Allelopathic potential of indigenous ... - Wiley Online Library

Weed Biology and Management 16, 119–131 (2016)

RESEARCH PAPER

Allelopathic potential of indigenous Bangladeshi rice varieties SHEIKH M. MASUM1, MOHAMMAD AMZAD HOSSAIN2* HIKARU AKAMINE2, JUN-ICHI SAKAGAMI3 and PRASANTA C. BHOWMIK4 1 United Graduate School of Agriculture Sciences, Kagoshima University, Kagoshima, Japan 2Subtropical Field Science Center, Faculty of Agriculture, University of the Ryukyus, Nishihara, Japan 3Special Course in International and Resource Sciences, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan 4Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, Massachusetts, USA A series of experiments was conducted in the laboratory and greenhouse of the Subtropical Field Science Center, University of the Ryukyus, Japan, from April to October 2015 to assess the allelopathic potential of 50 indigenous Bangladeshi rice varieties by using the donor–receiver bioassay, equal compartment agar method (ECAM), plant residue extract method and pot culture method. Lettuce (Lactuca sativa L.), cress (Lepidium sativum L.), radish (Raphanus sativus L.), barnyard grass (Echinochloa crus-galli L. Beauv.) and jungle rice (Echinochloa colona L.) were used as the test plants. The highest inhibition effect was given by Boterswar, while the stimulating effect was given by Kartikbalam and Panbira in the donor– receiver bioassay and ECAM tests. Boterswar, Goria, Biron and Kartiksail were selected as the highest allelopathic-potential varieties by the donor–receiver bioassay and ECAM. In the methanol extract test, Boterswar gave the strongest inhibitory effect on both barnyard grass and jungle rice, while Kartiksail gave the highest inhibitory effect on the jungle rice shoot. The growth parameters and total dry matter of barnyard grass in the greenhouse pot experiment were significantly reduced as a result of the application of aqueous extracts of the selected rice varieties, which was similar to the results of the laboratory experiments. The varieties of Boterswar, Goria, Biron and Kartiksail were selected as the most allelopathic among the 50 indigenous Bangladeshi rice varieties. These rice varieties could be used for the isolation and identification of allelochemicals and to further develop new varieties that are tolerant to weeds. Keywords: Bangladeshi indigenous rice, Echinochloa colona, Echinochloa crus-galli, rice allelopathy.

Rice (Oryza sativa L.), one of the most important food crops, provides 21% of the world’s food calories (Pacanoski & Glatkova 2009). Worldwide, 480.71 million metric tons of paddy rice are produced annually, of which 90.90% is in Asian countries, such as China, India, Indonesia, Bangladesh, Vietnam, Thailand, Myanmar, Communicated by C. Kong. *Correspondence to: Mohammad Amzad Hossain, Subtropical Field Science Center, Faculty of Agriculture, University of the Ryukyus, Senbaru 1, Nishihara 903-0213, Japan. Email: [email protected] Received 2 March 2016; accepted 17 August 2016

doi:10.1111/wbm.12103

Philippines and Japan (FAOSTAT 2014). On the contrary, weeds pose an important biological constraint to rice productivity (Zimdahl 1999; Rao 2000) and result in a 30–100% loss in the upland rice yield (Hassan et al. 1994). Weeds compete seriously with crops for resources, especially during their establishment and the early growth stages (Zimdahl 1980). Both Echinochloa crus-galli L. Beauv. (barnyard grass) and Echinochloa colona L. (jungle rice) are among the top 10 most troublesome rice weeds (Smith 1983). Rice production now has been characterized by the heavy use of herbicides that cause environmental and health problems. The prolonged and widespread use of herbicides in rice-growing regions © 2016 Weed Science Society of Japan

120

S.M. Masum et al.

increases the threat of herbicide-resistant weeds. Therefore, non-chemical tactics need to be included in rice weed management systems. Allelopathy, as first described by Molisch (1937), is the stimulatory or inhibitory impact of any biochemical interaction between plants (Rice 1984). Such a phenomenon occurs widely among natural plant communities and is postulated to be one mechanism by which weeds interfere with crop growth (Rice 1984; Smith & Martin 1994). As Dilday et al. (1989, 1991, 1994) have reported, some rice accessions possess allelopathic activity in weed suppression and thus rice allelopathy has received a great deal of attention. The allelopathic effect of rice itself on weeds could be applied in order to reduce the use of herbicides, which might result in less environmental contamination (Kong 2008). Therefore, one option could be for rice allelopathy to solve the dependency on herbicides (Olofsdotter et al. 1999). The potential use of allelochemicals in controlling weeds in rice fields also has been explored by various researchers worldwide (Fujii 1992; Hassan et al. 1998; Kim et al. 1999; Olofsdotter et al. 1999; Azmi et al. 2000; Chau et al. 2008; Kato-Noguchi et al. 2008; Khanh et al. 2009; Salam & Kato-Noguchi 2010). Accessions with high inhibitory activity were found among wild, traditional and red rice species (Fujii 1994). Besides this, the genetic variability in weed control among allelopathic rice varieties shows that breeding is a possible strategy to improve the capacity for self-defense against paddy weeds. Thus, research on the development of commercially acceptable allelopathic rice has been carried out throughout the world (Kong et al. 2011). Bangladesh, a small country, is fourth in rice production in the world (FAOSTAT 2014). Both the low and upland rice fields in Bangladesh are generally infested with many tropical and subtropical weeds, such as E. cruss-galli, E. colona, Leersia hexandra, Oryza rufipogon, Fimbristylis miliacea, Cyperus esculentus, Cyperus difformis, Monochoria vaginalis, Spilanthe sacmella and Eclipta prostrata. Farmers in Bangladesh usually control weeds by mechanical, cultural and chemical methods. It is reported that the International Rice Research Institute Gene Bank contains > 8000 traditional rice varieties that have been collected from Bangladesh (Hossain et al. 2013). It is thought that the indigenous rice varieties contain different allelochemicals that could suppress the population and growth of weeds. Main et al. (2007) observed that, in Bangladesh, most of the common weed species are dominant in the semidwarf modern variety than in the traditional tall cultivars. Salam and Kato-Noguchi (2009) compared the allelopathic activity among 102 modern and traditional varieties and they reported that BR17 (modern variety) is the most allelopathic. They also reported that Kartiksail © 2016 Weed Science Society of Japan

(indigenous variety) might have great inhibitory activity against barnyard grass. Karim et al. (2014) found that the highly allelopathic varieties were Kataribhog, WooCo, WITA12, Dular, Lalpaika, BRRI dhan27, WITA3, FARO8, BR26, BRRI dhan39, IR64, WITA8, Dharial and Nizersail among the 120 modern and traditional rice varieties in Bangladesh. However, limited information exists on weed suppression-enabling indigenous rice varieties, despite >60 indigenous rice varieties being cultivated regularly in Bangladesh, and no bioactive chemical identification study has been done yet. Therefore, the present research was undertaken in order to screen for the allelopathic potential of the indigenous rice varieties of Bangladesh that could suppress paddy weeds and be used for commercial cultivation, as well as for a genetic source for rice breeding.

