African Journal of Agricultural Research Vol. 6(13), pp. 3092-3097, 4 July, 2011 Available online at http://www.academicjournals.org/AJAR DOI: 10.5897/AJAR10.1058 ISSN 1991-637X ©2011 Academic Journals
Full Length Research Paper
Influence of nitrogen fertilization on yield and yield components of rain-fed lowland NERICA® rice in the northern Guinea savanna of Nigeria A. Y. Kamara1,2*, F. Ekeleme3, L. O. Omoigui4 and D. Chikoye1 1
International Institute of Tropical Agriculture Ibadan, Nigeria. c/o IITA Ltd, Carolyn House, 26 Dingwall Road, Croydon, CR 9 3EE, UK. 3 College of Crop and Soil Sciences, Michael Okpara University of Agriculture, Umudike, P. M. B. 7267, Umuahia, Abia State, Nigeria. 4 Department of Plant Breeding and Seed Science, College of Agronomy, University of Agriculture, Makurdi, Nigeria. 2
Accepted 17 June, 2011
This study evaluated the response of four rain-fed lowland New Rice for Africa (NERICA) varieties (NERICA-L-12, NERICA-L-41, NERICA-L-42 and NERICA-L-56) and a popularly grown Oryza sativa (ITA 150) to nitrogen (0, 30, and 100 kg N ha-1). The interactions between nitrogen and variety were not significant for all measured traits. Grain yields of the NERICAs were higher than the yield of ITA 150 (check) by 0.5 to 1.0 mg ha-1. When pooled across N rates and years, yield differences among the NERICAs were not significant. Grain yield response to nitrogen was linear. At 100 kg N ha-1, grain yield -1 -1 was significantly increased by 3.0 and 1.5 mg ha over the yields at 0 and 30 kg N ha respectively. Since grain yield response to N application was linear, further studies are recommended to determine the optimum rate of N for rain-fed lowland NERICA rice production. Key words: NERICA rice, lowland rice, nitrogen fertilization. INTRODUCTION Rice (Oryza sativa L.) is the sixth major crop in area cultivated in Nigeria after sorghum, millet, cowpea, cassava and yam (FAO, 1994; Vange and Obi, 2006). Rice production rose from 2.4 million metric tons in 1994 to 3.1 million metric tons in 2002 (Oyekanmi et al., 2008). Rice is grown in all the agro-ecological zones of Nigeria (Olaleye et al., 2008). Rainfed lowland systems account for 50%; rainfed upland rice production accounts for approximately 25% of the harvested area; while the rest are produced in other ecologies. Rainfed lowland systems include the broad valley bottoms, or fadama in the north and the flood plains along the Niger and Benue River systems (USDA, 2002). Although lowland rice ecosystems have high production potential (Abo et al., -1 2003), with grain yield ranging from 2 to 8 mg ha (Olaleye et al., 2008), rice production in the lowlands is limited by unavailability of improved varieties (most of the improved rice available to the farmers are upland
*Corresponding author. E-mail:
[email protected]
cultivars), pest and diseases and poor soil fertility. In Borno State, Nigeria, where rice production is on the increase, rice is mainly grown in upland and lowland ecosystems under rain-fed conditions with a greater percentage of land cultivated to rain-fed upland rice varieties. One of the major constraints to rain-fed lowland rice production in Borno State is lack of appropriate improved varieties. The widely grown varieties (IT-56 and Liberia) in the lowlands of the State are late-maturing upland varieties obtained from IITA/Africa Rice Center (WARDA) about 20 years ago. They are usually susceptible to pests and diseases and do not compete well with weeds. As a result of late maturity and inadaptability to lowland conditions there is considerable risk of crop failure arising from rainfall instability in the region. Due to intensification of rice production in the lowlands with minimal use of fertilizers, the soils are poor in nutrients. A land suitability study for lowlands rice production in Nigeria showed that the soils are generally low in organic carbon with widespread deficiency in nitrogen (Olaleye et al., 2008). In 2006, the project PROSAB (Promoting Sustainable
Kamara et al.
