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Cultivation methods of paddy: new opportunities for Bangladesh

Quazi Nasim Ahmed1, Parimal Kanti Biswas2 and MD Hazrat Ali2

1School of Biological Sciences, USM, Malaysia: nasim_agril@yahoo.com
2
Department of Agronomy, Sher-e-Bangla Agricultural University (SAU), Bangladesh

Abstract

A field experiment was carried out at Agronomy Field Laboratory, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh from December 2005 to May 2006 to study the influence of different cultivation methods of paddy. The experiment compared two varieties grown with five cultivation methods: sprouted seeds in line, sprouted seeds broadcast, nursery seedlings, SRI (System of Rice Intensification) and clonal tillers. Nursery seedlings (traditional) showed the best performance. The highest grain yield and straw yield was obtained from nursery seedlings and the lowest grain yield and straw yield was obtained from SRI. Maximum harvest index was 52.5% for SRI and minimum harvest index was 46.2% for broadcast sprouted seeds. Tillers hill-1 of SRI was the highest among treatments, however, it failed to perform well in terms of effective tillers m-2, though sprouted seeds sown in line and broadcast showed opposite trends. Plants from sprouted seeds and SRI matured earlier than nursery seedlings and clonal tillers. Sprouted seeds of the hybrid variety sown in line matured in 113 days, which was 33 days less than the nursery seedlings.

Keywords

Cultivation methods, SRI, clonal tillers, direct seeding, varieties

Introduction

Rice is the most important cereal crop in Bangladesh. About 75% of the total cropped area and more than 80% of the total irrigated area is planted to rice (Hossain and Deb 2003). The country now produces about 46.9 million tons of clean rice at an average of 3.99 t ha-1 on 11.2 million ha of land (FAO, 2008). Rice cultivation in Bangladesh is predominantly practiced with a transplanting method that involves raising, uprooting and transplanting seedlings. This is a resource and cost-intensive method given the preparation of the seedbed, raising and transplanting seedlings are labor and time-consuming operations. Labor involvement for these operations comprises nearly one third of the total cost of production in Bangladesh. To overcome these difficulties several rice cultivation methods have been developed. ‘System of Rice Intensification’ (SRI), drum seeder technique and clonal tillers are steadily gaining acceptance by growers.

SRI is a system for managing plants, soil, water or nutrient together in mutually beneficial ways (Laulani 1993). Vegetative propagation of rice using clonal tillers collected from the mother plant without hampering its yield is also a proven technology especially in adverse environmental situation as well as for expansion of hybrid rice cultivation area (Biswas 2001). This direct wet-seeding method contrasts with conventional transplanting where pre-germinated seeds are sown on well prepared puddled land. The purpose of the study is to find out the different growth and yield component of these methods of seeding rice.

Materials and methods

The experiment was conducted at the Agronomy field, Sher-e-Bangla Agricultural University, Dhaka-1207 during the period from December, 2005 to May, 2006. The experiment compared two varieties viz. inbred variety (BRRI dhan 29)-V1 and hybrid variety (Sonarbangla-1)-V2 and five planting techniques viz. sprouted seeds in line (P1), sprouted seeds broadcast (P2), nursery seedlings (P3), SRI (P4) and clonal tillers (P5). The experiment was laid out in a split-plot design with four replications having varieties in the main plots and cultivation method in the sub-plots. Seeds were sown on the seedbed for raising seedlings of nursery seedlings and clonal tillers treatments from which 40 days old seedlings were retransplanted in the same plot with 25 cm 15 cm spacing. Clonal tillers were separated (30 days after transplanting) from the mother crop by uprooting, splitting and retransplanted on the same plot. For SRI, 14 days old seedlings were transplanted with 40 40 cm spacing. Sprouted seeds were sown in line with 25 cm row to row distance and in another treatment sprouted seeds were randomly broadcasted. All the collected data were analyzed following the analysis of variance (ANOVA) technique using the MSTAT computer package and the mean differences were adjudged by the least significant difference test at 5% level of significance.