MATERIALS AND METHODS Seed collection and experimental materials The research was conducted in the laboratory and greenhouse of the Subtropical Field Science Center, Faculty of Agriculture, University of the Ryukyus, Nishihara, Japan, from April to October 2015. Fifty indigenous Bangladeshi rice varieties were collected from the Bangladesh Rice Research Institute, Bangladesh Geetanjoly Agro Society, and from farmers of the Barisal and Bandarban districts of Bangladesh. These collected seeds were brought into Japan by maintaining official procedures. All the rice varities are non-sticky and indica rice. Lettuce (Lactuca sativa L.), cress (Lepidum sativum L.), radish (Raphanus sativus L.), barnyard grass (E. crus-galli) and jungle rice (E. colona) were used as the receiver plants because cress, lettuce and radish are usually used as model plants for bioassay, while barnyard grass and jungle rice are important rice weeds. The barnyard grass seeds were collected from the rice field of the Okinawa Agricultural Research Center, Nago, Japan, and the jungle rice seeds were collected from the research field of the University of the Ryukyus. In this study’s experiments, two screening methods were used, as described by Kato-Noguchi et al. (2002) and Wu et al. (2000), in order to select some possible allelopathic varieties. Potential allelopathic varieties also were selected by using aqueous methanol (MeOH) extracts, including the effects of the aqueous extracts on the weeds in laboratory and greenhouse experiments, respectively. Donor–receiver bioassay In order to break rice dormancy, the seeds were incubated at 45–48 C for 7 days. Then, the seeds were

Allelopathy of Bangladesh rice soaked in distilled water for 24 h and transferred onto moistened filter paper (no. 2; Toyo Roshi Kaisha, Tokyo, Japan) in Petri dishes (9 cm; Fisher Company, Hanover Park, IL, USA). Following incubation in darkness at 25 C for 48 h, the seeds were transferred to a growth chamber (versatile environmental test chamber MLR-351; SANYO Electric Company, Ltd., Moriguchi City, Osaka, Japan) with a 12 h photoperiod for another 48 h (25 C, 80–100 μE m−2 s−1). The uniform germinating rice seedlings were transferred to Petri dishes (six rice seedlings per Petri dish) that contained a sheet of filter paper that was moistened with 2.5 mL of 1 mM phosphate buffer (pH) and grown for an additional 48 h. Then, 10 seeds of cress, lettuce or radish were placed onto the filter paper with the growing rice seedlings. In the case of barnyard grass or jungle rice, the seeds were pregerminated by soaking them in distilled water for 36 h, transferring them onto a Petri dish with a sheet of moistened filter paper, as described above, and then incubated in darkness at 25 C for 48 h. Finally, the germinating barnyard grass seeds were placed onto the filter paper with the growing rice seedlings. Rice and the receiver species were allowed to grow in the growth chamber (conditions as described above) for 48 h prior to the growth measurements. The shoot (hypocotyls and/or coleoptiles) and root lengths of cress, lettuce, radish, barnyard grass and jungle rice were measured. The controls were established by treating and incubating the receiver species, as described above, in the absence of the rice seedlings (Kato-Noguchi et al. 2002). Each experimental unit contained six donor (rice) seedlings and/or 10 receiver (cress, lettuce, radish, barnyard grass and jungle rice) seedlings. The experimental design was completely randomized, with four replications. Equal compartment agar method bioassay The equal compartment agar method (ECAM) that had been developed by Wu et al. (2000) and was modified by Seal et al. (2004) was used for the screening of the rice accessions. Glass beakers (500 mL, 12 cm depth, 9 cm diameter) containing 30 mL of 0.3% water agar (no nutrients, 1.3 cm depth) were autoclaved (HG-50/ HG-80; HMC EUROPE, Tuessling, Germany). Six pregerminated rice seeds of each accession were uniformly selected and aseptically sown on one half of the agar surface with the embryo upwards. The beaker was wrapped with parafilm to prevent contamination and evaporation from the agar’s surface and placed in the controlled growth incubator with a daily light/dark cycle of 12:12 h and a temperature cycle of 25 C/ 25 C. The fluorescent light intensity in the cabinet was

121

3.56 0.16 × 103 lux. Seven days later, 10 pregerminated seeds of barnyard grass and jungle rice were aseptically sown on the other half of the agar’s surface. A piece of pre-autoclaved white paperboard was inserted across the center and down the middle of the beaker, with the lower edge of the paperboard kept at 1 cm above the agar surface. After the sowing of the receiver seeds, the beaker again was wrapped with parafilm and placed back in the growth incubator for a further 7 days of co-growth before the parameter measurements. The growth of the receiver species alone was considered as the control. The experimental design was completely randomized, with four replications. Plant extract bioassay: Aqueous and methanol extracts Based on the donor–receiver bioassay and ECAM bioassay, the four-highest inhibition capability rice varieties were selected. Rice plants (20 days old) from each variety (100 g fresh) were extracted with 500 mL of 80% (v/v) aqueous MeOH for 2 days. After filtration using filter paper (no. 2; Toyo Roshi Kaisha), the residue was extracted again with 500 mL of MeOH for 2 days and filtered, and the two filtrates were combined. An aliquot of the extract (the final assay concentration was 0.3 g fresh rice plant equivalent extract per mL) was evaporated to dryness, dissolved in 0.2 mL of MeOH and moistened on a sheet of filter paper (no. 2; Toyo Roshi Kaisha) in a Petri dish (3 cm diameter). The MeOH was evaporated in a draft chamber. Then, the filter paper in the Petri dishes was moistened with 0.8 mL of a 0.05% (v/v) aqueous solution of Tween®20 (polyoxyethylene sorbitan monolaurate). After germination in the darkness at 25 C for 16–120 h, 10 seeds of lettuce, cress, radish, barnyard grass or jungle rice were sown on the Petri dishes. The length of their shoots and roots were measured after 48 h of incubation in the darkness at 25 C. For the control treatments, MeOH (0.2 mL) was added to a sheet of filter paper in the Petri dish and evaporated, as described above. After germination, the control seedlings were placed on the filter paper that was moistened with the aqueous solution of Tween®20 without the MeOH extract. The bioassay was repeated four times by using a completely randomized design, with 10 plants for each replication. Greenhouse pot culture bioassay A greenhouse pot (Wagner pot, 0.02 m2) experiment was conducted in order to evaluate the effect of the residue extracts of the four-highest allelopathic capability rice varieties on barnyard grass. Each pot was filled with © 2016 Weed Science Society of Japan

122

S.M. Masum et al.

4 kg of gray soil (3.61% coarse sand, 30.94% fine sand, 24.32% silt, 32.84% clay, 0.90 g cm−3 apparent density, pH = 7.43, 0.96% C, 0.12% N, 4.60 μg soil P, 42.89 μg soil K, 2604.15 μg soil Ca−, 279.30 μg soil Mg, 2765.07 μg soil S, 0.16 μg soil Fe, 102.36 μg soil Na and 5.42 μg soil Al). One-hundred milliliters of distilled water was added to 10 g of ground fresh plants (20 days old). Each sample was stirred on a rotary shaker at 50 g for 24 h (NEO shaker; AS ONE, Osaka, Japan) and centrifuged (KUBOTA, Tokyo, Japan) at 1900 g for 15 min. At the three-leaf stage of barnyard grass (12 days after sowing), the pots were irrigated with 250 mL of aqueous extract or with distilled water (control treatment). A factorial experiment that was based on a completely randomized design, with four replications, was used. Ten days after the addition of the extracts to the pots, the barnyard grass seedlings (22 days old) were harvested and their height (from the basal node to the end of the leaf ), tiller number, leaf number, largest leaf area and total leaf area were measured. Then, the plants were dried in an oven at 70 C for 48 h and the dry weights were recorded. Statistical analysis All the experiments were repeated twice by using a completely randomized design, with four replications, and the percentage inhibition then was determined by the following formula (Lin et al. 2004): Inhibition ð%Þ =

Control plant length− plant length infested with rice Control plant length

× 100:

