Benefits of mini-sett seed multiplication method


IN traditional farming systems, farmers depend on seasonal harvest to supply planting materials for the following season.
This is a common practice among smallholder farmers of staple food crops like yam, sweetpotato, taro, banana and cassava in PNG.
However nowadays, this method of propagating seeds or planting materials is not very reliable due to increased prevalence of extreme natural events such as droughts, sea level rise and spread of harmful pests and diseases.
The National Agricultural Research Institute (Nari) has assessed available rapid multiplication techniques used elsewhere in the world for those crops and identified the mini-sett method as useful in the local context to improve the supply with planting materials especially for the staple food crops.
Mini-setts are pieces which have new shoot buds or eyes that are cut and extracted from “mother” tubers or corms.
A mini-sett is a squarish or cylindrical piece of plant cutting that could range from five to 25 cm2 and weighs around 15-20 grams, on average.
Careful steps are observed in extracting and preparing the mini-setts to avoid damaging the new buds.
After recommended curing processes like drying have been carried out; these pieces can be grown in nurseries to generate large quantities of new seedlings for planting.
Extraction of mini-setts has a number of advantages.
It is especially beneficial in terms of convenience in generating sufficient planting materials.
Farmers could extract a large number of budding seeds from just a handful of mother tubers or corm in just a few minutes compared to using setts made with tuber or corm heads, known as headsetts.
On average, a “mother” seed tuber or corm could provide up to 40 mini–setts.
This saves farmers the trouble of spending valuable time and resources in collecting and transporting new planting materials.
Mini-setts can also be treated to create disease free planting materials.
This could be done through cleansing processes where freshly cut mini-setts are placed baskets or string bags and dipped into four litres of a wood ash solution.
They could alternatively be coated with dry wood ashes.
Another option is to use five litres of bleach solution to treat the cuttings.
These processes help to prevent the carryover of nematodes and other soil-borne pests and diseases.
The use of treated mini-setts increases the potential of realising healthy crop development and yields.
There is also the opportunity for farmers to use the mini-sett technology as an income generating activity.
This can be achieved when they become specialised in planting and generating mini-setts on a large scale.
They could establish extensive seed farms to produce “mother” tubers and corms for the extraction of mini-setts.
Extracted mini-setts could then be sold to other farmers.
This has the potential of creating local supply bases to sustain convenient access to staple crop planting materials.
However, this opportunity is yet to be realised by entrepreneurial farmers.
Establishing mini-sett production and distribution chains for local staple crops’ would be a very proactive strategy; in light of prevailing fluctuations in climatic and environmental conditions.
In fact, the technique for rapid multiplication of mini-setts was first used in the 1987 drought relief efforts to re-establish the production of yam in East Sepik.
Local mini-sett farms can play a crucial role in boosting the level of preparedness and resilience of the smallholder sector against extreme natural events such as cyclones and droughts.
Mini-sett technology is also considered to be more environmentally sustainable.
This is mainly due to the use of continuous mounds and a combination of organic and artificial mulch options.
These practices help to reduce loss of soil mass and nutrient quality through erosion; control weed growth and help to manage intensive farming and improve yield volumes per hectare of cultivated land.
Generally, yields produced
with mini-sett seeds could produce as much as 75 per cent of tubers
or corms per hectare of cultivated land.
These are twice the output that could be gained from using traditional planting methods and are also of better marketable quality.
For example, mini-sett generated yams are straighter and larger and, therefore, easier to grade and package.
These qualities have generated commercial interest in both local and export markets for yam as an emerging commodity.
Similar opportunities are also being considered for other crops that are embracing the mini-sett seed multiplication technology, like taro and sweet potato.
There is great potential for this technology to be adopted among a greater number of vulnerable farming communities around PNG.
Nari is currently rolling out certain climate change adaptation projects like the European Union Climate Change Resilience.
These projects are avenues that have helped to promote the use of mini-sett technology to help diversify smallholder farming practices and, thereby, boost sustainable levels of food and socio-economic security for the country, as a whole.

  •  Pascal Pandau is an associate researcher in crops. He is attached with Nari’s Mamose
    Research Centre in Lae, Morobe.