Challenges and opportunities for seed availability and quality in Yemen

Mohammed Ali Muthanna Saleh (mmuthanna14@gmail.com), Dhamar University, Dhamar, Yemen
Abdul-Allah Mohammed Dhaif-Allah, Dhamar First Center for seed potato, Dhamar, Yemen
Peter VanderZaag, Sunrise Potato Systems Institute, Alliston, Canada

Background

Yemen has experienced nine years of war resulting in a humanitarian crisis for 65% of the population, increased prices for all commodities and scarcity of agricultural inputs. With only about 3% of the total land area of Yemen being arable, the potato can play an important role in food security. The potato produces more food and more energy per unit area and per unit time than any other crop. Potato production primarily takes place in three locations in the southern part of Yemen. Production has decreased from over 303,000 tonnes (mt) in 2010 to 228,000 mt in 2021.

Table 1 Climate (Temperature and rainfall) data for Dhamar and solar radiation for Taiz (climate-data.org)

	Jan	Feb	Mar	Apr	May	June	July	Aug	Sept	Oct	Nov	Dec
Avg Tem. Max (°C)	21.2	22.6	25.1	24.9	26	28.1	25.8	25.3	25.2	23.6	21.1	20.8
Avg Tem.Min (°C)	2.4	2	6.3	7.6	9.9	9.8	13.4	13.1	10.7	9.3	6.7	4.9
Rainfall (mm)	7	8	18	50	45	15	76	110	31	6	8	3
Solar (MJ/m ²)	17.2	19.2	22.1	20.8	21.8	20.1	17.9	19.3	18.1	22.4	20.2	17.3

The Dhamar valley, where about 50% of the total potato production grows, is situated between two volcanos at 2,400 meters above sea level. This is an ideal environment for potatoes with drilled wells making irrigation water available throughout the area all year round, even during the dry spell (Table 1). Farming practices are simple and well managed by the farmers, who use animal power for most operations and labor for planting and harvesting (Pictures 1 and 2). The main rotation crops are wheat and barley.

A cooperative relationship with a Dutch organization in 1977 provided seed potatoes and expertise and started the process of potato production in Dhamar valley. After the cooperation ended, the Yemeni government would occasionally import some seed potatoes. In the last few years, the private sector has been permitted to import seed potatoes. The main objective of this story is to assess seed quality and yield of 1 or 2 multiplications of imported seed potatoes.

Results

Five farmers agreed to cooperate in collecting data for this study. Data observed visual viruses, black leg and Rhizoctonia based on four replications of 43 meters of row. At harvest, three meters of row across 4 replications were weighed and graded. The imported Dutch seed (G1) of three varieties grown by three different farmers were planted in mid-February and harvested between June 16-18. The G1 seed crop had no visual viruses nor black leg nor Rhizoctonia (Table 2). The total tuber yields were from 59.4 mt/ha for Panamera down to 47.8 mt/ha for Diamant (Table 2).

Table 2 Generation 1 (G1) and G2 seed planted to grow crops with 5 farmers in Dhamar Valley in 2023

Generation	Variety	Farm	PLRV (%)	Mosaic (%)	Black leg (%)	Rhizoctonia (%)	Total Yield mt/ha
1	Diamant	1	< .01	< .01	0	0	47.8
1	Fabula	2	< .01	< .01	0	0	54.8
1	Panamera	3	0	0	0	0	59.4
2	Panamera	4	2.9	0.9	1.1	0.8	48.5
2	Panamera	5	4	2.4	2.3	1	43.5

The G2 crop sampled only the variety Panamera in two farmer fields planted in mid-January and harvested in mid-May. The infection with visual symptoms of PLRV and mosaic averaged 3.5 and 1.6% of the total plants in the sampled areas. Black leg and Rhizoctonia reached levels of 3.9 and 0.9% respectively (Table 2). Tuber yields averaged 46 mt/ha for the 2 fields.

Although it isn’t right to compare the yields between the G1 and G2 crops due to different times of planting and being in different farmer’s fields, we can see that the G1 crop gave higher yields for the variety Panamera. There was significantly more rainfall this year in March, April and May totaling over 600mm as compared to the overall averages (Table 1). This caused some late blight (LB) infection levels to occur even though farmers sprayed contact fungicides frequently. Panamera is a preferred variety because it is less susceptible to LB than Diamant.

All the five farm fields studied had yields that were three to almost four times higher than the national average. These yields would be the norm through the valley with the G1 or G2 seed that is grown. The solar radiation levels increase from January to March and remain high through June (Table 1). This allows for high yield potential along with the ideal low night temperatures during the growing season from March to June. There was no frost damage. Temperatures fell below 0 degrees Celsius on a few evenings, but not cold enough to cause foliar damage.

G3 and further multiplied seed is grown in the more remote areas from the Dhamar valley and yields are much lower due to limited fertilizer inputs, a lack of irrigation water and/or fungicide sprays.

Lessons Learned

Intensive farming in the Dhamar valley leads to challenges with virus spread and pathogen infection from G1 to increased infection in G2 seed. Farmers are encouraged to harvest all infected plants and use them as table potatoes prior to dehaulming.

Yields of the G2 seed of Panamera variety, although less than the G1 seed, were still high. The variety is known for being less susceptible to LB and grows well under more difficult conditions. It is the farmers’ first choice for keeping seed of G2 and G3 for replanting.

In all the field observations there were no cases of Bacterial wilt caused by Ralstonia solanacearum. The high altitude of the Dhamar valley at 2,400 masl prevents its presence.

The cost benefit analysis of using G2 seed is difficult to ascertain but it is of great positive value. The flexibility of timing in planting G2 fits well within the cropping patterns of Dhamar valley, as well as other locations in Yemen. The G1 seed from The Netherlands can only be planted in February when the dormancy of the imported seed has ended. This becomes a win-win by multiplying a good portion of the G1 crop for further multiplication.

The production data shown are from farmers who had the means to pay for their crop investments or had a contract with Dhamar First Center for seed potatoes (DFC). The role of DFC in purchasing the seed tubers, storing them properly in either refrigerated or ambient air-cooled bins and later reselling them as seed, is a great service to farmers in the area (Picture 3).

Picture 4 speaks to the food insecurity issue facing a large part of the Yemeni population. As the field harvest is about to be completed, the gleaners (at the bottom and right side of the picture) are ready to search for any tubers that remain after the harvest crew departs.

Apical Rooted Cuttings (ARC) are an alternative to expensive imported seed of varieties not ideally suited to the environments of Yemen. Once new varieties are selected that are locally adapted and have virus and LB resistance, this low cost, simple technique could replace the need for imported seed potatoes. Also, the ARC strategy could be an important component for the segment of the population that still have space to grow potatoes for their home consumption.

ARCs of new varieties are being evaluated at the university and are now being grown in small plots in a few farmers’ fields. Results will be shared in a future story.