New Rice For Africa Varieties Research Articles

English

Climate change and inefficient water utilization have led to marked fluctuations of the mean rice crop production in sub-Sahara Africa. In order to improve food security and households’ income, adaptation strategies to climate change such as the adoption of new rice varieties are inevitable. This study examined the farmers’ perception and adoption of climate change friendly New Rice for Africa in Mwea West Sub-county. The study applied the descriptive survey design with questionnaires being administered to a sample of 376 farmers. Key informants included four officers from Mwea Irrigation Agricultural Development and the Ministry of Agriculture. Quantitative data were analysed using Statistical Package for Social Sciences whereas qualitative data were analysed through establishing the categories and themes, relationships/patterns, and conclusions drawn in line with the study objectives. Results indicated a highly significant difference in adoption between farmers affiliated to Mwea Irrigation Scheme and the out-growers (X2= 18.5, df =2, p= 1.67×10-6). The study concluded that the adoption of New Rice for Africa varieties in the Mwea West Sub-county is low and slow. This is mainly caused by inadequate information among the farmers as well as low market demand for the rice varieties. There is a need to enhance these rice varieties by intensifying efforts to sensitize farmers.   Key words: Climate change, new rice for Africa, adaptation strategies.

Određivanje reoloških osobina pojedinih varijatiteta nove sorte pirinča (NERICA) relevantnih za preradu

The pasting properties of some NERICA (New Rice for Africa) varieties were determined using the rapid visco-analytical machine (RVA). The studied varieties include FARO 44, FARO 52, FARO 57, FARO 60, and FARO 61. The parameters assessed include the pasting temperature, peak time, peak or maximum viscosity, hot paste viscosity or trough, cold paste or final viscosity, breakdown, and setback. Results obtained indicated that the pasting characteristics of NERICA varieties studied exhibited good pasting behavior. Results showed that peak viscosity, final viscosity, hot paste viscosity, breakdown, and setback ranged from 30.83 to 85.17 RVU; 62.21 to 167.13 RVU; 25.83 to 76.88 RVU; and 5.01 to 8.29 RVU; and 31.38 to 81.96 RVU, respectively. There were significant effects of moisture content and temperature (p < 0.05) on all parameters studied. These generated results of the pasting characteristics of NERICA will be extremely useful in determining their suitability in food and other relevant industries.

History and progress in genetic improvement for enhancing rice yield in sub-Saharan Africa

Abstract Genetic improvement has been given high priority in rice research for development in sub-Saharan Africa (SSA). This paper provides an overview of historical efforts of genetic improvement in SSA focused on improving rice productivity. It further describes yield gain of new rice varieties evaluated in recent field experiments in four selected breeding target domains, and summarizes adoption studies on rice varieties. Efforts to develop rice varieties adapted to diverse rice production systems in SSA have been made by several research organizations, including national agricultural research institutes, bilateral organizations, and three CGIAR centers. The efforts have resulted in the release of around 570 rice varieties in 10 major rice-producing SSA countries by 2020. Among these varieties, the most well-known are interspecfic upland rice varieties “New Rice for Africa (NERICA)” that were developed from crosses between improved Oryza sativa tropical japonica and Oryza glaberrima varieties. However, recent field assessements demonstrated that upland rice yield can be further improved through introduction of upland indica materials from Asia. In contrast, lowland interspecific rice varieties out-yielded the previously released improved O. sativa varieties in selected SSA countries. Field assessments in Senegal and Madagascar did not demonstrate the yield advantage of the recently-developed varieties including hybrids over best performing ones released before. The adoption level of improved varieties in terms of share of area occupied by improved varieties in 18 SSA countries was 40 % in 2008 with old varieties that were released before 2000 being dominant and 7% of the total rice area occupied by NERICA varieties. Especially in irrigated and rainfed lowland rice systems, the majority of dominant varieties were still those introduced from Asia. Panel data between 2002 and 2019 from the Senegal River Valley also confirmed this, and Sahel 108, which was introduced from Asia and released in Senegal in 1994, accounted for >70 % of the total rice area in both the wet and dry seasons in 2019. The implications of this review for future rice genetic improvement and varietal replacement in SSA are discussed.