The treatment means were separated by using Fisher’s Protected Least Significant Difference test. The Type I error was set at 0.01 for all the statistical comparisons. RESULTS Donor–receiver bioassay Significant differences in growth inhibition were observed among the rice varieties in the donor–receiver bioassay test on the test plants (Table 1). Out of the 50 Bangladeshi indigenous rice varieties, seven varieties – Bailabokri (50.60%), Biron (58.33%), Boterswar (73.00%), Goria (69.88%), Hashikalmi (50.03%), Kartiksail (58.70%) and Kataktara (50.45%) – demonstrated >50% growth inhibition of the lettuce roots. A good number (10) of the varieties exhibited 40–50% inhibition of the lettuce roots. Interestingly, some varieties, like Kalokhoia (−30.97% inhibition), Kartikbalam (−39.77% inhibition) and Panbira (−34.23% inhibition), © 2016 Weed Science Society of Japan

stimulated the root growth of lettuce. The level of growth inhibition of the lettuce shoot was relatively lower than that of the lettuce root. The highest (28.83%) lettuce shoot inhibition was observed from Rataboro. On the contrary, the varieties, Dharial (−2.53% inhibition) and Kartikbalam (−4.53% inhibition), stimulated the growth of the lettuce shoot. In response to cress weed, the variety Boterswar gave the highest inhibitory effect (61.62% in the root and 20.85% in the shoot), followed by Goria (57.23% in the root and 26.36% in the shoot). However, Kalizira (−8.82% inhibition in the root), Kartikbalam (−29.88% inhibition in the root and −4.03% inhibition in the shoot) and Panbira (−10.14% inhibition) gave a stimulating effect. Among the tested varieties, Boterswar demonstrated the highest inhibitory effect (81.96%) on the radish root but the shoot growth was inhibited by Goria (83.66%). The variety Biron (79.66% in the root and 78.92% in the shoot) gave the second-highest inhibitory effect on both the root and shoot of radish, while Kalizira (−6.89% inhibition in the root) and Kartikbalam (−19.63% inhibition in the root and −1.64% inhibition in the shoot) gave a stimulating effect on radish. The highest level of inhibition by the Boterswar variety resulted in maximum inhibition of the barnyard grass root and shoot growth (71.50 and 30.45%, respectively), followed by Goria (69.32% in the root and 25.19% in the shoot), Kartiksail (64.55% in the root and 23.26% in the shoot) and Biron (62.67% in the root and 24.02% in the shoot). However, Bashful chikon (−1.17% inhibition in the shoot), Khaiaboro (−1.60% inhibition) and Panbira (−7.30% inhibition in the root and −1.49% inhibition in the shoot) stimulated the growth of barnyard grass. Out of the test varieties, only Kartiksail showed >50% growth inhibition (59.73%) on jungle rice root; however, Boterswar (46.69%), Goria (40.77%) and Biron (35.80%) showed a promising effect on the root of jungle rice. The highest level (21.11%) of shoot inhibition in jungle rice was observed from Marichbate. Equal compartment agar method bioassay Significant differences existed among the rice varieties in their ability to suppress the root and shoot of each weed species that was studied (Table 2). The highest root inhibition (62.06%) of barnyard grass was recorded from Boterswar. In contrast, the shoot growth of barnyard grass was not considerably reduced. The highest shoot inhibition (26.58%) was observed from Boterswar. The stimulating effect was observed by Bashful chikon (−2.20% in the shoot), Khaiaboro (−1.10% in

Allelopathy of Bangladesh rice

123

Table 1. Allelopathic potential of the indigenous rice varieties in the donor–receiver bioassay under laboratory conditions Variety

Inhibition (%) Lettuce Root

50.60 2.94c Bashful chikon 42.73 2.37ef Basmoti/ 47.93 Sakkorkhana 1.52cd Begunbahar 15.70 3.62lm Bini dhan 29.40 0.96h Biron 58.33 2.06b Bolorum 18.06 1.11kl Bonjira 8.70 1.70o–q Boterswar 73.00 1.61a Cahngsai 22.47 0.71ij Chinigura 9.83 0.81n–p Cockrro 49.43 1.50c Dharial 47.54 1.35cd Dholi boro 37.47 1.12g Dholi chikon 6.27 1.27p–r Dudh kolom 15.33 1.42lm Dular 23.27 4.22ij Goria 69.88 4.33a Hashakumira 48.80 2.69c Hashikalmi 50.03 1.76c Holoi 3.80 0.40r–t Kalizira 5.63 0.21q–s Bailabokri

Cress

Radish

Shoot

Root

Shoot

16.26 1.66ef 16.37 0.80ef 21.60 1.11bc 3.47 0.12l–p 6.10 0.44i–k 11.93 2.17gh 11.83 0.23gh 5.53 0.55i–l 22.20 1.63bc 3.30 0.36m–p 5.30 0.61j–m 16.00 1.59ef −2.53 0.88r 22.91 0.54b 2.50 0.30o–q 10.10 0.27h 6.40 0.99i–k 27.08 0.20a 10.36 0.74h 26.97 1.44a 0.93 0.12q 12.43 2.15g

42.27 0.49de 45.61 1.23c 31.10 0.64i–k 8.84 0.95n–q 18.97 3.20m 19.03 1.61m 31.67 1.50i–k 9.13 0.60n–q 61.62 1.64a 17.83 1.09m 41.47 1.15e 32.97 1.91i 44.77 2.43cd 11.70 1.06n 6.92 0.77pq 29.20 0.80kl 40.52 2.18ef 57.23 1.85b 39.74 1.36ef 40.01 1.23ef 2.02 0.84r −8.82 0.98s

10.38 0.55gh 5.19 0.61k 2.40 1.04m–q 2.09 0.75m–q 4.36 0.33kl 8.79 0.65h–j 17.06 0.71d 4.50 0.53kl 20.85 0.62bc 1.57 0.35n–q 16.86 0.75d 8.55 0.59ij 3.26 0.31l–p 3.87 0.70k–m 1.37 0.38pq 13.26 0.73ef 19.64 0.87c 26.36 1.00a 17.27 1.26d 9.25 0.57hi 1.27 0.40q 2.01 0.55m–q

Root 49.75 0.89d 31.67 1.37i 20.04 0.15kl 8.51 1.52o 22.39 1.29k 79.66 1.72a 49.88 1.00d 12.45 1.12n 81.96 2.42a 19.19 1.50l 50.35 0.45d 34.96 2.41h 48.37 2.24d 15.65 1.19m 5.55 0.28pq 34.98 2.35h 49.75 0.84d 69.48 0.89b 1.62 0.08s 49.44 0.96d 2.03 0.76s −6.89 0.82t

Shoot

39.49 0.78c 7.94 1.51m–o 1.41 0.17pq 3.08 0.55pq 7.57 0.61no 78.92 2.38b 20.34 1.33g 7.85 1.06m–o 79.51 1.08b 3.41 0.23pq 25.09 1.57ef 13.37 1.40i 33.68 1.61d 6.83 1.00no 3.15 0.16pq 10.16 0.95l 26.48 1.28e 83.66 1.28a 7.87 0.83m–o 23.12 0.87f 1.26 0.07pq 1.08 0.23q

Barnyard grass

Jungle rice

Root

Shoot

Root

Shoot

52.15 0.74d 18.34 1.52k–m 12.92 0.52n 1.64 061st 14.29 0.75n 62.67 2.1b 21.25 1.33j 1.22 1.06t 71.50 1.08a 5.71 0.23p–r 20.67 1.57jk 17.55 1.39lm 20.05 1.26j–l 6.44 0.68o–q 6.07 0.18o–q 24.90 1.35i 40.04 1.24f 69.32 1.47a 25.54 2.43i 34.75 1.41g 1.33 0.10t 17.31 0.53m

24.29 3.87b −1.17 0.15rs 8.65 1.21gh 1.28 0.17o–q 3.49 0.46l–n 24.02 1.00b 12.24 0.91e 1.80 0.11n–q 30.45 2.12a 2.52 1.13m–q 5.66 0.19i–k 10.77 0.50ef 9.96 0.25fg 4.88 0.68j–l 2.59 0.46m–q 2.91 0.49l–p 20.55 1.24c 25.19 0.82b 2.30 0.06m–q 9.09 0.68f–h 1.18 0.23pq 5.70 0.07i–k

22.36 1.19i 12.33 1.11kl 7.01 0.49n–p 6.14 0.64op 6.61 0.47n–p 35.80 0.30d 33.38 0.13e 2.41 0.13q–t 46.69 1.12b 3.71 0.17qr −5.39 0.06u 22.47 0.57i 13.18 1.02k −16.95 0.18x 32.04 3.58ef 12.99 0.41k 30.42 0.71fg 40.77 0.41c 2.67 0.48q–t −11.56 0.29w 0.90 0.03st 29.97 1.07fg

3.33 0.42q–s 20.05 0.15bc 2.597 0.34s–u 3.96 0.45pq 6.69 0.25o 19.17 0.61c 13.52 0.72g 1.48 0.35v 16.16 0.71e 2.23 0.10t–v 12.69 0.73gh 10.15 0.23jk 8.08 0.17mn 3.34 0.48q–s 9.92 0.07jk 4.58 0.52p 9.27 0.28kl 12.65 0.50gh 8.46 0.10lm −2.52 0.17y 1.81 0.16t–v 10.90 0.87ij

© 2016 Weed Science Society of Japan

124

S.M. Masum et al.

