Arbuscular mycorrhizal fungi (AMF) enhance the uptake of water and nutrients by host plants. In this study, we examined the response of six rice varieties from two ecotypes (three irrigated and three rainfed upland varieties) to AMF inoculation at five fertilizer levels, under continuous flooding (CF) and alternate wetting and drying (AWD) irrigation over two consecutive years in field conditions. Both irrigated and upland rice varieties experienced significant yield losses with AWD irrigation and reduced NPK fertilizer levels, with irrigated rice being more severely affected. Under AWD irrigation, AMF inoculation mitigated relative yield losses, especially when half of the recommended fertilizer dose was applied. In CF conditions, AMF inoculation often fully compensated for yield losses caused by reduced NPK levels. Furthermore, irrigation regime, fertilizer levels, and ecotype were significant sources of variation in the effects of AMF inoculation on several yield-related traits, such as total biomass, tiller number, panicle number, fertility, and maturity dates. Our findings suggest that AMF inoculation could be integrated with AWD irrigation and/or low NPK inputs to contribute to fertilizer and water savings in both irrigated and upland rice production systems.

ABSTRACTIn Senegal, the average rice consumed is 100 kg per capita per year. The objective was to evaluate and select the well‐adapted high‐yielding lines in Ndiaye and Fanaye growth conditions in Senegal River Valley. One hundred and twelve advanced lines were evaluated in consecutive wet and dry seasons at AfricaRice Fanaye and Ndiaye sites challenged by drought and high temperatures. Unlike Fanaye, Ndiaye faces severe water scarcity and extreme heat. An alpha‐lattice design was used with three replications. The number of tillers and plant height at 30 days after sowing, plant height at maturity, days to 50% heading, and grain yield; physiological: leaves chlorophyll content at 50% heading stage, yield grain, thousand grain weight, and number of panicles per plant were recorded to evaluate the increasing of rice productivity. Results showed significant variation among the advanced lines and the test “Kruskal‐Wallis medians” was used for the mean comparison for the five descriptors during growth and development stages. Path analysis revealed that Ndiaye's harsh conditions negatively impacted NT30, PH30, PHmat, PNP, Dmat, and GY, with negative effects on NT30 (ρ = −0.63), PH30 (ρ = −0.67), and PNP (ρ = −0.15). However, SH (ρ = 0.71) and TGW (ρ = 0.37) had positive direct effects. Cluster analysis generated four groups showing the characteristics of 112 advanced lines. Most of the advanced lines were outperforming local elite varieties. The lines WAC 18‐WAT15‐3‐1, WAC 18‐WAT65‐1‐1, WAC 13‐WAT32‐2‐1, and WAB 2150‐TGR1‐WAT3‐1 produced the highest yields for Ndiaye, with 4752, 5589, 5589, 5644, and 6943 kg/ha. For Fanaye, the best genotypes were IR 09 N523, CT18919‐4‐2‐2‐2SR‐1P, CT18494‐4‐4‐3‐3‐1SR, WAB 2125‐WACB‐1‐TGR1‐WAT1‐1, and CT19541‐13‐3‐1‐2P‐3P, with 8824, 8984, 9014, 9639, and 8496 kg/ha, respectively. The authors recommend that these lines be released or used as donors in breeding programs, and further studies can consider stability analysis using the best adapted varieties.

Understanding metal accumulation at organ level in roots, leaves and seeds in O. glaberrima (OG) is crucial for improving physiological and metabolic aspects in growing Asian and African rice in salted areas.The micro-analytical imaging techniques are required to reveal its accumulation and distribution within plant tissues.PIXE studies have been performed to determine different elements in rice plants.The existing microbeam analytical technique at the iThemba LABS will be applied for the 2D image mapping of fresh rice tissues to perform a concentration of low atomic mass elements (such as Al, Si, P, S, Cl, Ca, Ti, Mn, Fe, Cu, Br, Zn and K) with detection limits of typically 1 -10 µg/g.Comparison of the distribution of the elements between leaves, root and seed samples using uptake and distribution of elements in particular environmental conditions with potential amount of salt in water have been performed.We are also expecting to indicate metal exclusion as salt tolerance strategies from leaves, root, and seed compartments using matrix correlation between samples and between elements on rice species.