A method for evaluating cold tolerance in rice during reproductive growth stages under natural low-temperature conditions in tropical highlands in Kenya

ABSTRACT Cold tolerance of New Rice for Africa (NERICA) and their parent varieties was evaluated under natural air temperature conditions of Kenyan tropical highlands using the multiple-sown field evaluation method. Rice varieties were cultivated 10 times to expose them to a shift in temperature during 20-day periods before heading (critical period), measuring the average daily mean temperature during the critical period (Tmean) for each variety and filled grain ratio, which was used as an indicator of cold tolerance. Tmean of each variety was low in 6 out of 10 experiments. In the remaining four high-temperature experiments, there were no significant varietal differences in filled grain ratio. In the six low-temperature experiments, all varieties experienced 20.1−21.5°C Tmean. After comparison under virtually the same cold stress, NERICA 1, 3, 4, 7−10, 12, 17, 18, and WAB 56–104 were judged as cold-tolerant; NERICA 2, 5, 11, 13, and 14, and WAB 56–50 and 181–18 were moderately tolerant, and NERICA 6, 15, and 16 were cold-susceptible varieties. These evaluations generally corresponded with previous experimental results under temperature-controlled environments, showing the practicality of multiple-sown field cold tolerance evaluation in Kenya. It also indicated that NERICA varieties, which recorded different levels of cold tolerance and whose average number of days to heading in all experiments were 66−78, are suitable as a set of standard check varieties in this region to evaluate cold tolerance of rice varieties with this range of days to heading.

Root and shoot responses of upland New Rice for Africa varieties to fluctuating soil moisture conditions as affected by different levels of nitrogen fertilization

AbstractDrought cycling and soil re‐watering trends due to intermittent rainfall patterns are key stress factors that influence rice growth and yield under upland cultivation conditions. However, upland rice adaptation responses to fluctuating soil moisture conditions remain poorly understood. This study investigated root and shoot responses of upland New Rice for Africa (NERICA) varieties to episodic drought and re‐watering during growth. We examined root and shoot growth of NERICA 1 and NERICA 4 compared with those of IR72, an improved lowland variety, and Dular, a traditional drought‐tolerant variety, in terms of soil moisture fluctuations with different levels of nitrogen fertilization under field conditions that impeded deep root development. During soil moisture fluctuation, all varieties reduced shoot dry weight compared with well‐watered plants, regardless of nitrogen fertilization levels. However, total root length for the three upland varieties was enhanced by soil moisture fluctuations at moderate and high nitrogen fertilization, while that of the lowland variety was reduced. Comparing root development during water fluctuations revealed that NERICA 1 had a greater root system than NERICA 4, which was attributed to lateral root development. Furthermore, we found that NERICA varieties increase lateral root mass during soil desiccation under adequate nitrogen fertilization, while Dular and IR72 reduced their root growth rate during drought and increased it after re‐watering. Both root growth patterns developed, from around maximum tillering to heading. The analysis of regression between root elongation and shoot growth with fluctuating soil moisture indicated that an enhanced root system during drought, on adequate nitrogen fertilization, can contribute to shoot growth when sufficient water becomes available, specifically around the maximum tillering to the heading growth stage of rice.

Agronomic Assessment of Upland Rice Varieties under Unpredictable Rains in the Semi-Arid Conditions of South-Western Agro-Ecological Zone of Uganda

This paper examined agronomic performance of three upland New RICE for Africa (NERICA) varieties promoted by the Government of Uganda in its efforts to improve household food and income security among smallholder farmers. Three rain-fed experimental trials were conducted on station at Mbarara Zonal Agricultural Research and Development Institute (MBAZARDI), with semi-arid climate conditions typical of more than 50% of the South-Western Agro-Ecological Zone (SWAEZ) of Uganda. The experimental trials were established in the long rain seasons that often occur in September-December period. But results for only one successful long rain seasonal trial of 2010 are presented in this paper. Successful experimental trial for upland NERICA had an average precipitation of 130 mm that was well distributed especially from booting stage, which is the most sensitive growth stage for upland NERICA. During the growth period, NERICA 1 and NERICA 4 were significantly taller (p -1. Although, NERICA 4 ranked top in terms of grain yields among the tested upland NERICA varieties and therefore, most possible candidate for smallholder rice farmers in the humid parts of the SWAEZ, it called for more breeding for upland NERICA varieties with traits that could increase their tolerance to low soil moisture most prevalent in the SWAEZ.