Table 1 (continued) Variety


6.60 0.90p–r Kalaboro 43.34 1.05ef Kalokhoia −30.97 1.42u Kartikbalam −39.77 1.27v Kartiksail 58.70 1.10b Kataktara 50.45 0.18c Kataribhog 30.07 0.35h Kazliboro 24.33 1.11i Khaiaboro 38.34 0.63g Kushiara 12.17 1.00m–o Kilong 19.97 1.31jk Lalbini 8.57 monoching 1.08o-q Lal muta 13.07 1.24mn Langda 11.10 1.25no Lekuch 11.00 1.15no Marichbate 6.59 1.43p–r Mohonbhog 1.03 0.21t Moulata 8.37 0.29o–q Naizersail 18.67 2.83kl Nakhusimuta 12.23 0.67m–o Nayan tara 10.69 0.50no Panbira −34.23 1.31u Kalobini

Cress

Radish

Shoot

Root

Shoot

3.53 0.15l–p 15.08 0.35f 3.53 0.15l–p −4.53 0.31s 21.93 1.46bc 11.53 0.05gh 11.63 0.06gh 7.37 0.87e 17.16 0.31e 3.47 0.31l–p 4.87 0.3k–n 6.10 0.44i-k 4.47 1.15k-o 4.60 0.36pq 2.30 0.00pq 5.41 0.47i–m 3.53 1.30l–p 3.50 0.56l–p 7.33 0.51ij 4.40 0.46k–p 2.49 0.24o–q 3.33 0.32m–p

6.86 0.81pq 39.84 0.96ef 1.64 0.20r −29.88 1.01t 26.84 1.01l 38.16 1.51fg 40.67 1.17ef 46.46 0.61c 40.46 0.73ef 9.31 0.51n–q 10.33 0.22no 8.69 0.12n-q 9.86 0.95n-p 7.55 0.50o–q 7.44 1.53o–q 32.30 2.23ij 6.96 0.65pq 6.49 0.19q 29.52 0.93j–l 9.29 0.79n–q 3.18 0.96r −10.14 0.24s

2.67 0.29l–q 12.63 2.10f 1.00 0.10q −4.03 0.55r 19.74 0.78c 11.89 1.00fg 21.63 1.02b 7.25 0.73j 11.51 0.56fg 3.18 0.07l–p 3.23 0.10l–p 4.45 0.14kl 3.29 0.14l-n 3.70 0.34k–m 2.24 0.13m–q 11.71 0.65fg 7.58 0.28ij 2.50 0.23m–q 17.52 0.61d 3.21 0.09l–p 1.43 0.11n–q 1.40 0.41o–q


Root 8.42 0.58o 36.96 0.79gh 2.41 0.06rs −19.63 0.75u 66.69 2.86c 40.12 1.24f 50.07 1.24d 48.59 2.44d 39.13 0.35fg 10.14 0.24no 8.51 0.62o 4.76 0.21qr 12.55 0.59n 2.35 0.03rs 12.78 0.62n 28.84 0.99j 7.92 0.18op 1.28 0.10s 43.86 0.64e 8.41 1.13o 12.12 1.20n 18.64 0.46l

Barnyard grass

Jungle rice

Shoot

Root

Shoot

Root

Shoot

7.31 1.18no 10.71 0.57j–l 2.15 0.18pq −1.64 0.61r 26.59 1.02e 16.90 0.80h 17.70 0.92h 6.63 0.34no 10.07 0.18lm 2.52 0.53pq 3.51 0.33p 1.25 0.08pq 2.41 0.06pq 1.46 0.08pq 1.22 0.02pq 10.33 0.50kl 5.92 0.17o 1.30 0.24pq 40.16 2.67c 3.40 0.31pq 2.23 0.10pq 17.37 0.89h

2.67 0.66st 14.63 0.51n 8.58 0.60o 4.15 0.61q–s 64.55 1.76b 38.55 1.02f 57.68 1.31c 43.34 1.85e 19.79 1.04j–m 1.53 0.24st 4.22 0.67q–s 7.07 1.57op 8.03 0.79op 4.21 0.24q–s 4.18 0.67f 39.99 1.62r–t 3.38 0.23t 1.44 0.22op 7.37 0.46op 2.19 0.13st 1.18 0.17t −7.30 0.78u

1.52 0.34n–q 3.30 0.13l–p 4.15 0.62k–m 1.29 0.16o–q 23.26 0.72b 7.34 0.51hi 2.37 0.52m–q 17.69 0.86d −1.60 0.36s 0.67 0.12qr 2.28 0.16m–q 2.30 0.17m-q 4.04 0.52k-m 2.50 0.32m–q 3.45 0.22l–o 8.78 0.90gh 3.01 0.62l–p 1.26 0.07o–q 11.91 0.59e 1.26 0.07o–q 0.70 0.17qr −1.49 0.28s

7.58 0.25no 18.42 0.38j 23.95 0.73i −3.77 0.20u 59.73 1.00a 22.91 0.67i 28.55 0.59gh 18.43 0.61j 22.80 0.58i 8.60 0.93mn 3.59 0.27qr 3.60 0.17qr 4.63 0.16pq 3.21 0.11q–s 3.37 0.34q–s 27.47 0.69h −4.66 0.10u 1.30 0.15r–t 10.19 2.06lm −7.87 0.20v 0.59 0.08t −6.07 0.55uv

2.26 0.20t–v 9.32 0.48kl 20.49 0.74ab −1.38 0.17x 17.51 0.63d 3.41 0.17q–s 14.99 0.76f 10.61 0.42j 16.78 0.1de 8.32 0.58l–n 1.370 0.17vw 2.773 0.12r-t 1.59 0.22uv 1.66 0.33uv 4.48 0.27p 21.107 1.00a 3.34 0.11q–s 1.29 0.07vw −1.25 0.23x −8.32 0.87z 0.41 0.06w −3.51 0.34z


125


Inhibition (%) Lettuce

Pankiraj Ranisalute Rataboro Surajamukhi Tongvoga, Lalbini Tupa boro

Root

Shoot

40.23 0.44fg 31.53 0.49h 40.94 1.70e–g 44.28 1.03de 2.30 0.92st 40.46 2.43e–g

19.23 0.59d 2.77 0.58n–q 28.83 0.96a 11.51 0.51gh 1.23 0.15q 20.84 0.57cd

Cress Root 33.74 2.56hi 19.82 0.83m 37.80 2.69fg 32.26 0.91ij 1.19 0.07r 36.44 1.00gh

