IJERD – International Journal of Environmental and Rural Development (2023) 14-2

Research articleerd

On the Number of Seedlings for the System of RiceIntensification: Experiment Results from Lombok Island,Indonesia
YAMAJI EIJI
The University of Tokyo / Research Center, Institute of Environmental Rehabilitation andConservation, Tokyo, Japan
Email: yamaji@edu.k.u-tokyo.ac.jp

SATO SHUICHI
Consulting Engineering, Hayama, Japan
Received 4 October 2023

Accepted 28 December 2023(*Corresponding Author)

Abstract The System of Rice Intensification (SRI) is an environmentally friendly andsustainable rice farming practice developed in the 1980s in Madagascar. It has spread to many
countries in the early years of the 21st century, with Indonesia becoming one of the early
adopters of SRI practices. The authors conducted experiments on SRI plots on Lombok Island,Indonesia, measuring water consumption, rice growth, GHG emissions and other variables.
The focus of the current study was on accessing the appropriate number of seedlings under
different irrigation regimes. This experiment prepared 30 small plots and set 2 types ofirrigation: intermittent and continuous; 3 types of seedlings by nursery age: 0, 7, and 21 days;and 3 types of seedling groups: 1, 2, and 4 seedlings. At the harvest stage, the number oftillers, number of panicles, grain weight, filled grain weight, and root weight of 5 samples
were measured from each plot. In terms of the irrigation method, intermittent irrigationachieved a higher yield than continuous irrigation. 2 seedlings achieved the best yield underintermittent irrigation, regardless of nursery age, while 4 seedlings achieved the best yieldunder continuous irrigation for both 7 day- and 21 day-old seedling types. In Indonesia, SRI
promoters including local government and NPO staff recommend farmers to transplant one
7-day seedling. However, the experiment conducted in this study demonstrated that two dayold seedlings achieved better results. The two-seedlings method costs twice as much as theone-seedling method, but is only about half the cost of the traditional method. Moreover, thetwo-seedlings method gives farmers peace of mind at the transplant stage. The two-seedling
method can thus be considered more reasonable than the one-seedling method.
Keywords system of rice intensification, number of seedlings, intermittent irrigation, yield

INTRODUCTION
The System of Rice Intensification (SRI) is an environmentally friendly and sustainable rice farming
practice developed in the 1980s in Madagascar. This practice can reduce resources, such as irrigationwater, chemical fertilizer, number of seedlings by keeping and sometimes increasing the yield of rice.
It has spread to many countries in the early years of the 21st century. Indonesia is one of the early
diffused countries and many farmers adopted this practice (Sato, 2006; Sato, 2007).
In Indonesia, SRI promoters of local government and NPO recommend farmers to transplant
One 7-day seedlings. However, farmers are very afraid of less growth, and they often transplant two
seedlings although they were taught to transplant one.
Previous research has shown that the adoption of intermittent irrigation reduced water use but
not yield (Shimizu et al., 2007). However, a deeper consideration of the appropriate number ofseedlings was needed. So, the authors made an SRI Experimental station at Puyung village, Lombok
Island of Indonesia, and executed an experiment to identify an appropriate number of seedlings,
measuring water consumption, rice growth, GHG emissions and other variables.
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IJERD – International Journal of Environmental and Rural Development (2023) 14-2OBJECTIVE
The authors set the objective to identify which number of seedlings would be appropriate inconventional rice growing and in the System of Rice Intensification.
METHODOLOGY
The experiment involved setting up 30 small plotsof size 5.0 m x 2.5 m (Fig. 1) and applying anumber of different experimental treatments,
including 2 types of irrigation: intermittent andcontinuous; 3 types of seedlings by nursery age: 0,7, and 21 days, and 3 types of seedling groups: 1,2, and 4 seedlings. The most popular rice variety inthe area around the experiment station, Ciherang
rice, was planted. The spacing of each seedling was
25 cm by 25 cm and irrigated each plot as anirrigation schedule (Table 1). At the growing stage,
the number of tillers and height of 5 samples fromeach plot are precisely measured every week. At
the harvest time, the number of panicles, grain
Fig. 1 View of experimental plotsweight, filled grain weight, and root weight of 5samples from each plot. Also, grain weight with moisture content is measured in each plot. Grainweight was converted to yield (t/ha) at 14% moisture.
Table 1 Setup of the experiment
Treatment
Directseeding
Nursery
7 days

D1 D2 D4 S1〇

〇

S2S4〇

〇

〇
〇

Number ofSeedlings〇〇

Intermittent

〇

1〇

〇

〇

〇

〇

〇

〇
〇

〇

〇

〇
〇

〇

〇

〇

〇

〇

〇

〇

〇

〇
〇

〇
〇

〇

〇

〇
〇

〇

〇

〇

〇
〇

〇

〇
〇

22〇

〇

〇

Continuous

4Repetition〇〇

21 daysIrrigation

T1 T2 T4 N1 N2 N4 C1 C2 C4〇〇〇〇〇〇〇〇〇〇

Table 2 Variety characteristics of ChiherangGrowing period
Average 1000-grain weight
Average number of tillers
Average plant height
Average yield
Yield potential

