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Effect of some rice based herbicides on yield and yield components of maize
ARTICLE IN PRESS
Crop Protection 26 (2007) 1601–1605 www.elsevier.com/locate/cropro
Effect of some rice based herbicides on yield and yield components of maize M.A. Mahadi, S.A. Dadari, M. Mahmud, B.A. Babaji, H. Mani Department of Agronomy, Faculty of Agriculture, P.M.B. 1044, Ahmadu Bello University, Zaria, Nigeria Received 26 August 2005; received in revised form 26 October 2005; accepted 31 October 2005
Abstract Field trials were conducted during 2001 and 2002 rainy seasons in the Northern Guinea Savanna zone of Nigeria, to evaluate the performance of some pre-emergence herbicides used in rice for weed control in maize. Weed dry weight was significantly reduced by cinosulfuron and the two hoe weedings in 2001 and butachlor in 2002. All the treatments with the exception of piperophos and cinosulfuron significantly increased crop vigour. Plant height and plant dry matter was increased by all the treatments with the exception of cinosulfuron. Cob length of maize was significantly increased by butachlor, oxadiazon and the two hoe weedings in both years. The grain yield of maize was significantly increased by all treatments except piperophos and cinosulfuron and the weedy check in both seasons. These trials show that butachlor and oxadiazon can be used for effective weed control in maize in Nigeria. r 2007 Elsevier Ltd. All rights reserved. Keywords: Weedy check; Hoe weeding; Butachlor; Oxadiazon; Piperophos
1. Introduction Maize (Zea mays L.) originates from Mexico in Central America and is the most widely adapted and the third most important cereal of the world after wheat (Triticum aestivum L.) and rice (Oryza sativa L.) (Kowal et al., 1975). Today the crop is one of the most important sources of the world’s food supply (FAO, 2004). Over the years maize production in Nigeria has expanded to the Northern guinea savanna, which offers greater yield potential than the forest agro-ecology that was traditionally used for cultivation. The abundance of sunshine, low incidence of pests and diseases and dry weather conditions at the end of the crop growing season have made the savanna area a favourable environment for maize production (Kowal et al., 1975). An estimated production of 6.9 million metric tones from 5.43 million hectares was reported in Nigeria (Anonymous, 1994). The maize grain is processed into various forms of porridge after grinding or milling and boiling. It can also Corresponding author. Tel.: +234 69 551293; fax: +234 69 551293.
E-mail address: [email protected] (S.A. Dadari). 0261-2194/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.cropro.2005.10.016
be eaten as a whole grain when roasted or boiled. Maize is used in the production of livestock feeds and forage. The industrial products of maize include cornflakes, maize flour, sugar, oil, alcohol, semovita, etc. (Lagoke, 1978). Among the factors constraining the production of maize worldwide are weeds. In Nigeria losses of up to 80% in the potential grain yield of maize have been attributed to unchecked weed growth throughout the crop’s life cycle (Lagoke, 1978). Methods used to control weeds in maize include manual, mechanical and biological which are known to be labour intensive, costly and may not be easily available at the time of need. The cost and drudgery involved in manual hoe weeding has prompted the search for an alternative method devoid of the above constraints. Nigerian farmers can consider the use of herbicides as an alternative option provided they are easily affordable. Some pre-emergence herbicides, which are generally used in the control of weeds in rice, may offer potential for weed control in Maize. The objective of the study, was to evaluate the performance of some pre emergence herbicides used in rice for their effect on weeds, yield components and yield of Maize.
