Alternate phenotype–genotype selection for developing superior high-yielding irrigated rice lines

Increase grain yield potential is one of the most important objectives of any cereal crop breeding program. To efficiently develop superior rice lines by the introgression of favorable alleles for yield and yield component traits, a strategy of alternate phenotype–genotype selection was used. The present study aimed to (i) investigate the allelic diversity of loci associated with major yield-component traits and (ii) phenotype and genotype advanced populations derived from crosses between NERICA-L-20 and Giza178 for yield component traits using agro-morphological descriptors and GRiSP polymorphic markers to select superior high-yielding rice lines. A total of 100 F2:3 progeny were selected from 1000 F2 plants and genotyped with 16 polymorphic markers linked to four major yield- component traits. Four promising F2:3 lines (ARS 563–14, ARS 563–62, ARS 563–286, and ARS 563–41) bearing combinations of desirable alleles were selected. A selected set of 20 F2:4 lines showed moderate to high heritability for all target traits. Fourteen F2:5 lines derived from ARS 563–14 and 17 F2:5 from ARS 563–286 families were evaluated in preliminary trials to estimate yield gain. The three top lines, ARS 563–286–16-1-1, ARS 563–286–5-1-1, and ARS 563–14–10-1-1, showed an increase of more than 10% grain yield over the best check, Sahel 108, which is widely cultivated in the Senegal River valley. The 16 markers linked to the target yield component traits can be used to fast-track breeding programs targeting rice productivity

Effect of Nitrogen Fertilizer Dose and Application Timing on Yield and Nitrogen Use Efficiency of Irrigated Hybrid Rice under Semi-Arid Conditions

Nitrogen fertilizer is the major input in rice production and the optimum rate and application timing management assure profitability and sustainability of the production system. This study aims to investigate hybrid rice response to different nitrogen fertilizer levels and the timing of application and quantify hybrid rice nitrogen use efficiency. Field experiments were conducted during the dry and the wet seasons 2016 at the research station of Africa Rice at Ndiaye in Senegal. Six nitrogen rates (0, 60, 90, 120, 150 and 180 kg N/ha) and three hybrid rice varieties (AR031H, AR032H, AR033H) and one inbred variety (Sahel108) and two nitrogen fertilizer application timings (three split and four split) were combined within a split-split plot design. The results showed significant effect of nitrogen rate and timing on rice grain yield that varied from 4.10 to 11.58 tons/ha and most the yield components. Rice grain yield exhibited curvilinear relationship with the applied nitrogen rates during the dry season under both nitrogen application timings and a linear relationship during the wet season under three splits. Nitrogen rate of 150 kg/ha was revealed optimum with best performance achieved by the Hybrid rice AR033H. Hybrid rice genotypes achieved greater nitrogen use efficiency compared to the inbred rice Sahel108. Hence, hybrid rice genotypes, and nitrogen rate of 150 kg/ha applied in four splits could be recommended to improve rice production and food security for achieving self-sufficiency in rice as targeted by Senegal and the neighboring countries

Assessment of Rice Inbred Lines and Hybrids under Low Fertilizer Levels in Senegal

This research was conducted at the Africa Rice Sahel Regional Station (near Saint Louis, Senegal) during two wet seasons (i.e., July to November) in 2010 and 2011 with the aim of assessing the performances of introduced hybrid cultivars along with an inbred check cultivar under low input fertilizer levels. The five treatments used in this study were (a) the control (without any fertilizer application), (b) 37.5-4.4-8.3 kg N-P-K ha(-1), (c) half of recommend application in Senegal (75-8.75-16.5 kg N-P-K ha(-1)), (d) 112.5-13.3-24.8 kg N-P-K ha(-1), and (e) the recommended application in the country (150-17.5-33 kg N-P-K ha(-1)). There were significant year and cultivar effects for all traits. The fertilizer levels affected significantly most traits except panicle length and 1000-grain weight. The year x fertilizer level and year x cultivar interactions were significant for most traits, but the fertilizer level x cultivar and year x fertilizer level x cultivar interactions were not significant. Days to maturity, plant height, panicle per m2, and grain yield increased with increasing fertilizer levels during the two wet seasons. The grain yield of rice hybrids (bred by the International Rice Research Institute) was not significantly higher than that of the check cultivar widely grown in Senegal. The assessment of other rice hybrid germplasm showing more adaptability to low fertilizer levels will facilitate further hybrid cultivar development in Africa

Microsatellite-aided screening for fertility restorer genes (Rf) facilitates hybrid improvement

DNA markers enabled to determine the chromosomal locations of the two Rf genes (Rf3 and Rf4) in the wild abortive-cytoplasmic male sterility (WA-CMS) system. Four simple sequence repeats (SSR or microsatellites) RM171, RM258, RM315 and RM443 were used to detect the allelic status with respect to the fertility restoring genes (Rf3 and Rf4) in 300 rice cultivars and breeding lines. Furthermore, 45 lines selected using SSR markers were mated with a CMS line (IR58025A) to analyze their restoring ability. The results revealed that 90 lines had Rf3, 65 lines had Rf4 and 45 lines had Rf3 and Rf4 alleles out of 300 lines screened. Offspring of all test lines except HHZ 8-SAL9DT1-Y1, HHZ 5-SAL9-Y3-1 and IDSA 77 exhibited high pollen and spikelet fertility (> 80%), thus confirming they bear Rf alleles. the hybrid offspring of ARH12-6-1-1-B-3-1, IR32307-10-3-2-1 and Sahel329 had the highest pollen and spikelet fertility, (95.1–97, 4%, and 97.1–98.3%, 97.1-96.1% respectively)