116 ~ 125 days
28 g
14 ~ 17 tillers
107 ~ 115 cm
6.0 t / ha
8.5 t / haNote: Data from Suprihartno et al., 2006

Seedlings for all plots were transplanted on May 17th, 2007. Rice variety is a local high-yield
variety called Chiherang, which is widely cultivated on Lombok Island. Characteristics of ChiherangⒸ ISERD139

IJERD – International Journal of Environmental and Rural Development (2023) 14-2

are summarized in Table 2.
RESULTS AND DISCUSSION
Weather and Irrigation
In this experiment, the sowing and harvesting dates were aligned. Sowing took place on 5 December
2007. Direct sowing was fielded on that day, 7-day seedlings were transplanted to the main field after
7 days in the nursery, as were 21-day seedlings. The harvest date was 8 April 2008 in every plot.
It was the rainy season and there was occasional precipitation. The total precipitation for the 118
days until harvest was 1,286 mm. During the experiment, the average temperature was 30.1 degrees,
and the relative humidity was 60.2%.
Intermittent irrigation is applied until the end of the vegetative growth stage, about 60 days after
transplanted, and after this water depth is also kept shallow (1-2 cm water depth) until stopping water
to harvest, while conventional irrigation uses continuous flooding with deep water (4-5 cm waterdepth) (Fig. 2).
Treatments are two irrigation patterns, three seedlings, and three transplanting methods, a totalof 15 treatments l duplicated two times, are prepared. A control plot was also prepared.
For all plots, seedling age, spacing, weeding method, fertilizer amount, and variety of rice are
selected to match for local rice cultivation method. Fertilizers are chemical fertilizers standing on theposition SRI technology does not include the application of compost. Weeding for 15 treatment plots
was done 3 or 4 times depending on weed condition.
D : Direct Seeding and Intermittent Irrigation

HARVEST-7 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

S : 7 Day Seedling Transplant and Intermittent Irrigation-7 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

N : 7 Day Seedling Transplant and Continuous Irrigation-7 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

T : 21 Day Seedling Transplant and Intermittent Irrigation-7 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

C : 21 Day Seedling Transplant and Continuous Irrigation-7 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

Ponding Depth : Intermittent Irrigation just wet, maximum 2cm depth
Continuous Irrigation keep 4 cm depth

Fig. 2 Irrigation schedule (2007/2008 rainy season)
GrowthRice seedlings were planted in each plot at 200 rice plant hills. Measurements of height and stem
number were taken weekly on five plant hills in the middle of the plot. After the earing stage, thenumber of tillers is also counted. Changes in the number of tillers are shown in Fig. 3. One seedlingset (D1, S1, N1, T1, C1) starts with one seedling, two seedlings set (D2, S2, N2, T2, C2) with twoseedlings and four seedlings set (D4, S4, N4, T4, C4) with four seedlings. The seedlings then growand divide by earing. The number of tillers declines after the maximum tillering period. The numberof tillers at harvest time was almost all between 15 and 20.
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IJERD – International Journal of Environmental and Rural Development (2023) 14-2

Fig. 3 Number of tillers
The plant height is shown in Fig. 4. Although plant height was low in the nursery due to dense
cover, growth was vigorous after transplanting, with almost all reaching 130-140 cm at harvest time.

Fig. 4 Height of rice plant
Yield and Components
At the harvest, the number of tillers, number of panicles, grain weight, filled grain weight, and root
weight of 5 plant hills from each plot are measured. One plant hill produces 43-73 grams of grains,meaning 1500-2600 grains. To identify 1000 grains' weight, sampled grains are well mixed, and 2030% of grains are used for counting. By this method, 1000 grains weight from each plot wascalculated.
From this measurement, the following was revealed. The intermitted irrigation group (D, S, T)
had a few fewer panicles but greater grain weight, which was attributed to the fact that each grain
was larger and heavier. It was revealed that the roots of the intermitted irrigation group were very
heavy. Especially, the root weight of treatment D4 were several times heavier than in continuousirrigation. This suggests that many roots grow deeper under intermittent irrigation, which is presumed
to be the reason for the higher growth. The comparison between seedling numbers did not show aclear difference.
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IJERD – International Journal of Environmental and Rural Development (2023) 14-2

Table 3 Details of rice plant at the harvest time
Number of Number ofTreatment
tillers
paniclesSample grains

Grainweight(gr)Filledgrain
weight(gr)Rootweight(gr)Weight(gr)NumberWeight ofMoisture1000 grains
(%)
(gr)
23.4
29.2
22.9
30.5
22.8
30.3
23.4
25.4
23.3
33.1
23.3
28.1
23.6
25.3
23.5
27.6
23.1
28.6
22.7
24.2
23.5
24.2
21.5
24.0
23.2
24.4
22.5
23.9
21.7
23.4

