Strengthening high-quality seed potato multiplication and supply (Solanum tuberosum L.) in family production systems

 Ing. Agr. Dra. Paula Colnago, Universidad de La Republica Uruguay
(pcolnago@fagro.edu.uy) 

Background 

Potatoes are the main vegetable crop in Uruguay where production volume (20% of total vegetables), level of consumption (30 kg/inhabitant/year), and nutritional benefits make potatoes a staple food that contributes to food security. The country’s agroclimatic conditions enable two annual crops – autumn and spring. Production mainly relies on imported commercial varieties prone to diseases, challenging adaptation to agroecological systems. Many diseases spread through seed tubers, requiring frequent seed renewal. The genetic uniformity of clonally propagated varieties further promotes disease development and spread, impacting yield and quality. Additionally, low multiplication rates and seed degeneration restrict local seed. High seed costs, external dependency, and frequent replacement limit potato farming on a reduced scale. Additionally, farmers face challenges integrating into markets that require stable supply volumes. 

In recent years, INIA1’s National Genetic Improvement Program has developed cultivars immune to the PVY virus and more resistant to Phytophthora Infestans and Alternaria Solani, which supports local multiplication. To increase the availability of seed from these materials, INIA has fostered agreements and partnerships with potato-specialized companies to multiply and commercialize pre-basic and subsequent seed categories, aiming to improve the short-term availability of the most in-demand national varieties. However, the supply of high-quality seeds to small-scale, non-specialized farms remains a key barrier for improving productivity. This limitation is primarily due to access issues (cost, scale, and organization) generally associated with niche materials that offer unique traits valued by a limited portion of the market. 

1 National Institution of Agricultural Research (INIA) 

To enhance national potato seed production, the University of Republic and INIA are collaborating to develop seed multiplication systems that better reach small farmers. Adapting alternative multiplication methods is crucial for improving access to quality seeds and establishing a robust production and multiplication chain. Various planting techniques and materials can facilitate tailored multiplication schemes suited to the diverse conditions of family farming systems. 

With the aim of enhancing the use of high-quality seeds and favoring availability and accessibility of alternative plant material, we assessed different methods of potato multiplication. 

Though widely adopted abroad, these methods were newly implemented in Uruguay without prior formal research. Semi-autotrophic hydroponics (SAH) systems use micro-propagated tissue to produce plantlets for aeroponic mini-tuber production. Another alternative material is true potato seed (TPS) progenies with high genetic diversity, reducing disease and environmental impacts, while limiting the spread of viruses and pathogens. In addition, it is easy and inexpensive to store and transport, allows for timely planting, and facilitates crop expansion. 

We performed a two-year research (2022-2024) project in screenhouse to: 

✔ Evaluate the production potential of seed tubers from two genetic materials and different planting materials (table 1) 

✔ Validate multiplication techniques for the installation of potato seed crops in family farms 

Genetic Material: 

INIA Arequita variety and TPS color progeny 

Plant Material: 

1) Multiplication through cuttings from micropropagated mother plants (SAH). This is the standard method for increasing the initial number of plants in clonal multiplication. 

2) Multiplication from Sprouts: This method involves obtaining seedlings from sprouts as the initial propagation material. It’s essential to know the origin of the mother tubers to ensure their health. The shoots can be harvested and planted in nursery beds for further plant production. 

3) Multiplication from TPS for selected progenies. The TPS progenies used in these trials were selected in collaboration with farmers during a prior progeny evaluation. 

4) Multiplication from minitubers (less than 10 grams). 