Cultivation systems using vegetation cover Improves Sustainable Production and Nutritional Quality of New Rice for Africa in the Tropics

Little is known about the impact of direct sowing under vegetation cover on the production and quality of New Rice for Africa (NERICA) on poor oxisol. In this study, two NERICA varieties (NERICA 3 and NERICA 8) were grown under tropical oxisol soil with very low nutrient contents. Four cultivation systems were used in completely randomized block design, including plowing (control), unplowed soil with dead vegetation cover (DVC), unplowed soil with live vegetation cover (LVC) and unplowed soil with mixed vegetation cover (MVC). DVC significantly improved the exponential growth of NERICAs. NERICA 3 was the more productive (2.16–3.05t/hm2) compared with NERICA 8 (0.71–1.21t/hm2). Cultivation systems improved the nutritional quality of NERICAs. The total protein content of NERICA 3 under DVC and MVC was 84.8% and 75.0% higher than control, respectively. The total soluble carbohydrate contents of NERICA 8 under LVC and MVC was 73.2% and 57.3% higher than control, respectively. These results suggested that conservative approach like direct sowing on unplowed soil with vegetation cover systems can improve the nutritional quality of rainfed NERICAs and their sustainable production under poor oxisol soil in sub-Saharan Africa.

Comparative whole genome re-sequencing analysis in upland New Rice for Africa: insights into the breeding history and respective genome compositions

BackgroundIncreasing rice demand is one of the consequences of the steadily improving socio-economic status of the African countries. New Rice for Africa (NERICA), which are interspecific hybrids between Asian and African rice varieties, are one of successful breeding products utilizing biodiversity across the two different rice crop species. Upland NERICA varieties (NU) exhibit agronomic traits of value for the harsh eco-geography, including shorter duration, higher yield and stress tolerance, compared to local African varieties. However, the molecular basis of the traits in NU varieties is largely unknown.ResultsWhole genome re-sequencing was performed of four NU lines (3, 4, 5, and 7) and for the parental Oryza sativa WAB56–104 and Oryza glaberrima CG14. The k-mer analysis predicted large genomes for the four NU lines, most likely inherited from WAB56–104. Approximately 3.1, 0.10, and 0.40 million single nucleotide polymorphisms, multi nucleotide polymorphisms, and short insertions/deletions were mined between the parental lines, respectively. Integrated analysis with another four NU lines (1, 2, 8, and 9) showed that the ratios of the donor CG14 allelic sites in the NU lines ranged from 1.3 to 9.8%. High resolution graphical genotype indicated genome-level similarities and common genetic events during the breeding process: five xyloglucan fucosyltransferase from O. glaberrima were introgressed in common. Segregation of genic segments revealed potential causal genes for some agronomic traits including grain shattering, awnness, susceptibility to bacterial leaf bright, and salt tolerance. Analysis of unmapped sequences against the reference cultivar Nipponbare indicated existence of unique genes for pathogen and abiotic stress resistance in the NU varieties.ConclusionsThe results provide understanding of NU genomes for rice improvement for Africa reinforcing local capacity for food security and insights into molecular events in breeding of interspecific hybrid crops.

Assessment of Genetic Variation and Population Structure of Diverse Rice Genotypes Adapted to Lowland and Upland Ecologies in Africa Using SNPs.

