Organic soil amendments, such as composts, mitigate the negative impacts on the environment that are caused by poor waste management practices. However, in the sub-Saharan African region, and Malawi in particular, studies investigating the agronomical efficacy and their ability to ameliorate drought stress when used as a soil amendment are minimal. This study aimed to evaluate the efficacy of sewage sludge and municipal solid waste (MSW) co-compost to ameliorate drought stress and improve crop productivity. Three experiments were conducted (i) to determine optimal application rate for co-compost, (ii) to evaluate yield response of maize and lettuce to co-compost application under contrasting soils, and (iii) to assess the effect of co-compost under water-limited conditions. Our results indicate that an application rate of 350 g co-compost per station was the most effective. This rate is 50% and 37% lower than the currently recommended rate for applying conventional compost to green vegetables and maize, respectively. In addition, under drought conditions, the co-compost application enhanced growth in lettuce, with less wilting, increased biomass and yield, approximately 130% greater leaf yield, and a 138% improvement in root growth. Furthermore, the relative root mass ratio (RRMR) was enhanced with the co-compost application by 103% under drought stress. This suggests that the co-compost amendment resulted in a greater allocation of biomass to the roots, which is a crucial morphological attribute for adapting to drought conditions. The concentration of K in the leaves and roots of plants treated with co-compost was significantly increased by 44% and 61%, respectively, under drought conditions, which may have contributed to osmotic adjustment, resulting in a significant increase in leaf relative water content (RWC) by a magnitude of 11 times. Therefore, in light of the rising inorganic fertilizer costs and the limited availability of water resources, these results demonstrate the potential of MSW and sludge co-composting in ameliorating the drastic effects of water- and nutrient-deficient conditions and optimizing growth and yield under these constraining environments.

Amaranth (Amaranthus spp.) is an underutilized, climate-resilient crop with the potential to improve food and nutritional security, particularly in sub-Saharan Africa. Despite its potential as a climate-resilient and nutritious crop, limited research on the genetic diversity and agronomic performance of locally adapted amaranth genotypes restricts understanding of key trait relationships and slows breeding progress. This study aimed to address this gap by evaluating the genetic variation and trait-based classification of six amaranth genotypes using univariate, bivariate, and multivariate statistical analyses on seven quantitative traits. Principal component analysis revealed that the first two components explained 63.6% of the total variation, effectively distinguishing genotypes based on key vegetative traits (leaf length, leaf width, stem girth, and plant height) and yield-related parameters (inflorescence length, grain yield and dry biomass). Cluster analysis identified two statistically distinct groups, with grain yield and inflorescence length contributing most to genetic divergence. Strong positive correlations among grain yield, stem girth, leaf length, and inflorescence traits suggest opportunities for indirect selection. Genotypes CK-BH-01 and LL-BH-04 exhibited superior performance in yield-related traits, making them as promising candidates for breeding improvement. These findings provide a robust, data-driven framework for trait-based selection in amaranth breeding, supporting the development of high-yielding, stress-resilient varieties adapted to diverse agroecological zones.

This study assessed the chemical composition of amaranth leaves from six different accessions (MN-BH-01, PE-UP-BH-01, PE-LO-BH-01, CK-BH-01, NU-BH-01, and LL-BH-04) grown in various locations in Malawi. Key nutritional traits, including crude protein, calcium, zinc, iron, and potassium content, were analyzed, revealing significant variability influenced by genotype–environment interactions. MN-BH-01 exhibited the highest protein, calcium, zinc, and potassium levels, making it a promising candidate for nutritional enhancement. PE-UP-BH-01 had elevated iron content, while LL-BH-04 showed superior crude protein in certain locations. Nutrient composition varied significantly across different environmental conditions, emphasizing the impact of these interactions on nutrient accumulation. Cluster analysis and AMMI analysis identified consistent accessions (MN-BH-01 and NU-BH-01) valuable for breeding nutrient-rich varieties. Farmers preferred NU-BH-01 for its flavor, yield, and marketability, while MN-BH-01 was less favored due to its bitterness. These findings offer valuable insights for developing climate-resilient and biofortified amaranth varieties, contributing to food security and nutrition in Malawi and similar regions.

