ISSN: 0041-3216

ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 70 Number 2
Research Papers
The effects of methods of planting cuttings of sweet potato [Ipomoea batatas (L.) Lam.] on yield
Malcolm P. Levett
The effects on sweet potato (lpomoea 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 investigate, 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. However, 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 tuber 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-1) 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 node vertical or horizontal' resulted in minimum weevil damage. Delaying the harvest from 108 to 13 days after planting resulted in significant increases in internal damage of marketable size tubers an in the percentage of small nonmarketable tubers.
Keywords: Sweet potato; Cutting orientation; Number of nodes planted· Plant population density; Harvest date; Cultivar; Yield