Radish Shoot

12.42 2.21f 1.80 0.08n–q 12.01 1.50fg 8.22 0.49ij 1.59 0.29n–q 14.82 1.51e

Root 40.11 0.23f 37.13 0.65gh 30.11 1.24ij 30.40 0.73ij 1.10 0.11s 40.15 1.24f

Shoot

12.37 0.45i–k 12.56 0.59ij 8.51 0.47l–n 34.62 1.26d 1.14 0.08pq 9.99 1.07lm

Barnyard grass Root

Shoot

40.53 2.32f 19.24 0.53j–m 29.03 0.56h 45.66 1.24e 2.56 0.81st 18.55 1.52k–m

12.66 1.07e 1.62 0.27n–q 4.36 0.44k–m 3.31 0.12l–p 1.34 0.40n–q 6.73 1.19ij

Jungle rice Root 27.17 0.64h 1.40 0.44r–t 4.66 0.47pq 17.47 0.37j 3.58 0.45qr 18.49 3.17j

Shoot 7.44 0.23no 1.56 0.36uv 3.74 0.27p–r 11.77 0.19hi 2.59 0.49s–u 1.87 0.11t–v

In a column means having similar letter(s) are statistically similar and those having dissimilar letter(s) differ significantly at 0.01 level of probability.

the shoot) and Panbira (−8.63% in the root and −1.50% in the shoot). In the case of jungle rice, the highest level of inhibition (40.06% in the root and 16.38% in the shoot) was observed by the infestation of Kartiksail, while the stimulating effect on jungle rice was given by Chinigura (−4.39% in the root), Dholi boro (−8.29% in the root), Hashikalmi (−8.39% in the root and −2.06% in the shoot), Kartikbalam (−3.07% in the root and −1.27% in the shoot), Mohonbhog (−4.06% in the root), Nizersail (−1.12% in the shoot), Nakhusimuta (−6.54% in the root and −8.06% in the shoot) and Panbira (−10.73% in the root and −10.51% in the shoot). On the basis of the donor–receiver bioassay and ECAM bioassay results, the highest average inhibition on the test plants and weeds was from Boterswar (46.07%), followed by Goria (43.78%), Biron (36.58%) and Kartiksail (35.97%) (Fig. 1). Plant extract bioassay Activity of the aqueous methanol extracts of Boterswar, Goria, Biron and Kartiksail on cress, lettuce, canola, barnyard grass and jungle rice The aqueous MeOH extracts of Boterswar, Goria, Biron and Kartiksail rice tissue inhibited the shoot and root growth of all the test species at concentrations that were 0.3 g fresh rice plant equivalent extract per mL (Table 3). The extract from Boterswar inhibited the root growth of lettuce, cress, radish, barnyard grass and jungle rice by 65.37, 60.40, 84.10, 65.50 and 26.67%, respectively, and the shoot growth by 43.50, 38.41,

52.84, 49.44 and 7.66%, respectively. The extract from Goria inhibited the root growth of lettuce, cress, radish, barnyard grass and jungle rice by 53.02, 57.29, 71.42, 62.14 and 22.77%, respectively, and the shoot growth by 39.38, 26.99, 55.13, 46.88 and 6.30%, respectively. The extract from Biron inhibited the root growth of lettuce, cress, radish, barnyard grass and jungle rice by 60.24, 36.94, 75.82, 44.51 and 20.01%, respectively, and the shoot growth by 40.79, 13.22, 58.40, 43.32 and 6.54%, respectively. The extract from Kartiksail inhibited the root growth of lettuce, cress, radish, barnyard grass and jungle rice by 35.33, 47.14, 49.89, 37.02 and 25.34%, respectively, and the shoot growth by 21.67, 48.97, 38.99, 40.59 and 16.38%, respectively. The extracts from all the rice varieties resulted in a greater inhibition of the root growth than the shoot growth of the receiver plants. However, the shoot growth of cress was more sensitive than the root growth to the extracts from Kartiksail. Pot culture bioassay: Allelopathic potential of the rice varieties in the greenhouse bioassay The response of the growth parameters of barnyard grass to the rice extracts indicated a significant allelopathic potential of the tested rice varieties (Fig. 2). The results of the most inhibitory effects from the Boterswar variety extract on the different growth parameters of barnyard grass were 41.73, 64.43, 74.72, 72.04, 92.15 and 50.41% in plant height, number of total tillers, number of leaves, largest leaf area, total leaf area and shoot dry matter, respectively. © 2016 Weed Science Society of Japan

126

S.M. Masum et al.

Table 2. Allelopathic potential of the indigenous rice varieties in the equal compartment agar method bioassay under laboratory conditions Variety

Inhibition (%) Barnyard grass Root

Bailabokri Bashful chikon Basmoti/ Sakkorkhana Begunbahar Bini dhan Biron Bolorum Bonjira Boterswar Cahngsai Chinigura Cockrro Dharial Dholi boro Dholi chikon Dudh kolom Dular Goria Hashakumira Hashikalmi Holoi Kalizira Kalobini Kalaboro Kalokhoia Kartikbalam Kartiksail Kataktara Kataribhog Kazliboro Khaiaboro Kushiara Kilong Lalbini monoching Lalmuta Langda Lekuch Marichbate Mohonbhog Moulata Naizersail Nakhusimuta Nayan tara Panbira Pankiraj

46.52 18.37 14.25 0.91 11.62 48.04 23.24 6.37 62.06 3.77 28.30 10.85 22.75 3.70 8.48 26.24 30.37 60.32 20.54 25.42 1.37 17.67 2.30 22.99 10.65 3.48 50.05 36.22 39.14 32.64 18.79 1.32 3.38 5.30 7.33 4.38 8.56 18.59 2.78 1.04 6.71 7.19 1.02 −8.63 32.86

2.18c 0.52n 0.12o 0.06z 1.06p 0.71c 0.79j 1.01s–u 1.28a 0.22v–x 0.93h 0.95p 0.59jk 0.25v–x 0.34q–s 1.01i 1.69g 0.90a 0.53lm 1.80i 0.06yz 0.95n 0.06x–z 0.75j 0.99p 0.07v–y 0.67b 0.67e 0.54d 1.57f 1.08mn 0.45z 0.06v–z 0.40t–v 0.47r–t 0.13u–x 0.91r 1.25mn 0.34w–z 0.02z 0.23r–t 0.13r–t 0.02z 0.21z 1.50f


Jungle rice Shoot

20.26 −2.20 8.50 1.32 2.42 16.41 15.33 1.86 26.58 4.22 8.33 6.77 11.29 1.48 3.35 8.24 23.22 23.53 3.33 11.39 1.04 5.70 1.54 5.64 4.35 1.15 11.59 6.73 1.37 18.63 −1.10 0.47 2.05 2.17 2.67 2.14 4.52 6.78 2.17 1.39 10.14 4.26 1.06 −1.50 8.66

1.05c 0.10q 0.62f–h 0.42no 0.10l–o 0.74d 0.89d 0.06m–o 0.86a 0.11j–l 0.76gh 0.95hi 0.91e 0.32m–o 0.21k–m 0.91gh 2.96b 2.37b 0.01k–m 0.66e 0.05no 0.95ij 0.30m–o 0.53ij 0.86jk 0.22no 1.21e 0.35hi 0.07no 0.33c 0.09pq 0.06op 0.05m–o 0.25m–o 0.68k–n 0.14m–n 0.23jk 1.05hi 0.15m–o 0.32no 1.05ef 0.07j–l 0.03no 0.40q 0.71fg

Root 15.42 17.06 3.34 4.21 6.28 34.91 17.34 1.05 35.96 1.32 −4.39 23.81 13.52 −8.29 20.91 10.56 30.76 32.77 2.33 −8.39 0.73 25.30 6.54 16.42 20.28 −3.07 40.06 20.91 27.21 13.59 20.23 5.60 2.76 3.13 4.63 3.88 5.37 20.40 −4.06 1.26 10.39 −6.54 0.63 −10.73 22.53

0.70k 0.55ij 0.01q–s 0.23o–r 0.33n 0.50b 0.89ij 0.03uv 0.71b 0.24t–v 0.06w 0.59g 0.53l 0.61y 0.51h 0.76m 0.57d 0.41c 0.57s–u 0.06y 0.14uv 2.25f 0.18n 0.72jk 0.80h 0.03w 0.88a 1.10h 0.57e 0.75l 0.96h 0.25no 0.37r–t 0.10q–s 0.16o–q 0.47p–s 0.34n–p 1.25h 0.01w 0.15t–v 0.85m 0.43x 0.08v 0.95z 1.87g