Agriculture in Borno State) introduced four rain-fed lowland varieties of NERICA® (New Rice for Africa) obtained from WARDA to farmers to replace existing varieties that are poor yielding and are prone to drought, pests and diseases. Varieties of lowland NERICA® are the product of interspecific hybridization between IR64 [O. sativa] and TOG5681 [Oryza glaberrima] (Ndjiondjop et al., 2008). These varieties are resistant to pest and diseases and are also tolerant to drought (Jones et al., 1997). Although land areas cultivated to NERICA in Borno State have continued to expand in the past 3 years, yield levels on farmer’s field remain below the potential yield of these varieties due to poor soil fertility and the low use of fertilizer nitrogen (Kwari, 2005). As noted by Oikeh et al. (2009), nutrient deficiency in rice is a major constraint to rice production in West Africa. Among various nutrients, nitrogen has the strongest influence on the growth and yield of rice (Ahmed et al., 2005). Previous studies showed that proper use of fertilizer can increase the yield and improve the quality of rice significantly (Awan et al., 2003; Ahmed, 2005; Oikeh et al., 2008). Several studies have shown that application of N fertilizer to rice, leads to increase in plant height, panicle number, leaf size, spikelet number and grain yield (Balasubramanian, 2002; Walker et al., 2008). While information on nitrogen requirements of rainfall upland rice exists (Rodenburg et al., 2006; Oikeh et al., 2008), little or no information exists on the N fertilizer requirements of rainfed lowland rice in the savannas of northeast, Nigeria. Given the importance of N fertilizer on the grain yield of rice, there is a need to know the appropriate rates for the production of rain-fed lowland NERICA in the study area. This study evaluated the yield performance of four selected rain-fed lowland NERICA varieties under different nitrogen rates in the dry savanna agroecosytem.
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equal splits, 14 days after planting (DAP), at panicle initiation (50 DAP) and at booting stage. The second and third splits were applied as side dressing. The subplot treatments were five rice varieties: four rain-fed lowland interspecific varieties (NERICA®) acquired from the African Rice Center (WARDA), NERICA-L-12, NERICA-L-41, NERICA-L-42, and NERICA-L-56; and a popularly grown O. sativa (ITA 150) used as a local check. The lowland NERICAs were selected based on their performance in participatory varietal selection trials across West Africa (Moussa Sie, personal communication). The local check (ITA 150) is popularly grown by farmers in both upland and lowland rainfed conditions in the study area. Each subplot was 30 m2 in size. The land was ploughed and harrowed before planting. Rice was sown on 16 June in 2007 and on 15 June in 2008. Six seeds were sown per hill at a spacing of 0.2 × 0.2 m and later thinned to 3 seedlings stand-1 to give a total population of 750, 000 plants ha-1. Each plot received basal application of 30 kg ha-1 each of phosphorus (single superphosphate, 18% P2O5) and potassium (muriate of potash, 60% K2O) at planting. Each plot received three hoe weeding. A 1 m2 quadrat was placed at the beginning of each plot (leaving out the border rows and border plants). At physiological maturity all plants in the quadrat were harvested separately to determine yield components (grains per panicle, 1000-grain weight). Ten panicles were randomly selected, threshed to determine the number of grains per panicle. The remaining portion on the field was harvested, threshed, and combined with grain from the 1 m2 quadrat to estimate yield at 140 g kg-1 moisture content. Five replicates of five hundred seeds were counted per plot, weighed and converted to 1000-grain weight. Statistical analysis All data were analysed using the mixed model procedure of SAS (Littell et al., 1996) where replication was considered random effect; N and rice varieties were considered fixed effects. Standard error of the difference (SED) was estimated for each treatment. Differences between two treatment means were compared with t-test, based on the SED at 5% level of probability. Pearson correlation coefficients (r) were calculated by year to examine associations among grain yield, spikelets number plant-1, seeds panicle-1, and 1000-grain weight (SAS Institute, 2001).
RESULTS AND DISCUSSION MATERIALS AND METHODS
Grain yield Site description The experiment was conducted in Tum [10º 35.94' N; 12º 05.31' E, 644 m asl], Borno State in the Northern Guinea savanna (NGS) agroecosystem of Nigeria in 2007 and 2008. The experimental site is characterized by a unimodal rainfall distribution, with long term averages of about 1324.5 mm year-1. Total annual rainfall was 1029.5 mm in 2007 and 1263.5 mm in 2008. Daily rainfall distribution during the study period is presented in Figure 1. The soil at the site was silt clay loam, classified as Vertic Luvisol with 10.8 g kg-1 organic carbon, 1.4 g kg-1 N, 2.2 mg available P kg-1 (Mehlich III), 0.52 Cmol+ K kg-1 and pH of 6.56. Prior to the trial, the site was under continuous cultivation of local rice varieties.
Experimental design The experiment was set up as a split-plot in randomized complete block with three replications. The main plot treatments were three rates of N (0, 30, and 100 kg ha-1) applied as urea (46% N) in three
Year and nitrogen fertilization had significant effects on grain yield (P < 0.05). The interaction of year and nitrogen fertilization was not significant for grain yield (P = 0.3974). Year × variety interaction was however, significant for grain yield (P = 0.0052) and 1000-grain weight (P = 0.0269). Grain yield response to nitrogen fertilization was linear (Figure 2) indicating that the optimum grain yield may be higher than what was obtained at the highest N rate of 100 kg N ha-1. This rate is higher than those recommended by Enwezor et al. (1989) for rainfed lowland O. sativa varieties in the Nigerian savannas. They recommended 40 and 70 kg N ha-1 for tall and short varieties, respectively. Singh et al. (2000) reported a similar trend with optimum grain yield -1 obtained at 120 kg N ha for upland rice in Himalayan foothills. In contrast, Fageria and Baligar (2001) reported
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216Sep Sep
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Figure 1. Daily rainfall distribution during the growing season at Tum, Nigeria in 2007 and 2008.