Using interspecific crosses involving Oryza glaberrima Steud. as donor and O. sativa L. as recurrent parents, rice breeders at the Africa Rice Center developed several ‘New Rice for Africa (NERICA)’ improved varieties. A smaller number of interspecific and intraspecific varieties have also been released as ‘Advanced Rice for Africa (ARICA)’. The objective of the present study was to investigate the genetic variation, relatedness, and population structure of 330 widely used rice genotypes in Africa using DArTseq-based single nucleotide polymorphisms (SNPs). A sample of 11 ARICAs, 85 NERICAs, 62 O. sativa spp. japonica, and 172 O. sativa spp. indica genotypes were genotyped with 27,560 SNPs using diversity array technology (DArT)-based sequencing (DArTseq) platform. Nearly 66% of the SNPs were polymorphic, of which 15,020 SNPs were mapped to the 12 rice chromosomes. Genetic distance between pairs of genotypes that belong to indica, japonica, ARICA, and NERICA varied from 0.016 to 0.623, from 0.020 to 0.692, from 0.075 to 0.763, and from 0.014 to 0.644, respectively. The proportion of pairs of genotypes with genetic distance > 0.400 was the largest within NERICAs (35.1% of the pairs) followed by ARICAs (18.2%), japonica (17.4%), and indica (5.6%). We found one pair of japonica, 11 pairs of indica, and 35 pairs of NERICA genotypes differing by <2% of the total scored alleles, which was due to 26 pairs of genotypes with identical pedigrees. Cluster analysis, principal component analysis, and the model-based population structure analysis all revealed two distinct groups corresponding to the lowland (primarily indica and lowland NERICAs) and upland (japonica and upland NERICAs) growing ecologies. Most of the interspecific lowland NERICAs formed a sub-group, likely caused by differences in the O. glaberrima genome as compared with the indica genotypes. Analysis of molecular variance revealed very great genetic differentiation (FST = 0.688) between the lowland and upland ecologies, and 31.2% of variation attributable to differences within cluster groups. About 8% (1,197 of 15,020) of the 15,020 SNPs were significantly (P < 0.05) different between the lowland and upland ecologies and formed contrasting haplotypes that could clearly discriminate lowland from upland genotypes. This is the first study using high density markers that characterized NERICA and ARICA varieties in comparison with indica and japonica varieties widely used in Africa, which could aid rice breeders on parent selection for developing new improved rice germplasm.

Technical Efficiency And Impact Evaluation Differentials Between The Adopters And Non-adopters Of Nerica In The Six Baseline States In Nigeria

The study examined the adoption rate of New Rice for Africa (NERICA), technical efficiency differentials of production of these varieties between adopters and non-adopters and the determinants. It further analysed the impact of adoption of NERICA on area cultivated, output, yield, expenditure and total income of rice farmers in the NERICA baseline states in Nigeria. To achieve the objectives, it employed the descriptive statistics, stochastic production frontier and counterfactual outcomes framework of modern evaluation technique (the Local Average Treatment Effect) to analyse 621 rice farmers across the six NERICA baseline states in Nigeria in 2012. The findings show that NERICA adopters were more technically efficient than the non-adopters. In addition, adoption of NERICA was found to significantly increase the areas of land cultivated, output, yield, household expenditure, per capita household expenditure and total income among NERICA adopters by 1.2ha (p < 0.01), 1998.2kg (p< 0.01), 191.2kg/ha (p < 0.1), N13,222.63≈$66.4 (p < 0.05), N2,015.6≈$10.1 (p < 0.05) and N145,098.7 ≈$728.0 (p < 0.01) respectively despite their high level of inefficiency (39 percent) by the adopters. The positive impact of NERICA adoption on rice yields, poverty status measured by the per capita household expenditure and total farm income of farmers is a clear indication that NERICA has the potential to increase rice productivity, reduce poverty and food insecurity. NERICA adoption rate will rise if more farmers are aware of the varieties in the study. Farmers who had adopted, and government at all levels should therefore intensify their efforts to encourage others rice farmers possibly through the extension agents on the need to grow NERICA varieties so as to increase rice production level, reduce rice importation and ensure a sustainable rice production.