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2. Materials and methods Two field trials were conducted at the Institute for Agricultural Research farm, Samaru (111110 N, 071380 E and 686 m above sea level) in the northern guinea savanna zone of Nigeria, during the rainy seasons of 2001 and 2002. The soil was a well-drained sandy loam, having a 5.1pH, available nitrogen (0.59%), phosphorus (4.57 ppm in NaCl), organic carbon (27%) and 5.9% meq/100 g of soil cation exchange capacity, the total rainfall received during the cropping seasons was 1228 and 1007 mm in 2001 and 2002, respectively. The experimental land was ploughed at the beginning of the rainy season, harrowed and ridged 75 cm apart. Three seeds of maize variety (TZE Composite-3C) were sown on 2 July 2001 and 6 June 2002 on 75 cm ridges at an intra-row spacing of 25 cm and later thinned to two plants per stand at 2 weeks after sowing. The land was then divided into plots and sub-plots, the gross and net plot sizes in the two experiments were 12 and 8 m2, respectively. The treatments consisted of butachlor, oxadiazon and piperophos at 1.0 and 1.5 kg a.i/ha and cinosulfuron at 0.06 and 0.08 kg a.i/ha with two hoe weedings and a weedy check included in a randomized complete block design of four replicates. The pre-emergence herbicides were applied a day after sowing using a Cp3 knapsack sprayer in 2501/ha spray volume at a pressure of 2.1 kg/cm3 using a green deflector polyjet nozzle. Weeding was carried out at 3 and 6 WAS for the two hoe weeded treatment. Fertilizers were applied by hand placement at 120 kgN, in two equal split doses at 3 and 6 WAP, while 60 kg P205 and 60 kg k20 per hectare were applied at 3 WAP only to the maize using urea, single super phosphate and muriate of potash as sources of N, P and K, respectively. Data were collected on weed cover score, weed dry weight, crop vigour score, plant height, plant dry matter, cob length, cob diameter, cob dry weight, and grain yield. The data were subjected to
statistical analysis of variance and the significant difference among the means were compared using Duncan multiple range test (Duncan, 1955). 3. Results 3.1. Effect of herbicides on weeds Broadleaved species such as Commelina bengalensis L., Convulvulus arvensis L., Portulaca oleraceae L. and the sedge Cyperus rotundus L. were the most dorminant weeds on the experimental site. Weed infestation was generally worst in 2002 than in 2001. With the exception of piperophos at 1.0 kg a.i/ha in 2001 and piperophos at 1.0 and 1.5 kg a.i/ha in 2002, all the other herbicide treatments including the two hoe weedings reduced weed cover score at 6 WAS (Tables 1 and 2). Cinosulfuron at 0.06 and 0.08 kg a.i/ha and the two hoe weedings in 2001 effectively depressed weed dry weight at harvest. However, in 2002 butachlor at 1.5 kg a.i/ha effectively reduced weed dry weight, which was statistically similar to all the other treatments with the exception of piperophos at both rates and the weedy check. The weedy check treatment produced the highest weed cover score and weed dry weight at harvest in both years (Fig. 1). 3.2. Effect of herbicides on crop growth In 2001 season, all the herbicide treatments except oxadiazon at 1.0 kg a.i/ha, piperophos at 1.5 kg a.i/ha, cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check enhanced crop vigour. However, in 2002 growing season, all the herbicides treatments with the exception of Cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check improved maize vigour score (Tables 1 and 2). Most of the herbicides applied and the two hoe weedings
Table 1 Effect of pre-emergence herbicides on weed dry matter, growth, yield and yield components of maize at Samaru 2001 wet season Treatment
Dose Weed scorea Weed weight at (kg a.i/ha) (6 WAPc) harvest (kg/ha)
Butachlor
1.5 1.0 1.5 1.0 1.5 1.0 0.08 0.06
Oxadiazon Piperophos Cinosulfuron Hoe weedings at 3 and 6 WAP Weedy check SE7 a
3.7bd 4.1b 3.9b 5.0b 5.1b 6.3ab 2.7c 3.0c 5.8b 8.0a 0.43
523cd 586bcd 503cd 667bc 702bc 965ab 255e 306e 317e 1131a 4.91
Crop vigourb Plant (6 WAP) height at harvest (cm)
Dry matter/ stand (kg/ha)
Cob length (cm)
Cob Dry cob Grain yield diameter weight (kg/ha) (cm) (gm)
6.5a 5.7ab 6.7a 5.3b 4.2c 5.8ab 2.7de 3.5cd 6.1ab 2.3e 0.21
1842.9ab 1141.5b 1289.1b 2211.4a 1319.3b 504.3c 347.5c 570.1c 1369.5b 424.3c 19.77
9.8ab 8.6bc 7.7bc 7.4bcd 5.9cde 6.4cde 4.6de 4.2e 12.2a 4.1e 0.45
4.2a 4.0ab 4.1ab 4.4a 3.5abc 3.4abc 2.9c 3.1bc 4.0ab 2.6c 0.20
174.2ab 186.7a 163.2ab 183.5a 150.0b 160.5ab 117.0c 147.2b 154.7ab 162.00ab 5.81
88.8a 76.5a 44.8ab 96.7a 51.6ab 15.6b 13.7b 16.3b 52.8ab 13.9b 11.68
2314a 1805ab 1613ab 2441a 1712ab 608b 621b 559b 2216a 736b 9.80