Result and Discussion

Effect of variety

Rapid increase of plant height and dry matter were observed in seedlings of the hybrid variety Sonarbangla-1 compared to the inbred variety BRRI dhan 29. However at harvest, BRRI dhan 29 produced the taller plants than Sonarbangla-1. BRRI dhan 29 produced the maximum leaf area index and flowered later than Sonarbangla-1 and matured 17 days later than the hybrid (Table 1). BRRI dhan 29 produced maximum number of effective tillers/m2 and the Sonarbangla-1 produced highest number of filled grains/panicle, weight of 1000-grains, grain yield and harvest index compared to those of BRRI dhan 29 (Table 2). The yield improvement in the hybrid has been associated with an increase in total biomass as well as higher harvest index. Lafarge et al. (2004) reported that grain yield was significantly higher for hybrid rice as hybrid increased assimilates allocation towards productive tillers. Higher grain yield and lower biological yield was the probable reason for the maximum harvest index in Sonarbangla-1.

Table 1. Influence of variety and cultivation method on growth characteristics of boro rice.

Treat-ments

Plant height (cm)

Leaf area index

Total dry weight (g/m2)

Days to flow-ering

Days to mat-urity

30 DAS/T

50 DAS/T

70 DAS/T

At harvest

30 DAS/T

50 DAS/T

70 DAS/T

At harvest

30 DAS/T

50 DAS/T

70 DAS/T

At harvest

V1

39.8

69.1

91.9

106.3

1.1

5.5

7.5

1.8

70

369

896

1774

108

143

V2

46.4

79.1

95.8

102.2

1.0

5.5

5.8

1.7

100

424

985

1513

88

126

LSD(0.05)

0.6

3.7

2.8

2.8

Ns

0.0

0.8

0.0

27

ns

ns

252

0.19

0.35

P1

25.9

60.1

87.3

103.7

0.5

6.3

8.6

1.8

14

255

935

1671

83

119

P2

27.6

60.2

88.5

102.0

0.5

6.7

9.6

1.9

21

312

906

1660

83

121

P3

43.5

80.7

94.2

106.1

0.8

5.9

5.9

1.7

59

410

888

1855

111

147

P4

44.4

73.8

97.2

107.7

0.3

3.0

5.0

1.5

13

232

703

1440

98

134

P5

74.1

95.5

102.1

102.2

3.2

5.6

4.1

1.6

318

773

1273

1592

116

150

LSD(0.05)

4.2

4.5

3.5

ns

0.2

0.7

0.8

0.0

23

77

137

137

0.16

0.33

V1P1

24.0

54.8

83.7

103.0

0.5

6.1

8.4

1.8

13

211

906

1785

93

125

V1P2

27.0

60.6

87.8

104.5

0.4

6.8

9.8

2.0

20

276

879

1738

92

127

V1P3

40.1

74.3

95.9

109.6

0.7

5.1

6.5

1.8

38

359

868

1864

117

155

V1P4

42.2

64.8

88.4

110.3

0.3

3.4

6.4

1.6

11

206

696

1743

112

147

V1P5

65.9

91.0

103.8

104.1

3.6

6.3

6.6

1.6

268

791

1132

1741

125

159

V2P1

27.8

65.4

90.9

104.4

0.5

6.6

8.8

1.7

15

298

963

1556

72

112

V2P2

28.2

59.8

89.1

99.5

0.5

6.6

9.4

1.8

21

349

932

1581

73

114

V2P3

47.0

87.2

92.5

102.6

1.0

6.7

5.3

1.7

80

460

907

1847

104

138

V2P4

46.6

82.9

106.1

105.2

0.2

2.6

3.7

1.5

15

257

709

1138

84

121

V2P5

82.3

100.0

100.3

100.2

2.9

4.9

1.6

1.6

367

755

1414

1443

106

141

LSD(0.05)

