Influence of Fimbristylis miliacea on growth and yield of onion

Abstract

An experiment was conducted to determine the influence of F. miliacea (FIMMI) on the growth and yield of transplanted onions (TPO) and direct-seeded onions (DSO) grown in plastic box with FMMI at 0, 10, 15, 20, and 25 plants/box until maturity. From 5 densities, shoot biomass of FIMMI increased by 1.3 - 2.7 folds in TPO; 1.6 - 13 folds in DSO as density increased by 15 - 25. Bulb weights of TPO were reduced by 11, 17.4, 22.1, and 38.7%; DSO by 86.4, 89.6, 88.8, and 88.1% at 10, 15, 20, and 25 FIMMI densities, respectively. Bulb weights of DSO suffered the greatest reductions due to weed competition. Density and shoot biomass of FIMMI were strongly negatively correlated to bulb weights of TPO (r = -0.987, -0.995) and DSO (r = -0.986, -0.999). Regression analysis showed that 97.49 and 99.95% of TPO bulb weights and 97.25 and 99.95% of DSO were attributed to the density and shoot biomass of FIMMI. This study showed that FIMMI is an important weed of bulb onion and could reduce yield if left uncontrolled throughout the crop’s growing season.

Full text

RICE-BASED BIOSYSTEMS JOURNAL (2022) 10: 9-14 9
INFLUENCE OF FIMBRISTYLIS MILIACEA (L.) VAHL ON
GROWTH AND YIELD OF BULB ONION (ALLIUM CEPA L.)
Kaiser Angelo A. Morla1, Celynne O. Padilla1, and Dindo King M. Donayre2
1Central Luzon State University, 2Philippine Rice Research Institute,
Science City of Muñoz, Nueva Ecija
*Corresponding author: dindoking08@gmail.com
Abstract
An experiment was conducted to determine the inuence of F. miliacea (FIMMI) on the growth and yield of
transplanted onions (TPO) and direct-seeded onions (DSO) grown in plastic box with FMMI at 0, 10, 15, 20, and
25 plants/box until maturity. From 5 densities, shoot biomass of FIMMI increased by 1.3 - 2.7 folds in TPO; 1.6 -
13 folds in DSO as density increased by 15 - 25. Bulb weights of TPO were reduced by 11, 17.4, 22.1, and 38.7%;
DSO by 86.4, 89.6, 88.8, and 88.1% at 10, 15, 20, and 25 FIMMI densities, respectively. Bulb weights of DSO
suffered the greatest reductions due to weed competition. Density and shoot biomass of FIMMI were strongly
negatively correlated to bulb weights of TPO (r = -0.987, -0.995) and DSO (r = -0.986, -0.999). Regression
analysis showed that 97.49 and 99.95% of TPO bulb weights and 97.25 and 99.95% of DSO were attributed to the
density and shoot biomass of FIMMI. This study showed that FIMMI is an important weed of bulb onion and
could reduce yield if left uncontrolled throughout the crop’s growing season.
Keywords: Cyperaceae, Globe-fringe Rush, Quadratic Equation, Additive Desig n
Introduction
Onion (Allium cepa L.) is one of the major
vegetable crops in the Philippines planted after rice
(PhilRice, 2007). In 2019, bulb onion was planted in
19,900 hectares with production volume of 222,100
metric tons valued at PhP 5.6 billion (PSA, 2020).
These gures are expected to further rise to meet the
demands for culinary purposes.
Growth and development of onions can be
negatively affected by weeds. In a eld study in
Nueva Ecija, weeds left uncontrolled reduced the
yield of red and white onions by as much as 78 and
97%, respectively (Baltazar et al., 1998a). In another
study, yield of red onion was also reduced by 79%
when major weeds such as Cyperus rotundus L.,
Echinochloa colona (L.) Link., and Trianthema
portulacastrum L. were left uncontrolled (Baltazar
et al., 1998b). It is important, therefore, that these
weeds must be controlled to safeguard the quantity
and quality of yield as well as ensure decent income
from onions.
Fimbristylis miliacea (L.) Vahl, commonly known
as globe fringe-rush, is a C4 and perennial plant that
has an erect and attened stem; linear, at, and soft
leaves that are overlapping in two rows; numerous,
globose to ovoid in shape; and brown to brown-
orange spikelets (Moody et al., 2014). It has similar
distinguishing characteristics as F. littoralis Gaudich.
var. littoralis except that it has 4 - 5 involucral bracts
that are much shorter than its inorescence (Pancho
and Obien, 1995).
FIMMI is a weed of irrigated and rainfed rice
in the Philippines (Donayre et al., 2014; Pancho
and Obien, 1995). It mainly propagates by seeds at
a reproduction rate of 42,275 seeds/plant (Begum et
al., 2008a). Many of its seeds germinate by as much
as 50% when dropped at soil surface under saturated
conditions or ooding is delayed up to 28 days after
seeding (DAS), according to Chauhan and Johnson
(2009) and Begum et al. (2006). When not controlled,
FIMMI could reduce the yield of rice by as much as
49% (Begum et al., 2008b).
FIMMI had been reported infesting onion elds
along with other weed species (Baltazar et al., 1999).
Its negative impact on growth and yield of bulb onion
has not been quantied. This paper hypothesized
that (a) FIMMI, when allowed to grow at certain
density level until maturity, will reduce growth
and yield of transplanted and direct-seeded onions
under greenhouse conditions, and (b) there will be
difference on yield reductions between transplanted
and direct-seeded rice.
Materials and Methods
Location and materials
The study was conducted under greenhouse
conditions at Barangay Matingkis, Science City of
Muñoz, Nueva Ecija from November 2018 to April
FULL PAPER

