Yam Agronomy
Yam agronomy work previously based at the Sir Alkan Tololo Research Centre at Bubia in the Morobe Province has been transferred to DLP Laloki. The work comprises the yam collection (South Pacific Yam Network or SPYN project) with the following species and accession numbers;
| Yam species | Acc. # |
| Dioscorea alata | 182 |
| D. esculenta | 76 |
| D. numularia | 34 |
| D. rotundata | 21 |
| D. bulbifera | 8 |
Out of the 50 SPYN elite selections, 28 accessions are being multiplied for further agronomic evaluation.
Two promising varieties of African yam, which belongs to the D. rotundata species, have been officially released by NARI to farmers for production. However, a weakness observed in these varieties is that its tubers rot if left in the ground for more than a day under flood or wet conditions. It should therefore be grown away from flood-prone areas.
Accessing staking materials and staking operations constitute a major component of yam production cost. Investigations are underway to evaluate the suitability of Gliricidia and Sesbania for live-staking of yam.
The idea of producing yams on a continuous basis is being tried out through sequential plantings to see if yam can be grown all the year round under irrigated conditions. If proven positive, this concept would greatly enhance food security and income earning opportunities for the farmers in the dry-lowland areas of the country.
Diagnosis and Correction of Nutritional Disorders of Yam
The nutritional disorders of the yam project, funded by the Australian Centre for International Agricultural Research has ended and the final report is being prepared. The rapid decline in soil fertility and lack of “yam sticks” for staking were the most common constraints to yam production in the main yam growing provinces of PNG.
Yam growing in the grassland areas of Bogia District of Madang showed some deficiency symptoms of nitrogen, phosphorus, sulfur, iron, manganese and copper. In the Kiriwina area of Milne Bay Province, soil fertility and staking issues were more severe than Bogia and other sites. Yam growing in atoll soils of Kiriwina showed severe deficiencies of nitrogen, phosphorus, potassium, sulfur, iron, manganese, copper and zinc.
Additionally, nematode diseases in yam are becoming a problem in Bogia. In Kiriwina and other atoll areas of Milne Bay, nematode is the immediate threat to yam production followed by soil fertility.
Planting Material Multiplication Blocks
(Sweet potato, cassava, banana and yam)
Superior varieties of sweet potato, cassava, banana and yam are currently being maintained in the field for distribution to farmers as planting materials.
Cassava: Five (5) high yielding superior varieties of cassava selected for planting in the dry-lowland areas are being multiplied for distribution to farmers.
Yam (Dioscorea rotundata): A block of African or rotundata yam was harvested and 100 yam tubers weighing between 1.0 to 2.5 kg were selected, cut into mini setts, germinated in the nursery and planted in the field for planting materials distribution work.
Taro (Dioscorea esculenta): The four NARI taro hybrids (NARI Taro 1 or NT 1, NT 2, NT 3 and NT 4) and 16 other promising varieties collected from the Southern region are being multiplied in the working collection at Laloki for distribution to farmers
Nursery Activities
The primary purpose of the fruit and nuts nursery is to multiply common species of fruit and nut tree seedlings for distribution and sale to farmers. These include different varieties of mango, citrus, guava, five-corner, cashew nut and others.
Grafting is the main propagation technique used on mango and citrus. The nursery is producing and selling the following grafted materials and seedlings:
| Mango varieties | Glen, Irwin, Kensington apple, Large apple, Nam-dok-mai, Karabao, MA 12, Rabaul and Banana Callo |
| Citrus varieties | Naval orange, Valencia orange, Ellendale mandarin, local mandarin, troyer lime, grape fruit, kamquat and pomelo |
| Guava seedlings | Giant Vietnam and Hawaiian red |
| Other seedlings | Okari nut, galip nut, tamarind and carambola |
For further information, Contact
NARI Dry Lowlands Programme
P.O Box 1828, PORT MORESBY
National Capital District
Papua New Guinea
Phone: (675) 323 5511
Fax: (675) 323 4733
Email: naridlp@nari.org.pg