Ana səhifə

Wayan Wangiyana and Peter S. Cornish University of Western Sydney, Hawkesbury Campus, nsw, Australia 2753


Yüklə 138.8 Kb.
tarix25.06.2016
ölçüsü138.8 Kb.
VAM Populations in Rice-based Cropping Systems in Central Lombok, Indonesia

Wayan Wangiyana and Peter S. Cornish

University of Western Sydney, Hawkesbury Campus, NSW, Australia 2753

ABSTRACT
In Lombok, crops such as soybean, peanut, mungbean and corn are commonly grown in rotation with rice, without fertilizer, so VAM (vesicular-arbuscular mycorrhizas) are potentially important for these crops (Wetterauer and Killorn 1996; Smith and Read 1997; Arihara and Karasawa 2001).


This paper reports part of an extensive field survey of different combinations of soil types and rice-based cropping systems (45 sites) for 2-3 growing seasons to determine the dynamics of VAM in rotations including rice, conducted in Lombok from July 1999 to April 2000. Samples of soil and roots were taken from farmers’ fields on 4 different rice-based systems: upland, once-rice a year, twice-rice a year and “Gora” rice, 4-5 sites per system (5 replicates per site). The first sampling was during the non-rice season in 1999, around crop maturity or in fallow. The second and third samplings were during the following rice season, at the early vegetative stage and maturity.
There were significant differences (P<0.05) between systems in levels of root colonization and transparent-spore numbers, especially during and at the end of the rice season, being lowest in twice-rice and highest in upland and “Gora” rice. The percentage of black (presumably dead) to total spores (%BkT) at the end of the rice season was significantly different (P<0.05) between systems, being highest in twice-rice and lowest in “Gora” rice. This difference in %BkT was much larger when the crops before rice were non-legumes compared with legumes. The implications of these findings for growing VAM-dependent non-rice crops after rice are discussed in relation to the generally low capability of the majority of the farmers to afford inorganic phosphate fertilizers for their non-rice crops.
INTRODUCTION
Lombok is one of the main islands of the West Nusa Tenggara (NTB) Province in Indonesia, which is divided into three districts, i.e. West Lombok, Central Lombok and East Lombok. The achievement of self-sufficiency in rice production in this province was largely due to the successful implementation of the “Gora” (“gogo-rancah”) technique of growing rice in Central Lombok, where rainfall is relatively low with a short rainy season (2-3 months). “Gora” rice is direct-seeded rainfed rice, initially grown as upland rice, then flooded about 40 DAS if rainfall is enough. Vertisols with strong swell and shrink properties are the dominant soil types in Central Lombok, especially in the “Gora” rice areas. As in other areas in Indonesia, rice fields in Lombok are subject to temporal cropping patterns, which have become a Government regulation since 1985 (Diperta Tanaman Pangan NTB 1991). In fully irrigated areas, the pattern is two rice crops then one non-rice food crop a year (“twice rice”). In areas with less developed or traditional irrigation schemes, the pattern is normally one rice crop plus one non-rice crop followed by another non-rice crop or fallow during the driest months (“once rice”). In the “Gora” rice areas, one non-rice crop can mostly be grown immediately after “Gora” rice.
During the non-rice season, soybean is the most widely grown food crop in Lombok, besides maize, peanut and mungbean. Most farmers do not fertilize their non-rice food crops. Even for their rice crop, they applied fertilizers at less than the recommended rates due to the soaring prices of fertilizers and pesticides since the economic crisis in 1998. In this circumstance, VAM symbiosis is potentially very important for phosphate nutrition of the non-rice crops (Smith and Read 1997; Arihara and Karasawa 2001). This is particularly so because phosphate in dried flooded-rice soils becomes less available to non-rice crops due to fixation (Muirhead and Humphreys 1996; Wetterauer and Killorn 1996).
By field sampling three sites in the Philippines, Ilag et al. (1987) found that the infective VAM population is very low after the wet season rice, and increases again during the maturity of dry season rice or corn and mungbean. They suggested that this was due to anaerobic conditions during long periods of flooding during the wet season rice. In Lombok, field inoculation of VAM spores on some non-rice crops planted after (flooded) rice was found to significantly increase root colonization, spore production and yields of the crops, compared with uninoculated crops (Parman et al. 1997). This finding suggested that VAM was deficient in the rice soil.
Since there had been no field survey of VAM population in Lombok, an extensive survey was undertaken for 2-3 seasons on different combinations of soil types and cropping systems, covering West and Central Lombok, from July 1999 to April 2000, to determine VAM population dynamics on those cropping systems. This paper reports part of the results obtained from Central Lombok, in which the “Gora” rice system is practiced by farmers in addition to upland and normal flooded rice systems.
MATERIALS AND METHODS
Field sampling was done in the sub-districts where all rice-based cropping systems (upland, “Gora”, once-rice and twice-rice) can be found. The first sampling was during the non-rice (dry) season of 1999, where only some types of weeds were mostly found in the upland and “Gora” rice systems. The subsequent samplings were during the following rice season (one season), i.e. during the early vegetative stage and at maturity of the rice crop. Samples consisting of soil and roots of crops growing in the fields were taken from 4 sites of upland rice systems (UpR), 5 sites of once-rice systems (L1R), 5 sites of twice-rice systems (L2R) and 4 sites of “Gora” rice systems (GrR). There were 5 replicates taken diagonally from the sampling paddock of each site. Roots were separated from soils for inspection of VAM colonization rate after clearing with 10% KOH for 50-70 minutes in an autoclave and staining with 0.05% trypan blue in lacto-glycerol solution (Brundrett et al. 1996). VAM spore were extracted from soil using a wet sieving and decanting technique (McKenney and Lindsey 1987; Brundrett et al. 1996).
Spores were counted on a filter paper using a sub-sampling technique (Wangiyana and Cornish 2001). VAM root colonization rates were calculated based on the estimated proportion of each root fragment occupied by VAM fungal structures (mainly vesicles and hyphae) observed on an object glass using a compound microscope, using all root fragments obtained from the staining results up to 150 fragments for each sample. The observation variables for all samplings were %colonization (%Col), transparent spore number converted into per 20 gram oven-dry soil (TrS) and percentage of black to total (transparent and black) spores (%BkT).
To compare between systems, data were analyzed using One-way Analysis of Variance (Anova) on site mean data with Minitab 13 for Windows (%Col was transformed to hyperbolic arcsine (%colonization+0.5) and TrS was transformed to natural log). If F values showed significant differences, LSD values were used for mean comparison (Gomez and Gomez 1984). Since there were legume and non-legume plants growing on the sampling fields during the first sampling, sites were also grouped based on this classification, and then subjected to analysis of variance using a GLM technique with Minitab 13 for Windows, to see if there was an effect of types of crops growing before rice on VAM population at the end of the rice season. Only 3 systems (L1R, L2R and GrR) with a total of 70 data units were analyzed using this approach, because no legumes were found on the UpR sites.
RESULTS AND DISCUSSION
The results in Table 1 reveal significant differences (P<0.05) between systems, especially at the end of the rice season (sampling 3), in terms of %-colonization (%Col3), %-black spores (%BkT3) and transparent-spore number (TrS3). %Col3 and TrS3 were highest, while %BkT3 was lowest, in the L2R systems compared with other systems, which normally have less periods of annual flooding (for the L2R systems, this was the first flooded rice system). Other experiments have shown that VAM colonization in nursery-inoculated rice seedlings persists in the field, even though the levels are reduced over time by flooding (Solaiman and Hirata 1997). This means that adverse effects of rice in our survey were due to flooding conditions, rather than the rice plant itself. Note that upland and “Gora” rice systems had higher colonization rates than other systems with longer periods of flooding.
Table 1. Between-system comparison of root colonization (%Col), %-black spores (%BkT) and transparent spores (TrS) at three sampling times (1, 2, 3).