Influence of Fimbristylis miliacea (L.) Vahl on Bulb Onion (Allium cepa L.)
10 RICE-BASED BIOSYSTEMS JOURNAL (2022) 10: 9-14
2019. Red Pinoy onion variety was planted as it has
wide usage by growers in Nueva Ecija. Planting
materials were prepared following the standard
procedure of PhilRice (2003). The soil (Maligaya soil
series) used as medium for planting was collected
from the same eld area and location. To avoid
growth of other plants, collected soil samples were
pulverized, placed inside a polypropylene plastic
bag, and sterilized by mixing with water and heating
for 8 hours in a huge cylindrical metal drum. After
sterilization, soil sample in each bag was allowed to
cool and then transferred into black plastic boxes.
FIMMI plants, on the other hand, were prepared by
collecting mature seeds in the same location. Seeds
were pre-germinated on top of moist soil inside a
plastic box and allowed to germinate and grow for 25
days under moist condition and full sunlight.
Experimental design
Black, plastic box (area = 173 cm2, depth = 23
cm) lled with 10 kg of sterilized, moist soil was the
experimental unit of this study. Each box was planted
with either 30-40-day-old seedlings of TPO or 30
seeds of DSO. Twenty-ve-day old FIMMI plants were
simultaneously planted in each experimental unit at 0,
10, 15, 20, and 25 plants/box. Each experimental unit
with transplanted bulb onion and FIMMI or direct-
seeded bulb onion and FIMMI at different densities
were arranged separately in randomized complete
block design with four replications. All plants inside
each experimental unit were grown until the crop’s
ma turity. A ll plants were nourished with synthetic
fertilizers based on the recommended rates for onion.
Water was also supplied in each box, and maintained
at saturation level whenever necessary. An additive
design of crop-weed competition, where density of
onion was held constant and that of FIMMI was kept
increased, was utilized to determine the outcome of
FIMMI - onion competition (Swanton et al., 2015).
Data collected
Height of transplanted and direct-seeded onion at
77 days after planting (DAT) or DAS were determined
by measuring it from the base to tallest leaf of each
plant. Using a ruler, the average length of the leaves
was also determined by measuring the length of the
three leaves close to the base of each plant. Number of
leaves per plant was manually counted. Root and bulb
lengths and bulb width were also measured using a
ruler. Leaf and bulb weight and shoot-weights of
FIMMI were also recorded after harvest. Percentage
reductions on growth variables and bulb weight (Y)
of onion were calculated using the equation Y (%) =
[(Y0 – Y1)/Y0] *100, where, Y0 as the mean value at 0
weed density and Y1 as the mean values at 10, 15, 20,
and 25 weed densities, respectively.
Statistical analysis
All the data were subjected to ANOVA using
STAR 201 while treatment means were compared
using Fischer’s least signicant difference (LSD) at
5% level of signicance. A Pearson-product moment
correlation coefcient (r) was also computed to
determine the strength and direction of relationship
between FIMMI variables (density and shoot weight)
and bulb weight of onion. Data on density and shoot
weight of FIMMI and bulb weight of onion were tted
to the polynomial quadratic equation (Y = α + ax +
bx2) to determine if the density and shoot weight of
the weed are signicant contributors and predictors
to bulb weight.
Results and Discussion
Shoot biomass of FIMMI in TPO was 9.9, 12.6,
15.6, and 26.2 g/box while that in DSO was 86.9, 95.0,
114.4, and 128.6 g/box at 10, 15, 20, and 25 densities,
respectively (Figure 1). From 10 density each box, its
shoot biomass increased by 1.3, 1.6, and 2.7 folds in
TPO while 1.6, 11.6, and 13 folds in DSO as density
increased by 15, 20, and 25.
Values of all growth variables of TPO at 0 FIMMI
density were not signicantly different at 10, 15, 20,
and 25 FIMMI densities (Table 1). Nevertheless, the
values on leaf weight, root length, bulb length, and
bulb width were still highest at 0 FIMMI density
Figure 1. Shoot biomass of FIMMI at each density.