Drought-induced root plasticity of two upland NERICA varieties under conditions with contrasting soil depth characteristics

To identify differences in root plasticity patterns of two upland New Rice for Africa (NERICA) varieties, NERICA 1 and 4, in response to drought under conditions with contrasting soil profile characteristics, soil moisture gradients were imposed using a sloping bed system with depths ranging 30–65 cm and a line-source sprinkler system with a uniformly shallow soil layer of 20 cm depth. Varietal differences in shoot and root growths were identified only under moderate drought conditions, 11–18% v/v soil moisture content. Further, under moderate drought soil conditions where roots could penetrate into the deep soil layer, deep root development was greater in NERICA 4 than in NERICA 1, which contributed to maintaining dry matter production. However, under soil conditions with underground impediment to deep root development, higher shoot dry weight was noted for NERICA 1 than for NERICA 4 at 11–18% v/v soil moisture content, which was attributed to increased lateral root development in the shallow soil layer in NERICA 1. Enhanced lateral root development in the 0–20-cm soil layer was identified in NERICA 1 even under soil conditions without an impediment to deep root development; however, this did not contribute to maintaining dry matter production in upland rice. Thus, we show different root developmental traits associated with drought avoidance in the two NERICA varieties, and that desirable root traits for upland rice cultivation vary depending on the target soil environment, such as the distribution of soil moisture and root penetration resistance.

Factors affecting farmers’ adoption of NERICA upland rice varieties: the case of a seed producing village in central Benin

We investigated dissemination processes of New Rice for Africa (NERICA) varieties in central Benin in 2009 through structured interviews with 1,390 farmers and semi-structured interviews with 203 farmers. By 2009, 74 % of farmers belonging to a farmer group had experience of growing NERICA varieties, while only 29 % of farmers who did not belong to the group had such experience. This difference was attributed to approaches used by the public extension service, which has mainly worked with farmer groups as an entry point for NERICA dissemination. As women accounted for 70 % of farmers in farmer groups, this approach achieved gender equality on the adoption of NERICA varieties. The seed production business has become an incentive for farmers to grow NERICA varieties, as their seed may be purchased at higher than local market price by the public sector for further dissemination. Male farmers tended to sell greater amounts of NERICA varieties, as female farmers have limited land for their cultivation. Around 20 % of farmers had stopped growing NERICA varieties, because they did not receive proper information on their characteristics and the cultivation methods required. They therefore could not be involved in the seed business. Farmers who had never grown NERICA varieties reported that they had limited access to seed. Thus, opportunities to access technologies and business opportunities should be made equal for farmers, especially when they are introduced. In particular, farmer-to-farmer seed exchange needs to be enhanced.

Evaluation of Different Improved Upland Rice Varieties for Low Soil Nitrogen Adaptability

Scarcity of nitrogen fertilizer is a major constraint to rice production particularly in developing countries. Low soil fertility prevalent in farmer’s fields has led to low rice yields and the ever escalating fertilizer prices have made this important input unaffordable to most smallholder farmers who have limited resources for purchasing the required inputs. The Mwea Upland rice (MWUR) varieties were bred under low fertilizer input environment while other authors have indicated that the New Rice for Africa (NERICA) gives high yields under low input conditions. There is therefore need to identify the superior rice varieties that are adaptable to low nitrogen levels. Thus, the objective of this study was to investigate the effects of different rates of nitrogen fertilizer on improved upland rice varieties and identify the low input adaptable varieties. Field studies were conducted at Alupe in Western Kenya under rainfed upland conditions between August 2012 and April 2013. The experiment layout was split plot factorial in a Randomized Complete Block Design with three replicates. The main plot treatments were four rates of nitrogen fertilizer levels which were; 0 (control), 40, 80 and 120 kg ha-1 applied as calcium ammonium nitrate (26% N) in two equal splits; 21 days after sowing (DAS) and at panicle initiation (46 DAS). Sub-plots consisted of Original Research Article Sikuku et al; IJPSS, 5(1): 40-49, 2015; Article no.IJPSS.2015.058 41 four MWUR varieties namely MWUR 1, MWUR 2, MWUR 3, MWUR 4; and four NERICA varieties namely NERICA 1, NERICA 4, NERICA 10 and NERICA 11. The parameters measured included plant height, tiller number, filled grain ratio percentage and yield components. In the study, nitrogen treatment showed significant effect on plant growth and the measured parameters increased significantly with increase in nitrogen level. MWUR varieties studied were more adaptable to low nitrogen conditions as compared to NERICA varieties. The NERICA varieties recorded higher yield at high nitrogen levels as compared to MWUR varieties. However, NERICA 4 gave higher yield as compared to other NERICA varieties regardless of the nitrogen level. Results from our study suggest that MWUR 1 and 2 and NERICA 4 were more tolerant to low nitrogen as compared to MWUR 3 and 4 and NERICA 1, 10 and 11, because of higher height, more tiller number, higher filled grain ratio percentage and higher yield component as compared to the other studied varieties and may be suitable for soils low in nitrogen.

