Proper seed storage (Liveseed Practice abstract)

What causes seed ageing? Seed ageing is caused by oxidation of the cell membranes, mitochondria, DNA, RNA and proteins in the seeds. This oxidation is stimulated by four factors: seed moisture level, temperature, oxygen and time. The main factors stimulating this ageing are moisture and oxygen. How to reduce ageing Keep sealed commercial seed packages closed until use, to avoid moisture uptake from the air. Never store an open package in a cold place like a refrigerator, were the humidity is high and the seeds will absorb moisture. If not all seeds are used, store the remainder in a dry environment. For this we developed an easy system with a ‘seed drying and storage box’ (Fig 2). The principle is an airtight transparent box. In the box is a bag with silica gel and a relative humidity (RH) meter. The optimal RH is between 20 and 40%. Home produced seeds can also be dried in the box. If the RH surpasses the 40%, the silica gel needs to be regenerated in an oven at 100 °C. The dried silica gel can be cooled down in a closed clean jam jar or alike. It is possible to store the airtight box with seeds in a cooler place, to reduce ageing further. For larger amount of seeds the box could be replaced by a large vacuum bag, as available for storage of clothes

Physiology of Chatham Island forget-me-not (Myosotidium hortensia) seed : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Seed Science and Technology at Massey University

Chatham Island forget-me-not (Myosotidium hortensia (Decne) Baillon) is endemic to the Chatham Islands where it is mainly confined to the outer islands. There is speculation that seed of M. hortensia is recalcitrant and reports that germination can be slow and erratic. Moreover there is little information on the seed biology of M. hortensia available. In this study the seed structure and composition of the seed storage reserves of M. hortensia were determined. The seed is a dicotyledon. The embryo is predominantly cotyledonary tissue with a only small embryo axis present. There appears to be a single cell thick layer of endosperm tissue between the embryo and seed coat. Food reserves are stored as both protein and oil with no starch reserves apparent. The seed contains 24% oil and therefore can be considered an oilseed. These oil reserves include the commercially important γ-linolenic (cis, cis, cis-6, 9, 12-octadecatrienoic) acid (9% of the fatty acid content). Seed of M. hortensia was evaluated for recalcitrant behaviour by determining if desiccation to low seed moisture content caused a loss of viability. Seed was harvested at two moisture contents, 47.4% (green seed) and 35.5% (black seed), and air dried to a final moisture content of 7.5%. Seed viability and germination performance were monitored at harvest and as moisture content declined. At 7.5% seed moisture content viability was 89% and germination 92% for seed harvested at 47% seed moisture content, and 82% and 78%, respectively, for seed harvested at 36% seed moisture content. Within each colour classification, after desiccation there was no significant difference in germination compared to that at harvest, indicating that M. hortensia seed can be desiccated to a low seed moisture content without loss of germination and is therefore not recalcitrant. Seed stored at 5°C and 7.5% seed moisture content showed no decline in viability after 21 months, but, seed stored at the same temperature and 9.5% seed moisture content showed a significant loss of viability after 9 months storage. The loss of viability at this higher (9.5%) seed moisture content is characteristic of oilseeds, but it is not clear whether the high oil content of the seed alone can account for the loss of viability after nine months storage at a temperature of 5°C. This study confirmed earlier reports that germination of M. hortensia seed is slow and erratic. At maturity seed of M. hortensia is dormant. Seed dormancy is a function of the seed coat rather than the embryo. The dormancy is likely to be a result of either physical constraint of embryo growth or restriction of gas exchange by the seed coat, or a combination of both. Removal or weakening of the seed coat allowed germination to proceed. However, some of the treatments used to weaken the seed coat resulted in an increase in abnormal seedling development. An effective and non-damaging technique for alleviating dormancy was to prick the seed coat with a 0.6-0.8mm diameter dissecting needle in the middle of the cotyledons

Organizational analysis of the seed sector of rice in Guinea: stakeholders, perception and institutional linkages

This paper analyses the organization of the rice seed sector in Guinea with the overall objectives to assess how organizational settings affect seed supply to small-scale farmers and to suggest institutional changes that would favour seed service and uptake of varieties. Data were collected in Guinea, West Africa, using focus group discussions with extension workers, farmers, representatives of farmers’ associations, agro-input dealers, researchers and non-governmental organization (NGO) staff, and surveys of 91 rice farming households and 41 local seed dealers. Findings suggest that the current institutional settings and perceptions of stakeholders from the formal seed sector inhibit smallholder farmers’ access to seed. Seed interventions in the past two decades have mainly relied on the national extension system, the research institute, NGOs, farmers’ associations and contract seed producers to ensure seed delivery. Although local seed dealers play a central role in providing seed to farmers, governmental organizations operating in a linear model of formal seed sector development have so far ignored their role. We discuss the need to find common ground and alternative models of seed sector development. In particular we suggest the involvement of local seed dealers in seed development activities to better link the formal and the informal seed systems and improve smallholder farmers’ access to seed from the formal sector

