Effects of the inhibition of weed communities by winter-flooding

doi:10.4236/as.2011.24050

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Vol.2, No.4, 383-391 (2011)

doi:10.4236/as.2011.24050

Agricultural Scienc es

Effects of the inhibition of weed communities by

winter-flooding

Korehisa Kaneko1*, Toshihiko Nakamura2

1Hokuso Creature Associati on, Tabata, Tokyo, Japan; *Corresponding Author: [email protected]

2Natural History Museum and Institute, Chiba, Japan.

Received 9 September 2011; revised 14 October 2011; accepted 26 October 2011.

ABSTRACT

Winter-flooded paddy field is an agricultural

method which putting a water among the winter,

it is paid attention as an environmental friendly

agriculture. Especially, it is said, winter-flooding

is control paddy weeds and there is the farming

potential that the annual rice yield is high.

However, there is no detailed research about the

effects of weed communities by winter-flooding,

as the purpo se of this stu dy, we investigat ed the

effects of the inhibition of weed communities

(life cycle, harmful weed) by winter-flooding at a

shore of Inba Lake, Chiba Prefecture, Japan,

and compared them to paddy weeds in a dry

paddy field. Methods examined the plant height

(cm) and the cover degree class of all appear-

ance species in each quadrant frame (1 m2).

Quadrant in the two type paddies were 10

frames (D1-D10) at the control, and were 10

frames (W1-W10) at the treatment (Figure 1 ). In a

winter-flooded paddy field, species number and

plant volume of winter-annual plants decreased

in the third winter after winter-flooding, In par-

ticular, the plant v olume of Alopecuru s aequalis,

Cardamine flexuosa decreased significantly. We

considered that the cause of this decrease was

due to the depth of flooding (more than 10 cm).

Eleocharis kuroguwai and Sagittaria trifolia,

which are perennial plants, Echinochloa ory-

zoides, w hich is an annual plant, increased in a

winter-flooded paddy field in the third summer

after winter-flooding. We considered that these

species grew thicker at places where the seeds

germinated, and grew easily, because the con-

servation situation of the seeds fitted well under

the winter-flooding conditions. They started to

grow immediately after the drainage of water.

The period of drainage coincided with increas-

ing light intensity and temperature. In addition,

the annual rice yield of the third year after win-

ter-flooding was higher than that of the habitual

practice rice field．

Keywords: Winter-Flooded Paddy Field; Life Type;

Harmful Weeds; Biodiversity; Environmental

Agriculture

1. INTRODUCTION

In Basic Law on Food, Agriculture and Rural Areas

which enacted in 1999, it is requested the sustainable

demonstration of multi-functionality, not only the stable

supply of food, but also the conservation of country and

water-source, the formation of natural environment and

excellently landscape etc through th e productive activity.

Afterwards, original biodiversity strategy is enacted in [1]

and [2], environmental friendly agriculture has been

contained as o ne of the bi o diversity conse rv at ion.

In revision of Ramsar convention in 2005, rice paddy

fields were registered, in particular, winter-flooded rice

farming which is conducted in Kabukuri-numa and the

surrounding rice paddies is attracting attention as an en-

vironment to be worthy not only the safety and healthy

rice but also the respect of biodiversity as used land of

many waterfowls.

In winter-flooding, the paddy of non-irrigation period

is the flooding state, as the effects, the water-source

conservation in winter and water qu ality purification [3],

the offer of biotope to wetland including waterfowl etc.

[4], the effects of agricultural management of accompa-

nying additional value as the effects of the weed sup-

pression and environmental preservation rice [5-7]. [8]

reported that the effects of the weed suppression found

in the second winter after winter-flooding. However,

there is no research example of the detailed examination

as the effects that the winter-flooding exerts on life cycle

(annual plant, winter-annual plant and perennial plant) of

paddy weeds and harmful weeds. These are the problems

which should be examined to promote the winter-flood-

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

384

ing in the future.

This study aimed to clarify the effects of the inhibition

of weed communities by winter-flooding, comparing to

plant communities between before winter-flooding (the

first year) and the third year after winter-flooding (the

finality year), based on a vegetation survey of the win-

ter-flooding examination.

2. MATERIALS AND METHODS

2.1. Study Site

Study site is suited at a large-scale rice field of the

Hagiyama Shinden section in a shore of Inba lake in

Sakura City, Chiba Prefecture, Japan.

Paddy field in this area has produced Koshihikari.