System

N

%Col1

%Col2

%Col3

%BkT1

%BkT2

%BkT3

TrS1

TrS2

TrS3

Mean

Mean

Sig

Mean

Sig

Mean

Mean

Mean

Sig

Mean

Mean

Sig

Mean

Sig

UpR

4

32.97

22.61

a

14.55

b

70.31

63.18

64.95

a

819

526

ab

364

a

L1R

5

52.63

4.17

b

6.12

cd

61.86

67.57

64.15

a

662

271

c

230

ab

L2R

5

26.55

1.95

b

5.86

bc

60.03

57.94

71.12

a

468

381

bc

134

b

GrR

4

27.77

19.29

a

31.49

a

51.75

50.67

53.57

b

855

724

a

389

a

Anova F

ns

11.31

**

10.69

**

ns

ns

5.08

*

Ns

5.07

*

3.48

*

Note: Mean figures of each observation variable followed by the same letters are not significantly different based on F or their LSD values at 5% significance level.
During the first sampling, all the observation variables were not significantly different between systems (Table 1). Nevertheless, when sites were grouped based on crops growing before rice season (Br), i.e. between legumes (Br=1) and non-legumes (Br=0), the results showed that there were different effects between legumes and non-legumes, as well as crop-system interactions (Sys*Br) on most observation variables (Table 2). Legumes (which were mostly soybean) did better (significantly higher colonization rates) than non-legumes, which means that legumes provided more conducive rhizosphere conditions for VAM infection. This could be due to types of chemicals exuded by legume roots. Kape et al. (1992), for example, found that the flavonoid daidzein exuded by soybean seedlings increased germination of VAM (Glomus mosseae) spores.
Table 2. The effects on root colonization (%Col) and %black spores (%BkT) and transparent spores (TrS) of grouping sites based on the crops growing before the rice season (Br) into legumes (Br=1) and non-legumes (Br=0), and its interaction with 3 cropping systems (L1R, L2R and GrR).

