Crop yields are declined due to low soil fertility, insufficient soil water availability and poorly managed cropping systems in Limpopo province of South Africa. Phosphorus (P) is a major essential nutrient element required by crops for enhanced growth and development. Interactions between different rates of P fertilization and strip intercropping system have not been studied in detail under rainfed conditions in semi-arid region of Limpopo province. Therefore, this study was conducted to assess the performance of four cowpea varieties at four levels (0, 15, 30, 45 kg P ha-1) of P fertilization in a cowpea-maize intercropping system in a split-split plot design during two seasons. Significant interactions were obtained between variety and phosphorus application as well as variety and cropping system for 90% physiological maturity, root mass and grain yield in both seasons. P levels significantly influenced and enhanced grain yield, land equivalent ratio, profit and benefit cost ratio achieved. PAN311 and TVu13464 matured earlier across P levels and they were selected promising cowpea varieties based on their early maturity and high yield. Land equivalent ratio values were greater than 1.0, which indicated performance and advantage of an intercropping system over monocropping system in land utilisation. The optimum P level for cowpea-maize strip intercropping was at 30 kg P ha-1 based on yield and financial return. The results showed that P application enhanced the productivity of the cowpea varieties in cowpea-maize strip intercropping in the semi-arid environment of Limpopo province. © 2021 Friends Science Publishers

Cassava is an important staple in Sub-Sahara Africa. While its production has rapidly expanded to the dry savannahs of the continent, productivity is low in this ecology due to drought by farmers, extending the growth cycle from 12 months to 18, and sometimes 24 months to ensure better harvests. Yield is a complex trait and often difficult to manipulate for genetic gain in conventional breeding. Unfortunately, the dearth of molecular tools for decades has hampered molecular breeding (MB) to improve cassava productivity. This study was conducted to explore KASpar SNPs to generate more molecular tools to enhance genetic dissection of elite African germplasm for improved cassava productivity in dry environments of Africa where molecular resources are highly limited for crop improvement. To aid molecular genetic analysis of traits, a linkage map covering 1582.8 cM with an average resolution of 3.69 cM was constructed using 505 polymorphic SNP markers distributed over 21 linkage groups. Composite interval mapping using 267 F1 progeny in initial QTL mapping identified 27 QTLs for productivity traits in the dry savannah of Nigeria. The availability of KASPar SNPs are anticipated to improve the implementation of MB for the development of high performing drought-tolerant cassava varieties in Africa.

Cowpea is an important grain legume because it is a major source of cheap dietary protein. In the last four decades, the production of cowpea in South Africa is limited by lack of improved varieties that exhibit good agronomic traits and pest resistance. The purpose of the study was to develop cowpea varieties with important economic traits to meet the needs of the farmers. Germplasm lines were evaluated in field trials to select the promising lines that were used in hybridization to develop well-adapted elite genotypes. Pair-wise crosses were made to develop broad-based segregating populations. Pedigree, recurrent selection methods were used to advance the promising genotypes. Ten genotypes expressed high grain yield with combined pest resistance (aphids, bruchid, virus, leafhopper and bacterial blight). The implication of this achievement is that farmers can attain more grain yield per land area with reduced cost of pest control and increase the profit margin of the farmers. Furthermore, four elite varieties (JanaFod, ARC-GCI-CP76, UL-58 and UL-1010) have been registered and awaiting commercialization. The future activity is to commercialize the varieties to enhance uptake and availability of seeds to seed growers, farmers and consumers.

Farmers‟ traditional cropping practice in Limpopo Province is to mix and broadcast crops at planting without definite row arrangement. Although this practice is very easy and cost-saving, it leads to low plant density, hinders farm input application, and results in low crop yields and poor return on investment. Strip intercropping, where crops are planted with definite row arrangement, reduces inter-species competition, optimises plant population, and increases crop yield. Five cowpea varieties i.e. „TVu 13464‟, „IT86D-1010‟, „Glenda‟, „IT82E-16‟ and „IT87K-499-35‟ and maize was grown under strip intercropping, monocropping, and mixed intercropping as a control during two seasons. During both years, significant interactions were obtained between the cowpea varieties and the cropping systems in most of the variables measured. Cowpea sown in the strip intercropping performed better compared those sown in mixed intercropping. Cowpea varieties „IT86D-1010‟, „IT82E-16‟ and „IT87K-499-35‟ harvested more grain yield under monocropping and strip intercropping than under mixed intercropping. The land equivalent ratio (LER) of strip intercropping during the two seasons ranged between 1.25 and 2.29 and was higher compared to mixed intercropping, which ranged between 0.50 and 1.32. In conclusion, cowpea varieties „IT86D-1010‟, „IT82E-16‟ and „IT87K-499-35‟ sown with maize as strip intercropping resulted more profits under intercropping systems and were recommended for cultivation by farmers in the Limpopo region with low rainfall. Moreover, grain yield, LER, and net profit achieved by strip intercropping was three-fold more than mixed intercropping. © 2021 Friends Science Publishers