Research Notes____________________________________________________________
Short communication of practical oriented research or relevant information in agriculture or seed technology are presented in this section.

Production of Organic Seeds: Status, Challenges and Prospects
by
Steven P.C. Groot, Ruud W. van den Bulk, W. Joost van der Burg, Henk Jalink, Cees J. Langerak and Jan M. van der Wolf ¹

Organic Crop Production Requires Use of Certified Organic Seeds
To maintain long-term food production there is a need for sustainable agricultural practices. This is one of the aims of organic farming and consumers are prepared to pay higher prices for certified organic products. In many developing countries agriculture is still largely based on low inputs, because farmers cannot afford the high costs of chemical fertilizers and pesticides. For such farmers, organic farming can provide a better economic alternative, especially if they are able to sell their products on the European and North American markets. For certification of organic products, it is important that the entire production process conforms to the rules for organic production. Although there are some minor differences between the regulations for the European and the North American market, both require that whenever available, organic seeds or plant material should be used.

However, this is not as simple as it looks. First, organically produced propagation material is not available for all crops or there are no appropriate varieties. Second, to produce seeds under organic conditions and to obtain seeds of the same quality similar to conventionally produced seeds may often prove more difficult. Third, for several crops organically produced seeds are more expensive and in practice farmers may choose the cheaper conventional seeds. Fourth, seeds may be obtained through farm-saved seeds or through exchange within the community which are not always from a certified organic production. The latter can especially be the case in developing countries, where seed quality can be a serious problem compared to that of organic seeds supplied by major seed companies.

Availability of High Quality Organic Seeds
Organic crop production may demand even higher quality propagation material compared to conventional farming. Farmers should rely on the quality of the seeds they are using. Preventive measures using chemicals are prohibited and competition with weeds requires high vigor planting material. Moreover, for organic farmers, seed health and the absence of genetically modified (GM) contamination is also very important.

Several seed companies have invested heavily in the production of high quality organic seeds and planting material for the main production areas in Europe, North America, New Zealand, etc. There, organic seeds are available for a number of food crops. However, for some vegetable or agricultural crops it is very difficult to produce organic seeds of the same quality standards as for conventional farming, while for ornamental crops there is hardly any organically produced propagation material available. For biennial vegetable crops, such as cabbages, carrot and onion, it is even more difficult to produce high quality organic seeds because the two seasons required for seed production increase the risk of diseases and pathogen contamination. In cereals, organically produced wheat seed is available, but seedling emergence is often less than conventionally produced fungicide treated seeds mainly due to seed-borne fungal infections.

In the EU the use of organic produced propagation material is obligatory and permission for derogation should be requested for the use of non-organically produced material. However, there are still large variations in seed availability and the regulation was adjusted where three categories are defined. The first category includes crops where no derogation is allowed because enough organically produced propagation material is available. EU member states produce a national list of these crops. For example, crops such as cucumber, garlic, potato, wheat and barley are listed for the Netherlands. A second category includes crops where hardly any organically produced propagation material is available and there is at present no obligation to request for derogation. The list includes ornamental crops and trees, but also strawberry, sweet corn, asparagus and hemp. For the third category, derogation can still be requested and granting depends on the availability of organically produced propagation material of the crop, which may vary between countries. The permission for derogation is the responsibility of the national authorities.

In other parts of the world the availability of certified organically produced seeds and plant material is even less, and serious difficulties are encountered to obtain organic seeds of a guaranteed high quality. For organic farmers in these areas the challenges may even be greater.

Challenges Encountered
In addition to the difficulties in production and availability of organic propagation material, organic farmers encounter other problems compared to conventional crop production. Since chemicals cannot be used during seed production, organic seed has a greater risk of contamination, both with weed seeds and with seed borne pathogens. Moreover, sowing of seeds in soils with organic manure, that has slower mineralization rate in cold spring, and a stronger competition from weeds may require high seed vigor and seedlings with a faster developing root system. Also, the guaranteed non-GM nature of organically produced products is an important marketing strategy to the consumers. With the global increase of GM crops, there is a risk of increased GM contamination. Discussions are underway at international level whether organic seeds need lower thresholds for contamination with GM seeds than non-organic seeds.

Seed Research
These challenges call for solutions, which can only be obtained through research. Appropriate methods for the detection of pathogens and determination of critical control points during seed production will provide the basis for disease monitoring activities and treatments. New seed sanitation treatments need to be developed that should not only be effective in the elimination of pathogens, but should also maintain the viability of the seeds. Such new treatments should meet both the standards for organic farming and international regulations for use of crop protection agents. Novel seed sorting techniques may also be of use by removing diseased seeds from contaminated lots or less vigorous seeds. Plant Research International is involved in a national research program on organic seeds funded by the Dutch government and in two EC funded projects; and collaborates with the seed industry, organic farmers and policy makers, to guarantee that results from research are acceptable to the organic sector and implemented in practice. Some examples of this research are presented below.

