ABSTRACT

Three field experiments were conducted between 2016 and 2018, in the rainforest belt of south eastern Nigeria at Umudike, to study the response of white yam (cultivar TDr 89/02475) to slip weight and NPK fertilizer,  determine the effect of sett size and time of sett immersion in water on white yam (cultivar yandu) and examine effect of stake height on four aerial yam cultivars. The three experiments were all laid out as factorial in randomized complete block design (RCBD) with three replications. Results indicated that increasing white yam slip weight from 25-45g significantly increased vine length, leaf area index, shoot dry matter, number of tubers per plant and tuber yield. Application of  NPK fertilizer at the highest rate of 600kg/ha increased shoot dry matter but, the optimum tuber yield was obtained from application of the moderate fertilizer rate of 400kg/ha. The 70g whole tuber of white yam increased significantly crop establishment while 60g sett weight increased  shoot dry matter and tuber yield. The highest tuber yield was obtained from 60g sett, although the smaller 50g sett produced similar results. Increasing time of sett immersion in water reduced leaf area index but, increasing the time of immersion to 12 hours increased crop establishment and shoot dry matter. On the average, time of sett immersion in water did not significantly affect tuber yield. Increasing the height of stake to 1 or 2m increased significantly aerial yam vine length, number of bulbils per plant and bulbil yield in 2017 and leaf area index in 2018. The best stake height in 2017 was 2m, although, the 1m stake gave similar results. Irrespective of height of stakes, staking had no effect on yield in 2018. Cultivar Adu Ugo had significantly longer vines, greater shoot dry matter, bulbil dry matter and bulbil weight than others in 2017. Bulbil yield was significantly higher in Adu Ugo  and  Adu Okai than in Adu Egbe in 2017 while, no differences in yield occurred among the cultivars in 2018.