Effect of planting date on tuber yield and quality of potato (Solanum tuberosum L.) Varieties at anderacha district, southwestern Ethiopia

Abstract

Optimum planting date is highly location specific and the most important subject in rain-fed potato production. However, there are no research recommendations pertaining to adaptable cultivars and their optimum planting date with due consideration of the environmental condition of Anderacha area. Thus, this study was conducted to assess the effect of planting date and variety on yield and quality of potato at Anderacha woreda, Western Zone of SNNPRS, from October 2011 to March 2012. Five planting times (October 20, October 30, November 9, November 19 and November 29) and three varieties (Jallene, Guidene and local) were combined in 3x3 factorial arrangement and laid out in randomized complete block design with three replicates. Data were collected on growth, yield and quality parameters and analyzed using SAS Version 9.2 statistical software. The result showed that early planting (October 20) delayed emergence and flowering by about 4 and 15 days, respectively and increased plant height by 10.68cm than the latest planting on November 29. The number of stems per plant increased with delayed planting, however tuber number decreased in late plantings and planting on October 30 that resulted in significantly (P<0.05) better number of tubers. Early planting produced significantly heavier tuber weight (83.80g) which progressively reduced in subsequent plantings, whereas delay in planting resulted in higher unmarketable yield. Percentage of medium sized tubers (65.17 %), tuber specific gravity (1.092) and dry matter content (23.02) showed the highest value in early planting and decreased with subsequent planting dates. Guidene took significantly longer days to emerge and flower (19.2 and 65.6 days, respectively) and plants were significantly taller (77.77cm) than Jalene and local variety. Jalene produced significantly (P<0.05) the highest stem number and consequently produced highest tuber numbers per plant. It also showed increased average tuber weight by 29.12% as compared to the local variety. Guidene and Jalene produced low unmarketable tuber yield by 44.35 and 31.06 %, respectively compared to local variety. The highest percentage of medium sized tubers, tuber specific gravity and dry matter value was obtained from variety Guidene.Guidene planted on earliest date took the maximum number of days (124 days) to mature, while last planted local was earliest to mature (90 days). Jalene planted at the earliest planting of October 20 produced maximum percentage of large sized tubers (17.91%), whereas the highest percentage of small sized tubers (35.83%) was recorded from late planted (November 29th) local variety. Variety Jalene planted on October 30th produced the highest harvest index (0.84), marketable and total tuber yield (34.82 and 38.6 ton/ha), respectively. The two earlier plantings and variety Jalene showed superior performance in most studied growth, yield and quality parameters even though variety Guidene was superior in some quality parameters. Correlation analysis also indicated that the relationship between marketable tuber yield with days to 50% flowering, days to maturity, plant height, total tuber number/hill, average tuber weight, harvest index and large tuber percentage was positive and highly significant(P<0.01). Therefore, based on the findings of the current study, early planting (October 20 up to 30) and potato variety Jalene can be used for high marketable tuber yield and better quality. Since, the present study was done xv only for one season at one location; it would be advisable to repeat the experiment for more number of years and places to come up with comprehensive recommendations.