The seed constitutes the main vector of plant propagation and it is a critical development stage with many specificities. Seed longevity is a major challenge for the conservation of plant biodiversity and for crop success. Seeds possess a wide range of systems (protection, detoxification, repair) allowing them to survive in the dry state and to preserve a high germination ability. Therefore, the seed system provides an appropriate model to study longevity and aging.

Iconography : Seed longevity: Survival and maintenance of high germination ability of dry seeds

Seed marks the beginning of each plant production and therefore ensuring its quality is the priority of modern seed science and a prerequisite for obtaining high yields of all plant species. Determination of seed quality and its viability indicates what seed lots can be placed onto the market, and for that reason it is very important to have reliable methods and tests to be used for seed quality and seed vigour testing. The term vigour of viability is used to describe the physiological characteristics of seeds that control its ability to germinate rapidly in the soil and to tolerate various, mostly negative environmental factors. MCDONALD grouped vigour tests into three groups: Physical tests - determine seed characteristics such as size and mass. These tests are inexpensive, quick, can be applied to large number of samples, and are positively correlated with seed vigour. The main feature of seed development is accumulation of nutritive materials, which is also in direct correlation with vigour, i.e. with size and mass of seed; Physiological tests - using germination and growth parameters. There are two types of these tests. First type, when germination is done under favourable conditions (standard laboratory germination, and test of growth intensity). Second type, when seed is exposed to unfavourable environmental conditions (cold test, accelerated aging test, and Hiltner test); Biochemical tests - are considered as indirect methods for estimation of seed value. These are Tetrazolijum test, conductometric measurements, enzyme activity and respiration.

http://www.doiserbia.nb.rs/ft.aspx?id=0534-00121001103M

Vigour tests as indicators of seed viability

Seed deterioration is an undesirable and detrimental attribute of agriculture. This process is a separate event from seed development and germination. Losses in seed quality occur during field weathering, harvesting and storage. Deterioration caused by field weathering is directly related to seed exposure to adverse conditions. Seeds are highly susceptible to damage and mechanical injury during post-harvest handling. Several environmental factors contribute to seed deterioration and these conditions make very difficult to maintain viability during storage. Seed quality is depends upon initial seed quality, temperature, moisture content and mycoflora. Rapid deterioration occurs due to these environmental conditions make very difficult to maintain its viability during storage. However, the seed quality and viability during storage depend upon the initial quality of seed and the manner in which it is stored. Seed deterioration is associated with various cellular, metabolic and chemical alterations including lipid peroxidation, membrane disruption, DNA damage, impairment of RNA and protein synthesis and cause several detrimental effects on seed. INTRODUCTION Seed deterioration is loss of seed quality, viability and vigor due to effect of adverse environmental factors (Kapoor et al., 2010). Deteriorative changes enhance when seed exposure to external challenges increases and decrease the ability of the seed to survive. It is an undesirable attribute of agriculture. Annual losses due to deterioration can be as much as 25% of the harvested crop. It is one of the basic reasons for low productivity (Shelar et al., 2008). The process has been described as cumulative, irreversible, degenerative and inexorable process (Kapoor et al., 2011). As seed deterioration increases, seed performance is progressively decreases. The physiology of seed deterioration is a distinguish consequence from seed development and germination. Losses in seed quality occur during field weathering, harvesting and storage. Several factors contribute to the susceptibility for seed deterioration. The basic causes are temperature, relative humidity, seed moisture content and by invasion of and damage to tissues by microorganisms, insects. The rate of deterioration fluctuates critically from one species to another and also among varieties of the same species (Jatoi et al., 2001). Deterioration is evident as a reduction in percentage germination, produce weak seedlings, loss of vigor, become less viable and ultimately seed death (Maity et al., 2000; Tilebeni and Golpayegani, 2011). The percentage emergence of deteriorated seeds is less than healthy seeds. Hence, deteriorated seed produces uneven stands, spotty fields, and fewer plants per hectare than healthy seed (Biabani et al., …

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Seed deterioration: a review