Identification of QTLs and candidate genes for days to heading in an upland New Rice for Africa (NERICA) variety

To produce rice varieties adaptable to unfavorable environments in Africa, New Rice for Africa (NERICA) varieties have been developed by inter-specific crossings. The basic idea of NERICA was to combine the useful characteristics of the African rice species Oryza glaberrima and an Asian rice species, Oryza sativa. However, the genetic basis of the agronomic characteristics of NERICA varieties is not fully understood. We performed a QTL analysis to examine the genetic basis of days to heading (DTH) in an upland variety, NERICA10. We found that NERICA10 had weaker photoperiod sensitivity (PS) and shorter DTH under long day-length conditions than its parental varieties. We then examined QTLs controlling DTH under natural long-day-length conditions by using segregating populations. We found three QTLs for DTH, on chromosomes 4, 6, and 8. Among them, qDTH8.1, located on chromosome 8, had the strongest effect. By comparing nucleotide sequences, we found that NERICA10 had a loss of the functional allele of DTH8, which was located in the candidate region of qDTH8.1. These results suggested that loss of function of DTH8 is the causal factor of weakened PS in NERICA10. The information on these QTLs will be useful for improving rice varieties for better adaption to African conditions.

Response of new rice for Africa (NERICA) varieties to different levels of nitrogen fertilization in Zimbabwe

The new rice for Africa (NERICA) varieties were bred and released in West Africa. This rice has high yield, good quality and other agronomic traits that include adaptability to harsh environments found in Africa. Zimbabwe, recently introduced NERICA varieties, however, the best performing NERICA varieties under local conditions were not known and the optimum level of nitrogen fertilization for those varieties was unknown. A study was carried out to evaluate the response of introduced NERICA varieties to different levels of nitrogen fertilization in Zimbabwe during the 2011/2012 summer season. A four by four factorial experiment in a randomized complete block design was used. One factor consisted of four levels of nitrogen (0, 39.5, 64.5, and 89.5 kg / ha) and the other had four varieties (NERICA 1, NERICA 3, NERICA 7 and Mhara 1). Analysis of variance showed that there was no significant interaction between nitrogen fertilization rates and varieties. However, significant nitrogen effects (P < 0.05) were found on plant height, panicle length, filled grains per panicle, unfilled grains per panicle, grains per panicle and grain yield. Grain yield for level 1 (0 kg N / ha) was significantly reduced compared to nitrogen addition, but level 2 (39.5 kg N / ha), level 3 (64.5 kg N / ha) and level 4 (89.5 kg N / ha) were not significantly different. This showed that the optimum level of nitrogen fertilization is 39.5 kg N / ha. Varieties showed significant differences (P < 0.05) for days to 50% heading, plant height, filled grains per panicle, filled grain ratio, grains per panicle, 1000 grain weight and grain yield. All NERICA varieties performed better than the local check variety, Mhara 1 and NERICA 3 had the best yield followed by NERICA 7. Growing of these NERICA varieties using the nitrogen rate of 39.5 kg / ha can boost rice yield in Zimbabwe. Key words: Upland rice, new rice for Africa, nitrogen fertilization, grain yield.