Weed cover score using a scale of 0–10; where, 0 means no weed cover at all, while 10 means complete weed cover. Crop vigour score using a scale of 0–10; where, 0 means dead plants, while 10 means very healthy plants. c WAP ¼ weeks after sowing. d Means within a column followed by the same letter do not differ at 0.05 level of probability using Duncan multiple range test (DMRT). b
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Table 2 Effect of pre-emergence herbicides on weed dry matter, growth, yield components and yield of maize at Samaru 2002 wet season Treatment
Dose Weed scorea Weed weight at (kg a.i/ha) (6 WAPc) harvest (kg/ha)
Butachlor
1.5 1.0 1.5 1.0 1.5 1.0 0.08 0.06
Oxadiazon Piperophos Cinosulfuron
5.8bcdd 5.6cd 5.5cd 6.1bcd 6.7abc 7.0ab 3.6e 2.7e 5.7bcd 8.6a 0.28
Hoe weedings at 3 and 6 WAP Weedy check SE7
497c 675bc 688bc 797bc 993abc 1015ab 733bc 637bc 594b 1622a 7.74
Crop vigourb Plant (6 WAP) height at harvest (cm)
Dry matter/ Cob stand (cm) length (kg/ha)
Cob Dry cob Grain diameter weight yield at (cm) (cm) harvest (gm)
6.5a 6.1ab 6.3a 6.5a 6.1ab 6.6a 4.0cd 2.7d 5.8ab 4.6bc 0.32
1740ab 1408abc 1206bcde 2237a 1252bcd 431def 223f 645cdef 1497abc 297.8ef 19.71
9.4a 7.6b 6.6bc 9.2a 5.2cd 3.2e 4.3de 4.9cde 10.9a 3.4de 0.39
179.0a 172.7a 153.7ab 178.7a 151.5ab 139.0abc 94.7c 117.2bc 141.5abc 131.00abc 9.93
7.5a 6.3ab 6.5ab 7.1a 3.2d 4.1bc 3.7d 3.1d 7.2a 3.6cd 0.61
81.7a 79.8a 43.9bcd 92.10a 45.4bcd 15.45c 8.50d 22.88cd 46.88bcd 9.50e 11.12
2015a 1759acd 1459bcd 2271a 1564bc 618d 631d 777cd 2091a 674d 292.0
a
Weed cover score using a scale of 0–10; whereas, 0 means no weed cover at all, while 10 means complete weed cover. Crop vigour score using a scale of 0–10; whereas, 0 means dead plants, while 10 means very healthy plants. c WAP ¼ weeks after sowing. d Means within a column followed by the same letter do not differ at 0.05 level of probability using Duncan multiple range test (DMRT). b
3000 Maize grain yield (kg/ha)
2001
2002
2500 2000 1500 1000 500 0 1
2
3
4
6 5 7 Herbicide treatment
8
9
10
Fig. 1. Maize grain yield (kg/ha).
produced taller maize plants than when piperophos at 1.5 kg a.i/ha and cinosulfuron at 0.06 and 0.08 kg a.i/ha in 2001 and cinosulfuron at 0.06 and 0.08 kg a.i/ha in 2002 were applied (Tables 1 and 2). Cinosulfuron at 0.06 and 0.08 kg a.i/ha produced the shortest maize plant height. Plant dry matter was enhanced by oxadiazon at 1.0 kg a.i/ha, which was similar to butachlor at 1.5 kg a.i/ha in 2001, and oxadiazon at 1.0 kg a.i/ha, butachlor at both doses and the two hoe weedings in 2002. The least maize dry weight was recorded when piperophos at 1.0 kg a.i/ha, cinosulfuron was applied at both doses and the untreated control (Fig. 2). 3.3. Effect of herbicides on yield components and yield The significant influence of herbicide treatments on the cob length, cob diameter and cob dry weight of maize is shown on (Tables 1 and 2). In 2001, the two hoe weedings
and butachlor at 1.5 kg a.i./ha had the longest maize cob. Butachlor and oxadiazon each at both doses and the two hoe weedings in 2002 produced the longest maize cobs (Tables 1 and 2). With the exception of cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check in 2001, all the other herbicide treatments increased maize cob diameter. In 2002 cob diameter of maize was largest when butachlor at 1.5 kg a.i/ha and oxadiazon at 1.0 kg a.i/ha were applied together with two hoe weedings. All other treatments recorded lower maize cob diameter (Tables 1 and 2). Heavier maize cob dry weight was recorded by all the treatments except piperophos at 1.0 kg a.i/ha, cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check in 2001. However, in 2002 butachlor at 1.0 and 1.5 kg a.i/ha and oxadiazon at 1.0 kg a.i/ha had heavier maize cobs than all the other treatments (Tables 1 and 2). Piperophos at 1.0 kg a.i/ha, cinosulfuron at 0.06 and 0.08 kg a.i/ha and the
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1800 Weed dry weight (kg/ha)
1600 1400 1200 1000 800 600 400 200 0
1
2
3
4
5 6 Herbicide treatment
7
8
9
10
Fig. 2. Weed dry weight (kg/ha). Key: 1 ¼ butachlor (1.5 kg a.i/ha), 2 ¼ butachlor (1.0 kg a.i/ha), 3 ¼ oxadiazon (1.5 kg a.i/ha), 4 ¼ oxadiazon (1.0 kg a.i/ ha), 5 ¼ piperophos (1.5 kg a.i/ha), 6 ¼ piperophos (1.0 kg a.i/ha), 7 ¼ cinosulfuron (0.08 kg a.i/ha), 8 ¼ cinosulfuron (0.06 kg a.i/ha), 9 ¼ hoe weedings (3 and 6 WAP), 10 ¼ untreated, *a.i ¼ active ingredient.
weedy check in 2001 gave the lowest grain yield. Whereas in 2002, only the application of butachlor, oxadiazon at 1.0 kg a.i/ha and the two hoe weedings resulted in higher grain yield (Tables 1 and 2).
