Desiccation Of Seeds Research Articles

Desiccation tolerance and longevity of germinated Sesbania virgata (Cav.) Pers.seeds

Abstract: Seed desiccation tolerance (DT) and longevity are necessary for better dissemination of plant species and establishment of soil seed bank. They are acquired by orthodox seeds during the maturation phase of development and lost upon germination. DT can be re-induced in germinated seeds by an osmotic and/or abscisic acid treatment. However, there is no information on how these treatments affect seed longevity. Germinated Sesbania virgata seeds were used as a model system to investigate the effects of an osmotic treatment to re-establish DT on seed longevity. Longevity of germinated S. virgata seeds treated and non-treated by an osmoticum was analysed after storage or artificial ageing. The radicle is the most sensitive organ, the cotyledons are the most resistant, and the ability to produce lateral roots is the key for whole seed survival. Germinated S. virgata seeds with 1mm protruded radicle tolerate desiccation and storage for up to three months without significant losses in viability. An osmotic treatment can improve DT in these seeds, but not longevity. Germinated S. virgata seeds are a good model to study DT uncoupled from longevity. Further studies are necessary to unveil the molecular mechanisms involved in both DT and longevity.

Germination ecology of the endemic Iberian daffodil Narcissus radinganorum (Amaryllidaceae). Dormancy induction by cold stratification or desiccation in late stages of embryo growth

Aim of study: We studied the germination ecology of a threatened daffodil in order to develop a protocol to produce plants ex-situ from seeds, a key tool for population reinforcement.Area of study: Experiments were carried out both outdoors and in the laboratory in Albacete (Spain).Material and methods: Embryo length, radicle and shoot emergence were analyzed to determine the level of morphophysiological dormancy (MPD). Effects on germination of cold stratification or desiccation in late stages of embryo growth were also studied.Main results: Mean embryo length in fresh seeds was 1.36 mm, needing to grow up to 2.20 mm to be able to germinate. In the laboratory, embryo growth occurred during warm stratification (28/14, 25/10ºC), and then radicle emerged when temperatures went down (15/4ºC in darkness). Phenology study in outdoors conditions revealed that embryo grew during summer-early autumn, short time after seed dispersal in nature (i.e., May); radicle emerged in autumn. The shoot however did not emerge until late winter-early spring, because it was physiologically dormant and required a cold (5ºC) period of 30 days to break dormancy. Early cold temperatures interrupted the embryo growth and induced dormancy in seeds whose embryo had grown 30% with respect to the initial length. Desiccation in seeds whose embryo had grown 30% did not induce dormancy, but did it when the embryo growth reached 70%.Research highlights: Seeds of Narcissus radinganorum have deep simple epicotyl MPD.Key words: dormancy break; radicle emergence; shoot emergence; epicotyl MPD; phenology; secondary dormancy.

A new insight in desiccation tolerance and cryopreservation of mazzard cherry (Prunus avium L.) seeds

Abstract A variable response of Prunus avium L. seeds to desiccation and storage in liquid nitrogen (LN) has been reported in the literature. The majority of these experiments were conducted on initially dried seeds. The desiccation and LN exposure tolerance of fresh P. avium seeds is unknown. In the present study, fresh seeds were used to determine seed response to desiccation and cryopreservation. Desiccation of seeds from a moisture content (MC) of 19.7-20.2% to 10.1-10.9% or 07.6-8.5% reduced seedling emergence from approximately 73 to 19 and 16% for first provenance; and from approximately 89 to 10-12% for second provenance of seeds. After exposure to LN, seeds had the highest seedling emergence when seed MC was the highest (19.7 and 20.2%, respectively) prior to cryostorage. Results indicated that P. avium seeds should be classified as intermediate. For cryopreservation in seed banks, we recommend that seeds be dried directly after extraction from fruits in the range of 16.8-20.2% of MC (0.21-0.25 g·g–1 of WC) and directly immersed in LN in tightly closed cryovials.