D1D2
D4
S1
S2
S4
T1
T2
T4
N1
N2
N4
C1
C2
C4

16.3
17.9
20.6
15.7
12.9
15.0
16.8
19.6
18.5
14.7
18.0
18.9
14.8
16.4
18.0

15.2
17.4
19.4
14.8
12.7
14.7
15.8
15.9
17.4
14.6
17.3
17.6
14.3
16.2
17.4

63.1
64.5
73.5
50.9
53.8
50.8
53.8
52.9
59.2
45.8
50.6
60.4
43.5
49.4
43.7

61.8
62.5
72.3
48.9
52.8
48.2
50.8
51.1
57.4
43.9
48.3
58.8
42.1
47.0
42.0

24.4
20.3
43.0
16.4
19.123.2
19.9
23.7
21.0
8.7
10.5
10.7
7.9
10.1
7.4

16.4
15.8
15.9
20.0
19.3
20.5
20.9
18.2
21.4
12.4
10.8
14.3
13.6
16.9
11.4

561.3
517.7
523.9
784.3
583.5
731.5
824.4
658.6
751.0
512.7
445.0
595.7
558.7
705.4
485.4

D, S, T
N, C

17.0
16.8

15.9
16.2

58.1
48.9

56.2
47.0

23.4
9.3

18.7
13.2

659.6
550.5

23.2
22.5

28.7
24.0

12
4

15.7
17.0
18.2

14.9
15.9
17.3

51.4
54.2
57.5

49.5
52.3
55.7

15.5
16.821.0

16.6
16.2
16.7

648.3
582.0
617.5

23.3
23.1
22.5

25.7
27.9
26.9

Yield
12(t/ha)10Intermittent Irrigation
Direct a

7 days a

21 days aContinuous Irrigation
7 days b

21 days c

86420
D1 D2 D4 S1 S2 S4 T1 T2 T4 N1 N2 N4 C1 C2 C4Treatment

Fig.5 Yield of each treatment
After measuring five plant hills in detail, the rest 195 plant hills were harvested from the entire
plot. There are 2 plots for each treatment and the average yield is shown in Fig. 5.
From these results, intermittent irrigation produces greater yields than continuous irrigation.
On the number of seedlings, 2 seedlings achieved the best yield in intermittent irrigation and 4
seedlings achieved the best yield in continuous irrigation. Comparison between the five groups showsthat 3 groups of intermittent irrigation achieved best, 7 days seedling in continuous irrigation wassecond-, and 21-days seedling in continuous irrigation was third. All comparisons are statisticallysignificant at the risk of 5%.
CONCLUSION
The results of this experiment showed that in continuous irrigation, two seedlings were better thanⒸ ISERD142

IJERD – International Journal of Environmental and Rural Development (2023) 14-2

one, and four seedlings were better than two in terms of yield. In traditional farming, the number oftransplanted plants is 3-5. As a result, the correctness of the farmers’ choice of number of seedlingsin traditional farming methods was proved as rational.
In intermittent irrigation, the highest yield was obtained with two seedlings. The two-seedling
method needs two times the cost of seedlings than one seedling method. However, this method costsabout half the cost compared with the traditional method. Moreover, two seedlings method gives
farmers peace of mind or a sense of security during the transplant stage. So, this method is to be said
as more reasonable than one seedling method. We need to execute this experiment in every place
where the SRI method is introduced.
ACKNOWLEDGEMENTS
The authors are deeply grateful for the support of the DISIMP team, Mr. Bagus Santika, and teammembers.
REFERENCES
Sato, S. 2006. An evaluation of the System of Rice Intensification (SRI) in Eastern Indonesia for its potential
to save water while increasing productivity and profitability. International Dialogue on Rice and Water:
Exploring Options for Food Security and Sustainable Environments, IRRI, Los Baños, Philippines, March
7-8, 2006, Retrieved from URL http://sri.ciifad.cornell.edu/countries/indonesia/wwfindosato06.pdf
Sato, S. 2007. 4 Years experience with SRI practice under DISIMP in Eastern Indonesia. Decentralized
Irrigation System Improvement Project in Eastern Region of Indonesia Report.
Sato, S., Yamaji, E. and Kuroda, T. 2011. Strategies and engineering adaptions to disseminate SRI methods inlarge-scale irrigation systems in Eastern Indonesia. Paddy and Water Environment, 9, 79-88, Retrieved fromDOI https://doi.org/10.1007/s10333-010-0242-2
Shimizu, K., Yamaji, E., Sato, S., Budiharto, P.S. and Mizoguchi, M. 2007. Sustainability of system of riceintensification, Benefits of SRI focusing on effects of intermittent irrigation on yield increase and watersaving. Proceedings of the 6th International Conference on Sustainable Rural Development andManagement, 25-37.
Suprihartno, B., Dradjat, A.A., Satoto., Baehaki, S.E., Widiarta, N., Setyono, A., Indrasari, S.D., Lesmana, O.S.,
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