Response of Sorghum bicolor genotypes for yield and yield components and organic carbon storage in the shoot and root systems.

Sorghum is a vital food and feed crop in the world's dry regions. Developing sorghum cultivars with high biomass production and carbon sequestration can contribute to soil health and crop productivity. The objective of this study was to assess agronomic performance, biomass production and carbon accumulation in selected sorghum genotypes for production and breeding. Fifty sorghum genotypes were evaluated at three locations (Silverton, Ukulinga, and Bethlehem) in South Africa during 2022 and 2023 growing seasons. Significant genotype × location (p < 0.05) interactions were detected for days to 50% heading (DTH), days to 50% maturity (DTM), plant height (PH), total plant biomass (PB), shoot biomass (SB), root biomass (RB), root-to-shoot biomass ratio (RS), and grain yield (GY). The highest GY was recorded for genotypes AS115 (25.08 g plant-1), AS251 (21.83 g plant-1), and AS134 (21.42 g plant-1). Genotypes AS122 and AS27 ranked first and second, respectively, for all the carbon stock parameters except for root carbon stock (RCs), whereas genotype AS108 had the highest RCs of 8.87 g plant-1. The principal component analysis identified GY, DTH, PH, PB, SB, RB, RCs, RCs/SCs, total plant carbon stock (PCs), shoot carbon stock (SCs), and grain carbon stock (GCs) as the most discriminated traits among the test genotypes. The cluster analysis using agronomic and carbon-related parameters delineated the test genotypes into three genetic groups, indicating marked genetic diversity for cultivar development and enhanced C storage and sustainable sorghum production. The selected sorghum genotypes are recommended for further breeding and variety release adapted to various agroecologies in South Africa.

Pre-harvest host-resistance to Aspergillus infection and aflatoxin B1 contaminations in groundnut (Arachis hypogaea L.) genotypes.

Groundnut (Arachis hypogaea L.) is an important oil crop in the tropical and sub-tropical countries. Pod and seed coat crack-inducing factors favour Aspergillus species infections and aflatoxin B1 (AFB1) contamination of groundnut. Aflatoxin B1 (AFB1), a toxic secondary metabolite of Aspergillus species, remains a global concern due to its human and animal health, and economic impacts. Thus, the study was conducted at Babile in 2018 with the objective to identify groundnut genotypes resistant to pre-harvest fungal infections, aflatoxin contaminations and associated effects in crop physiology. Seventeen advanced groundnut breeding lines including one commercial cultivar (Werer-961), were evaluated using randomized complete block design and completely randomized design under field and with four replications for laboratory experiments, respectively. Aflatoxin B1 analysis was carried out using Enzyme-Linked Immunosorbent Assay (ELISA) kits. Appropriate statistical procedures, including regression, were employed for data analyses. Highly significant (p<0.01) variation existed among the genotypes for A. flavus and A. niger infections, and the AFB1 contamination ranged from 13.98 (G14) to 1990.86 ppb (G12). The more A. flavus infection, the more reduction in harvest yield and seedling vigour. Fortunately, 53 % of the test materials were found to be resistant to AFB1 production, and frighteningly, none of the AFB1 contaminated genotypes were within the acceptable limit of the lenient standard (10 ppb). All in all, the groundnut genotype (G4) was identified as a good source of pre-harvest resistance to A. flavus infection, AFB1 contamination and seedling vigour so that its inclusion in breeding programs is worthwhile utmost, specifically, in the test environment as pathogen-crop-environment interaction is natural. Since the experiment was employed at one location and for only one year, it is suggested to repeat the experiment across multiple locations and over seasons for reliable recommendation.

Assessment of the genetic diversity and population structure of groundnut germplasm collections using phenotypic traits and SNP markers: Implications for drought tolerance breeding.

Profiling the genetic composition and relationships among groundnut germplasm collections is essential for the breeding of new cultivars. The objectives of this study were to assess the genetic diversity and population structure among 100 improved groundnut genotypes using agronomic traits and high-density single nucleotide polymorphism (SNP) markers. The genotypes were evaluated for agronomic traits and drought tolerance at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT)/India across two seasons. Ninety-nine of the test genotypes were profiled with 16363 SNP markers. Pod yield per plant (PY), seed yield per plant (SY), and harvest index (HI) were significantly (p < 0.05) affected by genotype × environment interaction effects. Genotypes ICGV 07222, ICGV 06040, ICGV 01260, ICGV 15083, ICGV 10143, ICGV 03042, ICGV 06039, ICGV 14001, ICGV 11380, and ICGV 13200 ranked top in terms of pod yield under both drought-stressed and optimum conditions. PY exhibited a significant (p ≤ 0.05) correlation with SY, HI, and total biomass (TBM) under both test conditions. Based on the principal component (PC) analysis, PY, SY, HSW, shelling percentage (SHP), and HI were allocated in PC 1 and contributed to the maximum variability for yield under the two water regimes. Hence, selecting these traits could be successful for screening groundnut genotypes under drought-stressed and optimum conditions. The model-based population structure analysis grouped the studied genotypes into three sub-populations. Dendrogram for phenotypic and genotypic also grouped the studied 99 genotypes into three heterogeneous clusters. Analysis of molecular variance revealed that 98% of the total genetic variation was attributed to individuals, while only 2% of the total variance was due to variation among the subspecies. The genetic distance between the Spanish bunch and Virginia bunch types ranged from 0.11 to 0.52. The genotypes ICGV 13189, ICGV 95111, ICGV 14421, and ICGV 171007 were selected for further breeding based on their wide genetic divergence. Data presented in this study will guide groundnut cultivar development emphasizing economic traits and adaptation to water-limited agro-ecologies, including in Ethiopia.