Control of seed borne diseasees in organic seed propagation

Introduction The key control measure of plant diseases in organic agriculture is crop rotation, mixed cropping and moderate fertilization. A wide range of plant diseases can be controlled or minimized in this way. However, at least one group of plant diseases, the seed borne diseases, cannot. The seed borne diseases are not transmitted through the soil, and crop rotation is therefore an insufficient tool. Mixed cropping is impractical in seed propagation, where seed purity according to the seed legislation is imperative. The fertilization level primarily has an impact on facultative saprophytes, and not on the specialized seed pathogens. Seed borne diseases were the first plant pathogens to be controlled by pesticides. Heavy metals has been used as seed treatments for more than 200 years, and for almost 100 years, the seed borne diseases has been controlled exclusively and very effectively by chemical seed treatments. On this background, research in control of seed borne diseases has had practically no priority in research programs during the last century. Compared with other agricultural topics, the control of seed borne diseases in organic agricultural therefore suffers from the largest lack of knowledge, as we are 100 years behind in research. International seed legislation does with a few exceptions not define minimum quality standards for seed infections with pathogens, as seed sold on the international market normally are treated with fungicides. Surveys show that for some crops, the nationally recommended thresholds for seed pathogens are regularly exceeded in organic seed-lots, and some years the majority of organic seed lots are discarded due to seed borne diseases in propagation systems, where seed health is assessed on a routine basis. To ensure the availability of organic seed for the organic farmers, control measures for seed borne diseases are imperative, and an international system to ensure seed health in organic seed lots should be implemented. Methods to control seed borne diseases in organic agriculture exist. Resistant varieties exist in many cases, and could be used to a wider extent. Different heat treatment can control most seed borne diseases, and new technologies can make this opportunity practical to implement. Technology to separate seed exists, and could be used as a tool to promote the propagation of seed in mixed cropping systems to decrease plant pathogens, including seed pathogens in propagation. Heavy and large seed are generally less infected than small and light seed. The separation and removal of the latter can therefore reduce the infection level in a seed lot. Some seed amendments of natural origin can be used in organic agriculture to replace synthetic pesticides. Ongoing projects Agrologica is currently involved in several projects on control of seed pathogens. This includes 1)heat treatments of cereals by drum-dryer, (Pyrenophora teres, Tilletia tritici, Ascochyta pisi, Fusarium ssp) 2)heat treatments of vegetables seed with steam and ultrasound, (Altanaria radicina, A. petroselini, Cladosporium sp, Septoria Petro, Stemphylium ssp, Phoma lingam, Botrytis ssp, Xantomonas compestris) 3)seed dressings, including plant extracts, smoke, natural chemicals and biological control, 4)physical cleaning of seeds to remove pathogens and infected seeds from seed lots (Ustilago nuda, Pyrenophora graminea, P. teres, T. tritici, Fusarium ssp). 5)integrated control of common bunt (T. tritici) in spelta-wheat (Triticum spelta), 6)preventive cropping methods to reduce build-up of pathogenic fungi during propagation (mixed cropping, early harvest), 7)determining threshold values for organic cereals related to the susceptibility of the individual varieties (P. graminea, P. teres, T. tritici, Ascochyta ssp, Fusarium ssp). Conclusions and recommendations Research during the last two decades has shown that progress can be achieved and that solutions exist. Based on this, it can be concluded that seed borne diseases can be controlled in organic agriculture. However, extension and research to refine methods are urgently needed to do so

The State of Organic Seed in Europe

This booklet will present the information collected through research of the LIVESEED project in order to shed light on the actual situation of organic seed use in Europe. In particular, it will focus on the following questions: 1. How does the farmer know what varieties are available as organic seed? How do organic seed databases work in different EU countries and how could they be improved? 2. How much non-organic seed or planting material is used in EU organic farming? How many derogations are granted in different EU Member States and Switzerland? 3. Which are the factors encouraging or discouraging farmers to use organic seed? Which farm and farmer characteristics influence adoption of organic seed? How can organic plant breeding contribute to 100% organic seed use? 4. How has the organic seed market developed in the last years? According to seed suppliers` perspective, what factors hamper the further development of the organic seed sector? To answer these questions, researchers in the LIVESEED project applied integrated research tools and methodologies: a comparative review of the different databases on organic seed in 28 EU countries; an integrated analysis of national derogation reports to measure the current use of nonorganic seed in Europe; a survey among farmers, to understand their perspective on the use of organic seed; and finally a survey among seed suppliers to evaluate trends in the offer of organic seed on the market. A quantitative model was used to estimate the potential demand for organic seed in Europe on the basis of the data collected

Anthropogenic seed dispersal: rethinking the origins of plant domestication

It is well documented that ancient sickle harvesting led to tough rachises, but the other seed dispersal properties in crop progenitors are rarely discussed. The first steps toward domestication are evolutionary responses for the recruitment of humans as dispersers. Seed dispersal–based mutualism evolved from heavy human herbivory or seed predation. Plants that evolved traits to support human-mediated seed dispersal express greater fitness in increasingly anthropogenic ecosystems. The loss of dormancy, reduction in seed coat thickness, increased seed size, pericarp density, and sugar concentration all led to more-focused seed dispersal through seed saving and sowing. Some of the earliest plants to evolve domestication traits had weak seed dispersal processes in the wild, often due to the extinction of animal dispersers or short-distance mechanical dispersal

Farmer seed networks make a limited contribution to agriculture? Four common misconceptions

The importance of seed provisioning in food security and nutrition, agricultural development and rural livelihoods, and agrobiodiversity and germplasm conservation is well accepted by policy makers, practitioners and researchers. The role of farmer seed networks is less well understood and yet is central to debates on current issues ranging from seed sovereignty and rights for farmers to GMOs and the conservation of crop germplasm. In this paper we identify four common misconceptions regarding the nature and importance of farmer seed networks today. (1) Farmer seed networks are inefficient for seed dissemination. (2) Farmer seed networks are closed, conservative systems. (3) Farmer seed networks provide ready, egalitarian access to seed. (4) Farmer seed networks are destined to weaken and disappear. We challenge these misconceptions by drawing upon recent research findings and the authors’ collective field experience in studying farmer seed systems in Africa, Europe, Latin America and Oceania. Priorities for future research are suggested that would advance our understanding of seed networks and better inform agricultural and food policy