Cowpea [Vigna unguiculata (L.) Walp.] is an important crop in many African countries, though its use as a leafy vegetable has not received adequate research attention. Leaf and grain yields are low and unstable, especially in highly variable climates in marginal areas. A study was conducted to evaluate the impact of cowpea cultivar mixtures on leaf and seed yield and stability in a cowpea-maize (Zea mays L.) intercropping system. Four cowpea cultivars, and a local landrace check, were used in monoculture or in different mixture levels. When leaves were harvested, seed yield was reduced on average by 57% and 59%, on-station and on-farm, respectively, with large variation among treatments. The local landrace check had the highest leaf yields on-farm where it produced a mean of 25 g/plant/2-weekly harvesting interval. It also conveyed positive mixture effects, however, yield stability across successive harvests was lowest, indicating its capacity to react to positive environmental changes. Some mixtures of more

<span>Fifty Tanzanian local maize cultivars, seven popularly grown commercial varieties in Tanzania and eleven elite lines from CIMMYT, Nairobi, Kenya were evaluated for agronomic performance. The genotypes were subjected to randomized complete block design at three sites in 2015, both conducted at Arusha region, in Tanzania. The analysis identified highly significant variances among genotypes evaluated and their interactions with environments. The GGE biplot analyses identified the winning genotypes on mean yield and stability. An open pollinated variety (OPV) Situka 1 and an hybrid DH 04 had generally the best performance in terms of grain yield and stability across all three locations. A local cultivar TZA 2793 emerged to be the promising landrace with overall appealing yield and stability performance. The obtained information through this current study may be a good source of new allelic diversity that could be used for developing different important elite maize materials.</span>

Maize (Zea mays L.) is among the most important crops in Tanzania with still low average yield of 1.2 metric tonnes per hectare as compared with potential yields of 4 to 5 metric tonnes per hectare. Low yield is due to a number of factors including pests and diseases. Recently, East Africa has been hard hit by a new deadly disease of maize called Maize Lethal Necrosis Disease (MLND). The disease started in Kenya in 2011 and later spread to other countries including Tanzania and it continues to spread fast in other countries. It is caused by a combination of two viruses i.e., Maize chlorotic mottle virus (MCMV) and any other Potyvirus, with Sugarcane mosaic virus (SCMV) reported for East Africa. The aim of this study was to evaluate genetic diversities of maize accessions (focusing more on landraces) with respect to their MLND resistance and optimum yield in Tanzania. Fifty one maize landraces from National Plant Genetic Resources Centre (NPGRC) in Tanzania, thirty four commercial varieties as checks for yield and thirteen elite lines from CIMMYT Kenya as checks for resistance against MLND were used. Three field experiments were conducted at Tengeru, Mlangarini and Selian in Tanzania for genetic diversity study and MLND evaluation, one field experiment was conducted at Naivasha Kenya for MLND evaluation. Molecular study was conducted at Nelson Mandela African Institution of Science and Technology in Tanzania. Significant (p < 0.05) variations were observed among the tested accessions and an OPV Situka 1 and a hybrid DH 04 were the best yielding varieties across Tengeru, Mlangarini and Selian with 116.01g and 115.90g per plant respectively. Landraces TZA 2793 and TZA 5170 were among the highest yielding accessions with 100.46g and 99.80g per plant respectively. The allele distribution and frequency associated with quantitative trait loci for SCMV resistance were detected with landraces and TZA 2793 as well as TZA 3544 expressed low MLND progression across Mlangarini and Naivasha. The results of significant genetic diversity and response against MLND of maize landraces tested in this study calls for further investigation to ascertain their utilization in breeding and crop improvement.

Maize production challenges require well-known genetic diversity to ensure effective improvement. The study aimed at conducting morphological evaluation on 50 maize landraces from Tanzania compared with 7 commercial varieties and 11 elite lines from CIMMYT, Kenya. The experiments were conducted in randomized complete block design at three locations in Arusha region, Tanzania. Data were collected on 19 quantitative and 12 qualitative traits that were subjected to analysis of variance, descriptive and multivariate statistics. Significant variations (p<0.05) were observed for all traits while higher contribution for accessions variability were found with yield, a thousand kernel weight, flowering traits, kernel, ear and vegetative plant characteristics. Commercial varieties were characterized by significant yield (107.4g per plant) and yield related parameters of (a thousand seed weight, number of rows per ear, ear diameter, ear length) also early days to tasseling and silking of 67.7 and 73 respectively. CIMMYT elite lines were characterized by significant low plant and ear height of 138.9cm and 50.6cm respectively as well as flint kernel type. Landraces were more diverse in every trait evaluated with significant long anthesis-silking interval of 7.5 days and large ear height of 95.9cm. Some landraces (eg TZA 2793 and TZA 5170) expressed significant traits that would be tapped for further crop improvement. Other landraces clustered themselves irregularly in terms of their collection sites within their major group due to selection and exchange of seeds. Thus, farmers as custodians of landraces are supposed to be involved in a systematic selection and breeding.