Effects of NERICA - Cowpea intercropping systems on yield components and productivity of NERICA and Cowpea

New rice for Africa (NERICA) 1 and 2 are rice types recently introduced to upland farmers of West Africa by AfricaRice. Farmers in Ghana usually intercrop rice with other crops such as cowpea. The new rice types however have not been assessed for their suitability as intercropping partners of the other crops (for example, cowpea) grown in the savannah uplands of Ghana. Experiments were conducted at the upland rice experimental fields of the CSIR-Savanna Agricultural Research Institute (CSIR-SARI) in June 2008 and 2009 to determine appropriate cropping systems for cowpea and NERICA. The treatments composed of four intercropping systems, viz, sole cropping, strip cropping, alternate rows cropping and alternate hills cropping in a randomized complete block with three replicates. The results indicated considerable variations in yields and yield components of NERICA 1 and 2 in the presence of a companion crop, cowpea. Alternate rows of NERICA and cowpea consistently gave higher numerical cowpea grain yields, although not significantly different from the other intercrops. Yields of cowpea in partnership with NERICA 2 were generally higher than when partnered with NERICA 1. Economic analysis indicated that, given the choice of NERICA varieties, rice farmers who prefer NERICA 1 will have a better return to investment with alternate hills intercropping system while those who prefer NERICA 2 will be better off with the strip cropping system. Cowpea farmers on the other hand are better off with the alternate row cropping system. Key words: Land equivalent ratios (LER), new rice for Africa (NERICA), sustainable cropping systems, Vigna unguiculata L.

Determinant of technical efficiency of new rice for Africa (NERICA) production: A gender approach

The study estimated the determinants of technical efficiency of new rice for Africa (NERICA) in Ekiti State of Nigeria. It specifically estimated technical efficiency of NERICA production among the female and male farmers. Seven villages where NERICA diffusion activities trials were conducted werechosen through purposive sampling and data for the study were obtained from a total of 315 respondents who provided useful information through face-face interview using structured pre-tested questionnaires. Data analysis was done using Cobb – Douglas Stochastic parametric frontier model to elicit the technical efficiency. The results for all the rice farmers indicated that positive coefficient of farm size, family labour, hired labour quantity of fertilizer and herbicide used indicates that as each of these variables are increased, rice output increases. The negative sign of the seeds implies that seed is being over utilized suggesting an inefficient use of planting material in the production of rice in the study area. The mean technical efficiency is 75 % which implies that on the average, the respondents were able to obtain only 75 % of the optimal output from a given mix of production inputs. The study also showed that the mean technical efficiencies for female and male farmers were 71 % and 84% respectively. Therefore, it is recommended that more female farmers should be encouraged to plant NERICA varieties and they should be provided with credit and land tenure security. Also, concerted effort should be made to increase farmers’ farm size and they should be encouraged to use more fertilizer irrespective of their gender.Key words: Variables, Technical, Efficiency, NERICA, Rice, Farmers and Africa.

English

Luxuriant weed growth destroying rice crops is a major problem in tropical Africa. The objective of this study was to determine the critical period of weed infestation in upland rice varieties in order to enable the development of more precise weed management recommendations for farmers. The effects of 10 differing periods of weed management on upland rice yield were studied in experiments with five rice varieties (three interspecific NERICA: NERICA1, NERICA2, and NERICA4) and the parents (Oryza sativa&nbsp;WAB 56-104 andOryza glaberrima&nbsp;CG 14) during the 2004 and 2005 rainy seasons at Farako (Mali). INTERCOM model was used to explore the relationship between duration and timing of weed competition and rice crop yield loss, and the applicability of the model in rice cropping based weed management. The critical period of weed infestation determined from the field experiment was similar for the three New Rice for Africa (NERICA) varieties and theO. sativa&nbsp;parent (WAB 56-104), and was between 14 and 42 days after seeding (DAS). For the&nbsp;O. glaberrimaparent (CG 14), the critical period was between 28 and 42 DAS. Weed competition either before or after these critical periods had negligible effects on crop yield. During the 2 years, yields of NERICA varieties and WAB 56-104 averaged 2700 and 400 kg ha-1&nbsp;under weed-free plots and no weed control plots, respectively, indicating a yield loss of 85%. For GG 14, yields averaged 900 and 300 kg ha-1&nbsp;under weed-free plots and no weed control plots, respectively, resulting in a 66% yield loss. The occurrence and composition of weeds during the two years were similar with a mean of 40% broadleaves, 35% grasses and 25% sedges. The most important weeds were&nbsp;Imperata cylindrica,&nbsp;Cyperus sphacelatus&nbsp;and&nbsp;Digitaria longiflora. During both calibration and testing efforts, the INTERCOM model satisfactorily simulated rice NERICA1 LAI, shoot dry weight and yields (r2&nbsp;ranging from 0.71 to 0.87). There appears to be room for improvement in the model with regard to the assumption that nutrients are not limiting to crop growth, but the use of the model for simulating the interactions between rice crop yield losses, weed density, and duration of weed competition appears promising. Results of this study can serve as a guide for optimum timing of weed control to maximize upland rice yield in West Africa. &nbsp; Key words:&nbsp;Critical period, northern Guinea savanna, upland rice, New Rice for Africa (NERICA), INTERCOM.

