Soil Seedbank of the Muda Rice Granary in North- (Oryza Sativa)

Plant Protection Quarterly Vol.23(4) 2008 157 McGregor, J.T., Smith, Jr. R.J. and Tal- bert, R.E. (1988). Broadleaf signalgrass (Brachiaria platyphylla) duration in rice Soil seedbank of the Muda rice granary in north- (Oryza sativa). Weed Science 36, 747-50. west Peninsular Malaysia invaded by the weed Mohammadi, G., Javanshir, A., Khooie, F.R., Mohammadi, S.A. and Zehtab Sal- Fimbristylis miliacea (L.) Vahl masi, S. (2005). Critical period of weed interference in chickpea. Weed Research M. BegumA, A.S. JuraimiB, M. AzmiC, S.R. Syed OmarD and A. RajanB 45, 57-63. A Department of Agronomy, Bangladesh Agricultural University, Bangladesh. Noda, K. (1977). Integrated weed control B Department of Crop Science and, C Department of Land Management, in rice. In ‘Integrated control of weeds’, eds J.D. Fryer and S. Matsunaka, pp. Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Malaysia. D 17-44. (University of Tokyo Press, Ja- Malaysian Agricultural Research Development Institute, Pulau Pinang, pan). Malaysia. Pons, T.L. (1985). Growth rates and com- petitiveness to rice of some annual weed species. Biotrop Bulletin of Tropical Biology 23, 13-22. Sharma, H.C., Singh, H.B. and Friensen, Abstract weed fl ora to grasses (Azmi et al. 1995), G.H. (1977). Competition from weeds The experiment was conducted in the other surveys (Azmi and Mashhor 1995, and their control in direct-seeded rice. glasshouse at Universiti Putra Malaysia Ismail et al. 1995, Pane 1997) reported that Weed Research 17, 103-5. from March 2003 to June 2004 to deter- F. miliacea was still an important weed. A Swain, D.J., Nott, M.J. and Trounce, R.B. mine the soil seedbank of Fimbristylis more recent survey showed that F. miliacea (1975). Competition between Cyperus miliacea in the rice fi elds of the Muda was among the fi ve most dominant weed difformis and rice: the effect of time of rice granary in Peninsular Malaysia. Six species in the Muda area (Begum et al. weed removal. Weed Research 15, 149- soil cores of 5 cm in diameter and 10 cm 2005). It is a prolifi c seed producer and one 52. depth were sampled from each of 24 plant can produce more than 10 000 seeds, Van Acker, R.C., Swanton, C.J. and Weise, fi elds. All samples from each individual many of which are deposited and stored in S.F. (1993). The critical period of weed fi eld were bulked and placed in plastic the soil seedbank in each year. The seed- control in soybean (Glycine max (L.) trays of 38 × 25 × 10 cm. Soil was mois- bank is the major source of annual weeds Merr.). Weed Science 41, 194-200. tened as required and emergence of weed on most tilled agriculture soils (Cardina et Weaver, S.E. and Tan, C.S. (1987). Critical seedlings was recorded over a period of al. 1991, Yenish et al. 1992). Vengris (1953) period of weed interference in trans- one year. After one year, remaining seeds reported that weed seed populations in planted tomatoes and its relation to wa- were separated, removed and identifi ed. cultivated soils are generally composed of ter stress and shading. Canadian Journal The total seed bank was estimated a few dominant species that are present of Plant Science 67, 575-83. at 1136.48 million m−2 including 20 taxa. in high numbers, a few others present at Weaver, S.E., Kropff, M.J. and Groeneveld, Based on per cent composition the fi ve moderate levels, and a large variety of R.M.W. (1992). Use of ecophysiological most dominant species in terms of seed species present in the soil at low levels. models for crop-weed interference: the reserves were F. miliacea, Leptochloa Knowledge of the size and species compo- critical period of weed interference. chinensis, Ludwigia hyssopifolia, Cype- sition of this seedbank would be useful in Weed Science 40, 302-7. rus difformis and Cyperus iria. Fimbristy- predicting future weed