Evaluation of maize accessions for diversity, yield and tolerance to maize lethal necrosis disease in Tanzania

Abstract

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.