Yield and yield components of local cowpea (Vigna unguiculata L.) landraces grown in mixed culture with maize (Zea maysL.) in vertic cambisols in the Northern part of Tanzania

Abstract

Smallholder farmers in the North eastern Tanzania practice cereal-legume mixed culture to manage risks of crop failure in sole crops. The production and productivity of cereal-legume intercrops may be influenced by the practice of cultivating two or more crops in the same space and time and the status of land races/cultivars involved as intercrops. Data on the effect of intercropping system on cowpea landraces with maize grown on Vertic Cambisols on yield and yield components are inadequate in the North eastern Tanzania although considerable knowledge has been accumulated on mixed culture system. A field experiment involving two cropping systems (sole crop and intercropping) was therefore conducted for two years (2017 and 2018) at Shirimatunda village, Kilimanjaro Region, North East Tanzania, to evaluate three local cowpea (Vigna unguiculata L.) landraces (i.e. landrace 1 (L1), landrace 2 (L2) and landrace 3 (L3)) grown in association with maize (Zea mays L). Intercropping significantly (P≤.05) decreased cowpea and maize yields. Performance of local cowpea landraces, however, did not show (P≤.05) any variation except for 100–seed weight where cowpea landrace 2 (L2) showed superiority compared with the other cowpea landraces. Although there was no significant variation in maize yield when intercropped with cowpea landraces, maize intercropped with cowpea landrace 1 gave numerically the highest grain yield. Regardless of cropping system and cowpea landraces, combined productivity of cowpea and maize increased in the intercropped plots as indicated by higher total land equivalent ratios (1.64 to 1.94). Highest LERT value was observed in the ‘Cowpea landrace 1’+Maize mixed culture. The observed total Land equivalent ratio (LER) values correspond to 48.25, 38.54 and 43.66 % of lands saved which could be used for other agricultural purposes. In these cropping systems, both cowpea landrace 1 & 3 and maize crop components were significantly complementary and most suitable in mixed culture as shown by competitive ratio (CR) values of 1.85 and 1.45 respectively.