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Evaluating the vigour and viability of seeds can help in the production of seed lots with proven high physiological potential. In this regard, the tetrazolium (TZ) test is efficient, rapid and inexpensive; however, it not been fully explored for forest species. Further development of species-specific methodologies is required in order to maximise the test efficacy. The objective of this work was to define a tetrazolium test protocol to evaluate the vigour and viability of Genipa americana L seeds. Fruits and seeds were characterised for biometry and initial water content before and after hydration. Germination, germination speed index, electrical conductivity and seedling emergence was also performed. For the TZ test, G. americana seeds were cut longitudinally and submitted to different seed pre-conditioning methods (with and without 24 hours imbibition), different TZ concentrations (0.05, 0.075, 0.10 and 0.25%) and three immersion periods (2, 3 and 4 hours). The tetrazolium test allowed adequate evaluation of seed vigour levels (Viable; Viable and non-vigourous; and Non-viable). Immersion of non-imbibed seeds in 0.10% TZ solution, for three hours is the most efficient protocol for evaluating the vigour and viability of G. americana seeds.

Three different seed vigour tests, Accelerated ageing (AA), Germination index (GI) and Polyetylenglycol (PEG), were evaluated with regard to ranking six reference seed lots of timothy cv. Grindstad and red clover cv. Lea according to their physiological potential for storage. The seed reference lots, which all had germination percentages between 70-100%, had sustained different degrees of ageing before examination. In timothy, both the AA-test and the GI-test managed well to separate the low-vigour seed lots, having a poor storage potential, from the high-vigour seed lots with better storage longevity. The clearest separation was obtained using the GI-test, either as complete test (six out of six seed lots was significantly separated) or as a simplified test (five out of six seed lots was significantly separated). The germination index of the two tests was based on counting of germinating seeds either on a daily basis for ten days or after counting on day 3 and day 5, respectively. Also the AA-test managed to separate five out of six seed lots of timothy after optimal treatment for 56 h at 45 o C. In red clover, the AA-test gave the clearest separation between seed lots. At optimal conditions for 24 h at 43-45 o C, as many as five of the six red clover seed lots could significantly be separated from each other. Also the PEG-test discriminated well between reference seed lots of both species, but was considered as more labour-intensive than the two other vigour tests. The recommended seed vigour test for timothy (simplified GI-test) and red clover (AA-test for 24 h at 43-45 o C) has later been adopted for use in practical seed testing routines at the Norwegian National seed laboratory.

Summary Obtaining commercially useful coffee seedlings is hindered by slow, uneven germination and low tolerance to desiccation as well as reduced coffee seed longevity. Coffee seeds have been considered recalcitrant, orthodox and even intermediate with varying results. Current recommendations suggest that coffee seeds can be safely stored between 10-11% f.w.b. at 15°C. However, after drying and storage, coffee seeds lose vigour, and seeds stored after drying cannot be used for producing seedlings. Coffee seedling producers usually sow seeds immediately or lightly dry them after harvest for a short storage period, if necessary. It is highly desirable that seeds are stored safely to optimize coffee seedling production at the appropriate time and season with ideal climatic conditions for planting in the field. The objective of this study was to determine the quality of coffee seedlings produced from seeds stored with high, medium and low moisture levels under hermetic conditions at 10 and 20°C. Seed and seedling quality were assessed before and after nine months storage. Only the germination of seeds harvested at the cherry stage, evaluated before and after the storage at 10°C, was not affected by moisture content, but these seeds lost vigour and did not produce suitable seedlings for planting when stored for nine months. Seedlings produced in the nursery from seeds with 47 and 12% moisture content performed the same as those from greenish-yellow seeds, but they produced a leaf area that was five times smaller, a stem height three times shorter, and had 1.7 times fewer pairs of true leaves than coffee seedlings produced from fresh seeds. Storage at 20°C was not suitable for coffee seeds, especially those at 18% moisture content whose quality declined drastically. These results suggest that coffee seeds do not tolerate desiccation and that their storage behaviour classification should be reviewed.

The species Coffea arabica L. is one of the most important agricultural commodities in Brazil. Despite considerable effort at vegetative propagation of coffee plants, they still are propagated by seedlings produced directly from seeds. An undesired trait of coffee seeds is that they have slow and asynchronous germination, which makes it difficult to obtain seedlings of desirable quality. In addition, this slow and asynchronous germination makes rapid viability and/or vigor evaluations difficult because of the excessive time required to obtain results. The objective of this study was to describe coffee seedling growth developmental stages by documenting morphological changes during germination and post-germination growth. Eight seedling growth stages were described. Description of stages permits a more accurate characterization of coffee seedling development than days after imbibition since environmental factors have a major bearing on the speed and uniformity of seedling growth. In addition, current Rules for Seed Testing in Brazil require 30 days before germination can be assessed. These data demonstrate all essential seedling parts are present on coffee seedlings at stage 6, which occurs at 15 days. Such data suggest that the standard germination test for coffee seeds can be substantially shortened to provide more rapid seed quality assessment.