Field experiments were set as the treatment where the

winter-flooding was conducted and the control where the

habitual practice rice farm was continued. In the first

year of winter-flooding, water put in January 2006,

scratched and planted rice was conducted in May, the

herbicide was scattered in June, the drainage of water

was conducted in the middle of August, rice was har-

vested in the middle of September. The rice bran was

scattered in October, water was flooded in the beginning

of November. In the second year, the scratching, the

planting rice, the drainage of water, the harvesting rice,

the flooding were almost conducted at same periods in

the first year, the herbicide was not scattered. However,

the herbicide scattered in the third June.

The mean water depth was about 10 cm at the first

and the second year, and was about 12 cm in the third

year. The winter-flooding was supplied at constant in-

tervals using a pump. The scratching, the planting rice,

the drainage of water, the herbicide scatter conducted at

the same time on the control of dry paddy and the treat-

ment before winter-flooding.

2.2. Vegetation Survey

The vegetation survey was conducted in August, Oc-

tober, and December which are both the first year and

the third year, and methods examined the plant height

(cm) and the cover degree class of all appearance species

in each quadrant frame (1 m2).

Quadrant in the two type paddies were 10 frames

(D1-D10) at the control, and were 10 frames (W1-W10)

at the treatment (Figure 1).

Inba lake, Sakura city (Quotation from Inba laka HP)

W3 W4

W5 W6

W10

D3 D4

D5 D6

D10

水　路

印

旛

沼

冬期湛水水田

慣行水田

100ｍ50ｍ

0ｍ

Treatment

（Winter-flooded paddy）

100×90m

Control

（Dry paddy）

100×90m

Winter-Flooded paddy

Dry paddy

Inba Lake

Waterway

佐倉市

千葉県

Sakura city

Chiba Prefecture

Japan

Figure 1. Investigation position.

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

385385

2.3. Analysis

The plant volume of each species (=the average rate

(%) × the plant height (cm)) calculated as an index of the

plant biomass. The average rate converted each cover

degree class (+: <1%, 1: 1% - 5%, 2: 5% - 25%, 3: 25% -

50%, 4: 50% - 75%, 5: 75% - 100%) into 0.1%, 2.5%,

15%, 37.5%, 62.5%, and 87.5%, based on [9].

In addition, in order to examine the changes of the

composition and the structure of plant communities in

the two type paddies, the cover degree (+, 1, 2, 3, 4, 5)

of appearance species in the quadrant frame of each sec-

tion (+ class converted into 0.1 and the following class

was not converted) were analyzed by cluster analysis,

using the group average method (PC-ORD: Windows

version 4.01).

As for the life circle’s definition, the annual plant is a

plant that germinates the seed, flowers, brings forth

within one year, leaves the seed, and withers. The win-

ter-annual plant is a plant that the seed germinates in

autumn, passes the winter at rosette, it will flower and

bring forth next year. The perennial plant is a plant that it

is growing as an individual for two or more years.

3. RESULTS

3.1. Species Number in before and after

Winter-Flooding

Compared to species number between the treatment

and the control in before winter-flooding (2005) and the

third year after winter-flooding (2008), although all

founded species did not have a significant difference

with before winter-flooding, and were significant differ-

ence (5%) in the third December, species number was

little at the treatment. This result has seen the same ten-

dency with wi nt er-ann ual pl an t (Fi gure 2).

051015 0510 15

Des

Oct

Aug

051015 0510 15

Des

Oct

Aug

051015

0510 15

Des

Oct

Aug

n.s.

n.s. n.s.

n.s.

n.s

Control

Treatment

Annual

Winter-annual

Total

Before （2005）Third year （2008）

051015

n.s

051015

Des

Oct

Aug n.s

n.s

Perennial

Mean number of plant species(/m

)

Dec

Figure 2. Mean number of plant species of total and each life type in treatment (winter-flooded

paddy) and control (dry paddy). **: 1% significant, *: 5% significant, n.s.: non-significant.

Horizontal stick shows mean value of standard error margin. Significant used t-authorization of

student. N = 10 shows sample number of each quadrant.

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

386

3.2. Plant Volume in before and after

Winter-Flooding

Compared to plant volume between the treatment and

the control in before winter-flooding (2005) and the third

year after winter-flooding (2008), plant volume were

little at the treatment in the third December, a significant

difference was at 1%. This was the same tendency with

winter-annual pl ant s ( Figure 3).

010002000300040005000 01000 2000 3000 4000 5000

Des

Oct

Aug

010002000300040005000

＋

01000 2000 3000 4000 5000

Des

Oct

Aug

010002000300040005000 01000 2000 3000 4000 5000

Des

Oct

Aug

n.s.

n.s

n.s.

＋

n.s.

010002000300040005000

01000 2000 3000 4000 5000

Des

Oct

Aug n.s.

