An opportunity for increasing factor productivity for rice cultivation in The Gambia through SRI

Promising results from an increasing number of field evaluations of the System of Rice Intensification (SRI) conducted in Asia and Africa indicate that African farmers could increase their rice production while lowering costs of operation and reducing the need for water by utilizing its principles and practices. This system relies not on external inputs to raise productivity but on alternative methods for managing rice plants and the soil and water resources devoted to their cultivation. Farmers in sub-Saharan Africa increasingly have to cope with the impacts of adverse climate effects because water shortages and long dry spells during the cropping season are becoming common, even in lowland rice agroecosystems. SRI management practices create both larger rice root systems that make their plants more resistant to biotic and abiotic stresses and more conducive environments for beneficial soil microflora and fauna to flourish. Better plant growth and development result from promoting plant–soil synergies. Controlled fertilizer management experiments conducted with SRI practices in The Gambia have showed that grain production can be significantly increased without higher application of inorganic fertilizer and with less requirement for water. SRI management practices with fertilizer application at the national recommended dose produced a grain yield of 7.6 t ha⁻¹. Water productivity was greatly increased, with 0.76 g of grain produced per kg total water input, compared to 0.10 g of grain per kg of water when the crop was continuously flooded. Recent hikes in fuel prices and consequent rises in input costs are making domestic rice production less attractive and importation even more attractive. Computation of production costs showed that SRI production, not needing heavy applications of fertilizer, is economically cost-effective. Achieving yield increases through ever-higher fertilizer applications is not economically or environmentally viable. SRI management with recommended fertilizer applications produced a net return of $853 ha⁻¹ compared to $853 ha⁻¹ compared to 37 when using farmers’ present low-productivity practices.     

Oligodendrocyte morphology in the developing brain of the African giant rat (Cricetomys gambianus,Waterhouse): Histology,immunohistochemistry and electron microscopy

Oligodendrocyte and myelin‐related studies have been pivotal in understanding disruption of central nervous system (CNS) myelin through injury, toxicological, pathological degeneration or genetic intervention. The African giant rat (AGR) has been postulated as an indigenous wild‐type model within the African context. This work thus describes oligodendrocyte morphologies and myelin components of the developing African giant rat brain using histological, immunohistochemical and ultrastructural techniques. Five types, precursor‐progenitor oligodendrocytes, pre‐oligodendrocytes, immature oligodendrocytes, mature non‐myelinating oligodendrocytes and mature myelinating oligodendrocytes, were identified. The first four types were observed in neonates while juvenile and adult AGR had predominantly mature myelinating oligodendrocytes with evidence of myelin sheath deposition. All cell types identified showed positive CNPase‐positive immunosignalling across all age groups. This suggests CNPase as a suitable, sensitive and reliable biomarker for studying CNS neurodegenerative/demyelinating disorders in the AGR. This baseline study has given detailed insight into the morphology of oligodendrocytes and myelin in the AGR. It may be useful for anatomical studies and detection of alterations in neurocellular profile of oligodendrocytes and myelin in the AGR in real‐life or in experimental models.     

Effect of various levels of dissolved oxygen on reactive oxygen species and cryocapacitation‐like changes in bull sperm

The present investigation was carried out to study the effect of various levels of dissolved oxygen (DO) on reactive oxygen species (ROS) and cryocapacitation‐like changes in bull sperm. Egg yolk–Tris–glycerol (EYTG) extender was split into four subextenders; viz., Extender I (control; no flushing with liquid nitrogen (LN₂)), Extender II, Extender III and Extender IV were flushed with LN₂ for 40, 16 and 8 min, respectively. The DO levels were standardized to 11.7, 2, 4 and 8 ppm, respectively, in control (Extender I), Extender II, Extender III and Extender IV. Ejaculates with mass motility of ≥ 3+ were divided into group I (diluted with Extender I), group II (diluted with Extender II), group III (diluted with Extender III) and group IV (diluted with Extender IV) up to 80 × 10⁶ sperm/ml. Extended semen samples were packed in French mini straws (0.25 ml), equilibrated and cryopreserved. Semen samples were evaluated at prefreeze and post‐thaw stage for various parameters (DO, progressive motility (PM), viability (VIB), acrosomal integrity (AI), hypo‐osmotic swelling (HOS) test, ROS, cholesterol (C) and phospholipid (P). The percentage of PM, VIB, AI, HOS test, cholesterol (C) and phospholipid (P) levels, and capacitated sperm were significantly (p < 0.05) higher in groups III and IV as compared to groups I and II. However, the acrosome‐reacted sperm (%; pattern AR) were significantly (p < 0.05) decreased in group III as compared to all other groups. Besides the proportion of sperm displaying tyrosine‐phosphorylated pattern, EA (fluorescence at both equatorial and anterior acrosomal regions, i.e. high capacitation level) was significantly (p < 0.05) reduced in group III compared to all other groups. In conclusion, varying DO levels in the extender significantly affect sperm quality, ROS production and capacitation‐like changes in bulls.     

