Early maturing sweet potato varieties

Nari, Normal

The National, Tuesday November 17th, 2015

 When normal rains return after a drought, food production must begin again as soon as possible. Planting of quick maturing crops is the obvious solution to provide food. Therefore, the use of early maturing varieties in the post-drought period is recommended.  

In order to do this, planting materials must be available and should have been preserved through the drought period. This includes planting materials of sweet potato or kaukau – PNG’s staple food. 

During recovery, sweet potato should be intercropped with other important crops that will produce rapidly after drought like maize, beans, peanuts and potato. The reason is that during a drought, nitrogen levels rise in the soil, partly through death and decay of plants, animals and micro-organisms. 

Quick growing leafy vegetable crops can use the extra nitrogen to grow quickly and yield well but sweet potato tends to grow lots of leaves with disappointing tuber production. It is better to plant a crop of maize first, followed by a crop of early maturing sweet potato.

Early maturing lowlands sweet potato varieties

Research trials undertaken by NARI have found four early maturing sweet potato varieties for the PNG lowlands. Three of them (B11 PT, NUG 5 and SI 278) have also shown tolerance to drought. Variety SI 85 is an excellent variety for early harvest but lacks the drought tolerance as the other three varieties. All these varieties yielded well when harvested 13 weeks after planting in a Sogeri trial. These varieties were selected for trial as a result of past research done by the Pacific Regional Agricultural Program (PRAP) under the Department of Agriculture and Livestock (DAL).

NLSP stands for NARI Lowlands Sweet Potato or NARI Nambis Kaukau in Tok Pisin. These sweet potato varieties must be planted as soon as normal rains return after a drought. Supply should be available by the third month. Requests for foundation planting materials should be addressed to NARI Laloki in the Central Province.


Early maturing highlands sweet potato varieties

NARI Aiyura has selected nine sweet potato varieties. They have produced acceptable yields at four and five months after planting. The selection was based on results from two trials. The selected varieties yielded between four and seven tonnes/ha at four months after planting. The varieties are WHCK 005, SKK 010, WBS 010, PRAP 469, PRAP 714, SSYK 026, WHCK 007, PRAP 123 and PRAP 559.  To make naming easier, they have been listed as NHSP 1 to NHSP 9 respectively. NHSP stands for NARI Highlands Sweet Potato or NARI Hailans Kaukau. NHSP 1 to 5 are also tolerant to drought conditions. Of the nine varieties, five were collected from farmers’ fields and four from varieties held by NARI from previous research conducted by PRAP under DAL.

Farmers are encouraged to plant these early maturing sweet potato varieties after a drought to provide food during the recovery period. 

They should be planted as soon as the rains return. Trials at Aiyura have shown that acceptable yields can be obtained after four months, though tubers will continue to bulk up after this.  They can provide edible tubers sooner than most varieties, which take longer to mature.

Early Maturing High Altitude sweet potato varieties 

Further research by NARI Tambul has resulted in the recommendation of 12 sweet potato varieties for the high altitude highlands areas (more than 2000 metres above sea level) of PNG. 

These varieties can produce between 4–9 tonnes per hectare (marketable yield) at 6 months. This is an improvement because traditional varieties take 9-12 months to mature. The selection of these early maturing varieties provides an assurance for food security especially after frost events when all food crops are destroyed. As frost is prevalent at areas above 2000 meters, these are varieties are highly recommended.

The recent government decision to supply planting materials to the PNG farming community affected by the current El Nino-induced drought is a welcome news. 

Food rations are expensive and short term. Planting materials will cost less and but importantly enable people to sustain food supply through garden production. 

The Government has directed all districts to make a fraction of their DSIP funds available for drought recovery exercises. 

When funds become available, NARI will be keen in multiplying seeds and planting materials at its regional centres and supplying them to drought and frost affected communities through resource centres and district-based partners and authorities.