Varietal collection and evaluation of traditional sweet potato cultivars in Castilla, Sorsogon [Philippines]

Sweet potato is commonly grown in upland or hilly areas where it serves not only as a food source for farm families but also as an additional source of income. The municipality of Castilla, situated in the highland of Sorsogon, is a potential area for growing sweetpotato. However, there is no suitable production of sweetpotato in the province. One reason noted was the lack of appropriate planting materials suitable to the local conditions. Thus, there is a need to introduce and produce other traditional cultivars, which are not only high yielding but suited to local conditions. To evaluate and characterize traditional varieties found in La Union, Castilla, Sorsogon, Lasim et al. conducted a varietal collection and evaluation of traditional sweetpotato (Ipomoea batatas) varieties in 2003-2005. 'Inaswang' significantly produced the longest vines (218.6m) in the upland agroecology and 197.2 m in the sloping agroecology. This could be attributed to the growth habit of the plant. 'Sinorsoganon' obtained the highest variety mean dry weight (43.3 g) in the upland agroecology while the varieties 'Tinagiti', 'Sinorsoganon', and 'Buko-buko' 1 and 2 (41.7 g) significantly obtained a higher variety mean dry weight in the sloping agroecology. Majority of the morphological characteristics of nine traditional sweetpotato cultivars were found similar in terms of their plant type (spreading characteristic), foliage color (mostly green), root flesh color (mostly white), while variations in root skin color was observed. Tinagiti was the most preferred cultivar in terms of eating quality characteristics (appearance, color, flavor, and texture) of boiled storage roots. Sinorsoganon and 'Soraw' cultivars produced the highest yields per hectare. Under upland agroecology, Sinorsoganon produced 18.79 t/ha and Soraw, 17.80 t/ha. For the sloping agroecology, Sinorsoganon produced 22.38 t/ha and Soraw, 18.94 t/ha. All varieties ('Agahapon', 'Tres Colores', 'Binoras', Tinagiti, Sinorsoganon, Inaswang, Soraw, Buko-buko 1 and 2) were resistant to leaf scab. Only Buko-buko 2 was moderately resistant to weevil infestation in the sloping agroecology. Sinorsoganon and Soraw were potential varieties for planting in both seasons (dry and wet) and locations (upland and sloping). Performance of Tinagiti should be further evaluated due to the good eating quality characteristics (appearance, color, flavor, and texture) of boiled storage roots. Also, multilocation trials of the traditional cultivars are still needed.