4. Discussion Weed cover score and weed dry matter production were significantly influenced by these herbicide treatments. Generally among the treatments, cinosulfuron had significantly reduced the weed score and weed weight during the course of this investigation compared to the other treatments, which were less effective. Butachlor at 1.5 kg a.i/ha had effectively depressed the weed dry weight in 2002 season and was superior to the two hoe weedings. Cinosulfuron is a broad-spectrum herbicide which controlled most of the weed species in the field, thus reducing weed cover score and weed dry matter. In combination with piperophos it is used for the control of weeds in cereals such as rice and wheat (Arenas, 1997). Likewise, butachlor and its mixture with propanil have been reported to be selective on grain cereal crops under both rainfed and irrigated condition (Anonymous, 1978; Richard and Street, 1984; Okafor, 1986). In Nigeria information on the use of cinosulfuron and butachlor in maize is not well documented and this is the initial attempt to evaluate on its performance. The depression of weed dry weight in 2002 than in 2001 by butachlor might have been due to high amount of rainfall received in 2001 resulting in leaching into the rooting zone of the maize crop. Cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check significantly reduced maize cob length, cob diameter and cob dry weight, respectively in 2001 and 2002. The reduction in maize cob length, cob diameter and cob dry weight was due to the depressive effect of cinosulfuron on the establishment and growth of maize.
The low weed dry matter observed in plots that were sprayed with this herbicide further confirms the above findings. This corroborates the earlier reports of Adu-Tutu and Drennan (1991) in which they observed that sulfonylurea herbicides particularly cinosulfuron applied at 40–60 g a.i/ha damaged maize. The depression of these important parameters of maize by cinosulfuron at 0.06 and 0.08 kg a.i/ha was so much that it was comparable to that of the weedy check. The reduction in cob length cob diameter and cob dry weight as a result of leaving the plots of maize weedy throughout the crops life cycle is expected because of the deleterious effect of weeds on crop plants as a result of their stiff competition for nutrients, water, space, sunlight, etc. Hence the reason for higher weed dry matter observed in the weedy check. The negative effect of cinosulfuron on maize grain yield could be attributed to its effect on the physiology of maize, which depressed the growth, yield and yield parameters. The aggressiveness of weeds when it comes to competition for such growth factors such as moisture and nutrients with maize crop might have been the reason for the low productivity of maize in the untreated plots. It was reported by Zoschke et al. (1989) those phytotoxicity symptoms such as chlorosis, slight bleaching, growth and depression and subsequent death of crops were observed on most susceptible species when cinosulfuron herbicide was used. Butachlor at 1.5 kg a.i/ha and oxadiazon at 1.0 kg a.i/ha in both years gave effective weed control which consequently produced high maize grain yield (Fig. 1).
5. Conclusion From this study it could be concluded that two hoe weedings or the pre-emergence application of pre-emergence herbicides such as butachlor and oxadiazon can be adopted for effective control of weeds in order to obtain
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high grain yield production of maize in the savanna of Northern Nigeria. Acknowledgement The authors wish to thank the Institute for Agricultural Research, Ahmadu Bello University, Zaria for providing the logistic support to conduct the experiments. References Adu-Tutu, K.O., Drennan, D.S.H., 1991. Effect of sulfonylurea herbicides on striga in maize. In: Proceedings of the Fifth International Symposium of Parasitic Weeds, Nairobi, Kenya, pp. 361–370. Anonymous, 1978. Annual report. International Rice Research Institute Los Banos Laguria, Philiphines, pp. 230–231. Anonymous, 1994. Food and Agriculture Organisation. Quart. Bull. Statist. 9 (3), 39.
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Arenas, M., 1997. International Labels Text Ciba—Geigy, first ed. Basel, Switzerland, pp. 6–34. Duncan, D.B., 1955. Multiple range and multiple ‘F’ (test). Biometrics 11, 1–42. FAO, 2004. Bulletin of Statistics. http://www.FAO.org. Kowal, J., Kassam, A.H., Dagg, M., Harrison, M.N., 1975. Maize in West Africa and its potential in savanna areas. World Crops 27 (2), 73–78. Lagoke, S.T.O., 1978. Methods of Control of Speargrass (Imperata cylindrica L. Beanx) in maize, Ph.D. thesis. Department of Agronomy University of Ibadan, 410pp. Okafor, L.I., 1986. Chemical weed control in direct seeded irrigated rice in the Lake Chad Basin , Nigeria. Crop Prot. 5 (3), 203–208. Richard, E.P., Street, J.E., 1984. Herbicide performance in rice (Oryza Sativa L.) under three flooded conditions. J. Weed Sci. Am. 32 (2), 157–167. Zoschke, A., Yun, J.K., Kissling, Y., 1989. CGA 14264 plus BAS 514. A new timely flexible combination for broad-spectrum weed control in rice. In: Proceedings of the 12th Asia Pacific Weed Science Conference, Taipe, Taiwan, pp. 245–253.