6.0

6.4

3.5

5.7

0.2

1.0

1.1

0.0

32

ns

ns

193

0.23

0.46

V1 = BRRI dhan 29, V2 = Sonarbangla-1, P1 = Sprouted seeds in line, P2 = Sprouted seeds broadcast, P3 = Nursery seedlings, P4 = SRI and P5 = Clonal tillers

ns = Not significant

Effect of cultivation method

Clonal tillers produced the tallest plant and higher dry matter at early stages due to the long tillers which were planted in the field for their initial establishment. Sharma and Ghosh (1998) also observed higher dry matter in clonally propagated crop than in to the nursery seedlings. However at harvest, the tallest plant was obtained from SRI and the highest dry matter was recorded from nursery seedlings. The highest leaf area index was recorded in sprouted seeds broadcast at 50 and 70 DAS/T and at harvest. This result might be due to higher number of leaves/m2 in sprouted seeds. Clonal tillers needed the longest duration for both flowering and maturity. It required 3 days more for maturity than that of the nursery seedlings. This might be due to regrowth of the clonal tillers. In SRI, grain matured 13 days earlier than that of the nursery seedlings. Uphoff (2005) reported that SRI required less duration for maturity. Sprouted seeds in line and sprouted seeds broadcast matured 28 and 26 days earlier than that of the nursery seedlings, respectively (Table 1). Field duration of the crop was considerably reduced in direct seeded rice, possibly due to the absence of transplanting shock. Direct seeding enhanced crop establishment and vegetative growth and reduced crop duration by two weeks (Javellana et al. 1988).

Broadcast sprouted seeds gave the maximum number of effective tillers/m2, probably because the closer spacing of sprouted seeds increased plants/m2. Xiang et al. (1999) also observed more effective tillers/m2 with sprouted seeds than with nursery seedlings. The use of clonal tillers produced less effective tillers/m2 compared to the nursery seedlings due to the shortage of time for vegetative growth. Rahman (2001) also observed that the number of effective tillers was higher with intact crops than with clonal tillers. Though SRI produced the greatest tillers/hill, because of the wide spacing (40cm 40cm) it failed to perform well in terms of effective tillers/m2. However, Husain et al. (2004) observed a higher density of effective tiller under SRI than with farmers’ practice. Nursery seedlings produced the highest number of total grains/panicle and sprouted seeds sown in line gave the lowest number of total grains/panicle. Nursery seedlings produced significantly higher grain yield than the other systems, followed by clonal tillers and sprouted seeds in line. Similar rankings were also reported by Rahman (2001). SRI produced the lowest grain yield which might be due to their wider spacing. Number of tillers and panicle per unit area were lower in wider spacing and this contributed to this treatment obtaining lower yield. SRI produced the highest harvest index which was similar to the clonal tillers and the lowest harvest index was observed in sprouted seed broadcast (Table 2).

Interaction effect of variety and cultivation method

The tallest plants were from clonal tillers of the hybrid variety and the shortest plants were from sprouted seeds in line of the inbred variety. Clonal tillers of Sonarbangla-1 produced the highest seedling dry matter but at harvest, nursery seedlings of the inbred variety produced the highest dry matter. These characteristics of clonal tiller might be due to the combination of their initial higher length and the hastening of the completion of the life cycle of the clonally propagated crop (Sharma 1995). On the other hand, clonal tillers of BRRI dhan 29 produced the highest leaf area index at 30 DAS/T. At 50 and 70 DAS/T and at harvest, broadcast sprouted seeds of BRRI dhan 29 produced the highest leaf area index. Clonal tillers of Sonarbangla-1 required lowest duration to complete their life cycle and hence it produced lower leaf area index at 30 and 50 DAS/T and at harvest than the other treatments. However, clonal tillers of BRRI dhan 29 required the longest duration for flowering and sprouted seeds broadcast of Sonarbangla-1 needed the shortest duration for flowering. A similar trend was observed in maturity, where clonal tillers of BRRI dhan 29 needed the longest duration and sprouted seeds in line of Sonarbangla-1 required the shortest duration (Table1).

Table 2. Influence of variety and cultivation method on yield characteristics of boro rice.

Treatments

Effective tillers (No. m-2)

Panicle length

(cm)

Total grains/

panicle

(No.)

Filled

grains/

panicle

(No.)

