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Effect of sett-size on the yield of two yam (Dioscorea sp.) varieties grown in the dry- and rainy-seasons
Abstract
The sprouting time of yam tubers had been changed permanently from rainy-season to dry-season period with Giberillic Acid (GA) solution. The yield performance of minisetts and peelsetts of two yam varieties were compared in both seasons (using irrigation during the dry periods). Peelsetts (6.25g), obtained from the periderm of yam tubers, and minisetts( 25g), which were cut pieces of the yam tubers, were planted in April for the rainy-season crop and in October for the dry-season crop, starting from April 2004 to October, 2005. The yam varieties used were Obiaoturugo (Dioscorea rotundata) and Um 680 (Dioscorea alata). The rainy-season crop matured in November and the dry-season crop matured in May for (D. rotundata) and in June for (D.alata). In the rainy-season harvests, the yields of minisetts and peelsetts per hectare were similar in each variety, whereas in the dry-season harvests, the minisetts of outyielded (P =0.05) the peelsetts while the peelsetts of Dialata, Um680, on the contrary, outyielded the minisetts. Um680 outyielded (P = 0.05) Obiaoturugo in both seasons. On the average, yields were higher in the dry-season than in the rainy-season due mainly to size of tubers rather than number of tubers. The implication of the new technology of growing yams in the dry-season is discussed.
Keywords: Yam, Sett size,Yield, season, Peelsett, minisett