Crop Protection 26 (2007) 1601–1605 www.elsevier.com/locate/cropro
Effect of some rice based herbicides on yield and yield components of maize M.A. Mahadi, S.A. Dadari, M. Mahmud, B.A. Babaji, H. Mani Department of Agronomy, Faculty of Agriculture, P.M.B. 1044, Ahmadu Bello University, Zaria, Nigeria Received 26 August 2005; received in revised form 26 October 2005; accepted 31 October 2005
Abstract Field trials were conducted during 2001 and 2002 rainy seasons in the Northern Guinea Savanna zone of Nigeria, to evaluate the performance of some pre-emergence herbicides used in rice for weed control in maize. Weed dry weight was significantly reduced by cinosulfuron and the two hoe weedings in 2001 and butachlor in 2002. All the treatments with the exception of piperophos and cinosulfuron significantly increased crop vigour. Plant height and plant dry matter was increased by all the treatments with the exception of cinosulfuron. Cob length of maize was significantly increased by butachlor, oxadiazon and the two hoe weedings in both years. The grain yield of maize was significantly increased by all treatments except piperophos and cinosulfuron and the weedy check in both seasons. These trials show that butachlor and oxadiazon can be used for effective weed control in maize in Nigeria. r 2007 Elsevier Ltd. All rights reserved. Keywords: Weedy check; Hoe weeding; Butachlor; Oxadiazon; Piperophos
1. Introduction Maize (Zea mays L.) originates from Mexico in Central America and is the most widely adapted and the third most important cereal of the world after wheat (Triticum aestivum L.) and rice (Oryza sativa L.) (Kowal et al., 1975). Today the crop is one of the most important sources of the world’s food supply (FAO, 2004). Over the years maize production in Nigeria has expanded to the Northern guinea savanna, which offers greater yield potential than the forest agro-ecology that was traditionally used for cultivation. The abundance of sunshine, low incidence of pests and diseases and dry weather conditions at the end of the crop growing season have made the savanna area a favourable environment for maize production (Kowal et al., 1975). An estimated production of 6.9 million metric tones from 5.43 million hectares was reported in Nigeria (Anonymous, 1994). The maize grain is processed into various forms of porridge after grinding or milling and boiling. It can also Corresponding author. Tel.: +234 69 551293; fax: +234 69 551293.
E-mail address: [email protected] (S.A. Dadari). 0261-2194/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.cropro.2005.10.016
be eaten as a whole grain when roasted or boiled. Maize is used in the production of livestock feeds and forage. The industrial products of maize include cornflakes, maize flour, sugar, oil, alcohol, semovita, etc. (Lagoke, 1978). Among the factors constraining the production of maize worldwide are weeds. In Nigeria losses of up to 80% in the potential grain yield of maize have been attributed to unchecked weed growth throughout the crop’s life cycle (Lagoke, 1978). Methods used to control weeds in maize include manual, mechanical and biological which are known to be labour intensive, costly and may not be easily available at the time of need. The cost and drudgery involved in manual hoe weeding has prompted the search for an alternative method devoid of the above constraints. Nigerian farmers can consider the use of herbicides as an alternative option provided they are easily affordable. Some pre-emergence herbicides, which are generally used in the control of weeds in rice, may offer potential for weed control in Maize. The objective of the study, was to evaluate the performance of some pre emergence herbicides used in rice for their effect on weeds, yield components and yield of Maize.