Arbuscular mycorrhizal fungi (AMF) provide host plants with water and nutrients. Here, we investigated the response of six rice varieties from two ecotypes (three irrigated and three rainfed upland varieties) to inoculation at five fertilizer levels, under continuous flooding (CF) and alternate wetting and drying (AWD) irrigation in field conditions in two consecutive years. For both irrigated and upland rice, the application of AWD irrigation and reduction in NPK fertilizer levels resulted in significant yield losses, with a greater magnitude for irrigated rice. Under AWD irrigation, inoculation with AMF reduced relative yield losses with a more pronounced effect at half recommended dose of fertilizer. Under CF, the yield losses related to reduction in NPK fertilizer levels were often fully offset by inoculation with AMF. On the other hand, irrigation regime, fertilizer level and ecotype were identified as significant sources of variation in mycorrhizal inoculation effect for many yield-related traits including, total biomass, tiller number, panicle number, fertility and maturity dates. Our results suggest that inoculation with AMF could be associated with AWD irrigation and/or low NPK inputs to contribute to mineral fertilizer and water saving in both irrigated and upland rice production systems.

Short Retraction Notice The paper does not meet the standards of "Advances in Bioscience and Biotechnology". This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused. Editor guiding this retraction: Prof. Abass Alavi (EiC of ABB). Please see the article page for more details. The full retraction notice in PDF is preceding the original paper which is marked "RETRACTED".

BackgroundRhizosphere microbial communities are important components of the soil-plant continuum in paddy field ecosystems. These rhizosphere communities contribute to nutrient cycling and rice productivity. The use of fertilizers is a common agricultural practice in rice paddy fields. However, the long-term impact of the fertilizers usage on the rhizosphere microbial communities at different rice developmental stages remains poorly investigated. Here, we examined the effects of long-term (27 years) N and NPK-fertilization on bacterial and archaeal community inhabiting the rice rhizosphere at three developmental stages (tillering, panicle initiation and booting) in the Senegal River Delta.ResultsWe found that the effect of long-term inorganic fertilization on rhizosphere microbial communities varied with the rice developmental stage, and between microbial communities in their response to N and NPK-fertilization. The microbial communities inhabiting the rice rhizosphere at panicle initiation appear to be more sensitive to long-term inorganic fertilization than those at tillering and booting stages. However, the effect of developmental stage on microbial sensitivity to long-term inorganic fertilization was more pronounced for bacterial than archaeal community. Furthermore, our data reveal dynamics of bacteria and archaea co-occurrence patterns in the rice rhizosphere, with differentiated bacterial and archaeal pivotal roles in the microbial inter-kingdom networks across developmental stages.ConclusionsOur study brings new insights on rhizosphere bacteria and archaea co-occurrence and the long-term inorganic fertilization impact on these communities across developmental stages in field-grown rice. It would help in developing strategies for the successful manipulation of microbial communities to improve rice yields.

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.

The overuse of agricultural chemicals such as fertilizer and pesticides aimed at increasing crop yield results in environmental damage, particularly in the Sahelian zone where soils are fragile. Crop inoculation with beneficial soil microbes appears as a good alternative for reducing agricultural chemical needs, especially for small farmers. This, however, requires selecting optimal combinations of crop varieties and beneficial microbes tested in field conditions. In this study, we investigated the response of rice plants to inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) under screenhouse and field conditions in two consecutive seasons in Senegal. Evaluation of single and mixed inoculations with AMF and PGPB was conducted on rice (Oryza sativa) variety Sahel 202, on sterile soil under screenhouse conditions. We observed that inoculated plants, especially plants treated with AMF, grew taller, matured earlier and had higher grain yield than the non-inoculated plants. Mixed inoculation trials with two AMF strains were then conducted under irrigated field conditions with four O. sativa varieties, two O. glaberrima varieties and two interspecific NERICA varieties, belonging to 3 ecotypes (upland, irrigated, and rainfed lowland). We observed that the upland varieties had the best responses to inoculation, especially with regards to grain yield, harvest index and spikelet fertility. These results show the potential of using AMF to improve rice production with less chemical fertilizers and present new opportunities for the genetic improvement in rice to transfer the ability of forming beneficial rice-microbe associations into high yielding varieties in order to increase further rice yield potentials.