Physiological and biochemical responses of five nerica rice varieties (Oryza sativa L.) to water deficit at vegetative and reproductive stage

Food shortage is a major problem in sub Saharan Africa as population increases. Over 89% of Kenyans are food poor and are malnourished especially in rural areas. NERICA (New Rice for Africa) are high yielding rainfed rice varieties with early maturity and has shown high potential to revolutionize rice farming even in Africa’s stress afflicted ecologies. However, NERICA varieties vary in their response to water deficit. A pot experiment was conducted in 2009 at the Maseno University Botanic garden, to evaluate the responses of five NERICA varieties (NERICA1, NERICA 2, NERICA 3, NERICA 4 and NERICA 5) to water deficit during their vegetative or reproductive stage of their development. The response pattern of physiological and biochemical parameters to water deficit imposed at different growth stages might provide basis for selecting the most tolerant variety to water deficit in order to stabilize yield and solve food crisis. The treatments were; T1-irrigating the pots with a litre of water after every two days (Control), T2-water deficit at vegetative stage in which water was withheld by irrigating the plants using one litre of water after every six days from 30-50 days after planting; T3-water deficit at reproductive stage in which water was withheld by irrigating the plants using one litre of water after every six days from 51-71 days after planting. Water deficit caused a significant reduction in physiological parameters i.e. growth, chlorophyll fluorescence and biochemical parameters i.e. chlorophyll and protein content both at vegetative stage and at reproductive stage. However, Growth parameters i.e. plant height, root length and plant dry weight were affected more by water deficit imposed at the vegetative stage as compared to water deficit imposed at the reproductive stage while chlorophyll fluorescence, chlorophyll content and protein content were affected more by water deficit imposed at reproductive stage as compared to water deficit at reproductive stage. The results indicate that NERICA 2 and 4 were tolerant as compared to NERICA 1, 3 and 5 to water deficit occurring at vegetative stage or reproductive stage because their growth, chlorophyll fluorescence and biochemical parameters were least affected.

Genetic characterization of rainfed upland New Rice for Africa (NERICA) varieties

A total of 18 rainfed upland New Rice for Africa (NERICA) varieties were categorized as the heavy panicle and low tillering types and early heading, in compared with 32 different varieties. These chromosome components were clarified using 243 SSR markers which showed polymorphism among NERICA varieties and their parents, CG 14 (O. glaberrima Steud.) and one of the recurrent parents, WAB-56-104 (O. sativa L.). NERICA varieties were classified into three groups, which corresponded with these parents’ continuation including two exceptions, NERICAs 14 and 17, by a cluster analysis using polymorphism data of SSR markers and 14 differential markers among them were selected to classify NERICA varieties. However, three groups: NERICAs, 3 and 4, NERICAs, 8, 9 and 11 and NERICAs, 15 and 16 were not distinguishable. Association analysis was carried out for characterization of NERICA varieties by using SSR markers genotype and phenotype of agronomic traits. A total of 131 quantitative trait loci between SSR markers and 11 agronomic traits were detected. The characteristics of early maturity and heavy panicle of upland NERICA varieties were succeeded from Asian rice varieties and the characteristics of high dry matter production and late heading were introduced from CG 14 and the other varieties.