＋

n.s.

＋

n.s.

Before （2005）Third year （2008）

Annual

Winter-annual

Total

Perennial

Control

Treatment

Mean volume of plant species(/m

)

Dec

Figure 3. Mean volume (/m2) of plant species of total and each life type in treatment (winter-flooded paddy) and control (dry paddy).

**: 1% significant, *: 5% significant, n.s.: non-significant. Horizontal stick shows mean value of standard error margin. Significant

used t-authorization of student. N = 10 shows sample number of each quadrant.

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

387387

As the main paddy weeds wh ich influenced the changes

of the plant volume in the above-mentioned, an annual

plant was Echinochloa oryzoides, the winter-annual

plants were Alopecurus aequalis, Cardamine flexuosa,

the perennial plants were Eleocharis kuroguwai, Sagit-

taria trifolia. Compared to mean plant volume between

the treatment and the control, Echinochloa oryzoides

was hardly founded in before winter-flooding, however,

it was high at the treatment in the third summer . Alopecurus

aequalis, Cardamine flexuosa were high in the winter of

before winter-flooding, however, were low at the treat-

ment of the third year. Eleocharis kuroguwai, Sagittaria

trifolia were hardly founded in before winter-flooding,

however, they were extremely high at the treatment in

the third summer (Figures 4 and 5).

3.3. Species Composition in before and

after Winter-Flooding

Cluster analysis was conducted in order to examine

the changes of the composition and the structure in weed

communities in before winter-flooding and the third year

(Figure 6). It analyzed species composition according to

August, October, and December. As a result, the separa-

tion by clusters between the treatment and the control

were not confirmed in before winter-flooding, however,

in the third year, the treatment was separated with the

control except for W10 of October, W3 of December,

and was non-vegetation at 5 points (W1, W2, W7, W9,

W10).

4. DISCUSSION

As for the affects on weed communities by winter-

flooding, species number and plant volume of winter-

annual plants decreased in the treatment of the third De-

cember, especially, Alopecurus aequalis, Cardamine flexu-

osa greatly decreased. Although Alopecurus aequalis

germinate under conditions in which the temperature is

high, and the oxygen is satisfactory after the drainage of

water, germination is delayed in ill-drained paddy fields

and those th at are non-tilled with high groundwater lev el,

and will be carried over until spring of the following

year. The longevity of the seed is short from half a year

to a year, and the semination ability is low. The number

of seeds which dropped in the farmland provides for the

amount of generation in the farmland of the next genera-

tion [10] .

0100200300400500 0100 200 300 400 500

Des

Oct

Aug

0100200300400500 0100 200 300 400 500

Des

Oct

Aug

Alopecurus aequalis

（Winter-annual）

Cardamine flexuosa

（Winter-annual）

Before （2005）Third year （2008）

Control

Treatment

Mean volume of plant species(/m

)

Dec

Figure 4. Mean volume (/m2) of plant species which decreased by winter-flooded.

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

388

050010001500 05001000 1500

Des

Oct

Aug

＋

050010001500 05001000 1500

Des

Oct

Aug

Eleocharis kuroguwai

（perennial）

Echinochloa oryzoides

（perennial）

050010001500 05001000 1500

Des

Oct

Aug

＋

Sagittaria trifolia

（annual）

Before （2005）Third year （2008）

Control

Treatment

Mean volume of plant species(/m

)

Dec

Echinochloa oryzoides

Sagittaria trifolia

Figure 5. Mean volume (/m2) of plant species which increased by winter-flooded. +: means not showing on the drawing because of

extremely the value low.

Moreover, [11] reported that Alopecurus aequalis

withered in a paddy field where the flooding was main-

tained enough in winter, and was generated in a paddy

field where the flooding was not maintained, and a final

amount of generation tripled. [12] reported that the gen-

eration rates of Alopecurus aequalis and Cardamine

flexuosa in a moist soil state were h igher than those in a

flooding water depth of 5 cm.

We considered that the germination and growth of

these species were inhibited by the flooding water depth

of 12 cm in autumn that winter-annual plants germinate,

and it greatly had an effect on the difference of species

composition between the treatment and the control in

winter.

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

389389

Aug

※Treatment （W1～W2），Control （D1～D10）

Oct

Des

Quadrants where is no vegetation.