Variables:

System

Mean

StdDev

Summary of Anova results

Br=0

Br=1

Br=0

Br=1

Source

F

P

%Col1

L1R

21.09

60.52

19.84

22.26

Sys

0.37

0.693

L2R

12.75

35.75

11.10

21.07

Br

27.41

0.000

GrR

21.59

46.33

24.94

30.95

Sys*Br

0.44

0.646

%Col2

L1R

9.02

2.95

7.47

4.02

Sys

37.28

0.000

L2R

2.65

1.48

3.68

1.38

Br

0.15

0.698

GrR

16.63

27.30

14.18

8.07

Sys*Br

4.62

0.013

%Col3

L1R

8.26

5.59

6.61

6.28

Sys

24.46

0.000

L2R

3.85

7.19

2.53

3.37

Br

2.09

0.153

GrR

36.10

17.66

13.56

14.50

Sys*Br

6.08

0.004

%BkT1

L1R

75.69

58.41

2.31

10.62

Sys

4.83

0.011

L2R

56.71

62.25

8.06

14.73

Br

0.07

0.786

GrR

48.21

62.38

10.22

6.25

Sys*Br

9.12

0.000

%BkT2

L1R

80.47

64.34

3.31

7.28

Sys

21.38

0.000

L2R

53.90

60.63

7.91

12.68

Br

1.67

0.201

GrR

50.91

49.96

12.11

4.84

Sys*Br

6.71

0.002

%BkT3

L1R

66.81

63.49

17.49

9.87

Sys

12.29

0.000

L2R

75.02

68.51

11.11

9.04

Br

0.28

0.598

GrR

52.25

57.55

7.03

14.31

Sys*Br

1.53

0.224

TrS1

L1R

480

708

112

419

Sys

8.81

0.000

L2R

699

314

526

141

Br

0.05

0.827

GrR

787

1058

378

261

Sys*Br

6.82

0.002

TrS2

L1R

436

230

194

94

Sys

15.23

0.000

L2R

356

398

184

226

Br

0.00

0.971

GrR

644

965

351

227

Sys*Br

5.85

0.005

TrS3

L1R

294

214

130

132

Sys

11.90

0.000

L2R

98

158

23

58

Br

0.29

0.592

GrR

356

487

287

413

Sys*Br

2.54

0.087

Note: P values in bold show significant effects (P<0.05) between 3 systems (Sys), legumes vs non-legumes (Br) or Sys*Br interactions.
In sampling 3 (at the end of rice season), transparent-spore numbers were generally higher in sites with legumes (Br=1) than non-legumes (Br=0) before the rice season. The exception was the L1R system, where only 1 site with non-legume (the crop was tobacco) and 4 sites with legumes (soybean, cowpea and peanut) before the rice season. On average, the transparent-spore number was lowest in L2R system. The percentage of black (presumably dead) spores, however, was highest in L2R system and lowest in GrR system, which always has a shorter period of flooding, while L1R and L2R systems are normally continuously flooded. This could mean that longer periods of flooding kill more spores. However, in the continuously flooded systems, when the crops before rice were legumes (Br=1), the %-black spores was less at the end of rice season than in sites with Br=0 (Table 2). That is, the presence of a legume before flooded rice appears to enhance spore survival during flooding. The reasons for this are not known yet. Further flooding for L2R systems during another rice season would be expected to kill more spores.
Most farmers in these areas normally do not fertilize (especially with phosphate fertilizers) their non-rice food crops in rotation with rice, which is either partially or fully/continuously flooded. Therefore, these kinds of adverse effects of flooding on VAM population could have strong implications for the yields attained by the local farmers, which are usually lower than those obtained from experiments. Recent survey in Central Lombok by Murni (2000), for example, recorded average soybean yield obtained by the farmers in this area was 0.35 t/ha (the highest figure was 0.5 t/ha), while in a field experiment, it could be up to 2.98 t/ha (Wangiyana and Kusnarta 1998).
CONCLUSIONS
These results show that VAM populations in rice-based systems with longer periods of annual flooding are lower than in upland rice systems or those with shorter periods of flooding. Since drying flooded rice fields for growing upland crops following rice decreases phosphate availability, there are at least two options for increasing yield of non-rice crops after rice, i.e. phosphate fertilization and/or increasing VAM population, i.e. promoting VAM utilization in systems with low fertilizer inputs. Given that phosphorus fertilizer is not always used by farmers in Lombok, and that nursery inoculation with VAM has been shown to increase rice yields (Solaiman and Hirata 1997), it is possible that P deficiency, induced by inadequate VAM infection is one cause of the low yields recorded on farmer’s fields, especially for their non-rice crops. This survey reveals the potential to manage VAM populations within cropping systems, including nursery inoculation, to benefit farmers who cannot afford to use P fertilizer every season.
