Scientific Research and Essays Vol. 7(5), pp. 609-615, 9 February, 2012 Available online at http://www.academicjournals.org/SRE DOI: 10.5897/SRE11.1305 ISSN 1992-2248 ©2012 Academic Journals
Full Length Research Paper
Effects of farmers’ cultural practices on the weedy rice infestation and rice production Mashhor Mansor1, S. M. Rezaul Karim2* and Zainal Abidin1 1
School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia. Faculty of Agro Industry and Natural Resources, Universiti Malaysia Kelantan, Kota Bharu, 16100 Pengkalan Chepa, Kelantan, Malaysia.
2
Accepted 27 January, 2012
An on-farm trial was conducted at the Muda Agricultural Development Authority rice fields, Kedah, Peninsular Malaysia from November, 2003 to July, 2006 to study the impacts of farmers’ cultural practices on the weedy rice infestation and rice production. Five sample farmers (A, B, C, D and E) from five different sampling sites were selected on the basis of severity of weedy rice infestation on their fields in earlier seasons. Field observations and monitoring were carried out for collecting data and recording the agronomic practices done by the farmers from land preparation to harvesting of the crops. The number of weedy rice panicles per unit area was recorded from 50 sampling spots per plot using 1 × 1 m quadrat. Rice plants and the weedy rice within the quadrats were harvested. Data on grain yields and yield components were recorded. The collected data were analyzed statistically and mean differences in weed infestation were adjudged using standard error of means. Results revealed that the farmers used different rice varieties and applied different agronomic practices, which resulted in variable intensities of weedy rice infestations and production of variable rice grain yields. The farmers A and B, who followed transplanting and water seeding for crop establishment, applied pre-planting herbicides (2 to 3 times) during land preparation and used regular surveillance and monitoring (20 to 25 times) of their plots, had less weedy rice infestation (32.22 panicles/m2) and higher rice yields (6.70 to 8.88 t/ha). The farmers C, D and E, used wet direct seeding for crop establishment, applied no or less time of pre-planting herbicides (1 time) and had less field surveillance (10 to 15 times/season), had 2 consequently a higher weedy rice panicle density (154.94 panicles/m ) and less rice yields (3.57 to 6.27 t/ha). Key words: Farmers’ cultural practice, weedy rice infestation, wet direct seeding, water seeding, transplanting. INTRODUCTION Weedy rice is a noxious weed of rice and it belongs to the same species of cultivated rice (Oryza sativa L.). Different hypothesis have been proposed to explain its origin: it evolved from wild forms of Oryza or it originated from a hybridization of different Oryza species (Azmi and Karim, 2009) or is a weedy form of cultivated rice. Weedy
*Corresponding author. E-mail:
[email protected]. Tel: +6016-9355041, Fax: +609-9450266.
rice aggressively competes with rice crop reducing the yields and contaminating the harvests. This weed is particularly troublesome to rice growers because weedy rice seeds can easily shatter on the soil surface before maturation, assuring future infestations. Due to difficulties in controlling, it has been posing cancerous threat to the rice farmers of many South-east Asian countries including Malaysia and Thailand (Karim et al., 2010). Weedy rice is diffused in rice fields, and grows alongside cultivated rice, making its identification and control very difficult mainly because of the similarity with cultivated rice. In Malaysia,
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Table 1. Crop establishment methods used by the sample farmers in four consecutive seasons
Farmers A B C D E
Off season 1/2004 Mechanical transplanting Water seeding Wet direct seeding Wet direct seeding Wet direct seeding
Crop establishment methods Main season 2/2004 Off season 1/2005 Mechanical transplanting Water seeding Water seeding Water seeding Wet direct seeding Wet direct seeding Wet direct seeding Wet direct seeding Wet direct seeding Wet direct seeding
about 96,000 ha area of Muda Agricultural Development Authority (MADA) land is the important direct-seeded rice production area where the occurrence and emergence of new stain of rice populations (weedy rice) were marked in 1995 that caused more problems than the ordinary weedy species (Nashriyat et al., 1998). One of the main concerns of the Malaysian government about rice production is the massive loss of rice yield due to weedy rice infestation that may lead to further suffering of the already poor farmers of the country. Not only in Malaysia is the control of this weed very difficult but for most of the rice growers worldwide (Blake, 2009). Various control methods including hand weeding, mechanical weeding, chemical weeding, biological control and integrated approaches are available (De Datta et al., 1986; Akobundhu, 1987; Karim et al., 2005). However, these control methods need to be fine-tuned to different ecosystems and cropping practices. While many attempts have been made to quantify rice growth and grain yield as affected by growth environments (Jeng et al., 2006; Hossain et al., 2005; Burgos et al., 2006), only few studies have taken into consideration the effects of cultural practices on weed distribution and rice yields. It has been established that weeds are associated with different cultivation practices such as soil management and previous crops (Major et al., 2005), herbicide choice (Bhagat et al., 1996), nutrient management (Tisdale and Nelson, 1975), and the practice of fallowing (Derksen et al., 1996). Therefore, weed management strategies should be chosen taking into account all the factors affecting weedy rice populations in order to reduce the impacts of the weed to an economically acceptable level. The knowledge of the effects of cultural practices on weed infestation can guide management strategies to minimize weed densities (Kent et al., 2001). Research trials on the farmers’ plots that is to say, on-farmresearch are able to give more precise information than the laboratory or greenhouse experiments. The objective of this study was to evaluate the impacts of crop establishment methods and other agronomic practices applied by five selected farmers on weedy rice population and rice yield in Malaysia. Rice production in Malaysia is usually done through direct-seeding (mostly practiced) and transplanting which might influence the growth and development of weedy rice (Cao et al., 2007).