Quantitative trait loci (QTL) controlling germination, seed vigour and longevity, and early seedling growth were identified using a set of common wheat lines carrying known D genome introgression segments. Seed germination (capacity, timing, rate and synchronicity) was characterized by a standard germination test, based either on the 1 mm root protrusion (germination sensu stricto) or the development of normal seedlings. To quantify seed vigour, the same traits were measured from batches of seed exposed for 72 h at 43°C and high (ca. 100%) humidity. Seed longevity was evaluated from the relative trait values. Seedling growth was assessed both under non-stressed and under osmotic stress conditions. Twenty QTL were mapped to chromosomes 1D, 2D, 4D, 5D, and 7D. Most of the QTL for germination sensu stricto clustered on chromosome 1DS in the region Xgwm1291–Xgwm337. A region on chromosome 7DS associated with Xgwm1002 harboured loci controlling the development of normal seedlings. Seed vigour-related QTL were present in a region of chromosome 5DL linked to Xgwm960. QTL for seed longevity were coincident with those for germination or seed vigour on chromosomes 1D or 5D. QTL for seedling growth were identified on chromosomes 4D and 5D. A candidate homologues search suggested the putative functions of the genes within the respective regions. These results offer perspectives for the selection of favourable alleles to improve certain vigour traits in wheat, although the negative effects of the same chromosome regions on other traits may limit their practical use.

Genetic mapping within the wheat D genome reveals QTL for germination, seed vigour and longevity, and early seedling growth

Changes in endogenous hormones and seed-coat phenolics during the storage of the dimorphic seeds of two Suaeda salsa populations were investigated. The results showed that, regardless of salinity, storage did not reduce the germination of brown or black seeds from an inland population, but it significantly decreased the germination of dimorphic seeds from an intertidal population. Abscisic acid (ABA) concentration was significantly higher in old seeds than in fresh seeds (freshly harvested dry seeds), whereas the opposite trend was evident for gibberellic acid (GA, including GA1 and GA3) concentration and GA : ABA ratio in both populations, and especially in the intertidal population. Concentration of seed-coat phenolics extracted from brown seeds was much higher than in black seeds in both populations, regardless of extracting time and storage. Storage increased the concentration of phenolics extracted from brown seeds in the inland population, whereas the opposite trend was evident in the intertidal population. Storage did not significantly change seed-coat phenolics extracted from black seeds relative to brown seeds in either population. The results indicated that changes in seed vigour during storage in dimorphic seeds of the two S. salsa populations are related to changes in endogenous hormones and seed-coat phenolics.

Changes in endogenous hormones and seed-coat phenolics during seed storage of two Suaeda salsa populations

Changes occurring in seed during aging are significant as far as seed quality and longevity are concerned and are a consequence of the effects of different storage conditions. The chemical composition of seed with high oil content is related to specific processes occurring in seed during storage. In this trial, sunflower and soybean genotypes developed in Novi Sad were submitted to accelerated aging for three and five days, and natural aging for six and twelve months, under controlled and conventional (non-controlled) conditions. The obtained results showed that preservation of seed viability depended on storage condition and duration, as well as plant species. Accelerated aging test can be used to predict the length of storage life of sunflower and soybean seed. In comparison to sunflower seed, soybean seed is more sensitive to damage and reduced germination during storage.

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Seed viability of oil crops depending on storage conditions

This investigation was conducted in order to determine the degree of biochemical changes during accelerated and natural aging of sunflower seed. Five sunflower lines developed in Novi Sad, submitted to accelerated aging for three and five days, and natural aging of six and twelve months under conventional storage and controlled conditions, were used in these trials. Malondialdehyde, superoxide dismutase contents and peroxidase activities were studied. Lipid peroxidation and superoxide dismutase and peroxidase activities (especially pronounced in accelerated aging variant) were caused by both types of aging. The degree of seed damage and the ability of seed to resist the negative consequences of aging were influenced, beside duration of aging period, by type of storage and characteristics of sunflower lines.

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Influence of aging process on biochemical changes in sunflower seed / influencia del proceso de envejecimiento en los cambios bioquímicos en la semilla de girasol / effet du processus de vieillissement sur les changements biochimiques dans la graine de tournesol

Sunflower seed aging during storage affects seed vigor and content of fatty acids. In order to reveal severity of their influence, the following vigor tests were applied: standard laboratory germination test, cold test and Hiltner test. Five sunflower lines submitted to natural aging process for six and 12 months were tested under conventional storage and controlled conditions. The obtained results revealed that seed aging damaged the seed, which adversely affected seed vigor; most reliable results were obtained by the cold test and content of linoleic acids.

Mladen Tatić

Papers

Seed viability of oil crops depending on storage conditions

Influence of aging process on biochemical changes in sunflower seed / influencia del proceso de envejecimiento en los cambios bioquímicos en la semilla de girasol / effet du processus de vieillissement sur les changements biochimiques dans la graine de tournesol

Changes of fatty acids content and vigor of sunflower seed during natural aging

Assessment stability of maize lines yield by GGE-biplot analysis

Monitoring of the Roundup Ready soybean in the Vojvodina province in Serbia