REFERENCES
Arihara, J. and T. Karasawa 2001. "Phosphorus nutrition in cropping systems through arbuscular mycorrhizal management". In: N. Ae, J. Arihara, K. Okada and A. Srinivasan (Eds), Plant Nutrient Acquisition: New Perspectives. Tokyo, Japan: Springer-Verlag.
Brundrett, M., N. Bougher, B. Dell, T. Grove and N. Malajczuk 1996. Working with Mycorrhizas in Forestry and Agriculture. Aciar Monograph 32. 374 + x p.
Diperta Tanaman Pangan NTB 1991. Laporan Akhir Pelaksanaan UPSUS Percepatan Peningkatan Produksi Kedelai TA 1991/1992. Dinas Pertanian Tanaman Pangan Propinsi NTB, Mataram, Indonesia.
Gomez, K.A. and A.A. Gomez 1984. Statistical Procedures for Agricultural Research. 2nd edition. New York: John Wiley & Sons.
Ilag, L.L., A.M. Rosales, F.A. Elazegui and T.W. Mew (1987). Changes in the population of infective endomycorrhizal fungi in a rice-based cropping system. Plant and Soil, 103: 67-73.
Kape, R., K. Wex, M. Parniske, E. Gorge, A. Wetzel and D. Werner 1992. Legume root metabolites and VA-Mycorrhiza development. J. Plant Physiol., 141:54-60.
McKenney, M.C. and D.L. Lindsey, 1987. Improved method for quantifying endomycorrhizal fungi spores from soil. Mycologia, 79:779-782.
Muirhead, W.A. and E. Humphreys (1996). "Rice-based cropping systems in Australia: Constraints to non-rice crops". In: G. Kirchhof and H.B. So (Eds), Management of Clay Soils for Rainfed Lowland Rice-based Cropping Systems. p.181-185. Canberra, Australia: ACIAR.
Murni, D. 2000. Tingkat Kesejahteraan Ekonomi Rumahtangga Petani Lahan Sawah Tadah Hujan di Kabupaten Lombok Tengah. Fakultas Pertanian, Universitas Mataram, Mataram, Lombok, Indonesia Unpublished S-1 “Skripsi” (Undergraduate Thesis
Parman, W. Astiko, W. Wangiyana and I.R. Sastrahidayat (1997). "Studies on compatibility of various inoculum formulations of vesicular-arbuscular mycorrhiza with several post-"Gora" crops on Southern Lombok vertisols". Prosiding Kongres Nasional XIV dan Seminar Ilmiah Perhimpunan Fitopatologi Indonesia, Palembang, 27-29 Oktober 1997. Palembang, Indonesia.
Smith, S.E. and D.J. Read (1997). Mycorrhizal Symbiosis. Second Edition. London, UK: Academic Press. 605 pp.
Solaiman, M.Z. and H. Hirata 1997. Effect of arbuscular mycorrhizal fungi inoculation of rice seedlings at the nursery stage upon performance in the paddy field and greenhouse. Plant and Soil, 191: 1-12.
Wangiyana, W. and I.G.M. Kusnarta 1998. Peningkatan serapan N dan hasil tanaman jagung melalui system tumpangsari dengan beberapa jenis tanaman legum. J. Penelitian Univ. Mataram, 14(1): 41-49.
Wangiyana, W. and P.S. Cornish 2001. A sampling technique for counting VAM fungal spores extracted from soil. Abstract and Poster presented at the Third Conference on Mycorrhizas (ICOM3), 8-13 July, 2001, Adelaide, Australia (http://www.waite.adelaide.edu.au/Soil_Water/3ICOM_ABSTs/Abstracts/W/W.%20Wangiyana.htm).
Wetterauer, D.G. and R.J. Killorn 1996. Fallow- and flooded-soil syndromes: Effects on crop production. J. Prod. Agric., 9:39-41.
Corresponding author contact information:

Wayan, Wangiyana, PhD student, University of Western Sydney, Hawkesbury Campus (Building J4), Bourke St., Richmond, NSW, 2753, Australia, Phone:+61 2 45701980, Fax:+61 2 45701684, w.wangiyana@uws.edu.au, POSTER, Food Safety and Security [Usual address: Faculty of Agriculture, Mataram University, Mataram 83125, Lombok, NTB, Indonesia, wayan_wangiyana@yahoo.com]


Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©atelim.com 2016
rəhbərliyinə müraciət