Shoot 4.66 10.75 1.60 3.12 4.86 14.40 11.52 1.14 16.42 1.19 8.36 7.15 8.08 2.11 8.43 4.61 9.30 14.65 5.49 −2.06 1.21 6.66 1.81 9.05 12.53 −1.27 16.38 3.64 10.65 9.94 15.81 6.42 1.14 2.07 1.59 1.16 4.35 14.77 3.11 1.19 −1.12 −8.06 0.44 −10.51 9.52

0.80mn 0.99ef 0.25rs 0.16o–q 0.49mn 0.69c 2.63de 0.14rs 0.34a 0.15rs 0.80h–j 0.23jk 0.17ij 0.07qr 0.63h–j 0.46mn 0.78g–i 0.58bc 0.17lm 0.02t 0.22rs 0.23kl 0.54q–s 0.05g–i 0.60d 0.07t 0.46a 0.64no 0.48ef 0.12fg 0.84ab 0.41kl 0.16rs 0.02qr 0.22rs 0.14rs 0.37m–o 0.56bc 0.11o–q 0.14rs 0.16t 0.97u 0.01s 0.34v 0.24f–h


127


Inhibition (%) Barnyard grass Root

Ranisalute Rataboro Surajamukhi Tongvoga, Lal bini Tupa boro

10.51 19.69 26.89 4.52 20.95

2.72pq 0.06l–n 0.54hi 0.23u–w 0.96kl

Jungle rice Shoot

1.05 4.03 6.31 1.10 6.40

0.02no 0.03j–l 0.12i 0.12no 0.35

Root 1.04 4.10 18.14 3.38 16.55

0.04uv 0.10o–r 0.22i 0.35q–s 0.85jk

Shoot 1.26 3.61 10.77 2.29 1.30

0.16rs 0.49n–p 0.19ef 0.41p–r 0.40rs


DISCUSSION In order to establish an alternative strategy for weed management in rice, the phenomenon of allelopathy has been a subject of continued research for a long time. In this experiment, rice was extensively studied with respect to its allelopathy as part of a strategy for sustainable weed management. Some rice varieties were found to have allelopathic activity against lettuce, cress, radish, barnyard grass and jungle rice. Rice has been studied extensively with respect to its alleolopathy and a large number of rice varieties has been found to inhibit the growth of several plant species when they were grown together (Dilday et al. 1989; Olofsdotter et al. 1999; Azmi et al. 2000; Khanh et al. 2007a; Salam & Kato-Noguchi 2009; Thi et al. 2014). When the short-term co-cultivation of rice varieties with test species and weeds was conducted in this study, the highest inhibited growth level was recorded with Boterswar (46.07%), followed by Goria (43.78%), Biron (36.58%) and Kartiksail (35.97%), among the 50 indigenous rice varieties of Bangladesh. Previously, Salam and Kato-Noguchi (2009) compared the alleolopathic traits among 102 varieties and found the greatest inhibitory activity was of BR17 rice on cress, lettuce, barnyard grass and jungle rice; the average growth of the shoots and roots was inhibited by 39.5%. The inhibition of the root growth was greater than that of the shoot growth in all the receiver species in this study. This result was consistent with the reports of Olofsdotter and Navarez (1996) and Kim and Shin (1998), who reported that allelopathic rice varieties strongly inhibited the root growth more than that of the shoot growth of paddy weeds. A more inhibitory effect was found on the root and shoot growth of the dicotyledonous test plants (lettuce, cress and radish) than that of the monocotyledonous

plants (barnyard grass and jungle rice) in this study. Khanh et al. (2006) also found that Passiflora edulis aqueous extracts strongly suppressed the growth of lettuce and radish, whereas the growth of barnyard grass was less affected. These results are consistent with other findings, which found different allelopathic responses for different test plants to have asymmetrical selectivity of allelopathic substances (Inderjit & Duke 2003). In addition, the allelopathic activity of rice was varietyand origin-dependent (Khanh et al. 2007a). All the variability in the effects of the rice varieties on the root and shoot length of the receiver species also supports the fact that rice varieties possess different genotypic characteristics in respect to their allelopathic effects. In this study, the stimulating effect of rice varieties was found. Karim et al. (2006) observed increased root and shoot length of barnyard grass in some rice accession cases. Rice (1984) stated that the stimulatory effects could occur at a lower concentration of allelopathic substances, while a higher concentration could cause inhibitory effects. The reduction of receiver growth in the laboratory experiments by the aqueous MeOH extracts indicated the allelopathic potential of the four selected varieties. The sensitivity of the roots of all the target plant species against the rice extracts was greater than that of the shoots (Tables 1–3). These results are in agreement with the study of Zimdahl and Stachon (1980), who reported that the extracts of allelopathic plants had a more inhibitory effect on the root growth than on the shoot growth. It might be related to the fact that roots are the first to absorb the allelochemicals or autotoxic compounds from the environment. In addition, the permeability of allelochemicals to the root tissue was reported to be greater than that to the shoot tissue (Nishida et al. 2005). This similar pattern of inhibition in growth and development was reported by Escudero © 2016 Weed Science Society of Japan

128

S.M. Masum et al.

Fig. 1. Average level of inhibition (%) by the tested rice varieties on the receiver species from the donor–receiver bioassay and equal compartment agar method bioassay screening test. The bars represent the standard error of the mean.

et al. (2000). The reasons for the inhibitory effects that were caused by the allelopathic substances could be: (i) disruption and impairment of mitochondrial respiration; (ii) a breakdown of the activity of metabolic enzymes (Weir et al. 2004); (iii) a breakage of the cells, leading to cell death (Lin et al. 2000); and (iv) the correlation with increased cell membrane degradation (Bogatek et al. 2006). Besides these, plant physiological activities, such as respiration, photosynthesis, cell © 2016 Weed Science Society of Japan

division and structure, ion uptake and membrane permeability, could be affected by the actions of allelopathic substances and thus growth and development might be arrested (Gniazdowska & Bogatek 2005). Barnyard grass is one of the most noxious paddy weeds in the world because this weed competes with rice for nutrients, light and water and reduces the yield of rice. The reduction of the barnyard grass height and biomass in the greenhouse experiment indicated the


129

Table 3. Comparison of the allelopathic potential of the indigenous rice varieties in the aqueous methanol extract bioassay under laboratory conditions Variety


Boterswar Goria Biron Kartiksail

65.37 1.32a 53.02 1.51c 60.24 1.93b 35.33 0.64d

Cress

Shoot

Root

43.50 0.58a 39.38 0.84b 40.79 1.68ab 21.67 1.14c

60.40 1.19a 57.29 1.23a 36.94 1.35c 47.14 1.33b

Radish

Shoot

38.41 1.56b 26.99 1.09c 13.22 0.84d 48.97 0.89a

Root

84.10 1.07a 71.42 1.13c 75.82 0.91b 49.89 1.01d

Barnyard grass

Shoot

Root

52.84 1.78b 55.13 1.18ab 58.40 1.03a 38.99 1.45c

65.50 1.65a 62.14 1.58a 44.51 1.68b 37.02 2.10c

Jungle rice

Shoot

Root

Shoot

49.44 1.19a 46.88 2.93ab 43.32 0.85ab 40.59 1.76b

26.68 1.50a 22.77 1.16bc 20.01 0.85c 25.34 0.86ab

7.66 1.34b 6.30 0.30b 6.54 0.33b 16.38 0.46a


Fig. 2. Effect of the extracts of selected rice varieties on the different growth parameters of barnyardgrass. ( ), Boterswar; ( ), Goria; ( ), Biron; ( ), Kartiksail.

alleolopathic potential of the rice varieties (Fig. 2). The inhibitory effects of the rice varieties also have been reported by other researchers (Chung et al. 2001; Jung et al. 2004; Asghari et al. 2006; Pheng et al. 2009). Weir et al. (2004) declared that the inhibition of the photosynthetic rate, interruption of respiration, adenosine triphosphate synthesis and amino acid metabolism were major physiological and biochemical mechanisms that might be mediated by allelochemicals. The selection of rice cultivars with a greater allelopathic potential could be used as a tool in sustainable weed management and might be a way to minimize herbicide use (Asghari et al. 2006). Allelopathic and competitive rice lines could be particularly useful in subsistence farming systems, in which the cost of selective herbicides is prohibited, or when the organic production of rice is the objective (Pheng et al. 2009).

