Abstract:
Sweetpotato (Ipomoea batatas (L) Lam) is food security tuberous rootcrop in Ethiopia and
orange fleshed is the cheapestsource of beta-carotene. However, its vine yield, tuberous
root yield and quality are low due to various constraints.Inappropriate harvest stageand
lack of improved varietyhavebeen identified to be constraints in Central Rift Valley of
Ethiopia. Thus, field experiment was conducted atAdami Tullu Agricultural Research
Centerin 2018 under rainfed condition with supplementary irrigation to determine the
effect of harvest stage on vine yield, tuberous root yield and quality of orange fleshed
sweet potato varieties. The experiment consisted of fourharvest stages (105, 120, 135 and
150 days after planting) and three varieties (Kulfo, Tulla and Guntute). A 4 X 3 factorial
experiment arranged in randomized complete block designwith three replications was
used. Data on vine yield, tuberous root yield and tuberous root quality werecollected and
subjected to analysis of variance using SAS version 9.3. The analysis of variance revealed
that the interactionof harvest stage and varietysignificantly influenced (P<0.01) leaf
number (LN), above ground fresh biomass (AGFB), marketable tuberousroot number per
plant (MTNPP), marketable tuberousroot weight (MTWPP),tuberousroot dry matter
content (TDMC) and vine length (VL), marketable tuberousroot weight per plant
(MTWPP), unmarketable tuberousroot weight (UMTW), Commercial harvest index (CHI),
harvest index (HI) and ash content(P<0.05). Leaf area (LA), leaf area index (LAI),
tuberousroot length (TL), tuberousroot diameter (TD), vine dry matter content (VDMC)
and leaf dry matter content (LDMC) were significantly affectedby the main effects of
harvest stageand variety(P<0.01). The highest mean values of UMTWPP (0.90 kg),
UMTW(1.17t/ha) & ash (5.72 %)werescored byGuntute variety harvested at 105 DAP
andAGFB (66.12 t/ha), MTW (56.39 t/ha) and TTW (56.71 t/ha)were produced by the
same variety harvested at 135 DAP.The highest mean value of tuber dry weight (29.70%)
and crude fiber (8.16 %) were produced byKulfo varietyharvested at 150 DAP.Farmers of
the study area and areas having similar agro-ecologies can grow Guntute variety
harvested at 135 DAP can be recommended to obtain best vine and tuberous yields. Since
the present study was conducted under rainfed with supplementary irrigation, over
locationunder irrigated condition wassuggested.
