YAM VARIETY TRIAL


 Yam Is a popular crop In the Caribbean. Yams arefrequently used In Intercropping systems. In the Virgin Islands,
 yams are Interplanted with corn, pigeonpea, and cassava. Although yields of both crops are reduced In
 intercropping, total productivity is higher than that obtained with monoculture of either crop.
 Yields of local yam varieties are relatively lower than those of the improved varieties. To determine the potential
of improved yam varieties, a trial was conducted In the summer of 1988. The varieties were planted on June 1,1988.
In an unreplicated trial. The varieties came from three species: Dloscorea alate, DIoscora esculente and
Dioscma rotundats. Varieties of 0. alate were Binugus, Gnuung, Seal Top, Gemelos, Forastero and Florldo.
Varieties of 0. eoculants were: Doll, Kombi and Seti. Habanero was the only variety in the D. rotundata species.
 The varieties were planted using cut tubers weighing approximately 115 g. Plant spacing was 1 m between rows
and 50 cm between plants within rows. Each plot measured 12 m and consisted of only one row. The plots were
fertilized with SON, 0OP and 25K, all in kg hae'. The fertilizer was applied two months after germination. To correct
the symptoms of iron deficiency, Ferromec was applied two months after planting.
 All plots were drip-Irrigated to ensure good crop establishment. Weeds were controlled by hand-weeding while
Insect pests were controlled by two spraying of malathion. To protect the plants from fungal diseases one spraying
of Dithane M46, four spraying of kocide and two applications of Bordeaux mixture were performed.
 The crop was harvested on March 1, 1989, approximately ten months after planting. Data on Table 23 Indicate
that yields ranged from 8.9 to 33.8 t1 ha-' for the varietes in the D. slate and 5.3 to 20.1 t ha-' for the D. esculents
varieties. The lowest yield (2.6 t ha') was obtained from the D. rotundata variety. Among the D. late varieties,
Binugus produced the highest yieldfollowed by Seal Top and Forastero. Gemelos and Gunung both produced yields
of 12.01 ha-. Among the D. esculenta varieties, Setl was the best-yielding variety, followed by Doll.
 The result of this unreplicated trial would indicate that improved yam varieties of D. elate and D. esculentl
species may perform better than the D. rotundata, although more varieties should be Included from the later group
In future trials. Replicated trials are needed to verify these results.

 Table 23. Yield of yam varieties grown during summer 1988, to
 spring, 1989, at UVI-AES.

 Variety Species Yield
 (t ha-')

 Blnugus D. alate 33.8
 Seti D. esculenta 20.1
 Doll D. esculenta 17.1
 Seal Top D. slate 16.7
 Forastero D. late 13.3
 Gemelos D. late 12.1
 Gunung D. late 12.0
 Florido D. slata 8.9
 Kombi D. esculenta 5.3
 Habanero D. rotundate 2.6

 Note: Unreplicated trial.