Effect of desiccation on the dynamics of genome-wide DNA methylation in orthodox seeds of Acer platanoides L

5-methylcytosine, an abundant epigenetic mark, plays an important role in the regulation of plant growth and development, but there is little information about stress-induced changes in DNA methylation in seeds. In the present study, changes in a global level of m5C were measured in orthodox seeds of Acer platanoides L. during seed desiccation from a WC of 1.04 to 0.05–0.06 g H2O·g−1 dry mass (g·g−1). Changes in the level of DNA methylation were measured using 2D TLC – based method. Quality of desiccated seeds was examined by germination and seedling emergence tests. Global m5C content (R2) increase was observed in embryonic axes isolated from seeds collected at a high WC of 1.04 g·g−1 after their desiccation to significantly lower WC of 0.17 and 0.19 g·g−1. Further desiccation of these seeds to a WC of 0.06 g·g−1, however, resulted in a significant DNA demethylation to R2 = 11.52–12.22%. Similar m5C decrease was observed in seeds which undergo maturation drying on the tree and had four times lower initial WC of 0.27 g· g−1 at the time of harvest, as they were dried to a WC of 0.05 g·g−1. These data confirm that desiccation induces changes in seed m5C levels. Results were validated by seed lots derived from tree different A. platanoides provenances. It is plausible that sine wave-like alterations in m5C amount may represent a specific response of orthodox seeds to drying and play a relevant role in desiccation tolerance in seeds.

Global changes in DNA methylation in seeds and seedlings of Pyrus communis after seed desiccation and storage.

The effects of storage and deep desiccation on structural changes of DNA in orthodox seeds are poorly characterized. In this study we analyzed the 5-methylcytosine (m5C) global content of DNA isolated from seeds of common pear (Pyrus communis L.) that had been subjected to extreme desiccation, and the seedlings derived from these seeds. Germination and seedling emergence tests were applied to determine seed viability after their desiccation. In parallel, analysis of the global content of m5C in dried seeds and DNA of seedlings obtained from such seeds was performed with a 2D TLC method. Desiccation of fresh seeds to 5.3% moisture content (mc) resulted in a slight reduction of DNA methylation, whereas severe desiccation down to 2–3% mc increased DNA methylation. Strong desiccation of seeds resulted in the subsequent generation of seedlings of shorter height. A 1-year period of seed storage induced a significant increase in the level of DNA methylation in seeds. It is possible that alterations in the m5C content of DNA in strongly desiccated pear seeds reflect a reaction of desiccation-tolerant (orthodox) seeds to severe desiccation. Epigenetic changes were observed not only in severely desiccated seeds but also in 3-month old seedlings obtained from these seeds. With regard to seed storage practices, epigenetic assessment could be used by gene banks for early detection of structural changes in the DNA of stored seeds.

RNA-binding proteins associated with desiccation during seed development in rice

Long-lived mRNAs stored in mature seeds can remain active for long periods even if seeds undergo severe desiccation. They are then translated at the initiation of germination. To clarify the mechanism for stabilization of long-lived mRNAs during seed desiccation, fluctuations in RNA-binding protein (RBP) profiles that occur during seed formation in rice were analyzed. Proteomic analysis revealed that glycine-rich RBP 1A (GRP1A) is a highly abundant RBP in mature rice seeds. In addition, real-time RT-PCR analysis showed that putative RBP RZ-1A (RZ-1A) is seed specific. Moreover, transcripts of these two RBPs were clearly up-regulated during desiccation in rice seeds. The features of these two RBPs resemble those of late embryogenesis abundant proteins that function as molecular chaperones in dry seeds. Therefore, GRP1A and RZ-1A may have important roles in the stability of long-lived mRNAs in rice seeds.

A comparative study of desiccation responses of seeds of Asian Evergreen Oaks, Quercus subgenus Cyclobalanopsis and Quercus subgenus Quercus

The fruit biology of Quercus subgenus Quercus has received considerable attention. However, considerably less is known about the fruit (hereafter referred to as seed) biology of subgenus Cyclobalanopsis which is distributed mainly in tropical and sub-tropical Asia. Consequently, we investigated the responses to desiccation of seeds of 11 species from subgenus Cyclobalanopsis and compared these with responses of 11 species from subgenus Quercus from both China and Europe. Similar to species in the subgenus Quercus, we found that all 11 subgenus Cyclobalanopsis species had desiccation-sensitive (recalcitrant) seeds. For the 22 species, which had seed dry masses spanning 0.57 to 6.41 g, there were wide differences in drying rates, but drying rate was not related to either seed dry mass or oil content. Drying rates also varied across the individual seeds within a species. These differential drying rates within a seed resulted in some individual seeds remaining significantly moister than the mean water content which may explain the apparent ability of some seeds of several species e.g. Quercus schottkyana to tolerate desiccation.