Main season 2/2005 Wet direct seeding Wet direct seeding Wet direct seeding Water seeding Water seeding
MATERIALS AND METHODS The on-farm-trial was conducted on rice fields at the Muda Agricultural Development Authority, Kedah, Peninsular Malaysia during the period from November, 2003 to 2006 (four consecutive seasons:1/2004 off season, 2/2004 main season, 1/2005 off season and 2/2005 main season). The sites were selected on the basis of previous observation of the infestation of weedy rice. At the initial stage of the study, weed surveys were performed to record the severity of weedy rice infestation, based on visual scoring, to determine the sampling plots. Five rice farmers having one rice field per farmer, A, B, C, D, and E from 5 different sampling sites were selected on the basis of the severity of weed infestation in their rice fields, particularly weedy rice. From a preliminary survey, it was understood that those farmers followed differential cultural practices especially during land preparation, plant establishment methods and after cares. Regular field monitoring and weed sampling were carried out during four consecutive cropping seasons in order to record the agronomic practices of each farmer. Information on the cultural practices followed by the farmers was recorded on a daily basis from land preparation until harvesting of the crop for each season. The number of weedy rice panicles was recorded using 1 ×1 m quadrats, before crop harvesting about 125 to 130 days after sowing for each season, from 50 randomly selected sampling spots in each plot (about 1 ha). Both rice and weedy rice plants within the quadrats were harvested. Rice yield and yield components for example, number of panicles/m2, number of spikelet/panicle, percentage of ripened grains and 1000-grain weight, were also recorded for each season. Statistical analysis (ANOVA) of the data was performed using the statistical computer program SPSS and the mean differences among the rice yields of different farmers under different growing seasons were adjudged as per Duncan’s Multiple Range Test at 5% level of significance (Gomez and Gomez, 1984).
RESULTS Farmers’ profile The results of the survey on the cultural practices and rice varieties applied by the five rice farmers are shown in Table 1. Farmer A was the only one to use different rice varieties in different seasons. In particular, the variety MR208 was sown in the off season of 2004 (1/2004) and in the main season of 2005 (2/2005), while MR219 was grown in the remaining two seasons. The other farmers had sown MR219 variety in all the growing seasons. The crop establishment methods used by the farmers were also different. In particular, Farmer A used
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Table 2. Cultural practices followed by the sample farmers in their rice fields in preparing the seedbed*.
Cultural practices Before land preparation 1. Cut stubble and spread the straw evenly 2. Burn the straw after harvesting During land preparation 1. First tillage as dry culture (at 30 DBS) 2. Apply herbicide after first tillage 3. Second tillage as wet culture (at 15 DBS) 4. Spraying of pre-planting herbicide 5. Third tillage (wet/dry) (at 1-2 DBS) 6. Fourth tillage when necessary (wet culture) 7. Land leveling and smothering 8. Field surveillance and monitoring 9. Other routine activities a) Repairing irrigation channels b) Cleaning and repairing levees c) Using rat’s baits and traps
Farmer A
Farmer B
Farmer C
Farmer D
Farmer E
No Yes
Yes Yes
No Yes
No Yes
No Yes
Yes Yes (1 time) Yes Yes (1 time) Yes No Yes Yes (20-25 times)
Yes Yes (2 times) Yes Yes (3 times) Yes No Yes Yes (20-25 times)
Yes Yes (1 time) Yes Yes (1 time) Yes No Yes Yes (15-20 times)
Yes No Yes Yes (1 time) Yes No Yes Yes (10-15 times)
Yes No Yes No Yes No Yes Yes (10-15 times)
Yes Yes Yes
Yes Yes Yes
Yes Yes Yes
Yes Yes Yes
Yes Yes Yes
*Data are the mean of four consecutive seasons, DBS = days before sowing.