Influence of Fimbristylis miliacea (L.) Vahl on Bulb Onion (Allium cepa L.)
RICE-BASED BIOSYSTEMS JOURNAL (2022) 10: 9-14 11
compared with the 10 - 25 weed densities. In DSO,
values of all growth variables were highest at 0
FIMMI density except for the bulb length. These
values were signicantly different from the values of
growth variables at 10 - 25 FIMMI densities. Values
on height; number of leaves, leaf length, and leaf
weight; root length, and bulb width at 10 FIMMI
density were not signicantly different at 15, 20, and
25 FIMMI densities.
Bulb weight of TPO was highest at 0 FIMMI
density (337.8 g/box) (Figure 2). When the weed
was present at 10, 15, 20, and 25 densities, bulb
weights were 300.6, 279.2, 263.2, and 207.2 g/box
with equivalent reductions of 11, 17.4, 22.1, and
38.7%, in the same order. Bulb weight of TPO at 0
FIMMI density was not signicantly different at 10
the FIMMI density. Likewise, bulb weights at 10
FIMMI density were not signicantly different from
15 and 20 densities. Bulb weight at 25 density had the
lowest value among treatments. Bulb weight of DSO
was also highest in the absence of the weed (60.1 g/
box). When the weed was allowed to grow at 10, 15,
20, and 25 densities, bulb weights of DSO became
8.2, 6.3, 6.8, and 7.1 g/box with equivalent reductions
of 86.4, 89.6, 88.8, and 88.1%, in the same order.
No signicant differences were seen among these
values at 5% level of signicance. Bulb weights of
DSO suffered the greatest reductions due to FIMMI
competition compared with TPO.
Density and shoot biomass of FIMMI were
strongly, negatively correlated to the bulb weights
of transplanted onion (r = -0.987, -0.995) and
direct-seeded onion (r = -0.986, -0.999). Regression
analysis through the polynomial quadratic model
Tab le 1 . Growth variables of transplanted and direct-seeded bulb onions as influenced by dierent densities
of Fimbristylis miliacea.
FIMMI
Density
Height
(cm p lan t-1)
Leaves Root Length
(cm p lan t-1)
Bulb
Number
plant-1
Length
(cm)
Weight
(g box-1)
Length
(cm)
Width
(cm)
Transplanted
056.7a6.6a51.8a38.5a4.4a6.9a2.3a
10 56.6a6.3a51.8a34.2a3.0a6.7a2.2a
15 55.3a6.7a51.2a37.9a3.7a6.6a2.1a
20 57. 4a6.7a53.3a35.4a3.8a6.5a2.1a
25 54.6a6.0a50.3a31.7a3.3a6.5a2.1a
P0.556ns 0.13ns 0.777ns 0.606ns 0.423ns 0.822ns 0.874ns
Direct-seeded
036.8a4.2a35.8a8.8a2.6a3.8a1.4a
10 18.9b2.2b21.5b1.8b1.3b3.8a0.3b
15 17. 4b1.9b25.6b1.7b1.3b4.0a0.3b
20 17. 8b1.9b19.2b1.6b1.1b4.0a0.4b
25 18.7b1.9b22.6b1.0b0.9b4.2a0.4b
P0.025* 0.001** 0.008* 0.000** 0.011* 0.853ns 0.003**
Means wit h the same letter w ithin each col umn and planting m ethod are not signi ficantly die rent at 5% through LS D; *P<.05,
**P<. 005, ns- not sig nificant
Figure 2. Bulb weights (bar graphs) and bulb weight reductions (line graphs) of transplanted and direct-seeded bulb onions
as influenced by dierent densities of Fimbristylis miliacea (means on bars with the same letters are not significantly dierent
at 5% through LSD).