1000-

grain weight

(g)

Grain yield

(t ha-1)

Straw yield

(t ha-1)

Harvest index (%)

V1

413.0

28.2

244.0

193.5

23.0

7.5

9.6

42.7

V2

301.0

27.8

235.6

209.3

28.3

8.3

7.3

55.8

LSD (0.05)

24.3

ns

Ns

11.4

2.3

0.3

ns

4.4

P1

423.0

28.0

221.0

180.0

25.0

8.0

8.8

48.3

P2

529.0

27.5

225.0

182.5

24.0

7.6

9.0

46.2

P3

305.1

27.9

264.7

239.2

26.6

8.7

9.2

48.8

P4

249.3

28.3

242.2

201.3

26.6

7.2

7.2

52.5

P5

278.6

28.2

246.0

203.8

26.2

8.0

7.9

50.2

LSD (0.05)

24.9

ns

23.9

20.2

Ns

0.6

ns

3.3

V1P1

479.0

27.9

223.6

170.9

22.1

7.1

10.8

39.9

V1P2

594.0

27.0

221.5

173.1

22.3

6.4

11.0

37.0

V1P3

357.6

27.9

262.5

222.9

24.0

8.9

9.8

47.8

V1P4

302.1

29.0

255.5

196.3

23.7

7.4

7.8

42.7

V1P5

332.2

28.9

256.7

204.1

23.0

8.0

8.5

45.9

V2P1

367.0

28.0

218.5

189.1

27.9

8.8

6.7

56.7

V2P2

464.0

28.0

228.4

191.9

25.7

8.8

7.1

55.4

V2P3

252.5

27.9

267.0

255.5

29.1

8.6

8.6

49.8

V2P4

196.5

27.6

228.8

206.4

29.5

7.1

6.5

62.2

V2P5

225.0

27.5

235.4

203.5

29.4

8.0

7.3

54.6

LSD (0.05)

24.9

1.4

33.9

28.5

3.4

0.8

ns

4.6

V1 = BRRI dhan 29, V2 = Sonarbangla-1, P1 = Sprouted seeds in line, P2 = Sprouted seeds broadcast, P3 = Nursery seedlings, P4 = SRI and P5 = Clonal tillers

ns = Not significant

Broadcast sprouted seeds of the inbred variety gave the maximum number of effective tillers/m2 followed by sprouted seeds in line of the same variety. SRI with the hybrid variety produced the lowest number of effective tillers/m2. SRI of the inbred variety produced the longest panicles and broadcast sprouted seeds of the same variety produced the shortest panicles. Nursery seedlings of the hybrid variety produced the maximum number of grains/panicle and filled grains/panicle, while the lowest were observed in sprouted seeds. SRI with the hybrid variety produced the highest 1000-grain weight which was similar to the clonal tillers and nursery seedlings of the same variety. Sprouted seeds in line with the inbred variety produced the lowest 1000-grain weight. Rahman (2001) found highest 1000-grain weight in the combination of Sonarbangla-1 and nursery seedlings. Nursery seedlings of the inbred variety gave the highest grain yield which was similar with sprouted seeds in line, sprouted seeds broadcast and nursery seedlings of the hybrid variety. Akbar (2004) found highest grain yield in the combination of the inbred variety and 15 day-old seedlings. Broadcast sprouted seeds of the inbred variety produced the lowest grain yield which might be due to dense plant population. SRI with the hybrid produced the highest harvest index followed by the sprouted seeds in line of the same variety. Broadcast sprouted seeds with the inbred variety produced the lowest harvest index (Table 2).

Conclusion

Though the nursery seedlings produced the highest grain yield, the other treatments showed better performance in case of many growth and yield characteristics. The early harvest of SRI and sprouted seed broadcast and line can save time and exclude preparation of seed bed. Besides, the strong base of SRI plants due to their large number of tillers could reduce the risk of lodging due to summer storms and strong wind. Though clonal tillers did not exceed the yield of nursery seedlings, it could be still a better solution after the common yearly floods in Bangladesh.

Acknowledgement

The partial support of this work under grant by Sher-e-Bangla Agricultural University Research System is gratefully acknowledged.

References

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