W10

Before （2005）Third year （2008）

D10

W10

4.4E-02 2.5E+014.9E+017.3E+01 9.7E+01

Distance（Objective Function）

100 7550250

Information Remaining（％）

D10

07.7E+00 1.5E+01 2.3E+01 3.1E+01

Distance（Objective Function）

100 7550250

Information Remaining（％）

W10

D10

1.5E-02 1.5E+012.9E+01 4.4E+01 5.8E+01

Distance（Objective Function）

100 7550250

Information Remaining（％）

D10

W10

01.4E+01 2.8E+01 4.3E+01 5.7E+01

Distance（Objective Function）

1007550 250

Information Remaining（％）

D10

W10

4.7E-03 1.4E+002.9E+00 4.3E+00 5.7E+00

Distance（Objective Function）

1007550 250

Information Remaining（％）

D10

W10

5E-031.7E+00 3.3E+015E+01 6.6E+01

Distance（Objective Function）

100 7550250

Information Remaining（％）

Dec

Figure 6. Difference of vegetation of each quadrant in treatment (winter-flooded paddy) and control (dry paddy).

[8] reported that Monochoria vaginalis of the annual

plants grew thicker at the treatment in the second sum-

mer. However, Monochoria vaginalis of the third year

did not grow thicker in comparison to that of the second

year, but instead, Echinochloa oryzoides of the annual

plants and Eleocharis kuroguwai, Sagittaria trifolia

K. Kaneko et al. / Agricultural Sciences 2 (2011) 383-391

390

of the perennial plants grew thicker in summer of the

third year. Although a lot of seeds of Alopecurus ae-

qualis die out in dry paddy fields during the cryogenic

period from late autumn to the early spring, and the seed

survival time of Alopecurus aequalis in the soil is short,

in case of the paddy in the flooding state during year, the

extinction of the seeds in the process of the dormancy

awakening is hardly generated, the seed longevity are

longer compared with the dry paddy [13]. Moreover, the

population growth rate, the leaf area, and the net assimi-

lation rate of Alopecurus aequalis are high under the

conditions in which the quantity of solar radiation and

the temperature are high [14]. The sprout rate of tuber of

Eleocharis kuroguwai is high in flooded paddy fields of

paddling and under the strong reduction soil of non-

tillage, however, they are low under the conditions of

low temperature and drying treatment [15]. The germi-

nation rate of Eleocharis kuroguwai is high under flood-

ing condition s , and is low under drying conditions [16].

The production rate of the seed was high under the

conditions of strong light and eutrophication, and water

depth was growing excellently by 3 - 15 cm. In the case

in which these conditions exceeded the limit, it became

the life circle only vegetative propagation system, and

the tuber died out considerably by tillage an d g erminated

gradually after paddling [17]. We considered that the

seeds of Echinochloa oryzoides, Sagittaria trifolia, Eleo-

charis kuroguwai were in an excellent conservation state

by the winter-flooding, after the drainage of water, in

case that it became the state under the conditions in

which direct sunshine was strong and temperature was

high, the seed germinated and grew. Especially, in the

third year, Eleocharis kuroguwai and Sagittaria trifolia

grew remarkably thicker than Monochoria vaginalis. As

one of the agricultural factors related to the decrease of

annual plants and the succession to the perennial plant

communities such as Eleocharis kuroguwai and Sagit-

taria trifolia, a decrease of hand weeding by herbicide

scatter was the cause [18]. Therefore, we considered that

the use of the herbicide influenced the decrease of

Monochoria vaginalis in the third year. As other causes,

we considered that the tuber of Eleocharis kuroguwai

and Sagittaria trifo lia which germinated and grew in the

second year had increased after the winter-flooding, and

the vegetative propagation was actively done and grew

thicker in the third year, because the treatment plowed a

field lightly.

Although the volume of annual rice yield was high at

the control before winter-flooding, in the third year, it

was high at the treatment, therefore, we can be said that

there is little influence due to a mat of weeds in summer.

However, [19] reported that the production rate of rice

decreased in winter-flooded paddy fields (the flooding

began in the midd le of December) in which p addy weeds

grew thicker. This result is different from this research

study results. We have considered the beginning period

of winter-flooding and climate influences, and that they

are problems to be solved in the future.

5. ACKNOWLEDGEMENTS

This research conducted as a part of Mitamesi winter-flooding pro-

ject and Mitamesi action of “The Committee for Lake Inba-numa Wa-

tershed Management”. As for advancing the research, we are very

indebted to Dr. Katumi Musiake chaiman, Chiba Prefecture River

Environment Division, other parties concerned, and, Mr. Masuo Mi-

kado who cooperated in this research to offer the rice field while mak-

ing rice. Moreover, as for writing this paper, we got an offer of the

document material and valuable advice from Dr. Takuya Mineta of

National Institute for Rural Engineering, Dr. Hiroshi Jinguji who is

Associate Professor of Miyagi University. We wish sincerely to express

our gratitude to everybody.

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