infestations. Woolley, B.L., Michaels, T.E., Hall, M.R. lis miliacea exhibited a very abundant Most weeds show some periodicity of and Swanton, C.J. (1993). The critical 750.84 million seeds ha−1, 66.07% of the emergence (Roberts and Margaret 1980). period of weed control in white bean total seed reserve, of which 411.48 mil- Practical knowledge of periodicity of (Phaseolus vulgaris). Weed Science 41, lion seedlings ha−1 (55%) emerged in soil emergence is of signifi cant importance, 180-4. trays, 61.59 million seedlings ha−1 (8%) since it is a major factor in determining the Zimdahl, R.L. (1980). ‘Weed–crop compe- in Petri dishes and the remaining 277.77 association of weeds with cropping sys- tition: a review.’ pp. 11-29, 196. (Interna- million seeds ha−1 (37%) were dormant tems and to enable a degree of forecasting tional Plant Protection Center, Oregon, or dead. Fimbristylis miliacea seedling as to which weed species may occur in a USA). emergence was highest in the fi rst obser- seedbed. Predicting potential weed emer- Zimdahl, R.L. (1993). ‘Fundamentals of vation in April 2003 and seedling emergence is fundamental in the development weed science.’ p. 128. (Academic Press, gence showed no clear peaks. The study of integrated pest management strategies San Diego, California). suggests a large persistent seedbank of F. for weed control. Predictions of emerged Zoschke, A. (1990). Yield losses in tropical miliacea in Muda rice fi elds. seedling densities allows estimation of rice as infl uenced by the composition of Key words: Soil seedbank, rice gra- weed competition, crop yield loss, need weed fl ora and the timing of its elimina- nary, Malaysia, Fimbristylis miliacea (L.) for herbicides, fi nancial returns and weed tion. In ‘Pest management in rice’, eds Vahl. seed production at the end of the growing B.T. Grayson, M.B. Green and L.G. Cop- season (Forcella 1992). Furthermore, the ping, pp. 300-13. Introduction remaining seeds in the soil are also a major In any rice fi eld the dominating weed spe- concern to understand the soil seedbank cies may vary with region and type of crop- status (Cardina and Sparrow 1996). The ping (Wilson and Furrer 1996). Fimbristylis dynamics of the seedbank will determine miliacea of the family Cyperaceae is one of whether populations of the weed change the ten most dominant weeds in rice fi elds and if so, at what rate. Karim et al. (2004) in South-East Asia (Smith 1983). Even in undertook an extensive review of litera- Muda rice granary of Malaysia, where ture on weeds in Malaysian rice fi elds changes in cultural practices and use of and concluded that a greater ecological agrochemicals has led to a shift in species understanding of several weeds includ- from broad-leaved and sedge dominant ing F. miliacea is required for successful 158 Plant Protection Quarterly Vol.23(4) 2008 control. Therefore, this study was con- The remaining seeds of F. miliacea in Results and discussion ducted to determine the germinable seed- each sample were tested for viability by Seedbank density and species bank, remaining seeds, total seed reserve germinating in Petri dishes. The F. miliacea composition and emergence pattern of F. miliacea in the seedbank was thus differentiated as total Total seed reserve in the Muda area was soils at the Muda rice granary area. germinable seeds (during 12 months peri- 113 648 seeds m−2, equivalent to 1 136.48 od in soil media in trays and in Petri dish- million ha−1, of which 75 084 seeds m−2 Materials and methods es) and dormant or dead seeds. Seeds and were F. miliacea (Table 1). The total number The experiment was conducted in a glass- seedling counts were converted to num- of buried seeds reported here are higher house at Universiti Putra Malaysia and bers per m2 within a 10 cm soil depth. than the 29 551 viable seeds m−2 reported the temperature and light fl uctuations in the glass house are shown in Figure 1. Soil sample sites were located in Muda rice fi elds at Kedah in the north-west of Penin- 40 20000 sular Malaysia. Four sampling sites were 35 18000 randomly selected from parts of Muda, 16000 namely Alor Belat (AB), Batu-17 (BT), ) 30

