The nitrogen (N2)‐fixing bacterial inoculant strain for soybean [Glycine max (L.) Merrill] is not indigenous to South African soils. The interaction between soybean genotype, soil type and inoculant strain, however, has a definite influence on soybean production and compatibility should be optimized. This paper reports a growth chamber study using three different soybean genotypes (Barc‐9, Avuturda and Talana), three Bradyrhizobium japonicum inoculant strains (WB108, WB112 and WB1) and three soil types (Avalon, Arcadia and sand) to evaluate the effectiveness of N2 fixation by different genotype × soil type × inoculant strain combinations, using different measuring parameters. These parameters included nodule fresh mass (NFM), amount of N2 fixed (Pfix), as determined by the ureide method, seed protein content (SPC), average seed mass per plant (SMP) and average foliar N content (FNC). The comparison amongst the three‐way interactions, genotype × soil type × inoculant strain, did not differ significantly for the parameters used. Significant two‐way interactions were soil × inoculant for FNC, Pfix and SMP; soil × genotype for FNC and SMP, and inoculant × genotype for FNC (P < 0.05). The soil × inoculant strain interaction was significant for Pfix (P < 0.05). NFM, Pfix, FNC, SMP and SPC correlated positively with soil pH and negatively with soil clay content and soil NO3– and NH4+ content (P < 0.05). SPC was significantly different (P < 0.05) for soil type, genotype and inoculant strain. Pfix and NFM did not reflect the protein content of the seeds, indicating that nodule evaluation should be used with caution as a N2 fixation parameter. Low soil pH and high mineral N content inhibited N2 fixation. NFM correlated negatively with the clay content of the soil. This finding confirms that soybean production in South Africa can be improved by appropriate selection of genotypes and inoculant strains for their compatibility in different soils.

No abstract

No abstract

The genus Corchorus includes nutrient rich indigenous leafy vegetables often grown or harvested in the wild in Africa. It has potential to contribute to food security, but there is need to improve it as a crop through plant breeding. However, not much is known about the genetic variability among Corchorus species. The aim of this study was thus to characterise the available germplasm of Corchorus accessions and investigate heritability of their agro-morphological traits. Materials and methods: Eleven Corchorus accessions (4 South African and 7 from the World Vegetable Center) were evaluated in a field study at Roodeplaat, South Africa, for their morphoagronomic traits using a randomised complete block design with three replications across two seasons (2015/2016 and 2016/2017). Data were subjected to ANOVA, principal component analysis and cluster analysis. Broad sense heritability, genetic advance, genetic parameters and correlations were determined among the accessions and traits. 1 Results and conclusions: The Corchorus accessions showed significant (P<0.05) differences in all the quantitative traits evaluated. The data showed significant variability among the studied Corchorus accessions in their agro-morphological traits for exploitation in future breeding programs that in turn can contribute to the improvement of this crop.