6000 S.E.D
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5000 4000 3000 2000 1000 0
0
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100
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Figure 2. Mean grain yield at different nitrogen rates in Tum. Values are averages across years and varieties.
a quadratic grain yield response to nitrogen rates with 90% maximum grain yield obtained at 120 kg N ha-1 in -1 Palimital, Brazil. Application of 100 kg N ha increased grain yield by 42 and 153% over the yields obtained at 30 kg N ha-1 and without fertilization, respectively. Grain yield at 30 kg N ha-1 was 78% higher than the yield from the unfertilized treatment suggesting yield benefits even at lower rates of fertilization. All the NERICAs yielded higher in 2008 than in 2007 (Table 1). The higher grain yields of the NERICAs in 2008 may be associated with adequate moisture in the soil than in 2007. NERICA-L-41 out-yielded ITA 150 by about 14.3%, NERICA-L-42 by 35.7%, NERICA-L-12 and NERICA-L-56 by 7% in 2007. In 2008, NERICA-L-12 produced the highest grain yield of 4.9 mg ha-1 among the NERICAs evaluated. It outyielded the check, ITA 150 by 69%. In Niamey, Niger, grain yield of about 6.5 Mg ha-1 was reported for NERICA-L-41 (Sido et al., 2006). Baibinge (2006) reported grain yields that ranged from 2.7 to 4.5
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Table 1. Effect of variety and year on grain yield at Tum. -1
Grain yield (kg ha ) 2007 2008 Mean 3212.2 2916.9 2897.7 3430.2 4930.7 3885.3 2705.5 4482.4 3350.7 3672.0 3966.4 3617.5 3371.2 4660.3 3742.3 274.1 387.6
Variety ITA 150 NERICA-L-12 NERICA-L-42 NERICA-L-41 NERICA-L-56 S.E.D V S.E.D Y × V
S. E. D = Standard error of difference.
Spikelet number panicle-1
2007 S.E.D
16
2008
12 8 4 0
0
30 Nitrogen rates (kg ha-1)
100
Figure 3. Mean number of spikelets panicle-1 at different nitrogen rates in 2007 and 2008 at Tum. Values are averages across varieties.
mg ha-1 for other rain-fed lowland NERICAs evaluated in the DR Congo. This confirms the high yield potential of these varieties. Grain yield of NERICA-L-42 was the most affected by moisture stress in 2007 than the other -1 varieties. It was greater by 1776.9 kg ha (66%) in 2008 than 2007 when rainfall was relatively uniform suggesting that it is not drought-tolerant. Grain yield of ITA 150 was lower in 2008 than in 2007 by 9.2%, probably in response to the adequate moisture in 2008. The yield of this variety in 2007 was similar to the yield reported (3.17 t ha-1 in plots weeded twice) for rain-fed upland production system in the same agroecosystem by Ekeleme et al. (2009). This suggests that rainfall distribution and soil water content was adequate for this variety in 2007. Although this variety was developed for upland ecosystem, farmers in the study area have for the past 15 years cultivated it in both rain-fed upland and lowland ecosystems in the savannas of Nigeria due to lack of appropriate varieties. Our results showed that it is not suitable for production in lowland ecologies.