Summary A wide range of seedling emergence in commercial seed lots of watermelon (10 lots), melon (10 lots) and cucumber (9 lots), all with standard germinations above 98%, was seen in low temperature emergence (LTE), high temperature (HTE) and an 8 cm deep sowing (MSE) in the field and in salt stress conditions (SSE) in trays at 20°C. Final emergence was closely related to both the rate of emergence, measured as mean emergence time (MET; the reciprocal of the rate of emergence), and to the mean germination time (MGT; the reciprocal of the rate of germination) for physiological germination (2 mm radicle) in the laboratory at 25°C. Slower germinating and emerging lots, so-called low vigour lots, had lower levels of emergence in all sowings. Single early counts of physiological germination identified low vigour lots for all three species and are suggested as a quick routine test. The physiological age of the seed lots, determined using accelerated ageing (45°C in 100% relative humidity) and controlled deterioration (45°C and 20 or 24% moisture content), was significantly related to MGT which was higher (i.e. germination was slower) in physiologically older seed. Previous work suggests that cucurbit seeds appear to retain germination capacity over several years although ageing is reflected in a slower rate of germination (high MGT). MGT can also be described as the length of the lag period from the start of imbibition to radicle protrusion. We propose that this period is needed for the repair of the effects of ageing and is therefore longer in aged seeds.

Seed of 15 species of Brassicaceae were stored hermetically in a genebank (at -5 degrees C to -10 degrees C with c. 3% moisture content) for 40 years. Samples were withdrawn at intervals for germination tests. Many accessions showed an increase in ability to germinate over this period. due to loss in dormancy. Nevertheless, some dormancy remained after 40 years' storage and was broken by pre-applied gibberellic acid. The poorest seed survival occurred in Hormatophylla spinosa. Even in this accession the ability to germinate declined by only 7% between 1966 and 2006. Comparison of seeds from 1966 stored for 40 years with those collected anew in 2006 from the original sampling sites, where possible, showed few differences, other than a tendency (7 of 9 accessions) for the latter to show greater dormancy. These results for hermetic storage at sub-zero temperatures and low moisture contents confirm that long-term seed storage can provide a successful technology for ex situ plant biodiversity conservation.

An alternative to the cold test to evaluate maize seed vigor was investigated. The standard germination test, cool germination tests at 12, 15 and 18 degrees C, the cold test were performed for seven maize seed lots and field emergence at one site determined. The standard germination of all lots was >90% and was not correlated with field emergence, but the results of the cool germination test at 18 degrees C and the cold test were significantly correlated with field emergence (r=0.890** and 0.974** respectively). The results of the cool germination test at 18 degrees C were also significantly correlated with the cold test (r=0.828**). These results suggest that a cool germination test at 18 degrees C can be considered as an alternative to the cold test to evaluate vigour differences among maize seed lots.

The X-ray image analysis technique is a precise method that enables examination of regions that are damaged and/or altered in seed and their location and extension. It is a non-destructive method allowing the X-ray treated seed to be submitted to quality physiological tests. The objective of this study was to use X-ray image analysis technique to identify mechanical and stink bug damages in soybean seed. Seeds from different batches of the BRS184 cultivar were sorted by X-ray test and then were tested for germination with the aim to relate the damage with possible seed viability loss. Alternatively, the tetrazolium test was carried out to be compared with the X-ray test. Damage severity and location were considered for the interpretive analysis of X-ray images. The results showed that the X-ray image analysis technique was effective in detecting mechanical and stink bug damage in soybean seed.

This study was conducted to evaluate the infl uence of fruit maturity and post-harvest storage on physiological quality and LEA proteins activity of sweet pepper (Capsicum annuum L.) seeds. Fruits were harvested at 40, 50, 60 and 70 days after anthesis (DAA) and stored for 0, 3, 6, 9, 12 and 15 days before seed extraction. Seeds were evaluated by germination, fi rst count, seedling length, accelerated aging, speed emergence index, electrical conductivity and eletrophoretical analysis for proteins LEA. It was verifi ed that precocious harvest (40 DAA) was not benefi cial to physiological quality of pepper seeds even when associated to 15 days post-harvest storage. For fruits harvested at 50 DAA, 12 days post-harvest storage was indispensable to assure the physiological quality of seeds. Pepper seeds harvested from 60 DAA presented high quality, not being necessary the postharvest storage of fruits. LEA proteins synthesis occurred at 60 DAA, being directly related to physiological quality of pepper seeds.

