The effects of methods of planting cuttings of sweet potato (Ipomoea batatas (L.) Lam.) on yield
1993
Levett, M.P. (Papua New Guinea Univ., National Capital District (Papua New Guinea). Dept. of Geography)
The effects on sweet potato (Ipomoea batatas (L.) Lam.) yield and components of yield of planting methods, using vertical or horizontal orientation of cuttings, variable numbers of nodes (two, four, or six) placed in the soil at planting, and one or two cuttings at each planting location, were investigated in two experiments carried out in the dry lowlands of Papua New Guinea, using two cultivars ('L22' and 'L44'), and two harvest dates. Several yield components of the two cultivars were significantly different. Method of planting did not significantly affect total yield. In the first of the two experiments, the percentage of small nonmarketable tubers was affected by the method of planting. Planting four nodes vertically in the soil resulted in the smallest percentage of nonmarketable tubers for cultivar 'L22', while six nodes placed horizontally was the most effective for 'L44'. Increasing the number of cuttings at a planting location from one (36 700 cuttings/ha) to two did not significantly affect total yield but resulted in the production of substantially smaller tubers for 'L44' but not for 'L22', and increased the proportion of marketable size tubers which had internal damage by the sweet potato weevil Cylas formicarius formicarius. The amount of damage during the second experiment, when weevil damage was severe, was affected by the number of cuttings at a planting location and the method of planting. Two cuttings with 'two nodes vertical', and one cutting with 'four nodes vertical or horizontal' resulted in minimum weevil damage. Delaying the harvest from 108 to 133 days after planting resulted in significant increases in internal damage of marketable size tubers and in the percentage of small nonmarketable tubers.
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