As allelopathy in rice is polygenic and quantitatively inherited and thus allelopathic activity could be a polygenic trait, it could be slightly correlated with the yield or other agronomic features (Khanh et al. 2007b). The application of allelopathy through genetic manipulation by using molecular genetics and biotechnology or conventional breeding in rice varieties can be considered as a successful tool for weed management, insect pests and disease pathogens (Amb & Ahluwalia 2016). Jensen et al. (2001) carried out gene mapping and epistatic quantitative trait loci (QTL), which are associated with allelopathic activity by using DNA markers, and indicated that allelopathy in rice is a quantitative trait involving several loci and probably some level of epistasis. Varietal improvement is an essential prerequisite for the practical application of rice allelopathy for paddy weed management and thus much effort has been carried out © 2016 Weed Science Society of Japan

130

S.M. Masum et al.

in order to develop commercially acceptable allelopathic rice cultivars with high grain quality, high yield, labour-saving, low-cost and safe grain production (Khanh et al. 2007a; Chen et al. 2008). Selected elite allelopathic rice genotypes have enabled breeding efforts to improve weed-suppressive traits in modern cultivars (Belz 2007). Several studies showed that a traditional breeding method can be reasonable in order to develop commercially acceptable allelopathic rice cultivars (Dilday et al. 2000; Lin et al. 2000; Kim & Shin 2003; Chen et al. 2008). In this study, 50 indigenous rice varieties were evaluated, of which some varieties showed a strong allelopathic effect. In addition, some varieties show vigorous growth, with a higher number of effective tillers under drought and high temperatures in Bangladesh. The selected elite varieties could be used in variety development by using molecular genetics (QTL) and biotechnology or conventional breeding techniques. Success in breeding the allelopathic rice varieties of Bangladesh would make a great contribution to sustainable rice production. The present research suggests that Boterswar, Goria, Biron and Kartiksail are the most allelopathic among the 50 Bangladeshi indigenous rice varieties. Therefore, additional research is necessary in order to isolate and identify the allelochemical(s), as well as to characterize its production and release from rice plants. Moreover, these allelopathic rice varieties may be used for breeding in order to develop a new variety with good weedsuppressing ability that would be beneficial for farmers. REFERENCES Amb M.K. and Ahluwalia A.S. 2016. Allelopathy: potential role to achieve new milestones in rice cultivation. Rice Sci. 23, 165–183. Asghari J.S., Berendji H., Fotohi A., Matin A. and Mohammad-Sharifi M. 2006. Potential allelopathic effects of rice hull extracts on barnyardgrass (Echinochloa crus-galli) seedling growth. Iran. J. Weed Sci. 2, 31–44. Azmi M., Abdullah M.Z. and Fujii Y. 2000. Exploratory study on allelopathic effect of selected Malaysian rice varieties and rice field weed species. J. Trop. Agric. Food Sci. 28, 39–54. Belz R.G. 2007. Allelopathy in crop/weed interactions–an update. Pest Manag. Sci. 63, 308–326. Bogatek R., Gniazdowska A., Zakrzewska W., Oracz K. and Gawronski S.W. 2006. Allelopathic effects of sunflower extracts on mustard seed germination and seedling growth. Biol. Plant. 50, 156–158. Chau D.P.M., Kieu T.T. and Chin D.V. 2008. Allelopathic effects of Vietnamese rice varieties. Allelopath. J. 22, 409–412. Chen X.H., Hu F. and Kong C.H. 2008. Varietal improvement in rice allelopathy. Allelopath. J. 22, 379–384. Chung I., Ahn M. and Yun S.J. 2001. Identification of allelopathic compounds from rice (Oryza sativa L.) straw and their biological activity. Can. J. Plant Sci. 81, 815–819. Dilday R.H., Lin J. and Yan W. 1994. Identification of allelopathy in the USDA-ARS rice germplasms collection. Aust. J. Exp. Agric. 34, 907–910.


Dilday R.H., Mattice J.D. and Moldenhaur K.A. 2000. An overview of rice allelopathy in the USA. In: Rice Allelopathy (ed. by Kim K.U. and Shin D.H.). Kyungpook National University, Taegu, 15–26. Dilday R.H., Nastasi P., Lin J. and Smith R.J. Jr. 1991. Allelopathic activity in rice (Oryza sativa L.) against ducksalad (Heteranthera limosa (Sw.) Wild.). In: Symposium Proceedings on Sustainable Agriculture for the Great Plains (Fort Collins, CO, January 19–20, 1989) (ed. by Hanson J. N., Shaffer M.J., Ball D.A. and Vern Cole C.). U.S. Department of Agriculture, Washington, DC, 193–201. Dilday R.H., Nastasi P. and Smith R.J. Jr. 1989. Allelopathic observations in rice (Oryza sativa L.) to ducksalad (Heteranthera limosa). Proc. Arkansas Acad. Sci. 43, 21–22. Escudero A., Albert M.J., Pita J.M. and Pérez-Garcia F. 2000. Inhibitory effects of Artemisia herba-alba on the germination of the gypsophyta Helianthemum squamatum. Plant Ecol. 148, 71–80. Food and Agriculture Organization of the United Nations Statistics Division. 2014. Home page. [Cited 15 September 2015.] Available from URL: http://faostat3.fao.org/browse/Q/QC/E Fujii Y. 1992. The potential biological control of paddy weeds with allelopathy – Allelopathic effect of some rice cultivars. In: Proceedings of the International Symposium on Biological Control and Integrated Management of Paddy and Aquatic Weeds (Tsukuba, Japan, October 19–25, 1992). National Agriculture Research Center, 305–320. Fujii Y. 1994. The allelopathic effect of some rice varieties. In: Integrated Management of Paddy and Aquatic Weeds in Asia. Book Series No. 45. Food and Fertilizer Technology Center, Taipei, 160–165. Gniazdowska A. and Bogatek R. 2005. Allelopathic interactions between plants. Multi site action of allelochemicals. J. Acta Physiol. Plant. 27, 395–407. Hassan S.M., Aidy I.R., Bastawisi A.O. and Draz A.E. 1998. Weed management using allelopathic rice varieties in Egypt. In: Allelopathy in Rice (ed. by Olofsdotter M.). International Rice Research Institute, Manila, 27–37. Hassan S.M., Fao A.N., Bastawisi A.O. and Aidy I.R. 1994. Weed management in broadcast seeded rice in Egypt. In: Proceedings of the International Workshop on Constraints, Opportunities and Innovations for WetSeeded Rice (Bangkok, Thailand, May 31–June 3 1994). International Rice Research Institute, Manila, Ed. by Moody K. p. 257–269. Hossain M., Jaim W.H.M., Shamsul A. and Rahman A.N.M.M. 2013. Rice Biodiversity in Bangladesh: Adoption, Diffusion and Disappearance of Varieties. A Statistical Report from Farm Survey in 2005. BRAC Research and Evaluation Division, Dhaka. [Cited 19 September 2015.] Available from URL: http://research.brac.net/publications/ ricebiodiversity-book.pdf Inderjit and Duke S.O. 2003. Ecophysiological aspects of allelopathy. Planta 217, 529–539. Jensen L.B., Courtois B., Shen L., Li Z., Olofsdotter M. and Mauleon R.P. 2001. Locating genes controlling allelopathic effects against barnyardgrass in upland rice. Agron. J. 93, 21–26. Jung W.S., Kim K.H., Ahn J.K., Hahn S.J. and Chung I.M. 2004. Allelopathic potential of rice (Oryza sativa L.) residues against Echinochloa crus-galli. Crop Prot. 23, 211–218. Karim S.M.R., Ismail B.S. and Abdullah M.Z. 2006. The alleopathic potential of several rice varieties on barnyardgrass (Echinochloa crussgalli). J. Trop. Agric. Food Sci. 35, 173–182. Karim S.M.R., Mridha A.J. and Faruq G. 2014. Allelopathic potential of rice cultivars against Echinochloa crusgalli. Int. J. Biol. Pharm. Allied. Sci. 3, 2027–2039. Kato-Noguchi H., Ino T. and Ota K. 2008. Secretion of momilactone A from rice roots to the rhizosphere. J. Plant Physiol. 165, 691–696. Kato-Noguchi H., Ino T., Sata N. and Yamamura S. 2002. Isolation and identification of a potent allelopathic substance in rice root exudates. Physiol. Plant. 115, 401–405. Khanh T.D., Chung I.M., Tawata S. and Xuan T.D. 2006. Weed suppression by Passiflora edulis and its potential allelochemicals. Eur. Weed Res. Soc. 46, 296–303.