Sungai Daun (SD) and Simpang Tiga (ST) C 14000 to determine the species composition and 25 12000 seedbank size of F. miliacea. Soil samples were obtained from six ﬁ elds in each of 20 10000 the four sampling locations in March 2003. 15 8000

Six soil cores of 5 cm in diameter and 10 ht intensity (Lux) g Temperature (° Temperature Temperature 6000 cm depth were sampled from each fi eld 10 Li in a ‘W’ shaped pattern. Samples from Light intensity 4000 each individual fi eld were bulked and air- 5 2000 dried in the glasshouse. Subsequently, the 0 0 soil samples were passed through a 4 mm sieve to remove large debris and break 8 AM 10 AM 12 PM 2 PM 4 PM 6 PM up soil clods. Samples from each of the Time 24 fi elds were placed in 38 × 25 × 10 cm plastic trays. Each tray was fi lled with 2 kg Figure 1. Temperature and light fl uctuations in the glasshouse of Universiti of soil. The samples were sprinkled daily Putra Malaysia. with water as needed in order to maintain moisture levels. Weed seedlings that emerged were identifi ed, counted, and removed at one- Table 1. Number of total seed reserves (germinable seeds + remaining month intervals, throughout the one-year seeds) and their per cent composition in the Muda rice granary area. emergence period. Seedlings were identi- Weed species Number of total Per cent fi ed using the seedling keys of Chancellor seed reserve composition (1966). Seedlings of questionable identity were transferred to pots and grown until Fimbristylis miliacea 75 084 66.07 maturity to facilitate identifi cation. After Leptochloa chinensis 8 644 7.61 the removal of each batch of seedlings, soils were air dried for three days, thor- Cyperus difformis 4 989 4.39 oughly mixed in order to expose the weed Cyperus iria 4 958 4.36 seeds to the upper layer of the soil, and re- Ludwigia hyssopifolia 5 194 4.57 wetted to permit further emergence. This process was repeated 12 times from March Sphenoclea zeylanica 2 402 2.11 2003 to February 2004. Monochoria vaginalis 3 079 2.71 After one year, any remaining seeds Limnophila erecta 1 292 1.14 were separated by the method described by Wilson et al. (1985). The soil in each Hedyotis diffusa 1 129 0.99 tray was passed through a descending Ceratopteris thalictroides 1 045 0.92 series of fi ve sieves containing screens of the following sizes: 4 mm (5 mesh), 2 mm Echinochloa crus-galli 1 147 1.01 (10 mesh), 850 µm (20 mesh), 425 µm (40 Bacopa rotundifolia 644 0.57 mesh) and 250 µm (60 mesh). Water was Eleocharis variegata 227 0.20 run through the sieves to enhance sample separation through the screens. The Echinochloa colona 57 0.05 contents collected in each screen were Scirpus laterifl orus 1 613 1.42 removed, sun dried, and seeds were re- Scirpus juncoides moved under an illuminated magnifi er. 943 0.83 Seeds from entire samples were sorted us- Sagittaria guyanensis 742 0.65 ing a dissecting microscope and counted Nymphoides indica 235 0.21 according to species. The total of emerged seedlings during the one year period and Najas graminea 201 0.18 the remaining seeds represent the total Cleome viscosa 23 0.02 species composition and seed reserve of Total 113 648 100% the respective species. Plant Protection Quarterly Vol.23(4) 2008 159 by Pane (1997) and much lower than the (1996) observed that Fimbristylis miliacea populations, five low populations and densities of 712 228 to 930 910 seeds m−2 was still the most important sedge, irre- very low populations were recorded at recorded by Ismail et al. (1995) in direct- spective of the shift in cultural practice three sampling sites. Differences in weed seeded rice fi elds at Kampung