Healthy organic seed production
Prohibiting chemicals in organic crop production increases the risk of diseases of some crops where resistant varieties are not available especially for biennial crops, which are exposed to infection during two subsequent seasons. To find alternative measures for optimizing organic seed production, we focused on gathering knowledge on critical control points during seed production. The host-pathogen combination Daucus carota - Alternaria radicina was chosen as a model. Several field experiments were carried out under organic conditions, using basic seeds of six different cultivars with various levels of A. radicina contamination. Disease transmission was studied and measured in all crop production stages, from seed to seed. Minor seed infections, which could only be detected with a sensitive method, seem to be responsible for non-visible latent infections in the crown part of the carrot root. These infections may become visible as black rot either at a high temperature above 20°C during maturation of the carrots or during cold storage of the harvested carrots. When young carrot plants or mature roots are vernalized to induce flowering, latent infections mostly remain unnoticed. Such infections can finally result in infected flowers and diseased seeds, and may form a source of inoculum for secondary infection of seeds developing on healthy plants. Consequently, organic carrot seed production requires a high degree of sanitation such as disease free basic seed, roguing at any stage of plant growth and a stringent isolation of production fields from other umbellifers. Besides, experiments have shown that hot water treatment of basic seed could be a good disease management practice.

Natural compounds for seed treatment
In Europe, most commercially produced seed is presently treated with (synthetic) crop protection agents, in order to eliminate seed-borne pathogens and to protect emerging seedlings from soil- and air-borne pathogens and insects. For organic agriculture, physical treatments such as hot water treatments are being used, but they involve the risk of seed damage. We are trying to avoid this problem by developing a combination treatment using milder physical treatments with compounds of natural origin.

Within this concept, different natural compounds were tested, including essential oils and organic acids. From 30 essential oils tested, thyme oil exhibited the highest in vitro inhibiting activity against two bacterial and two fungal seed-borne pathogens. It is important that these natural agents are permitted for use on seeds according to the national and international regulations for crop protectants. Products that are not yet registered for use as a crop protectant will need the submission of new reports, often requiring costly toxicological studies that are not feasible for the small market of organic seed treatment. Besides, they should also be allowed for use in organic crop production (EEC regulation 2092/91 and FAO Codex Alimentarius). In the Netherlands, thyme oil fits both criteria and may be used for treatment of seeds when mixed with water.

Seed priming
When using organic manure, the microbial activity is very important for the release of nutrients. In the cold spring soil, microbial activity is low and nutrients become less readily available in comparison with the use of synthetic fertilizers in conventional farming. A vigorous seedling with a fast growing root system may improve the uptake of minerals and improve the establishment of the crop. In this respect vigorous, healthy seedlings may be even more important for the organic than for the conventional farmers. Moreover, faster growing seedlings can improve competition with weeds for nutrients and light. The latter is relevant, because manual and mechanical weed removals are major costs in organic farming. Seeds can be primed by imbibing them for a limited time prior to sowing. Mostly the primed seeds are dried so radicle protrusion during the priming process is avoided, to circumvent loss of desiccation tolerance. Primed seeds germinated faster in the field and this may contribute to an improved competition with weeds. Our research shows that plants derived from primed seeds show a faster initial growth and an earlier ground cover. It is interesting to note that farmers in India, Zimbabwe and several other countries obtained large increases in yield in low input farming systems, by using on-farm seed priming in wheat, rice and chickpea. Use of primed seeds can therefore be interesting for organic farming, especially in those areas where it is combined with low-input farming.

New seed sorting technologies
Alternative sanitation treatments (e.g. hot water treatment) require a high degree of tolerance of the seeds. During maturation, seeds reach their optimal physiological quality. Seeds which are not completely mature, germinate more slowly, have a lower germination capacity, produce less normal seedlings, can have higher contamination levels with pathogens, and can be more sensitive to diseases and to alternative sanitation treatments. Seeds of many crops are green during the first phase of their development, and the breakdown of chlorophyll is inversely correlated with seed maturity. A technique has been developed to sort seeds on the basis of their level of chlorophyll fluorescence (CF). The most mature cabbage seeds, with the lowest level of CF, had highest percentage germination, more uniform and higher speed of germination and lower amount of infected seedlings. Less mature seeds showed a lower germination capacity and were more heavily infected than seeds from the low CF fraction. They are also more sensitive to hot water treatments, indicating the need for harvesting at full maturity for seed production. For barley seeds, a relationship was established between the strength of the CF signal and the level of contamination with Fusarium spp. Seeds from the fraction with the highest CF signals were always the most heavily infected. CF sorting of barley seeds improved their physiological quality by removing less mature seeds and those with the largest fungal infection levels. Therefore, the technology can contribute to improve the quality of organic seeds

PRI research staff working on the improvement of organic seed quality