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Yield components Nitrogen fertilization had significant effects on number of spikelets panicle-1 (P < 0.05) and number of grains panicle-1 (P < 0.001). The interaction of year and nitrogen fertilization was significant for number of spikelets panicle-1 and grains panicle-1 (P < 0.05), but not for 1000grain weight (P = 0.3250). Mean number of grains panicle-1 and 1000-grain weight varied significantly (P < 0.05) among varieties. Differences among varieties were not significant for number of spikelets per panicle. Year × variety interaction was significant for 1000-grain weight (P = 0.0269). Grain yield in rice is a function of panicles per unit area, number of spikelets per panicle, 1000-grain weight and spikelet sterility (Fageria and Baligar, 2001). Therefore it is important to understand the management practices that influence yield components and consequently grain yield. Number of spikelets panicle-1 was higher in 2008 than in 2007 at all nitrogen rates. The difference in number of spikelets panicle-1 between the two years was greater in the unfertilised treatment (Figure 3) The native soil nitrogen may not have been sufficient for spikelet differentiation and development as noted by Fagaria and Baligar (2001). Nitrogen application influenced number of spikelets per panicle significantly. In both years, number of spikelets increased with increasing nitrogen rates. Similar results were reported by Mauad et al. (2003) in Brazil and Ahmed et al. (2005) in Bangladesh. This is important because high spikelet density has been reported to be associated with increased yield in rice (Hasegawa et al., 1994). On the contrary, Arf (1993) did not obtain an increment in the number of spikelets per panicle with increasing nitrogen rates. In both years, application of 100 kg N ha-1 increased spikelet number panicle-1 by 19 to 22% over the number obtained at 30 kg N ha-1, and 70 to 88% compared with when nitrogen was not applied. In 2007, number of grains panicle-1 at 30 and 100 kg N ha-1 were comparable but significantly higher than the number obtained without fertilization (Figure 4a). In 2008, number of grains panicle-1 increased significantly with increments -1 in nitrogen rates. At 100 kg N ha the number of grains -1 panicle was higher in 2008 than in 2007 when there was moisture stress, while the values were similar at other rates, suggesting that the effect of drought on the grains was more severe at high than at low nitrogen rates as previously reported for upland NERICAs (Oikeh et al., 2009). Averaged across years and variety, number of grains panicle-1 increased with increment in nitrogen -1 rates. Mean number of grains panicle was 53.4 ± 2.08 -2 -1 -2 -1 m at 0 kg N ha , 66.9 ± 3.07 m at 30 kg N ha and -1 81.4 ± 3.91 at 100 kg N ha . The number of grains panicle-1 on ITA 150 and NERICA-L-42 were comparable but were 13 to 17%, significantly higher than those produced on the other varieties (Figure 4b). Number of -1 grains panicle on NERICA-L-12, NERICA-L-41 and NERICA-L-56 were similar. Number of grains panicle-1
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Number of grains panicle-1
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100 Number of grains panicle-1
S.E.D
B
80 60 40 20 0 ITA150
NL12
NL41
NL42
NL56
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Figure 4. Mean number of grains panicle-1 as influenced by nitrogen rates (A) and variety (B) at Tum.
35 S.E.D B
1000-grain weight (g)
30
2007 2008
25 20 15 10 5
to the production of larger number of grains per panicle and subsequently higher grain yields of the varieties compared to 2007. Weight of 1000-grains (grain size) did not differ among nitrogen rates in both years (P > 0.05). There was no significant correlation between grain size and yield. Our result is in support of previous studies on upland NERICA rice in Nigeria which indicated no significant influence of nitrogen on grain size (Oikeh et al., 2008), but it is in contrast with the result of Fageria and Baligar (2001) who reported that the weight of 1000-grains increased significantly and quadratically with increasing nitrogen rates in Brazil. Other studies reported that the weight of 1000-grain decreased with increasing nitrogen rates (Mauad et al., 2003; Arf, 1993). Surekha et al. (2006) reported that the weight of 1000-grains was not affected significantly by crop management practices. Previous studies have considered grain weight as a genetic trait (Yoshida, 1972; Mauad et al., 2003; Surekha et al., 2006) which could possibly explain the inconsistent response to nitrogen fertilization and crop management practices. Weight of 1000 grains of ITA 150 and NERICA-L-12 was higher in 2007 than in 2008 (Figure 5). They also had higher 1000-weight than the other varieties possibly due to their earliness, which enabled them to escape the terminal drought that occurred in 2007. When rainfall was sufficient and well distributed in 2008, NERICA-L-56, NERICA-L-41 and NERICA-L-42 had higher grain weight than in 2007. Conclusions Nitrogen application increased rice grain yield and yield components with the highest grain yield obtained at 100 kg N ha-1. N application at even lower rates significantly increased grain yield of the rice varieties suggesting that N is a major limiting nutrient in the study area. All the rice varieties responded similarly to nitrogen application. Average across N rates, NERICA –L-12 and NERICA-L41 produced higher grain yield than the others. The least grain yield was produced by IT 150, suggesting that it is not suitable for production in the lowland ecologies. ACKNOWLEDGEMENTS
0 ITA150
NL12
NL41
NL42
NL56
Varieties
Figure 5. Mean 1000-grain weight of different rice varieties in 2007 and 2008 at Tum. Values are averages across nitrogen rates.
The authors thank the Canadian International Development Agency (CIDA) for funding the Project, PROSAB (Promoting Sustainable Agriculture in Borno State), which sponsored this study. The field technicians at IITA/PROSAB are acknowledged for managing the research fields. REFERENCES
was positively and significantly correlated with grain yield in 2008 (r = 0.64; P =