Alternative procedures for the tetrazolium (TZ) test to determine viability and vigour of tomato (Lycopersicon esculentum Mill.) seeds were studied in this research. In the fi rst phase of work, four lots of cv. Bruna were hydrated between moistened paper towels (3 h at 40°C and 45°C) followed by staining for 1, 2 and 3 h in a 0.075% tetrazolium chloride solution at 40°C. Viability TZ results were compared to percent germination, seedling emergence and the standard procedure for the TZ test described in the Rules for Seed Testing. In the second phase, viability and vigour (seeds classifi ed in three TZ categories) were determined after preconditioning for 3 h at 45°C and staining for 1, 2 and 3 h at 40°C for three seed lots each from cultivars Debora Max and Acclaim. Results were compared to germination, seedling emergence, saturated salt accelerated aging and controlled deterioration tests. In general, seeds exhibited adequate TZ staining patterns when seed moisture content attained at least 45%. The TZ test provided consistent data for the assessment of viability and vigour of tomato seeds. The results also indicated that reducing the preconditioning period is feasible and represents an important advance permitting faster decisions in seed quality control programs.

To develop a commercial-scale PCR-based assay for Acidovorax avenae subsp. citrulli in watermelon seed, parameters for immunomagnetic separation (IMS) were optimized. Optimal conditions for target cell recovery included 40 μg of polyclonal anti-AAC antibody per 10 immunomagnetic beads (IMBs) for coating, ca. 2.5 × 10 IMBs per sample and immunocapture for one hour at 4°C. These parameters consistently facilitated the recovery of A. avenae subsp. citrulli cells from suspensions containing ca.10 CFU/ml. Using lots contaminated with artificially infested seeds (10 A. avenae subsp. citrulli CFU/seed), IMS-PCR detected the pathogen in 25% and 87.5% of samples (n=10,000 seeds) with 0.01 and 0.1% infestation, respectively. For seedlots with similar infestation levels, the detection frequencies for the seedling grow-out assay (SGO) were 12.5% and 37.5%; however, the difference in detection frequency between SGO and IMS-PCR was not statistically significant. While liquid enrichment improved the detection sensitivity of IMS-PCR 100-fold, the difference in detection frequency between enrichment IMS-PCR and IMS-PCR was not statistically significant for seed samples contaminated with artificially and naturally infested seeds. These results suggest that IMS-PCR has great potential as an effective alternative to SGO for the detection of A. avenae subsp. citrulli in commercial watermelon seedlots.

A vigour test assesses, either directly or indirectly, the physiological and physical basis of potential seed lot performance and provides a more sensitive differentiation among seed lots than does the standard germination test. Although seed vigour tests are widely used by the seed industry and are now offered by two-thirds of ISTA seed testing laboratories, vigour testing was only recently (2001 ISTA Congress) approved for inclusion in the ISTA Rules for Seed Testing. The primary reason for this long delay in official recognition has been the lack of uniformity in vigour test results among seed testing laboratories. It is now recognized that greater precision is required for vigour testing than is required for standard germination testing. This recognition has led to improved standardization and uniformity in comparative tests. The objective of this paper is to describe why it has been much more difficult to achieve standardization in vigour testing. It will also outline the procedures, equipment and training needed for seed analysts to achieve and maintain the precision needed in vigour test methods. Finally, it will define the role of seed testing laboratories and the seed industry in the acceptance of seed vigour as a valuable test of physiological seed quality.

Seed testing laboratories worldwide analyse samples for quarantine assessments to prevent the entry of prohibited and restricted seeds. Current practices of identifying seeds by comparing an unknown seed with samples of known seeds or photographs of seeds are time consuming, costly and inefficient. A Seed Identification Key using a computerised database has been developed to identify prohibited and restricted seeds. There are currently 78 prohibited and 47 restricted seeds in the database. Lucid software was used to develop the Key because of its versatility in handling both text and image data. A total of 21 externally visible seed characters were identified as most suitable for development of the Key. Explanatory images and notes are attached to the character states to assist the user in correct selection of the state. The Key may be helpful to quarantine officers as well as seed analysts working in seed testing laboratories. It may also be used as an educational tool by agricultural scientists, students and others interested in seeds.