Morphological Basis for Yield Differences among Cowpea Varieties in the Sudan Savanna Zone of Nigeria

Abstract

Field trials were conducted at two locations, namely the Teaching and Research Farm, Faculty of Agriculture, University of Maiduguri, Maiduguri (11 o 47.840'N; 13 o 12.021'E; elevation 319 m asl) and Damboa (11 o 10.736'N; 12 o 47.100'E; elevation 398 m asl) on the trial site of the International Institute of Tropical Agriculture (IITA) in Borno State both in Sudan Savanna zone of Nigeria during the 2010 and 2011 rainy seasons. The objectives of the study were to evaluate the agronomic performances of some improved cowpea varieties and to identify the morphological traits associated with high grain yield in the Sudan Savanna zone of Nigeria. The trial consisted of eight treatments (cowpea varieties), which included two local varieties viz: Kannanado White and Borno Brown obtained from farmers in Damboa, Borno State and six improved varieties viz: IT90K-277-2, IT97K-568-18, IT89KD-288, IT97K-499-35, IT98K-131-2 and IT89KD-391 obtained from IITA stations in Kano and Maiduguri, Nigeria. The treatments/varieties were laid out in a randomized complete block design (RCBD) replicated three times at each site. The gross plot size was 5.0 m x 4.0 m (20 m 2 ) while net plot size was 3.6 m x 3.0 m (10.8 m 2 ). The results showed that the improved varieties produced significantly higher number of branches, peduncles, and pods per plant and number of seeds per pod than the local varieties. However, the local varieties produced significantly longer branches and higher number of branches though similar to that of the improved IT89KD-288 variety. Averaged over both locations in both years (overall mean) the results showed that cowpea grain yield was positively correlated with number of pods per plant, peduncle length and number of peduncles per plant. Conversely, the results indicated that cowpea grain yield was significantly negatively correlated with branch length. From the study the improved varieties performed better than the local varieties in the Sudan Savanna zone of Borno State. Among the improved varieties, IT90K-277-2, IT97K-499-35 and IT98K-131-2 were outstanding in terms of grain yield per hectare.