High yielding varieties and improved cultural management practices for increased yam production

Yam (Dioscorea) plays a vital role as a food source in the country especially in times of scarcity. Among the more than 50 yam species, only two species are of important economic value as food source - D. alata ('ube') and D. esculenta ('tugui'). Tugui is widely cultivated in northern Philippines like Ilocos Region that accounts for more than 50% of tugui production in the country. Tugui thrives well in marginal areas and is considered as cash crops by upland farmers. However, the lack of a recommended high-yielding and acceptable variety, and production technology limits the productivity of tugui farmers. Legaspi and Malab (Mariano Marcos State Univ., Batac, Ilocos Norte, Philippines), evaluated promising and high yielding accessions, and improved the cultural management practices in order to increase tugui productivity. Out of ten tugui accessions evaluated, PSB VT3 showed consistent high yields for three consecutive cropping seasons with an average yield of 19.80 t/ha. Other accessions also showed higher yield compared with the national (4.41 t/ha), regional (3.24 t/ha) and provincial (3.30 t/ha) average yield. Local accessions significantly produced more tubers, but PSB VT3 produced bigger and heavier tubers, consistent in the three cropping seasons. PSB VT3 also obtained the highest marketable yield (65.02%) among the accessions in the first cropping season, while the second and third cropping seasons did not show significant differences. Acceptability test showed that Accession no. 3 was the most acceptable in terms of appearance, color, aroma, taste, and texture. Tugui was successfully grown without fertilizer application the same area for at least 3 years, producing a comparable yield with those applied with either organic or inorganic fertilizer. However, after 3 years of continuous cropping without fertilizer, decline in yield was observed. Application of 2 t/ha of organic fertilizer produced comparable yield with those applied with inorganic fertilizer. It also resulted in the highest residual soil fertility after 3 years of cropping. Big and medium setts significantly produced plants with higher yield and better growth. Small-sized setts, on the other hand, had lower yield and produced plants with poor vigor.