Tandop from transplanting to direct seeding in all population and species composition are in the Muda area. A total of 20 taxa were four districts of Muda rice granary areas. affected by cultural practices, particularly recognized, of which the fi ve most domi- Fimbristylis miliacea would remain as the land preparation, water regime and type nant weed species in terms of total seed dominant weed species in direct seeded of herbicides used. Germinable seeds in reserves (seedlings + remaining seeds) in rice areas because of the tremendous size all fi elds were between 76–99.8%, except the Muda area were F. miliacea (66.1%), of the seed bank accumulated over years in Alor Belat (AB5), Sungai Daun (SD1, Leptochloa chinensis (7.6%), Ludwigia hys- of transplanting. SD2, SD4), Simpang Tiga (ST5 and ST6), sopifolia (4.6%), Cyperus difformis (4.4%) where dormant or dead seeds were re- and Cyperus iria (4.4%) while the remain- Fimbristylis miliacea seedbank in Muda corded at 57.4, 44.0, 44.4, 46.4, 38.2 and ing 15 species shared only 13% of the rice fi elds 47.2% respectively. Rahman et al. (1995) total seed reserve (Table 1). Pane (1997) Total F. miliacea seedbanks (seedlings + re- also recorded high (65–100%) germination reported a much lower F. miliacea germi- maining seeds) in the different fi elds are for three quarters of the species studied nable seedbank of 22.9%, although it was shown in Table 2. No signifi cant difference over six months. Emerging seedlings of the second most dominant species after was observed within or between location Amaranthus spp., black nightshade (Sola- L. chinensis (26.9%). Watanabe et al. (1997) by Statistical Analysis Software (SAS, 6.04 num nigrum) and mallow (Malva sp.) rep- observed higher emergence of F. miliacea versions). Apparently, Fimbristylis miliacea resented a small and variable fraction of seedlings in Muda area. In the Muda soils contributed the high seedbank composi- the weed seedbank in the soil (Hartley and F. miliacea seeds were present in high num- tion (more than 20 000 seeds m−2) except Rahman 1996). Ball and Miller (1989) re- bers and the domination of the seedbank in AB(1), AB(3), BT-17(1–5), SD(3) and ported that 20–30% of the seeds in the soil by a single annual species, in this case SD(6) sampling fi elds. Variations between emerged as seedlings over eight months. F. miliacea, is not unusual. A single spe- fi elds in F. miliacea seedbank size were ob- Seed dormancy is a major factor contrib- cies often comprises over half of the soil served by Pane (1997) at 33 sampling sites uting to persistence of seedbanks (Bewley seedbank (Thompson 1986, Clements et al. in Muda rice fi elds. Four sampling sites and Black 1982). This study suggests that 1996, Schott and Hamberg 1997, Navie et had very high weed seedling populations, F miliacea could maintain persistence in al. 2004). In addition, Azmi and Mashhor eight high populations, 13 medium weed some of the sampled seedbanks.

Table 2. Breakdown of ungerminated seeds and emerged seedlings of Fimbristylis miliacea at 24 sampling sites. Location (Field) Dormant and Seedlings m−2 in Seedlings m−2 in Total seedlings m−2 Total seeds and dead seeds m−2 soil media Petri dish (total germinable seedlings m−2 (% of total) (% of total) (% of total) seeds) % of total AB(1) 3.4 95.2 1.4 96.6 13 363 AB(2) 14.9 82.1 2.9 85.0 40 182 AB(3) 23.4 68.7 7.9 76.6 18 272 AB(4) 6.5 91.9 1.6 93.5 52 728 AB(5) 57.4 28.2 14.4 42.6 150 273 AB(6) 10.7 87.8 1.5 89.3 36 364 BT-17 (1) 3.3 96.7 0 96.7 2 727 BT-17 (2) 3.3 96.7 0 96.7 12 455 BT-17 (3) 0 100 0 100 4 000 BT-17 (4) 0 100 0 100 5 273 BT-17 (5) 0 100 0 100 18 000 BT-17 (6) 0 100 0 100 31 000 SD(1) 44 45 11 56 200 819 SD(2) 44.4 46.6 9 55.6 180 545 SD(3) 5.4 92.8 1.8 94.6 15 182 SD(4) 46.4 43.4 10.2 53.6 458 999 SD(5) 18.1 77.4 4.5 81.9 28 546 SD(6) 2.2 96.7 1.1 97.8 8 364 ST(1) 5.2 93.2 1.6 94.8 39 909 ST(2) 23.2 71.8 5 76.8 36 091 ST(3) 14.2 82.6 3.2 85.8 48 091 ST(4) 10.8 84.8 4.4 89.2 48 909 ST(5) 38.2 54.5 7.3 61.8 155 636 ST(6) 47.2 43.8 9 52.8 196 273 AB = Alor Belat, BT-17 = Batu-17, SD = Sungai Daun, ST = Simpang. 