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Aim:To investigate the performance of some improved sweet potato varieties obtained from the National Root Crops Research Institute (NRCRI), Umudike, Nigeria, for root yield and other yield components.

Field experiments were conducted at the National Root Crops Research Institute sub-station, Otobi, in 2006 and 2007 to assess the suitability of improved sweet potato varieties for intercropping with pigeonpea and also to determine the planting pattern and the productivity of the intercropping system. Intercropping decreased total fresh root and saleable root yields of sweet potato when mixed or row-intercropped with pigeonpea. All intercropping combinations of sweet potato varieties and pigeonpea had land equivalent ratio above 1.0, except intercropping with WA Gabolige, signifying high intercrop advantages. TIS 87/0087 produced the highest total fresh root and saleable root yields in both cropping systems, irrespective of the planting pattern used. TIS 2532.O.P.1.13 and TIS 86/00356 sweet potato varieties had comparable yields with TIS 87/0087 in both cropping systems. Pigeonpea was the more competitive component of the intercrop. Farmers showed willingness to adopt the sweet potato + pigeonpea intercropping.

ABSTRACT. Field experiments were conducted from July to October, during 2012 and2013 cropping seasons, at the Research Farm, University of Agriculture, Makurdi, Nigeria, to evaluate the effects of intra-row spacing of sesame and frequency of weeding on yields of maize-sesame intercrop. The trial was a 3 x 3 factorial experiment fitted in a randomized complete block design with four replications. Nine of the treatments consisted of intercropped maize with sesame sown at the intra-row spacing of 10 cm, 15 cm and 20 cm, and at the varied weeding frequencies: maizesesame intercrop sown on plots weeded once (1x) at 3 weeks after planting (WAP); maize-sesame intercrop sown on plots weeded twice (2x) at 3 and 6 WAP; maize-sesame intercrop sown on plots not weeded (NW). Sole sesame and sole maize respectively sown at their recommended intra-row spacing of 10 cm and 30 cm and at their recommended frequency of weeding (2x at 3 and 6 WAP) constituted the tenth and eleventh treatments, which also served as control plots. The results obtained showed that in a maize-sesame intercrop, increasing intra-row spacing of sesame up to 20 cm, on plots weeded 2x at 3 and 6 WAP, significantly (P≤0.05) produced the highest intercrop yields of maize and sesame. This level of treatment not only recorded the lowest competitive pressure, but gave the highest total intercrop yields, highest land equivalent coefficient values (1.01 and 1.13 respectively, in years 2012 and 2013), indicating the highest yield advantage, and highest land equivalent ratio (LER) values of 2.11 and 2.25 respectively recorded for years 2012 and 2013. With these LER values, 52.6 % and 55.6 % of land were respectively saved in years 2012 and 2013, which could be used for other agricultural purposes. The implication of study showed that, to maximize intercrop yields of maize and sesame in a maize-sesame intercrop, the appropriate intrarow spacing for sesame is 20 cm, while the optimal frequency of weeding is 2x at 3 and 6 WAP. This should therefore, be recommended for Makurdi location, Nigeria.

A field experiment was carried out during the cropping seasons of 2014 and 2015 at the Teaching and