Effects of Day Length and Air and Soil Temperatures on Sesamin and Sesamolin Contents of Sesame Seed

The lignans, e.g., sesamin and sesamolin, are components of the functional food sesame (Sesamum indicum L.) seed. This study aims to clarify the effects of environmental factors during ripening on the concentrations of these lignans to produce lignan-rich seeds. Here, we examined the effects of 4 factors (seeding time, day length, air and soil temperatures). The concentrations of sesamin and sesamolin in the seed from the capsule at different nodes on the stem were monitored using the high performance liquid chromatography (HPLC). A low air-temperature (22/15°C) during ripening increased the concentrations in the seed at the full-ripe stage of individual capsules compared with a high air-temperature (30/23°C). A short day-length (10-hr) and high soil-temperature did not affect the concentrations. The concentrations showed a tendency to increase with delay of seeding time. Under natural air-temperature conditions, the concentrations in the seeds from the capsules at a higher position on the stem were higher than those at a lower position, mainly due to the air temperature during ripening. The contents per seed were affected by the environmental factors through the difference in seed weight. The concentrations increased with the increase in seed dry weight and decreased with the desiccation of seeds during maturity. Under a low air-temperature condition, the rate of decrease in sesamin concentration was low, the accumulation period was longer and the maximum concentration of sesamolin was higher, resulting in higher contents of these lignans.

Seed Dehydration and the Establishment of Desiccation Tolerance During Seed Maturation is Altered in the Arabidopsis thaliana Mutant atem6-1

The end of orthodox seed development is typified by a developmentally regulated period of dehydration leading to the loss of bulk water from the entire structure. When dehydration occurs, the cytoplasm condenses and intracellular components become more crowded, providing an environment amenable to numerous undesirable interactions that can lead to protein aggregation, denaturation and organelle-cell membrane fusion. Acquisition of desiccation tolerance, or the ability to withstand these very low water potentials and consequent molecular crowding, has been correlated with the accumulation of various protective compounds including proteins and sugars. Among these are the late embryogenesis abundant (LEA) proteins, a diverse class of highly abundant, heat-stable proteins that accumulate late in embryo maturation coincident with the acquisition of desiccation tolerance. Previous work led us to hypothesize that the protein ATEM6, one of the two Arabidopsis thaliana group 1 LEA proteins, is involved in regulating the rate at which water is lost from the maturing embryo; homozygous atem6-1 mutants display premature dehydration of seeds at the distal end of the silique. Here we demonstrate that rehydrated, mature seeds from atem6-1 mutant plants lose more water during subsequent air drying than wild-type seeds, consistent with a role for ATEM6 protein in water binding/loss during embryo maturation. In addition, and possibly as a result of premature dehydration, mutant seeds along the entire length of the silique acquire desiccation tolerance earlier than their wild-type counterparts. We further demonstrate precocious, and perhaps elevated, expression of the other A. thaliana group 1 LEA protein, ATEM1, that may compensate for loss or ATEM6 expression. However, this observation could also be consistent with acceleration of the entire normal maturation program in atem6-1 mutant embryos. Interestingly, ATEM6 protein does not appear to be required in mature seeds for viability or efficient germination.

Seed germination of Lasia spinosa as a function of temperature, light, desiccation, and storage

Lasia spinosa seeds were not dormant at maturity in early spring. The most favorable temperatures for germination were between 25 and 30 °C, and final percentage and rate of germination decreased with an increase or decrease in temperature. When L. spinosa seeds were transferred to 25 °C, after 60 days at 10 °C (where none of the seeds germinated), final germination increased from 0% to 78%. Seeds germinated to high percentage both in light and in dark, although dark germination took more than twice as long as in the light. During desiccation of seeds at 15 °C and 45% relatively humidity, moisture loss decreased exponentially from 2.02 to 0.13 g H 2O g −1 dry wt within 16 days, and only a few seeds (12%) survived 0.13 g H 2O g −1 dry wt moisture content. Seeds stored at 0.58 g H 2O g −1 dry wt moisture content at four constant temperatures (4, 10, 15, and −18 °C) for up to 6 months exhibited a well-defined trend of decreasing viability with decreasing temperature. Thus, we concluded that freshly harvested L. spinosa seeds are non-dormant and recalcitrant. Also, the seeds with 0.58 g H 2O g −1 dry wt moisture content could be effectively stored for a few months between 10 and 15 °C although the most appropriate temperature for wet storage appears to be 10 °C, as it is close to the minimum temperature for germination and so there will be less pre-sprouting compared to 15 °C.