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2. Materials and methods Two field trials were conducted at the Institute for Agricultural Research farm, Samaru (111110 N, 071380 E and 686 m above sea level) in the northern guinea savanna zone of Nigeria, during the rainy seasons of 2001 and 2002. The soil was a well-drained sandy loam, having a 5.1pH, available nitrogen (0.59%), phosphorus (4.57 ppm in NaCl), organic carbon (27%) and 5.9% meq/100 g of soil cation exchange capacity, the total rainfall received during the cropping seasons was 1228 and 1007 mm in 2001 and 2002, respectively. The experimental land was ploughed at the beginning of the rainy season, harrowed and ridged 75 cm apart. Three seeds of maize variety (TZE Composite-3C) were sown on 2 July 2001 and 6 June 2002 on 75 cm ridges at an intra-row spacing of 25 cm and later thinned to two plants per stand at 2 weeks after sowing. The land was then divided into plots and sub-plots, the gross and net plot sizes in the two experiments were 12 and 8 m2, respectively. The treatments consisted of butachlor, oxadiazon and piperophos at 1.0 and 1.5 kg a.i/ha and cinosulfuron at 0.06 and 0.08 kg a.i/ha with two hoe weedings and a weedy check included in a randomized complete block design of four replicates. The pre-emergence herbicides were applied a day after sowing using a Cp3 knapsack sprayer in 2501/ha spray volume at a pressure of 2.1 kg/cm3 using a green deflector polyjet nozzle. Weeding was carried out at 3 and 6 WAS for the two hoe weeded treatment. Fertilizers were applied by hand placement at 120 kgN, in two equal split doses at 3 and 6 WAP, while 60 kg P205 and 60 kg k20 per hectare were applied at 3 WAP only to the maize using urea, single super phosphate and muriate of potash as sources of N, P and K, respectively. Data were collected on weed cover score, weed dry weight, crop vigour score, plant height, plant dry matter, cob length, cob diameter, cob dry weight, and grain yield. The data were subjected to
statistical analysis of variance and the significant difference among the means were compared using Duncan multiple range test (Duncan, 1955). 3. Results 3.1. Effect of herbicides on weeds Broadleaved species such as Commelina bengalensis L., Convulvulus arvensis L., Portulaca oleraceae L. and the sedge Cyperus rotundus L. were the most dorminant weeds on the experimental site. Weed infestation was generally worst in 2002 than in 2001. With the exception of piperophos at 1.0 kg a.i/ha in 2001 and piperophos at 1.0 and 1.5 kg a.i/ha in 2002, all the other herbicide treatments including the two hoe weedings reduced weed cover score at 6 WAS (Tables 1 and 2). Cinosulfuron at 0.06 and 0.08 kg a.i/ha and the two hoe weedings in 2001 effectively depressed weed dry weight at harvest. However, in 2002 butachlor at 1.5 kg a.i/ha effectively reduced weed dry weight, which was statistically similar to all the other treatments with the exception of piperophos at both rates and the weedy check. The weedy check treatment produced the highest weed cover score and weed dry weight at harvest in both years (Fig. 1). 3.2. Effect of herbicides on crop growth In 2001 season, all the herbicide treatments except oxadiazon at 1.0 kg a.i/ha, piperophos at 1.5 kg a.i/ha, cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check enhanced crop vigour. However, in 2002 growing season, all the herbicides treatments with the exception of Cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check improved maize vigour score (Tables 1 and 2). Most of the herbicides applied and the two hoe weedings
Table 1 Effect of pre-emergence herbicides on weed dry matter, growth, yield and yield components of maize at Samaru 2001 wet season Treatment
Dose Weed scorea Weed weight at (kg a.i/ha) (6 WAPc) harvest (kg/ha)
Butachlor
1.5 1.0 1.5 1.0 1.5 1.0 0.08 0.06
Oxadiazon Piperophos Cinosulfuron Hoe weedings at 3 and 6 WAP Weedy check SE7 a
3.7bd 4.1b 3.9b 5.0b 5.1b 6.3ab 2.7c 3.0c 5.8b 8.0a 0.43
523cd 586bcd 503cd 667bc 702bc 965ab 255e 306e 317e 1131a 4.91
Crop vigourb Plant (6 WAP) height at harvest (cm)
Dry matter/ stand (kg/ha)
Cob length (cm)
Cob Dry cob Grain yield diameter weight (kg/ha) (cm) (gm)
6.5a 5.7ab 6.7a 5.3b 4.2c 5.8ab 2.7de 3.5cd 6.1ab 2.3e 0.21
1842.9ab 1141.5b 1289.1b 2211.4a 1319.3b 504.3c 347.5c 570.1c 1369.5b 424.3c 19.77
9.8ab 8.6bc 7.7bc 7.4bcd 5.9cde 6.4cde 4.6de 4.2e 12.2a 4.1e 0.45
4.2a 4.0ab 4.1ab 4.4a 3.5abc 3.4abc 2.9c 3.1bc 4.0ab 2.6c 0.20
174.2ab 186.7a 163.2ab 183.5a 150.0b 160.5ab 117.0c 147.2b 154.7ab 162.00ab 5.81
88.8a 76.5a 44.8ab 96.7a 51.6ab 15.6b 13.7b 16.3b 52.8ab 13.9b 11.68
2314a 1805ab 1613ab 2441a 1712ab 608b 621b 559b 2216a 736b 9.80
Weed cover score using a scale of 0–10; where, 0 means no weed cover at all, while 10 means complete weed cover. Crop vigour score using a scale of 0–10; where, 0 means dead plants, while 10 means very healthy plants. c WAP ¼ weeks after sowing. d Means within a column followed by the same letter do not differ at 0.05 level of probability using Duncan multiple range test (DMRT). b
