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Influence of “‘milking’ date” on seed yield potential in hybrid yam varieties (<i>D. rotundata</i>)

GO Agbaje


An experiment was planted in 2005 and 2006 at Ikenne(6o 51’ N 3o 42’ E), the humid rainforest experimental station of Institute of Agricultural Research and Training. Ibadan, Nigeria. This project aim was to assess the seed yield potential of hybrid yam varieties at different time of ‘milking’ and its economic implications in order to increase seed supply for tuber yam production. Availability of seed is a problem in yam cultivation and expansion. Tuber vines from two hybrid yam varieties TDr 89/02565, TDr 89/02665 and Ikenne local cultivar were “milked” at six different dates beginning from early August to late October. The tuber yield prior to ‘milking’, seed yield and seed weight were obtained and statistically analyzed. Results showed that mother tuber yields prior to ‘milking’ increased with delay in ‘milking’ date but seed yield produced after ‘milking’ decreased with delay in ‘milking’ date. Mother tuber yield was 9.37 t/ha in early August but increased over 90% by late October. Seed yield was 9.03 t/ha in early August and 0.60 t/ha in late October. Seed weight was 0.92 kg seed -1 in early August and below 0.27 kg seed -1 after mid-September ‘milking’. Varietal differences were significant for mother tuber yield, seed yield and seed weight with the hybrid varieties performing better than the local cultivar. Economic analysis showed that highest net return was obtained in hybrids used when ‘milking’ was done by mid-August. The hybrid varieties had over $4,000 ha-1 yr -1 as net returns while it was lesser than $1,500 ha-1 yr -1 in Ikenne local. The result suggests that seed supply and the income of farmers will increase with the adoption of hybrid varieties TDr 89/02565 and TDr 89/02665. 

Keywords: ‘milking’; hybrid yams; seed yam; net returns; benefit to cost ratio