Sensitivity of seed to desiccation in cupuassu (Theobroma grandiflorum (Willd. ex Spreng.) K. Schum. - sterculiaceae

The response of seeds to reduction in moisture content will determine whether they can be stored by conventional methods. The objective of this study was to verify the effect of desiccation on the germination and vigor of cupuassu (Theobroma grandiflorum (Willd. ex Spreng.) K. Schum.) seeds, a tropical fruit species. The following seed moisture contents (SMC) were tested: 57.1%, 53.7%, 49.8%, 46.5%, 41.4%, 35.4%, 28.3%, 23.2%, 17.4%, 15.5% and 14.6%. Desiccation of seeds to as low as 41.4% (SMC) did not affect emergence, germination or vigor. However, reductions in speed of emergence were observed below 41.4%. When SMC was equal or lower than 35.4% a reduction in seed quality was observed. Loss of seed quality was increased when moisture content was equal or lower than 28.3%, and at 14.5% SMC all cupuassu seeds were dead. The observed sensitivity of cupuassu seeds to reductions in moisture content suggests that storage conditions maintaining SMC higher than 41% are necessary for good seed vigor of this species.

Ascorbate and glutathione metabolism during development and desiccation of orthodox and recalcitrant seeds of the genus Acer.

The ascorbate-glutathione system was studied during development and desiccation of seeds of two Acer species differing in desiccation tolerance: Norway maple (Acer platanoides L., orthodox) and sycamore (Acer pseudoplatanus L., recalcitrant). The results showed remarkable differences in the concentration and redox balance of ascorbate and glutathione between these two kinds of seeds during development, and a significant dependence between glutathione content and acquisition of desiccation tolerance in Norway maple seeds. There were relatively small differences between the species in the activities of enzymes of the ascorbate-glutathione cycle: ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and glutathione reductase (GR, EC 1.6.4.2). At the end of seed maturation, ascorbic acid content and the activities of the above enzymes was about the same in both species The electrophoretic pattern of APX isoenzymes was also similar for both species, and the intensity of the bands decreased at the end of seed maturation in both species. When sycamore seeds were desiccated to a moisture content of less than 26%, there was a marked decrease in seed viability and an increase in the production of reactive oxygen species. During desiccation, Norway maple seeds had a more active defence system, which was reflected in a higher glutathione content, a higher glutathione redox status, a higher ascorbate redox status, and higher activities of APX, MR, DHAR, GR and GPX (glutathione peroxidase). During desiccation, sulfhydryl-to-disulfide transition into proteins was more intense in Norway maple seeds than sycamore seeds. All of these results suggest that, in orthodox seeds, the ascorbate-glutathione cycle plays an important role in the acquisition of tolerance to desiccation, in protein maturation, and in protection from reactive oxygen species.

Effects of presowing treatments, desiccation and storage conditions on germination of Strychnos nux-vomica seeds, a valuable medicinal plant

Seeds of Strychnos nux-vomica have slow and erratic germination; thus different presowing treatments were applied to enhance the germination of its seeds collected from Tamaraikulam, Tamil Nadu, India. In addition, the effects of desiccation and different storage conditions on the germination of S. nux-vomica seeds were investigated. The results show that soaking in 500 ppm gibberellic acid (GA3) for 24 h, incubation of seeds at 40 °C for 3 days and alternate water soaking (16 h) and drying (8 h) for 14 days significantly increased the percentage germination compared to the control. Desiccation of seeds down to 10% moisture content resulted in better germination. Germination of S. nux-vomica seeds differed significantly between different storage periods, moisture contents of the seed and for first and second order interactions (p<0.001). The highest germination (92%) was achieved when seeds with 10% moisture content were stored at ambient temperature for 30 weeks. Evidence from the present study indicates that S. nux-vomica seeds possess physiological dormancy that can be broken effectively by after-ripening. As seeds of S. nux-vomica are found to be desiccation tolerant, dry seed (10% moisture content) can be hermitically stored at ambient temperature for 30 weeks without losing their viability.

Prediction of desiccation sensitivity in seeds of woody species: a probabilistic model based on two seed traits and 104 species.

