Soil property and crop yield responses to variation in land use and topographic position: Case study from southern highland of Ethiopia

Understanding soil property and crop yield responses to variations in land use and topographic gradient is vital for designing targeted soil and agronomic management practices. This study investigated the interrelationships between land use, topographic position, soil properties, and crop yield. Three replicates of three land use types - enset agroforestry, cropland (annual crop), and grazing land - were selected along a toposequence (upper, middle and lower) for the study. A total of 54 composite soil samples were collected and analyzed. Grain yield and above ground biomass were also gathered from the cropland and analyzed. Soil profile descriptions revealed notable variations in soil physical properties, including soil texture, bulk density, color, horizons, and depth among the pedons of the three topographic positions. Clay and silt fractions exhibited significant differences between land uses and topographic positions, while the sand fraction was influenced by topographic position alone. Crop and grazing lands displayed higher clay content compared to the enset field. A decreasing trend in clay fraction was observed from upper to lower topographic positions. The enset field had significantly higher soil pH, OC, TN, and K+ contents than crop field. A significantly higher available P of 16.61 mg kg−1 was measured from lower slope position followed by 14.08 mg kg−1 in middle slope. The upper slope position had the highest exchangeable acidity of 3.09 cmol(+) kg−1), followed by middle slope with 2.77 cmol(+) kg−1), 2.45 cmol(+) kg−1) in the lower slope position. Grain yield and above ground biomass decreased from lower slope to middle slope and upper slope positions. These observed variations in soil properties and crop yield among land uses and topographic positions underscore the necessity for tailored soil management strategies and agronomic practices specific to land use types and the specific localized topographic conditions to optimize agricultural productivity

Genetic analysis of purple pigmentation in rice seed and vegetative parts — implications on developing high-yielding purple rice (Oryza sativa L.)

Pigmentation in rice grains is an important quality parameter. Purple-coloured rice (Oryza sativa L.) indicates the presence of high anthocyanin with benefits of antioxidant properties. However, the genetic mechanism of grain colour is not fully understood. Therefore, the study focused on understanding pigmentation in grain pericarp and vegetative parts, and its relationship with blast resistance and enhanced grain yield. Three local cultivars from the northeastern region (NER) of India — Chakhao Poireiton (purple), Mang Meikri (light brown), and Kala Joha (white) — along with high-yielding varieties (HYVs) Shasharang (light brown) and Sahbhagi dhan (white) were used to develop biparental populations. The findings suggested that pigmentation in vegetative tissue was governed by the inter-allelic interaction of several genes. Haplotype analysis revealed that Kala3 complemented Kala4 in enhancing purple pigmentation and that Kala4 is not the only gene responsible for purple colour as evident by the presence of a desired allele for markers RID3 and RID4 (Kala4 locus) in Chakhao Poireiton and Kala Joha irrespective of their pericarp colour, implying the involvement of some other additional, unidentified genes/loci. RID3 and RID4 together with RM15191 (Kala3 locus) could be employed as a reliable marker set for marker-assisted selection (MAS). Pericarp colour was strongly correlated with colour in different vegetative parts, but showed a negative correlation with grain yield. Pb1, reported to be associated with panicle blast resistance, contributed to leaf blast resistance. Transgressive segregants for improved pigmentation and high yield were identified. The selection of lines exhibiting coloured pericarp, high anthocyanin content, aroma, blast resistance, and increased yield compared to their respective HYV parents will be valuable resources in the rice breeding programme

Vulnerability and resilience in the face of climate changes in Senegal's drylands: measurement at the household level and determinant assessment

The resilience capacity of smallholder households is one of the main drivers of their ability to continue to farm and make investments in the fragile dryland regions. This paper aims to assess the resilience profile of smallholder farmers in the face of climate change and the factors influencing it in three dryland sub-regions of Senegal, namely, Louga, Kaffrine, and Thies. We developed a composite index of climate resilience (CICR) using data on farmers' perceptions of climate variability and their perceived ability to withstand, adapt, and bounce back in the event of climatic shocks. Drought, strong winds, and soil fertility decline because of climate change emerged as the main climate hazards impacting smallholder farming systems. The CICR value ranged from −2 for the most vulnerable households to +2 for the most resilient households. On average, all the households were found to be vulnerable, with an average CICR value of −0.2. The LOUGA region was the most vulnerable, with an average CICR value of −0.36, followed by THIES (-0.2). The KAFFRINE region was relatively less vulnerable, with a CICR value of −0.1. Ordered logit model estimates show that the chances of improving CICR decrease with the increase of the household head's age until 59 years. Access to training on climate-smart agricultural (CSA) practices and climate information appeared to have the potential to increase by 171% the chance of the household improving its resilience status. Analysis also shows that one more woman working off-farm or in-home gardening has the potential to multiply by four times the chances of households being more resilient. This highlights the importance of empowering women to enhance household resilience to climate change. The off-farm revenue increased the chance to improve the resilience status of the farm household by 62% and the receipt of transfer revenue by 50%. This study provides a robust method for quantifying resilience or wellbeing and its drivers and enriches our understanding of the resilience ability of farmers to climate change in a West African context. It can be useful in designing effective adaptation interventions and improving the overall wellbeing of smallholder farmers