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Table 2 Effect of pre-emergence herbicides on weed dry matter, growth, yield components and yield of maize at Samaru 2002 wet season Treatment
Dose Weed scorea Weed weight at (kg a.i/ha) (6 WAPc) harvest (kg/ha)
Butachlor
1.5 1.0 1.5 1.0 1.5 1.0 0.08 0.06
Oxadiazon Piperophos Cinosulfuron
5.8bcdd 5.6cd 5.5cd 6.1bcd 6.7abc 7.0ab 3.6e 2.7e 5.7bcd 8.6a 0.28
Hoe weedings at 3 and 6 WAP Weedy check SE7
497c 675bc 688bc 797bc 993abc 1015ab 733bc 637bc 594b 1622a 7.74
Crop vigourb Plant (6 WAP) height at harvest (cm)
Dry matter/ Cob stand (cm) length (kg/ha)
Cob Dry cob Grain diameter weight yield at (cm) (cm) harvest (gm)
6.5a 6.1ab 6.3a 6.5a 6.1ab 6.6a 4.0cd 2.7d 5.8ab 4.6bc 0.32
1740ab 1408abc 1206bcde 2237a 1252bcd 431def 223f 645cdef 1497abc 297.8ef 19.71
9.4a 7.6b 6.6bc 9.2a 5.2cd 3.2e 4.3de 4.9cde 10.9a 3.4de 0.39
179.0a 172.7a 153.7ab 178.7a 151.5ab 139.0abc 94.7c 117.2bc 141.5abc 131.00abc 9.93
7.5a 6.3ab 6.5ab 7.1a 3.2d 4.1bc 3.7d 3.1d 7.2a 3.6cd 0.61
81.7a 79.8a 43.9bcd 92.10a 45.4bcd 15.45c 8.50d 22.88cd 46.88bcd 9.50e 11.12
2015a 1759acd 1459bcd 2271a 1564bc 618d 631d 777cd 2091a 674d 292.0
a
Weed cover score using a scale of 0–10; whereas, 0 means no weed cover at all, while 10 means complete weed cover. Crop vigour score using a scale of 0–10; whereas, 0 means dead plants, while 10 means very healthy plants. c WAP ¼ weeks after sowing. d Means within a column followed by the same letter do not differ at 0.05 level of probability using Duncan multiple range test (DMRT). b
3000 Maize grain yield (kg/ha)
2001
2002
2500 2000 1500 1000 500 0 1
2
3
4
6 5 7 Herbicide treatment
8
9
10
Fig. 1. Maize grain yield (kg/ha).
produced taller maize plants than when piperophos at 1.5 kg a.i/ha and cinosulfuron at 0.06 and 0.08 kg a.i/ha in 2001 and cinosulfuron at 0.06 and 0.08 kg a.i/ha in 2002 were applied (Tables 1 and 2). Cinosulfuron at 0.06 and 0.08 kg a.i/ha produced the shortest maize plant height. Plant dry matter was enhanced by oxadiazon at 1.0 kg a.i/ha, which was similar to butachlor at 1.5 kg a.i/ha in 2001, and oxadiazon at 1.0 kg a.i/ha, butachlor at both doses and the two hoe weedings in 2002. The least maize dry weight was recorded when piperophos at 1.0 kg a.i/ha, cinosulfuron was applied at both doses and the untreated control (Fig. 2). 3.3. Effect of herbicides on yield components and yield The significant influence of herbicide treatments on the cob length, cob diameter and cob dry weight of maize is shown on (Tables 1 and 2). In 2001, the two hoe weedings
and butachlor at 1.5 kg a.i./ha had the longest maize cob. Butachlor and oxadiazon each at both doses and the two hoe weedings in 2002 produced the longest maize cobs (Tables 1 and 2). With the exception of cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check in 2001, all the other herbicide treatments increased maize cob diameter. In 2002 cob diameter of maize was largest when butachlor at 1.5 kg a.i/ha and oxadiazon at 1.0 kg a.i/ha were applied together with two hoe weedings. All other treatments recorded lower maize cob diameter (Tables 1 and 2). Heavier maize cob dry weight was recorded by all the treatments except piperophos at 1.0 kg a.i/ha, cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check in 2001. However, in 2002 butachlor at 1.0 and 1.5 kg a.i/ha and oxadiazon at 1.0 kg a.i/ha had heavier maize cobs than all the other treatments (Tables 1 and 2). Piperophos at 1.0 kg a.i/ha, cinosulfuron at 0.06 and 0.08 kg a.i/ha and the
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1800 Weed dry weight (kg/ha)
1600 1400 1200 1000 800 600 400 200 0
1
2
3
4
5 6 Herbicide treatment
7
8
9
10
Fig. 2. Weed dry weight (kg/ha). Key: 1 ¼ butachlor (1.5 kg a.i/ha), 2 ¼ butachlor (1.0 kg a.i/ha), 3 ¼ oxadiazon (1.5 kg a.i/ha), 4 ¼ oxadiazon (1.0 kg a.i/ ha), 5 ¼ piperophos (1.5 kg a.i/ha), 6 ¼ piperophos (1.0 kg a.i/ha), 7 ¼ cinosulfuron (0.08 kg a.i/ha), 8 ¼ cinosulfuron (0.06 kg a.i/ha), 9 ¼ hoe weedings (3 and 6 WAP), 10 ¼ untreated, *a.i ¼ active ingredient.
weedy check in 2001 gave the lowest grain yield. Whereas in 2002, only the application of butachlor, oxadiazon at 1.0 kg a.i/ha and the two hoe weedings resulted in higher grain yield (Tables 1 and 2).