mechanical transplanting for two consecutive seasons (seasons 1/2004 and 2/2004), water seeding (sowing of rice seeds in the fields with 5 to 10 cm water depth) in the season 1/2005 and wet direct seeding (sowing of sprouted rice seeds on the saturated soil) during 2/2005. Farmers B used water seeding for three consecutive seasons, except in 2/2005 in which wet-direct seeding was adopted. Farmer C used wet direct seeding for all four seasons, whereas farmers D and E used only water seeding in 2/2005 and wet direct seeding in the remaining three seasons. Land preparation and other practices Rice straw burning was carried out by all the
farmers after rice harvesting during all cropping seasons (Table 2). Farmer B in addition to straw burning also applied the stubble cutting using a “roto slasher”. Straw burning technique was widely used by the farmers because it also served to destroy the superficial weed seed bank and to enhance germination of lower buried weedy rice seeds. Regarding land preparation, all the rice fields were ploughed three times to an average depth of 10 to 15 cm. The first tillage was done 30 days before sowing (dry rotovation), followed by the second tillage (wet rotovation) at 15 days before sowing. The third tillage and land leveling were carried out 1 to 2 days before sowing. Most of the farmers applied herbicide both after first and
second tillage (farmers A, B, C) while farmers D sprayed herbicides only after second tillage. Farmer E was the only one who did not perform herbicide applications. Regarding field surveillance, farmers A, B and C monitored and treated their plots with production inputs and cultural practices more often in comparison to the other farmers D and E. The farm survey showed that farmer A and B had the highest number of field surveillance (25 to 30 times) for weedy rice presence, while farmer C had only 15 to 20 field inspections. Farmer D and E had the least number of field surveillance (10 to 15 times) in their plots. All the farmers followed other routine activities for example, clearing of and repairing the irrigation and drainage channels,
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Figure 1. Mean number of weedy rice panicles/m2 in the plots of five farmers during four consecutive years. Vertical bars indicate the SE of means.
cleaning and repairing of the levees, using rat-baits and traps as when it was necessary. Distribution of weedy rice The density of weedy rice panicles during the whole study period was similar under similar crop establishment practices. All the majority of the farmers used wet direct seeding technique to some extent especially, farmers D and E, whereas farmers A and B used water seeding or transplanting in most of the planting times during four consecutive seasons. The different establishment
methods used by the farmers resulted in different weedy rice density. During the off season of 2004 (1/2004), the highest and lowest number of weedy rice panicles were recorded for farmers E and A with values of 154.9 and 32.2 panicles/m2, respectively. During the main season of 2004 (2/2004), the highest number of weedy rice panicles was recorded in farmer E’s plot with values of 130.84 panicles/m2, followed by farmer D (120.40 panicles/m 2) and farmer C (39.72 panicles/m2). A similar trend also occurred during season 1/2005 and season 2/2005, where farmer E had the highest number of weedy rice panicles with values of 139.2 and 151.2 panicles/m2, respectively (Figure 1). In general, the overall changes in
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Table 3. Actual and estimated grain yields of rice in sample farmers’ plots during four consecutive growing seasons.
A B C D E
5.8 9.0 5.8 3.0 3.5
Growing season Main season(2/2004) Off-season(1/2005) a. Actual yield (t/ha) 6.8 7.4 9.2 8.8 6.8 7.0 5.5 6.8 3.4 3.8
A B C D E
8.5 9.3 5.1 3.2 2.5
b. Estimated yield (t/ha) 7.0 9.0 8.1 8.9 4.4 6.0 4.7 4.6 2.3 3.1
Farmers
Off-season(1/2004)
Main season(2/2005)
Mean ± S.E
6.8 8.5 5.5 4.0 3.6
6.70b* ± 0.66 8.88° ± 0.30 6.27b ± 0.74 c 4.83 ± 1.67 3.57d ± 0.17
7.4 8.5 5.5 4.5 2.3
7.98b ± 0.93 a 8.70 ± 0.52 b 5.25 ± 0.68 c 4.25 ± 0.71 d 2.55 ± 0.38
S.E. = standard error of means, *Means with similar letter do not differ significantly at P < 0.05.