Genetic diversity analysis of Azerbaijani bread wheat (Triticum aestivum L.) genotypes with simple sequence repeat markers linked to drought tolerance

Water stress causes large agricultural losses worldwide and deteriorates its quality. Drought tolerance in plants is a complex trait governed by multigenes and infleunce of various environmental factors affecting the expression of these genes. Thus this complexity necessitates the application of new molecular methods to identify and develop drought tolerant genotypes. The present study was conducted to investigate the genetic diversity of 45 Azerbaijani wheat (Triticum aestivum L.) core collection genotypes utilizing simple sequence repeat (SSR) markers associated with drought tolerance. Our results showed that nine primers out of twelve showed polymorphism. Maximum number of alleles were detected for WMC177 marker (on chromosome 2A), WMC 264 (on chromosome 3A) and WMC219 (on chromosome 4A) with 5, 5 and 4 alleles, respectively. The lowest alleles were determined for WMC219 marker (chromosome 4A) with only one allele. The total number of the detected alleles on A and D genome was 18 and 11 respectively. The maximum number of unique bands (3) was scored with pimer WMC 177. Seven genotypes (cv Gobustan, and Gizil bugda, landrace 6262, and research materials 6170, 6286, 6296 and 6293) possessed unique bands. Based on polymorphism analysis of the wheat genotypes by SSR markers, drought tolerant genotypes for utilization in breeding programs were selected

Comparative transcriptome analysis of respiration-related genes in nodules of phosphate-deficient soybean (Glycine max cv. Williams 82)

A transcriptome analysis was used to compare the nodule transcriptomes of the model soybean ‘Williams 82’ inoculated with two Bradyrhizobium diazoefficiens strains (USDA110 vs. CB1809) under phosphate (Pi) deficiency. The entire dataset revealed a core set of low-Pi-responsive genes and recognized enormous differential transcriptional changes between the Pi-deprived USDA110-nodules and CB1809-nodules. The lower symbiotic efficiency of the Pi-starved USDA110 nodules was ascribed to the downregulation of an F1-ATPase gene engaged in oxidative phosphorylation, more likely contributing to diminished ATP production. To cope with energy shortage caused by Pi stress, the Pi-deprived USDA110-nodules preferentially upregulated the expression of a large number of genes encoding enzymes implicated in specialized energy-demanding pathways, such as the mitochondrial respiratory chain (i.e., cytochrome c oxidase), alcoholic fermentation (i.e., pyruvate decarboxylase and alcohol dehydrogenase) and glycolysis (e.g., hexokinase, phosphofructokinase, glyceraldehyde‐3‐phosphate dehydrogenase and pyruvate kinase). These respiratory adjustments were likely associated with higher metabolic cost and redox imbalance, thereby, negatively affecting nodule symbiosis under Pi deprivation. In contrast, the Pi-starved CB1809-nodules reduced the metabolic cost by regulating a lower number of genes and increasing the expression of genes encoding proteins implicated in non-phosphorylating bypasses (e.g., flavoprotein alpha and flavoprotein:ubiqionone oxidoreductase), which could promote the carbohydrate utilization efficiency and energy metabolism. Notably, the upregulation of a transcript encoding a malate dehydrogenase could boost the CB1809-nodules under Pi stress. The dynamic shifts in energy metabolism in the Pi-deprived USDA110-nodules and CB1809-nodules could be transformative to upgrade the mechanistic/conceptual understandings of soybean adaptation to Pi deficiency at the transcriptional level

Milestones in Biology, Genetics, and Breeding of Pearl Millet

Pearl millet is a fascinating species for conducting basic research in biology and genetics; and for applied research in breeding. With a small number of large somatic chromosomes, pearl millet lends itself to investigation in classical and molecular cytogenetics. Its short life cycle, protogynous flowers and ability to set a large number of seeds per panicle make pearl millet highly suitable for studying flow of genes between cultivated annual species and related wild species. Centre of origin, domestication, primary and secondary gene pools of pearl millet helped in selection of suitable geographical area for collecting unique and diverse germplasm resources. The outcrossing nature of pearl millet provided the basis of exploitation of heterosis at commercial scale. Another important discovery related to pollination of pearl millet was role of pollen in reducing the infection of ovary by pathogens of ergot and smut. Knowledge of photoperiod response helped in extending the crop cultivation in new seasons and geographical regions; in controlling flowering in order to facilitate hybridization; and in selecting suitable sites for offseason nurseries. Outcrossing rate of above 85%, ease of inbred development, discovery of cytoplasmic male sterility and fertility restorer genes, lack of any negative association of cytoplasmic male sterility with growth and development, diseases and insect-pests, expression of positive and high magnitude of heterosis in productivity of hybrids and economic seed production provided a perfect platform for commercial exploitation of heterosis in pearl millet for the benefit of farming community. The genome of a reference genotype Tift 23D2B1-P1-P5 has been reported to contain an estimated 38,579 genes. Thus, a good understanding of biology and genetics of pearl millet has helped tremendously in breeding for higher productivity and stability