4. Discussion Weed cover score and weed dry matter production were significantly influenced by these herbicide treatments. Generally among the treatments, cinosulfuron had significantly reduced the weed score and weed weight during the course of this investigation compared to the other treatments, which were less effective. Butachlor at 1.5 kg a.i/ha had effectively depressed the weed dry weight in 2002 season and was superior to the two hoe weedings. Cinosulfuron is a broad-spectrum herbicide which controlled most of the weed species in the field, thus reducing weed cover score and weed dry matter. In combination with piperophos it is used for the control of weeds in cereals such as rice and wheat (Arenas, 1997). Likewise, butachlor and its mixture with propanil have been reported to be selective on grain cereal crops under both rainfed and irrigated condition (Anonymous, 1978; Richard and Street, 1984; Okafor, 1986). In Nigeria information on the use of cinosulfuron and butachlor in maize is not well documented and this is the initial attempt to evaluate on its performance. The depression of weed dry weight in 2002 than in 2001 by butachlor might have been due to high amount of rainfall received in 2001 resulting in leaching into the rooting zone of the maize crop. Cinosulfuron at 0.06 and 0.08 kg a.i/ha and the weedy check significantly reduced maize cob length, cob diameter and cob dry weight, respectively in 2001 and 2002. The reduction in maize cob length, cob diameter and cob dry weight was due to the depressive effect of cinosulfuron on the establishment and growth of maize.
The low weed dry matter observed in plots that were sprayed with this herbicide further confirms the above findings. This corroborates the earlier reports of Adu-Tutu and Drennan (1991) in which they observed that sulfonylurea herbicides particularly cinosulfuron applied at 40–60 g a.i/ha damaged maize. The depression of these important parameters of maize by cinosulfuron at 0.06 and 0.08 kg a.i/ha was so much that it was comparable to that of the weedy check. The reduction in cob length cob diameter and cob dry weight as a result of leaving the plots of maize weedy throughout the crops life cycle is expected because of the deleterious effect of weeds on crop plants as a result of their stiff competition for nutrients, water, space, sunlight, etc. Hence the reason for higher weed dry matter observed in the weedy check. The negative effect of cinosulfuron on maize grain yield could be attributed to its effect on the physiology of maize, which depressed the growth, yield and yield parameters. The aggressiveness of weeds when it comes to competition for such growth factors such as moisture and nutrients with maize crop might have been the reason for the low productivity of maize in the untreated plots. It was reported by Zoschke et al. (1989) those phytotoxicity symptoms such as chlorosis, slight bleaching, growth and depression and subsequent death of crops were observed on most susceptible species when cinosulfuron herbicide was used. Butachlor at 1.5 kg a.i/ha and oxadiazon at 1.0 kg a.i/ha in both years gave effective weed control which consequently produced high maize grain yield (Fig. 1).
5. Conclusion From this study it could be concluded that two hoe weedings or the pre-emergence application of pre-emergence herbicides such as butachlor and oxadiazon can be adopted for effective control of weeds in order to obtain
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high grain yield production of maize in the savanna of Northern Nigeria. Acknowledgement The authors wish to thank the Institute for Agricultural Research, Ahmadu Bello University, Zaria for providing the logistic support to conduct the experiments. References Adu-Tutu, K.O., Drennan, D.S.H., 1991. Effect of sulfonylurea herbicides on striga in maize. In: Proceedings of the Fifth International Symposium of Parasitic Weeds, Nairobi, Kenya, pp. 361–370. Anonymous, 1978. Annual report. International Rice Research Institute Los Banos Laguria, Philiphines, pp. 230–231. Anonymous, 1994. Food and Agriculture Organisation. Quart. Bull. Statist. 9 (3), 39.
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Arenas, M., 1997. International Labels Text Ciba—Geigy, first ed. Basel, Switzerland, pp. 6–34. Duncan, D.B., 1955. Multiple range and multiple ‘F’ (test). Biometrics 11, 1–42. FAO, 2004. Bulletin of Statistics. http://www.FAO.org. Kowal, J., Kassam, A.H., Dagg, M., Harrison, M.N., 1975. Maize in West Africa and its potential in savanna areas. World Crops 27 (2), 73–78. Lagoke, S.T.O., 1978. Methods of Control of Speargrass (Imperata cylindrica L. Beanx) in maize, Ph.D. thesis. Department of Agronomy University of Ibadan, 410pp. Okafor, L.I., 1986. Chemical weed control in direct seeded irrigated rice in the Lake Chad Basin , Nigeria. Crop Prot. 5 (3), 203–208. Richard, E.P., Street, J.E., 1984. Herbicide performance in rice (Oryza Sativa L.) under three flooded conditions. J. Weed Sci. Am. 32 (2), 157–167. Zoschke, A., Yun, J.K., Kissling, Y., 1989. CGA 14264 plus BAS 514. A new timely flexible combination for broad-spectrum weed control in rice. In: Proceedings of the 12th Asia Pacific Weed Science Conference, Taipe, Taiwan, pp. 245–253.