Influence of Fimbristylis miliacea (L.) Vahl on Bulb Onion (Allium cepa L.)
12 RICE-BASED BIOSYSTEMS JOURNAL (2022) 10: 9-14
(second order) also showed that 97.49 and 99.95% of
bulb weight of TPO; 97.25 and 99.95% bulb weight
of DSO were explained by the density and shoot
biomass of FIMMI (Figure 3). The analysis also
showed that density and shoot biomass of the weed
were signicant predictors and contributors to the
bulb weights of TPO (P = 0.025, 0.005) and DSO
(P = 0.027, 0.000).
FIMMI reduced the bulb weights of transplanted
and direct-seeded onions suggesting that failure to
control the weed in the eld will denitely result in
reduction of crop yield. Begum et al. (2008b) also
reported that FIMMI at 1000 plants/m2 reduced the
number of panicles per plant by 39%, number of tillers
per plant (38%), shoot biomass (42%), and grain yield
of direct-seeded rice (49%) when the weed is allowed
to grow and compete until maturity. When herbicide
(Fentrazamide + propanil) was applied, no reductions
occurred on the same growth variables; only 2% on
grain yield.
The lighter weight of FIM MI in transplanted onion
could be attributed to its size and height disadvantage
over the crop during the competition periods. In rice
cropping system, weeds in transplanted rice have
lesser growths and negative effects on yield due to
the crop’s head start from the day of planting until
maturity (Ampong-Nyarko and De Datta, 1991).
In reverse, weeds in direct-seeded rice have better
growths and greater negative impacts on yield due to
earlier competition at younger growth stages of the
crop (Casimero, 2004).
FIMMI had more serious effects on yield of direct-
seeded onion than that of transplanted onion. In rice,
most weeds also had more serious effects on direct-
seeded seedlings than on transplanted seedlings. For
example, Commelina diffusa Burm f. at 1 - 7 plant/
pot, reduced the grain yield of direct-seeded rice 9.8
- 34% while only 5.4 - 22.4% on transplanted rice
(Cabiao et al., 2020). Ampong-Nyarko and De Datta
(1991) explained that transplanted seedlings hardly
lose yield due to their head start over the weeds.
Meanwhile, direct-seeded rice is highly prone to yield
losses because its germinating seeds grow together
with weeds (Casimero, 2004). The absence of early
ooding to suppress weeds during the initial growth
phase, absence of seedling size to compete with
weeds, and the uneven stand that provides space for
weeds to grow further aggravate the vulnerability
of direct-seeded seedlings to weed competition and
yield losses (Kumar et al., 2017; Chauhan, 2012).
Knowledge on weed biology and ecology
helps decide what, how, and when to implement
control measures effectively. In this study, FIMMI
signicantly reduced the growth and yield of onion
implying that control must be executed whenever the
weed grows and competes in the eld. In managing
Figure 3. Predicted bulb weights of transplanted and direct-seeded bulb onions as a function of density and shoot biomass
of Fimbristylis miliacea.

Influence of Fimbristylis miliacea (L.) Vahl on Bulb Onion (Allium cepa L.)
RICE-BASED BIOSYSTEMS JOURNAL (2022) 10: 9-14 13
FIMMI and other weeds of onion, PhilRice (2007)
recommends to implement the following control
measures: thorough land preparation, rice straw
mulching, rice hull burning, hand weeding, and
herbicide application. Use of stale-seedbed technique
was further recommended particularly for perennial
weeds like the Cyperus rotundus L.
Conclusion
This study showed that F. mili acea had inuence
on the growth and yield of transplanted and direct-
seeded bulb onions if left uncontrolled from the time
of planting until maturity. The weed reduced the bulb
weights of transplanted bulb onion by 11 - 38.7%;
direct-seeded bulb onion by 86.4 - 88.1% at 10, 15, 20,
and 25 density box-1. Bulb weights of DSO suffered
the greatest reductions due to weed competition.
There are several options on how to manage the
weed. However, careful selection, planning, and
implementation must be done to achieve effective,
economical, and environmentally sound weed
management. To know more about its ecology, the
predictive models under eld conditions and the
different weed management techniques through a
holistic approach must be evaluated.
Acknowledgment
The authors would like to thank Constante T.
Briones for the English critic.
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