Dryland cropping in different Land uses of Senegal using Sentinel-2 and hybrid ML method

In rainfed and dryland agricultural areas with smallholder farms (less than 2 ha), crop diversity is high due to farmers' decisions and local climatic conditions, leading to a complex spatial–temporal distribution of crops. Monitoring and mapping crops is crucial for food security and implementing agricultural support programs. This study aims to map crop types across Senegal using Sentinel-2 satellite imagery and the limited ground reference data available, which has been increasing recently. The study compares conventional supervised classification algorithms to unsupervised classification algorithms using high-resolution satellite imagery. Crop type classification for 2020 in Senegal employed supervised machine learning algorithms, including Classification and Regression Trees (CART), Random Forest (RF), and Support Vector Machine (SVM) on the Google Earth Engine (GEE) cloud platform, and the unsupervised Iso-clustering classification algorithm with Spectral Matching Techniques (SMTs). Due to limited ground data, supervised classifiers achieved 45-55% accuracy, whereas the unsupervised semi-automatic approach achieved over 75% accuracy. The study indicates that supervised classifiers' performance depends on ground data quantity, while SMT shows good performance even with limited ground data. This SMT approach is valuable for classifying crop types in dryland areas with smallholder farms and diverse cropping patterns

The impact of water hyacinth biochar on maize growth and soil properties: The influence of pyrolysis temperature

Introduction: Options for managing water hyacinths (WHs) include converting the biomass into biochar for soil amendment. However, less has been known about the impact of WH‐based biochar developed in varying pyrolysis temperatures on plant growth and soil qualities. Materials and Methods: A pot experiment was undertaken in a factorial combination of WH biochars (WHBs) developed at three temperatures (350°C, 550°C and 750°C) and two application rates (5 and 20 t ha−1), plus a control without biochar. Maize was grown as a test crop for 2 months under natural conditions. Results: Our study showed that applying WHB developed between 350°C and 750°C at 20 t ha−1 increased maize shoot and root dry biomass by 47.7% to 17.6% and 78.4% to 54.1%, respectively. Nevertheless, raising the biochar pyrolysis temperature decreased maize growth, whereas increasing the application rate displayed a positive effect. The application of WHB generated at 350°C and 550°C at 20 t ha−1 resulted in significant improvements in soil total nitrogen (17.9% to 25%), cation exchange capacity (27.3% to 20.2%), and ammonium‐nitrogen (60.7% to 59.6%), respectively, over the control. Additionally, applying WHB produced from 350°C to 750°C at 20 t ha−1 enhanced soil carbon by 38.5%–56.3%, compared to the control. Conversely, applying biochar produced at 750°C resulted in higher soil pH (6.3 ± 0.103), electrical conductivity (0.23 ± 0.01 dSm−1) and available phosphorus (21.8 ± 2.53 mg kg−1). Conclusion: WHBs developed at temperatures of 350°C and 550°C with an application rate of 20 t ha−1 were found to be optimal for growing maize and improving soil characteristics. Our study concludes that pyrolysis temperature significantly governs the effectiveness of biochar produced from a specific biomass source

Variation in protein and amino acids in global collection of pearl millet (Pennisetum glaucum) germplasm

Pearl millet is a major source of daily protein intake in south Asia and sub-Saharan Africa. Despite considerable importance, the extent of variation in protein and amino acids in pearl millet global germplasm is unknown. The present study assessed 165 genotypes from within the Pearl Millet Inbred Germplasm Association Panel (PMiGAP), that includes breeding lines, landraces and improved cultivars randomly drawn from a core collection from 23 countries, for protein content and 18 amino acids. The results showed considerable variation for protein content (10.06 – 20.31 %) and amino acids in PMiGAP. Diverse patterns were observed across the geographical distribution and clustered the germplasm into 7 clusters, with one cluster (“2”) containing most of the superior properties. Most amino acid levels were positively correlated but these were negatively correlated with protein content. A set of twelve genotypes was identified having higher protein with better amino acid compositions. These superior genotypes could directly feed into global and regional pearl millet improvement programs to counter hidden hunger in developing countries. We propose that these findings can be combined with the starches, lipids, antioxidants, micronutrients, and other healthful traits for which the PMiGAP resource has been extensively studied

The first intron of ARF7 is required for expression in root tips

Auxin regulates plant growth and development through the transcription factors of the AUXIN RESPONSE FACTOR (ARF) gene family. ARF7 is one of five activators that bind DNA and elicit downstream transcriptional responses. In roots, ARF7 regulates growth, gravitropism and redundantly with ARF19, lateral root organogenesis. In this study we analyzed ARF7 cis-regulation, using different non-coding sequences of the ARF7 locus to drive GFP. We show that constructs containing the first intron led to increased signal in the root tip. Although bioinformatics analyses predicted several transcription factor binding sites in the first intron, we were unable to significantly alter expression of GFP in the root by mutating these.We instead observed the intronic sequences needed to be present within the transcribed sequences to drive expression in the root meristem. These data support a mechanism by which intronmediated enhancement regulates the tissue specific expression of ARF7 in the root meristem