Amaranth, with its high genetic variability, holds promise for global food security, income generation and climate resilience. Developing stable, high-yielding genotypes is essential for sustainable production. In this study, stability analysis was conducted on five Amaranth accessions over two seasons at three Malawian sites. Significant trait variations, including grain yield, plant height and leaf characteristics, underscored the dynamic nature of Amaranth cultivation. Notably, LL-BH-04 consistently exhibited superior grain yield, while others showed variable performance, highlighting the importance of stability analysis. Employing the Eberhart and Russell model, stable accessions in leaf and grain yield were identified. Additionally, AMMI (Additive Main effects and Multiplicative Interaction) biplot analysis revealed genetic diversity and stability patterns, aiding resilient cultivar selection. Consequently, LL-BH-04 and PE-UP-BH-01, identified as stable genotypes, were recommended for release, thereby enhancing agricultural sustainability and food security. These findings emphasize the need for site-specific breeding evaluations for sustainable productivity and underscore the importance of selecting stable cultivars to address agricultural challenges. LL-BH-04 and PE-LO-BH-01 were proposed for release to boost Amaranth production in Malawi, serving as the foundation for tailored breeding efforts aimed at improving productivity and resilience. This study contributes valuable insights into the stability and performance of Amaranth cultivars, offering guidance for sustainable crop production and variety development strategies.

The chemical composition of amaranth leaves varies significantly across different accessions, with substantial differences in key nutrients, including crude protein, minerals, and micronutrients. This study evaluates the nutrient profiles of six amaranth accessions (MN-BH-01, PE-UP-BH-01, PE-LO-BH-01, CK-BH-01, NU-BH-01, and LL-BH-04), focusing on dry matter-based chemical composition and genotype-by-environment (G×E) interactions. Results show that MN-BH-01 exhibited the highest protein (43.18%), calcium (8.00 mg/100g), zinc (15.12 mg/100g), and potassium (19.47 mg/g) content, marking it as a potential candidate for nutritional enhancement. PE-UP-BH-01, notable for its elevated iron content (77.16 mg/100g), and LL-BH-04, exhibiting superior crude protein at some sites, also showed unique nutritional advantages. Nutrient composition varied significantly across locations, with genotype-by-environment interactions playing a crucial role in nutrient accumulation, particularly in iron and calcium. Cluster analysis revealed distinct groups based on nutritional content, with MN-BH-01 standing out for protein, iron, and potassium levels. Additive Main Effects and Multiplicative Interaction (AMMI) analysis further highlighted stable accessions (MN-BH-01, NU-BH-01) across multiple traits, essential for breeding programs. Farmers' preferences indicated that NU-BH-01 was the most favored for its flavor, yield, and marketability, while MN-BH-01 was least preferred due to bitterness. These findings provide crucial insights for the development of amaranth varieties with enhanced nutritional profiles and broader market appeal, guiding breeding strategies and biofortification initiatives.

Organic soil amendments, such as composts, mitigate the environmental burdens associated with wasting organic resources. Although compost application to soil enhances an agroecosystem's capacity to store carbon and produce food, studies investigating the agronomical efficacy and their ability to ameliorate drought stress when used as a soil amendment are minimal. In this study, we produced and used a nutrient rich co-compost through the composting of sludge, a nitrogen-rich organic material with carbon rich municipal solid wastes (MSW) to evaluate the agronomic efficacy of the MSW derived co-compost and their ability to ameliorate drought stress. Application of co-compost significantly enhanced growth and yield of lettuce and maize, by a magnitude comparable to chemical fertilizers. Furthermore, under drought stress, lettuce plants grown under co-compost soil amendment grew much better with less wilting, more biomass and yield, and improved root growth. Also, co-compost application enhanced relative root mass ratio (RRMR) under drought stress, indicative that co-compost amendment increased the allocation of biomass to the roots, which is an important morphological attribute for drought adaptability. K content in both leaves and roots of plants amended with co-compost was also higher under drought stress, which may have played a role in osmotic adjustment, consequently, the plants exhibited higher leaf relative water content (RWC). Other nutrient elements that were significantly enhanced by co-compost application included Mg, Ca, Fe and Cu. These results provide evidence that MSW co-composting could optimize organic resource recycling for climate change mitigation and agricultural productivity while minimizing nutrient losses from agroecosystems.