In Vitro Assessment of Balanites aegyptiaca Fruit Methanolic Extract on the Adult Toxocara canis

Background: The effectiveness of anthelmintics may diminish within approximately 10 yr of use relying on several factors such as anthelmintic resistance. This study aimed to assess in vitro effect of Balanites aegyptiaca fruits extract on the cuticle of adult worm of Toxocara canis as naturally alternative therapy. Methods: B. aegyptiaca fruits were procured from the local markets in Aswan, Upper Egypt and authenticated at the Herbarium of National Research Centre. The effect of methanolic extract of B. aegyptiaca fruits on adult T. canis after 24 and 48 h incubating the parasites in Ringer solution containing 240 μg/ml Balanites extract was determined by scanning electron microscopy. Results: The main changes induced by treatment with the tested extract were wrinkled cuticular surface and deformed sensory papillae. This cuticular distortion would undoubtedly disrupt its protective function and might be enough to expel Toxocara worms from dog’s intestine. Conclusion: The use of this plant offers a chance for new nematocidal agent, which is economical alternative for the more expensive anthelmintics

Effects of Alternate Wetting and Drying Irrigation Regime and Nitrogen Fertilizer on Yield and Nitrogen Use Efficiency of Irrigated Rice in the Sahel

The objectives of this study were to investigate water saving strategies in the paddy field and to evaluate the performance of some of the newly released rice varieties. Field experiments were conducted at Fanaye in the Senegal River Valley during two rice growing seasons in 2015. Three irrigation regimes ((i) continuous flooding, (ii) trigging irrigation at soil matric potential (SMP) of 30 kPa, (iii) trigging irrigation at SMP of 60 kPa) were tested in an irrigated lowland rice field. Irrigation regimes (ii) and (iii) are alternate wetting and drying (AWD) cycles. Four inbred rice varieties (NERICA S-21, NERICA S-44, Sahel 210 and Sahel 222) and one hybrid rice (Hybrid AR032H) were evaluated under five nitrogen fertilizer rates (0, 50, 100, 150 and 200 kg N ha-1). The results showed that rice yield varied from 0.9 to 12 t ha-1. The maximum yield of 12 t ha-1 was achieved by NERICA S-21 under AWD 30 kPa at 150 kg N ha-1. The AWD irrigation management at 30 kPa resulted in increasing rice yield, rice water use and nitrogen use efficiency and reducing the irrigation applications by 27.3% in comparison with continuous flooding. AWD30 kPa could be adopted as a water saving technology for water productivity under paddy production in the Senegal River Middle Valley. Additional research should be conducted in the upper Valley, where soils are sandier and water is less available, for the sustainability and the adoption of the irrigation water saving practices across the entire Senegal River Valley

Effects of Alternate Wetting and Drying Irrigation Regime and Nitrogen Fertilizer on Yield and Nitrogen Use Efficiency of Irrigated Rice in the Sahel

The objectives of this study were to investigate water saving strategies in the paddy field and to evaluate the performance of some of the newly released rice varieties. Field experiments were conducted at Fanaye in the Senegal River Valley during two rice growing seasons in 2015. Three irrigation regimes ((i) continuous flooding, (ii) trigging irrigation at soil matric potential (SMP) of 30 kPa, (iii) trigging irrigation at SMP of 60 kPa) were tested in an irrigated lowland rice field. Irrigation regimes (ii) and (iii) are alternate wetting and drying (AWD) cycles. Four inbred rice varieties (NERICA S-21, NERICA S-44, Sahel 210 and Sahel 222) and one hybrid rice (Hybrid AR032H) were evaluated under five nitrogen fertilizer rates (0, 50, 100, 150 and 200 kg N ha−1). The results showed that rice yield varied from 0.9 to 12 t ha−1. The maximum yield of 12 t ha−1 was achieved by NERICA S-21 under AWD 30 kPa at 150 kg N ha−1. The AWD irrigation management at 30 kPa resulted in increasing rice yield, rice water use and nitrogen use efficiency and reducing the irrigation applications by 27.3% in comparison with continuous flooding. AWD30 kPa could be adopted as a water saving technology for water productivity under paddy production in the Senegal River Middle Valley. Additional research should be conducted in the upper Valley, where soils are sandier and water is less available, for the sustainability and the adoption of the irrigation water saving practices across the entire Senegal River Valley

Putting Plant Genetic Diversity and Variability at Work for Breeding: Hybrid Rice Suitability in West Africa

Rice is a staple food in West Africa, where its demand keeps increasing due to population growth. Hence, there is an urgent need to identify high yielding rice cultivars that fulfill this demand locally. Rice hybrids are already known to significantly increase productivity. This study evaluated the potential of Asian hybrids with good adaptability to irrigated and rainfed lowland rice areas in Mali, Nigeria, and Senegal. There were 169 hybrids from China included in trials at target sites during 2009 and 2010. The genotype × environment interaction was highly significant (p < 0.0001)for grain yield indicating that the hybrids’ and their respective cultivar checks’ performance differed across locations. Two hybrids had the highest grain yield during 2010 in Mali, while in Nigeria, four hybrids in 2009 and one hybrid in 2010 had higher grain yield and matured earlier than the best local cultivar. The milling recovery, grain shape and cooking features of most hybrids had the quality preferred by West African consumers. Most of the hybrids were, however, susceptible to African rice gall midge (AfRGM) and Rice Yellow Mottle Virus (RMYV) isolate Ng40. About 60% of these hybrids were resistant to blast. Hybrids need to incorporate host plant resistant for AfRGM and RYMV to be grown in West Africa