160 Plant Protection Quarterly Vol.23(4) 2008 Emergence patterns of Fimbristylis 25 Fimbristylis miliacea miliacea Other species The highest percentage (22%) of F. milia- 20 cea emergence occurred within one month after the commencement of the germina- 15 tion trial. Seedling emergence was slightly lower in August and January and higher 10 in October compared with all other species (Figure 2). Seedling emergence rates

Per centPer emergence 5 with each soil disturbance were between 3.2–20.8%. After the ﬁ rst month, seed- 0 lings continued to emerge irrespective of Apr May June Jul Aug Sep Oct Nov Dec Jan Feb Mar the time of year, but in reduced numbers. There was no clear peak of emergence. Month In general, weed emergence is related to tillage (i.e. soil disturbance), temperature, Figure 2. Temporal variation in Fimbristylis miliacea seedling emergence rainfall, soil moisture and radiant energy. relative to other species during the 12 month incubation of the soil samples Zimdahl et al. (1988) observed that tillage from Muda rice ﬁ elds (mean of all locations). caused weed emergence regardless of the time that it occurred. They also noted that emergence was related to increasing ra- diation and during the peak period, 46% emergence of F. miliacea were accounted 50000 Number 70

2 for in 1984 and 54% F. miliacea emergence − 45000 Per cent was recorded in 1985. The cumulative dis- 60 40000 tribution for the proportion of F. miliacea 50 emerging was slightly higher in the fi rst 35000 seedlings two months compared with all other spe- 30000 40 cies combined. The results indicate an ear- 25000 lier initial rate of emergence for F. miliacea. 20000 30 Harley and Rahman (1995) noted that 74% of the total weeds recorded over a six week 15000 20 period could be identifi ed within the fi rst 10000 10 Per cent seeds or or Per cent seeds

two weeks. However, there was consid- m seedlings or seeds of No. 5000 erable variation in the emergence pattern 0 0 among species. For example, 93% of the Germinable in Germinable in Total seedlings Dormant or summer grass (Digitaria sanguinalis) and soil media Petri dish dead seeds fathen (Chenopodium album) emerged in the fi rst two weeks with virtually nothing in the last two weeks, while 63% of twin Figure 3. Mean number and percentage of Fimbristylis miliacea seeds/ cress (Coronopus didymus) emerged in the seedlings in seedbank within Muda area. last two weeks. Likewise, Parthenium hysterophorus seedlings emerged more rapidly from the soil than all other species (Navie et al. 2004). Total F. miliacea seedbank (seedlings + F. miliacea seedlings emerged within fi rst Acknowledgement remaining seeds) and their emergence (%) month after the commencement of the The authors would like acknowledge to are shown in Figure 3. A total of 41 148 germination trial and seedling emergence the grant for Ph.D. research sponsored by seedlings m−2 (55%) emerged within 12 continuously occurred by monthly soil Third World Organization for Women in months. Of the remaining seeds, 6159 disturbance without any clear peaks. Science (TWOWS), Trieste, Italy and Uni- seeds m−2 (8%) were germinable in the From this seedbank, total seed reserves versiti Putra Malaysia for providing re- Petri dish within one month, while 27 777 of F. miliacea was 750.84 million seeds ha−1 search facilities under the Intensifi cation seeds m−2 (37%) were either dormant or of which 411.48 million seedlings ha−1 of Research in Priority Areas (IRPA) (No.: dead. This is not unusual as seedbanks de- (55%) emerged within the 12 month pe- 01-02-04-0778-PR0068/05-05). crease over time, but some seeds remain in riod and the remaining 45% of