Allelopathy of Bangladesh rice Khanh T.D., Cong L.C., Chung I.M., Xuan T.D. and Shinkichi T. 2009. Variation of weed-suppressing potential of Vietnamese rice cultivars against barnyardgrass (Echinochloa crus-galli) in laboratory, greenhouse and field screenings. J. Plant Interact. 3, 209–218. Khanh T.D., Xuan T.D. and Chung I.M. 2007a. Rice allelopathy and the possibility for weed management. Ann. Appl. Biol. 151, 325–339. Khanh T.D., Elzaawely A.A., Chung I.M., Ahn J.K., Tawata S. and Xuan T.D. 2007b. Role of allelochemicals for weed management in rice. Allelopath. J. 19, 85–96. Kim K.U. and Shin D.H. 1998. Rice allelopathy research in Korea. In: Proceedings of the Workshop on Allelopathy in Rice (Manila, Philippines, November 25–27 1996) (ed. by Olofsdotter M.). International Rice Research Institute, Makati City, 39–44. Kim K.U. and Shin D.H. 2003. The importance of allelopathy in breeding new cultivars. In: Weed Management for Developing Countries (ed. by Labrada R.). Food and Agriculture Organization, Rome, 290–308. Kim K.U., Shin D.H., Kim H.Y., Lee Z.L. and Olofsdotter M. 1999. Evaluation of allelopathic potential in rice germplasm. Korean J. Weed Sci. 19, 1–9. Kong C.H. 2008. Rice allelopathy. Allelopath. J. 22, 261–273. Kong C.H., Chen X.H., Hu F. and Zhang S.Z. 2011. Breeding of commercially acceptable allelopathic rice cultivars in China. Pest Manag. Sci. 67, 1100–1106. Lin D., Tsuzuki E., Dong Y., Terao H. and Xuan T.D. 2004. Potential biological control weeds in rice fields by allelopathy of dwarf lilyturf. Plants Biocontrol 49, 187–196. Lin W., Kim K.U., Liang K. and Guo Y. 2000. Hybrid rice with allelopathy. In: Rice Allelopathy. Proceedings of the International Workshop in Rice Allelopathy (Taegu, South Korea, August 17–19 2000) (ed. by K.U. K. and Shin D.H.). Institute of Agricultural Science and Technology, Kyungpook National University, Taegu, 49–56. Main M.A.K., Main M.A. and Hossain M.A. 2007. Occurrence of weed species in transplanted aman rice field affected by cultivar. Bangladesh J. Bot. 36, 89–92. Molisch H., ed. 1937. Der Einflusseinerpflanze auf sie Andereallelopathie. Fischer, Jena. Nishida N., Tamotsu S., Nagata N., Saito C. and Sakai A. 2005. Allelopathic effects of volatile monoterpenoides produced by Salvia leucophylla: Inhibition of cell proliferation and DNA synthesis in the root apical meristem of Brassica campestris seedlings. J. Chem. Ecol. 31, 1187–1203. Olofsdotter M. and Navarez D. 1996. Allelopathic rice for Echinochloa crus-galli control. In: Proceedings of the 2nd International Weed Control Congress (Copenhagen, Denmark, June 25–28 1996) (eds by Brown H., Cussans G.W., Devine M.D., Duke S.O., Fernadez-Quintanilla C.,

131

Helweg A., Labrada R.E., Landes M., Kudsk P. and Streibig J.C. Department of Weed Control and Pesticide Ecology, Slagelse, 1175–1181. Olofsdotter M., Navarez D., Rebulanan M. and Streibig J.C. 1999. Weed-suppressing rice cultivars – does allelopathy play a role? Weed Res. 39, 441–454. Pacanoski Z. and Glatkova G. 2009. The use of herbicides for weed control in direct wet-seeded rice (Oryza sativa L.) in rice production regions in the republic of Macedonia. Plant Prot. Sci. 45, 113–118. Pheng S., Olofsdotter M., Jahn G., Nesbitt H. and Adkins S.W. 2009. Allelopathic potential of Cambodian rice lines under field conditions. Weed Biol. Manag. 9, 267–275. Rao V.S. 2000. Principles of Weed Science, 2nd edn. Science Publishers, Enfield, NH. Rice E.L. 1984. Allelopathy, 2nd edn. Academic Press, Orlando, FL. Salam M.D. and Kato-Noguchi H. 2009. Screening of allelopathic potential Bangladesh rice cultivars by donor–receiver bioassay. Asian J. Plant Sci. 8, 20–27. Salam M.D. and Kato-Noguchi H. 2010. Allelopathic potential of methanol extract of Bangladesh rice seedlings. Asian J. Crop Sci. 2, 70–77. Seal A.N., Pratley J.E., Haig T.J. and Lewin L.G. 2004. Screening rice varieties for allelopathic potential against arrowhead (Sagittaria montevidensis), an aquatic weed infesting Australian Riverina rice crops. Aust. J. Agric. Res. 55, 673–680. Smith A.E. and Martin L.D. 1994. Allelopathic characteristics of three cool-season grass species in the forage ecosystem. Agron. J. 86, 243–246. Smith R.J. Jr. 1983. Weeds of major economic importance in rice and yield losses due to weed competition. In: Proceedings of the Conference on Weed Control in Rice. (Manila, Philippines, August 31- September 4, 1981) International Rice Research Institute, Manila, 19–36. Thi H.L., Lin C.H., Smeda R.J. and Fritschi F.B. 2014. Isolation and purification of growth-inhibitors from Vietnamese rice cultivars. Weed Biol. Manag. 14, 221–231. Weir T.L., Park S.W. and Vivanco J.M. 2004. Biochemical and physiological mechanisms mediated by allelochemicals. Curr. Opin. Plant Biol. 7, 472–479. Wu H., Pratley J., Lemerle D. and Haig T. 2000. Laboratory screening for allelopathic potential of wheat (Triticum aestivum) accessions against annual ryegrass (Lolium rigidum). Australian J. Agric. Res. 51, 259–266. Zimdahl R.L. 1980. Weed–Crop Competition: A Review. International Plant Protection Centre, Corvallis, OR. Zimdahl R.L. 1999. Fundamentals of Weed Science, 2nd edn. Academic Publishers, New York. Zimdahl R.L. and Stachon W.J. 1980. Allelopathic activity of Canada thistle (Cirsium arvense) in Colorado. Weed Sci. 28, 83–86.