Effects of Deficit Irrigation and Fertilization on Quinoa (Chenopodium quinoa Willd.) Water Status and Yield Productions

Worldwide population is in permanent growth, leading to an over-presser on the food resources. This demand leads to an over-exploitation of land and water resources. Recently, the quinoa plant has attracted attention as alternative crop with high nutritive value and high tolerance to the marginal conditions. In this study, a field experiment was conducted during two successive seasons to investigate the effect of deficit irrigation on the agronomic performance. Four treatments of deficit irrigation (100%, 50%, 33% ETc and rainfed) were applied to one variety in the first season and to four genotypes (two varieties and two lines). The results were evaluated by measuring biomass and seed quinoa yield, water-use efficiency, harvest index, seed size and 1000 seeds weight. Results show that the implementation of deficit irrigation is an appropriate strategy to reduce the use of agricultural water and maintain relatively high yields. On the other hand, the results of the economic quality reflected by the size and weight of seed yield, indicates that quinoa can be considered a well-adapted to the conditions of water scarcity culture. According to agronomic parameters, L143 line followed by the line L11 showed a high potential of adaptation under the different treatments of stress, while the “Puno” variety presented the best performance under the favorable conditions of irrigation (100% ETc).

     

Association of KASP markers with Hessian fly resistance in wheat of diverse origin

Hessian fly (Mayetiola destructor (Say)) is a major pest in wheat producing areas of United States, Canada, Europe, and North Africa but has not been found in Australia. Host plant resistance is thought to involve a similar strategy used against plant pathogen, and in this study, we sought to investigate whether disease-resistance gene markers can also be useful in selecting against Hessian fly attack. The genome-wide association study involved 251 wheat genotypes of diverse origin and 72 SNPs, selected on the basis of significant similarity of their associated contig sequences to putative disease resistance genes. A novel statistical approach for genome-wide scan was applied, which utilised genotype data scored as Null alleles in the mixed model, instead of deleting or treating them as missing alleles. The analyses identified four markers with significant associations at the 5% level, after applying the false discovery rate. These were located on chromosomes 4A, 4B, 5A and 7D, with the 5A locus mapping to the cluster of major genes that confer resistance to multiple Hessian fly biotypes. Amongst the diverse wheat accessions analysed, most of the susceptible phenotypes carried the A–G–C–C haplotype at the BS00064369, BS00007416, BS00077047 and HfrDrd_nt_143 loci, respectively. When heterozygotes were excluded, all the Australian wheat accessions carried this allelic combination. The combination of alleles conferring resistance depended on the origin of the wheat accessions, with ICARDA accessions carrying a preponderance of the C–C–CG–T. Of the 11 USA accessions used for this study, only Lola carried a favourable combination of alleles for resistance at these loci.     

Recent advances in the chemistry of nitrogen,phosphorus and potassium as fertilizers in soil: A review

The advent of civilization has made humans dependent on plants for food and medicine, leading to the intensification of agricultural production. The intense cultivation of crops has resulted in the depletion of available nutrients from soil, thereby demanding the application of excess nutrients to soil to improve yield. Thus, mineral fertilizer discovery and application have, in many ways, contributed greatly to meeting global food demands. However, aside from the positive effects of mineral fer...