seeds were the soil for two years or more. Grace et al. either dormant or dead. Of the remain- References (2002) reported that seed loss in Carthamus ing seeds, 8% were germinable in the Petri Azmi, M. and Mashhor, M. (1995). Weed lanatus and C. vulgare through germina- dish, while 37% remained either dormant succession from transplanting to direct- tion was also faster in the fi rst year than in or dead. Fimbristylis miliacea seedbank seeding method in Kemubu rice area, subsequent years. contributed 66.07% of the total seed re- Malaysia. Journal of Bioscience 6(2), 143- serves. The result suggests a large seed- 54. Conclusion bank, which may be attributed to its pro- Azmi, M., Mashhor, M., Itoh, K. and Wa- In this soil seedbank a total of 20 taxa were lifi c seed production and the ability of its tanabe, H. (1995). Life cycle and seed recorded consisting of 1136.48 million ha−1 seeds to persist more than a year. The site longevity of Echinochloa crus-galli com- seed reserve. Fimbristylis miliacea, L. chin- specifi c information available from this plex in direct seeded rice in Malaysia. ensis, L. hyssopifolia, C. difformis and C. iria study may be used to make adjustments Proceeding of 15th Asian Pacifi c Weed made up the bulk of the seed populations to current weed management practices of Science Conference, Tsukuba, Japan, in the soil, with an average of 80% occur- Fimbristylis miliacea. 505-11. rence. The highest percentage (22%) of Plant Protection Quarterly Vol.23(4) 2008 161 Azmi, M. and Mashhor, M. (1996). Effect Pane, H., (1997). Studies on ecology and of continuous direct seeding on weed biology of red sprangletop (Leptochloa species diversity in Seberang Perai rice chinensis (L.) Nees) and its management granary, Malaysia. MARDI Research in direct seeded rice. PhD thesis. Uni- Journal, 24(1), 93-105. versiti Sains Malaysia, pp. 41-60. Ball, D.A. and Miller, S.D. (1989). A com- Rahman, A., James, T.K., Grbavac, N. and parison of techniques for estimation of Mellsop, J. (1995). Evaluation of two arable soil seedbanks and their rela- methods for enumerating the soil weed tionship to weed fl ora. Weed Research seed bank. Proceeding of 48th New 29, 365-73. Zealand Plant Protection Conference. Begum, M., Juraimi, A.S., Azmi, M., Rajan, Palmerston North, New Zealand, www. A. and Syed Omar, S.R. (2005). Weed hortnet.co.nz/publications/nzpps/ vegetation of direct seeded rice fi elds in proceedings/95/95_175.htm. Muda rice granary areas of Peninsular Roberts, H.A. and Margaret, E. (1980). Malaysia. Pakistan Journal of Biological Emergence patterns of weed seedlings Science 8(4), 537-41. in relation to cultivation and rainfall. Bewley, J.D. and Black, M. (1982). Physiol- Weed Research 20, 377-86. ogy and biochemistry of seeds. (Spring- Schott, G.W. and Hamberg, S.P. (1997). 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Weed populations as re- and Swanton, C.J. (1996). Tillage effects lated to certain cultivated crops in the on weed seed return and seedbank Connecticut River valley, MA. Weeds 2, composition. Weed Science 44, 314-22. 125-34. Forcella, F. (1992). Prediction of weed Watanabe, H., Azmi, M. and Ismail, Md. seedling densities from buried seed re- Z. (1997). Emergence of major weeds serves. Weed Research 32, 29-38. and their population change in wet- Grace, B.S., Sheppard, A.W., Whalley, seeded rice fi elds of the MUDA area, R.D.B. and Sindel, B.M. (2002). Seed- Peninsular Malaysia. Proceeding of banks and seedling emergence of saf- 16th Asian Pacifi c Weed Science Soci- fron thistle (Carthamus lanatus) in east- ety Conference, ed. A. Rajan, pp. 246- ern Australian pastures. Australian Jour- 50. (Malaysian Plant Protection Society, nal of Agriculture Research 53, 1327-34. Kuala Lumpur). Hartley, M.J. and Rahman, A. (1996). Wilson, R.G., Derr, E.D. and Nelson, L.A. 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