 

Table 1. Treatments and planting material origins for the high-density screenhouse test 

Genetic Material	Planting material	Origin
INIA Arequita	Plantlets from cuttings	Cuttings from micropropagated mother plants (in vitro)
INIA Arequita	Sprouts	Sprouted tubers placed in darkness. The sprouts are set in plastic trays in a chamber for rooting
INIA Arequita	Minitubers	Minitubers less than 10 grams
TPS-progeny	Seedling-TPS	Minis under 10 g. Placed at 20°C and treated with GAs
TPS-progeny	Sprouts	Sprouted tubers placed in darkness. The sprouts are set in plastic trays in a chamber for rooting
TPS-progeny	Minitubers	Minis under 10 g. Placed at 20°C and treated with GAs

Partners 

✔ Universidad de la República 

✔ National Institution of Agricultural Research (INIA) 

✔ Uruguayan Agroecology Net (Farmers) 

Project funded by Scientific Research Committee (CSIC), Universidad de la República.
Project that links the University and the Production Sector 

How do we take it forward? 

Trials were conducted in the Southern Regional Center (experimental station) together with farmers from Uruguayan Agroecology Net. Farmers were appointed to participate in the project with active roles in decision making. 

Farmer’s roles included: 

✔ On-farm trial management 

✔ Participation in recording and evaluation 

✔ Seed multiplication for their own use 

✔ Word of mouth spreading for extension activities among farmers 

Results 

✔ Kg/m² and g/plant showed no significant differences between genetic materials 

✔ TPS showed a higher multiplication rate (greater number of tubers per m²) 

✔ Sprouts exhibited a lower multiplication rate (fewer tubers per plant). 

✔ Planting material type and prior handling (juvenility of plantlets, mini-tuber size, and sprouting status) affect the multiplication rate. 

Based on 2023 results, an average of 10 m² of screenhouse space is needed to sow 1,000 m² of field crop in autumn (Figure 1). The autumn crop harvest then provides the seed required for 1 ha in spring. 

 

Table 2. Seed-tubers yields per year (kg/m2 and tuber #/m2)

	2022		2023
Treatment	kg/m2	# tb/m2	kg/m2	#tb/m2
Areq _Sprouts	6.3 b	104 a	9.6 a	234 a
Areq_MiniTub	3.6 ba	132 ab	24.1 b	429 b
Areq_Plantles	4.1 a	175 b	—	—
TPS_Sprout	3.9 a	177 a	13.9 a	401 a
TPS_MiniTub	6.3 b	315 b	24.2 b	780 b
TPS_seedlings	3.3 a	191 a	9.9 a	731 b

 

Table 3. Screen house area (m2) needed for sowing 1000 m2 of field if used in field crops different mini tubers weight (over 10 or 20 g)

Treatment	Minis > 10 g	Minis > 20 g
Areq _Sprouts	13.5	17.1
Areq_MiniTub	7.2	8.6
TPS_Sprout	8.6	11.5
TPS_MiniTub	5.4	7.4
TPS_seedlings	9.4	18.5

Lessons learned

– Farmers increased their knowledge of national varieties. 

-We advanced in local research in the use of adequate technology which was adapted to family farmers.

Networking -Institutions, farmers and technicians- were able to:

• Improve the availability of genetic material
• Adapt technology to diverse farming systems
• Enhance adoption and dissemination of high-quality seeds of national varieties in agroecological farmers 
• Know farmers’ preferences

Perspectives and next steps:

Currently, six farmers are cultivating their own seed from true potato seed (TPS). The project generated considerable interest among agroecological farmers, and the farmer’s organization, the Agroecology Network of Uruguay, is organizing collective seedling nurseries to support new farmers in this process (starting in 2024).

Based on these developments, we secured funding for a new research project aimed at refining a multiplication scheme (the production of foundation seed and subsequent generations) involving various stakeholders: farmers, extension technicians, and research institutions. This project will include the characterization of a new genetic material (TPS) to enable its differentiation as a novel commercial product: colored potatoes.

New partners from the production sector have joined this initiative, including the National Committee for Rural Development and the Native and Creole Seed Network of Uruguay. Additionally, cooperation with the International Potato Center (CIP) has been established to deepen the understanding of the potato seed system in Uruguay.