weedy rice infestation due to the effects of environmental factors of different growing seasons were very low (6 to 10%). Productivity of grains and yield components Yield recorded in the studied farms showed the highest and the lowest values for farmers B, in the seasons 2/2004 and 1/2004 (9.2 and 9.0 t/ha, respectively). The lowest yield was obtained by the farmer D in 1/2004 (3.0 t/ha), while the second lowest yield (3.4 t/ha) was observed in the plots of the farmer E during 2/2004 season. However, when the average of all four seasons was considered it was marked that the highest (8.88 t/ha) and lowest (3.58 t/ha) yields of rice grain were obtained by farmers B and E, respectively (Table 3). A more or less similar trend of grain production was noticed for the case of expected yields. The highest expected yield (9.3 t/ha) was also observed in the plots of farmer B in the season 1/2004 followed by farmer A in the season 1/2005 (9.0 t/ha). The lowest yields were observed by farmer E in the seasons 2/2004 and 2/2005 (2.3 t/ha). Averaging among the growing seasons, the highest yield was again recorded for farmer B (8.70t/ha) and the lowest (2.55 t/ha) was found in the field of farmer E (Table 3). DISCUSSION The present study showed that direct-seeding culture could favor weedy rice infestation. Zuki et al. (1996) stated that during the early 1990’s, when weedy rice infestation were at the early stages, direct seeding was practiced on more than 53% area in the MADA rice fields
of Malaysia. As a consequence of the large adoption of the direct seeding, weedy rice became a major problem of rice production. Under this study most of the farmers, for example, farmers C, D and E, followed direct seeding method and thereby observed higher infestation of weedy rice and lower yields of rice. Table 3 showed that during main seasons (2/2004 and 2/2005) most of the farmers obtained lower yields as compared to the off seasons (1/2004 and 1/2005). It should be noted that the main season (April to November) is usually characterized by heavy rains that could induce a lower herbicide efficacy in weed control. Kim (1981) in a study carried out in Korea reported a greater yield reduction due to weeds in the wet season than in the dry season. Another technique applied by the farmers for rice sowing is water seeding. This method leads to more weed inhibition than direct seeding, since water depth on the soil surface retards the germination of weedy rice (Muhamad and Azmi, 2004). In this study, farmer B used transplanting or water seeding method in three consecutive seasons and obtained the highest yield. Averaging across growing seasons, farmer B obtained a rice production of 8.67 t/ha, which was 59% more than farmer E, who performed wet direct seeding in most of the seasons. Similar results have also been reported by Chin (2001) in Vietnam, and Muhammad and Azmi (2004) and Azmi et al. (2005b) in Malaysia. Pudling during land preparation and height of standing water in case of transplanting methods might provide unfavourable condition for germination of weedy rice seeds. Regarding land preparation, repeated rotovation is effective to reduce weedy rice population in rice fields (Cao et al., 2007). The majority of the farmers usually apply only three times tillage. Greater numbers of tillage
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are able to reduce weedy rice in soil seedbank through enhancing germination and then ploughing down (Fogliatto et al., 2011). Zainal and Azmi (1996) proposed sequential tillage during land preparation to reduce weedy rice population. Forner (1995) conducted studies on the effect of cultural practices on weedy rice infestation in Spain and found that pudling (land preparation under wet condition) gave significant reduction of red rice panicle density. A different scenario was reflected for the farmers of Malaysia having problem with water sources. Here the fields are usually ploughed in dry condition and water is introduced into the field in stages as the rice seeds germinate after the onset of rainfall in late March or early April in the off season. This situation creates an aerobic condition which is suitable for germination of grassy weeds, especially weedy rice. Further observations showed that farmers A, B and C applied pre-emergence herbicides after first and second tillage (Table 2), which might be helped to control weedy rice in their plots. Since weedy rice and cultivated rice have similar morphological and physiological characteristics, it is very difficult to control weedy rice using post-emergence herbicides. Therefore, pre-planting application of herbicides is one of the suggested practices to control weedy rice infestations. It can be supposed that the changes observed in the intensity of weed infestation were mainly due to differences in the cultivation practices applied by the farmers in their fields. Field surveillance and weed monitoring appeared also associated with weed infestation in rice fields. Farmers D and E did not monitor their plots frequently and therefore, faced severe problems with weedy rice infestation and finally failed to increase the rice yield. High weedy rice infestations were also reported in the case of directseeding of rice in which competition between weedy and cultivated rice caused 25 to 50% yield loss in Thailand (Teerawaskul, 1981), 40% loss in Korea (Kim, 1981) and 54% loss in Malaysia (Azmi, 1994). Other measures can be used to control weedy rice and these include the use of weed-competitive varieties, transgenic herbicide resistant rice varieties, certified and clean rice seeds, sowing with high seed rates, flooding of rice field at the early stage of growth, crop rotation and use of clean machinery (Azmi et al., 2005a). However, no single method can effectively control this weed and therefore integrated weed management should be adopted. Special emphasis should be given on impeding weedy rice establishment in rice fields, using adequate preventive measures.
ACKNOWLEDGEMENT The authors thankfully acknowledged the supports of Universiti Sains Malaysia, Penang, Malaysia and Universiti Malaysia Kelantan, Kota Bharu, Malaysia in relation to publication of the article.
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