from 1 to 5 cm beyond which no sized seeds, hypoxia, and low gaseous diffusion are
seed could emerge. The fitted model estimated that 50% also responsible for zero germination. A sowing depth
emergence of the maximum was obtained at 1.56 cm of a few centimeters is adequate to avert emergence,
burial depth (Fig. 5). The earliest start of emergence encouraging the typical scalar emergence and emergence
(at 4.25th to 5th day of sowing) of its seeds was observed regularly present in disturbed habitats [42]. Germination
at 1 to 3 cm burial depth (Table 2). However, a sowing of different weed species gradually decreased by the
depth of 1 cm attained the highest emergence index (EI) increase in sowing depth [43]. The maximum emergence
(21.5), the least time to 50% emergence (T50) (5.92 days), of 69% was noted from the seeds planted on the surface
and mean emergence time (MET) (6.6 days). However, or near the surface and no seedlings rose up out of seeds
sowing of L. chinensis seeds below this depth resulted covered at profundities of 0.5 cm or more [44].
in a significant decline in EI and a delay in T50 and MET.
The L. chinensis showed better emergence at Effect of Flooding Depth
shallower sowing depths because it has minute seeds.
Small-seeded weed species may have an insufficient Data regarding the germination of L. chinensis
amount of food reserves to support seedling emergence as affected by the varying flooding depths have
at deeper depths. As the seed goes from shallower to been presented in Table 2. The results reveal that a
deeper sowing, the light incidence to it is gradually gradual decline in the emergence of L. chinensis seed
reduced [38]. Our findings are in conformity with those occurred as water flooding depth was increased from
8 Muhammad Ehsan Safdar, et al.

0 to 4 cm. However, no L. chinensis emerged out of 5th day of sowing) of this weed occurred at 0 to 2 cm
the soil as the flooding depth was increased beyond flooding depth. However, L. chinensis seeds attained
4 cm. A 3-parameters logistic model was fitted to the the highest EI (19.9), the earliest T50 (6.28 days), and
germination data obtained under different flooding MET (6.74 days) under zero flooded conditions. While
depth (Fig. 6). The model estimated that 50% of the flooding caused a significant decline in these parameters
maximum germination occurred at flooding depth of that undergo through further decline as flooding depth
2.2 cm. The quickest emergence initiation (at 4.25 to was increased.

Fig. 5. Effect of seed burial depth on emergence (%) of L. chinensis. The bold line represents a three-parameter logistic model
(G (%) = Gmax/[ 1 + (x/x50)g]) fitted to the data. The vertical dash line represents X-axis value at 50% of the maximum germination.
The dotted lines show 95% confidence intervals. Vertical bars represent ± standard error of the mean.

Fig. 6. Effect of flooding depth on germination (%) of L. chinensis. The bold line represents a three-parameter logistic model
(G (%) = Gmax/[ 1 + (x/x50)g]) fitted to the data. The vertical dash line represents X-axis value at 50% of the maximum germination.
The dotted lines show 95% confidence intervals. Vertical bars represent ± standard error of the mean.
Germination Ecology of Red Sprangletop... 9

The decline in germination of L. chinensis in post-silking heat stress reduce the yield and dry matter
response to an increase in flooding depth beyond 2 cm accumulation in waxy maize. Journal of Integrative
was due to its amphibious nature. Although this weed Agriculture, 19 (1), 78, 2020.
can grow under flooded rice conditions, yet degree of 6. LÓPEZ ROSAS H., CEJUDO E., MORENO-CASASOLA
P., PERALTA PELÁEZ L. A., HERNÁNDEZ M.E.,
its infestation in rice increased many folds as farmers
CAMPOS C.A., AGUIRRE LEÓN G. Environmental
shifted from puddled to dry-seeded rice. These outcomes Impact of Invasion by an African Grass (Echinochloa
are according to the conclusions of [45] who noted that pyramidalis) on Tropical Wetlands: Using Functional
flooding conditions significantly reduced the emergence Differences as a Control Strategy. Springer International
and dry matter of red sprangletop. These outcomes Publishing, Cham, 2019.
also corroborate the observations of [46] who stated 7. NADEEM M.A., KHAN B.A., ANWAR S., MAQBOOL
that Texas weed seed did not grow under immersed or R., AMIN M., AZIZ A., BATOOL I., MAHMOOD A.,
flooded conditions, yet the seed endured flooding and REHMAN A., ALI A. Allelopathic potential of aqueous
sprouted (23 to 25%) after flood evacuation. extracts of sow thistle weed on emergence and seedling
growth of red rice. Pakistan Journal of Weed Science
Research, 27 (2), 201, 2021.
8. NAWAZ A., REHMAN A.U., REHMAN A., AHMAD S.,
Funding SIDDIQUE K.H., FAROOQ M. Increasing sustainability
for rice production systems. Journal of Cereal Science,
The authors would like to extend their sincere 103, 103400, 2022.
appreciation to the Researchers Supporting Project 9. NADEEM M.A., KHAN B.A., CHADAR A.R.,
Number (RSP2024R134), King Saud University, Riyadh, MAQBOOL R., RAZA A., JAVAID M.M., MAHMOOD
Saudi Arabia. A., KHAN M.I., AHMAD M., IRFAN M. Weed control
and sustainable rice production through rice intensification
system and conventional practices of weed competition
periods and age of transplanted seedlings. Semina:
Acknowledgment Ciências Agrárias, 43 (5), 2271, 2022.
10. SHEKHAWAT K., RATHORE S.S., CHAUHAN B.S.
The authors would like to extend their sincere Weed management in dry direct-seeded rice: A review
appreciation to the Researchers Supporting Project on challenges and opportunities for sustainable rice
Number (RSP2024R134), King Saud University, Riyadh, production. Agronomy, 10 (9), 1264, 2020.
Saudi Arabia. 11. JAVAID M.M., MAHMOOD A., NADEEM M.A.,
SARWAR N., SAFDAR M.E., AHMAD M.,
HASANUZZAMAN M., AHMAD S. Weed Management
Strategies in Direct Seeded Rice. Springer Singapore,
Conflict of Interest Singapore, 2022.
12. ROY S., CHOWDHURY N. Salt stress in plants and
The authors declare that this article has no conflict of amelioration strategies: A critical review. Abiotic stress in
interest with any party. plants, 2020.
13. TRAVLOS I., GAZOULIS I., KANATAS P., TSEKOURA
A., ZANNOPOULOS S., PAPASTYLIANOU P.
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