Seed desiccation sensitivity limits the ex situ conservation of up to 47 % of plant species, dependent on habitat. Whilst desirable, empirically determining desiccation tolerance levels in seeds of all species is unrealistic. A probabilistic model for the rapid identification of woody species at high risk of displaying seed desiccation sensitivity is presented. The model was developed using binary logistic regression on seed trait data [seed mass, moisture content, seed coat ratio (SCR) and rainfall in the month of seed dispersal] for 104 species from 37 families from a semi-deciduous tropical forest in Panamá. For the Panamanian species, only seed mass and SCR were significantly related to the response to desiccation, with the desiccation-sensitive seeds being large and having a relatively low SCR (i.e. thin 'seed' coats). Application of this model to a further 38 species, of known seed storage behaviour, from two additional continents and differing vegetation types (dryland Africa and temperate Europe) correctly predicted the response to desiccation in all cases, and resolved conflicting published data for two species (Acer pseudoplatanus and Azadirachta indica). This model may have application as a decision-making tool in the handling of species of unknown seed storage behaviour in species from three disparate habitats.

Changes in the Water Content and Germination Rate During Seed Desiccation and Their Inter-Specific Differences among Zizania Species

Changes in the Water Content and Germination Rate During Seed Desiccation and Their Inter-Specific Differences among Zizania Species

English

&nbsp; The effect of desiccation on lipid content, fatty acid composition and the antioxidative enzymic capacity was investigated in seeds of&nbsp;Telfairia occidentalis, harvested at physiological and agronomic maturity. Seeds were dried at 5 and 28&nbsp;oC, environments that induced different drying and metabolic rates. Desiccation of seeds was associated with decreased antioxidative enzymic capacity (of peroxidase and polyphenoloxidase), and thus increased likelihood of free radical attack and decreased viability (germinability). Agronomically mature seeds contained predominantly saturated fatty acids (tridecanoic), with very low levels of the major fatty acids of edible oilseeds (palmitic, stearic or the unsaturated C18 fatty acids). There was increased accumulation of the mono-unsaturated (oleic) and polyunsaturated (linoleic) fatty acids when seeds were dried at 28&nbsp;oC and moisture contents have reduced to about 42 % or lower. In contrast, seeds dried at 5&nbsp;oC maintained high levels of saturated fatty acids and lower levels of monounsaturated or polyunsaturated fatty acids. Results suggest the need to develop different post-harvest protocols for seed storage, and for processing&nbsp;T.occidentalis&nbsp;to &lsquo;improve&rsquo; the seed fatty acid profile as an oilseed for human and animal food. Key words:&nbsp;Agronomic maturity, desiccation, fatty acid, lipid peroxidation, oilseed.

종피의 연화처리, 세척 및 건조가 박 종자의 발아에 미치는 영향

본 연구는 파종전 종자처리에 의해 박 종자의 발아율을 최대한 향상시킬 수 있는 방법을 강구하고자 종피연화, 세척, 저온 및 건조 중 적색광 처리가 발아에 미치는 영향을 조사하였으며 그 결과를 요약하면 다음과 같다. 1) 종피연화는 염기성인 KOH 또는 NaOH로 처리하는 것보다 산성인 acetone과 acetonitrile 10% 용액에 1시간 처리하였을 때 발아율이 증가되고 발아가 촉진되는 것으로 나타났다. 2) Acetone으로 종피연화 시킨 종자는 이후에 행하여지는 저온처리의 영향을 적게 받는 반면, KOH로 종피연화 시킨 종자는 저온처리가 행해지지 않을 경우 발아가 현저히 억제되었다. 3) 종피연화 후 흐르는 수돗물로 1시간 세척시킨 종자의 발아율은 세척하지 않은 것보다 높았다. 4) 종피연화, 세척 및 저온처리를 경과가 이루어진 종자는 건조과정에서 암처리보다는 적색광을 처리하였을 경우 발아율이 높았다. The present experiment was carried out to determine the effect of seed-coat softening by various chemicals, washing, chilling, and light treatment alone and in combination during desiccation of seeds on germination of gourd (Lagenaria siceraria Standl.) seeds. Potassium hydroxide, sodium hydroxide, acetone, acetonitrile, and acetamide were used as chemicals for the softening. Washing, prechilling, drying and light treatment of the softened seeds were done for a hour with tap water, for one or three weeks at 3<TEX>$^{\circ}C$</TEX>, 12 hr at 35<TEX>$^{\circ}C$</TEX>, and 14 hr a day at 3<TEX>$0^{\circ}C$</TEX> with red light illumination or darkness, respectively. FR-yongjadaemok and FR-kunghap were used as test cultivars. Seed-coat softening with 10% acetone and acetonitrile for 1 hour enhanced and accelerated seed germination compared to the other chemicals and water imbibition. KOH treated for the softening was necessary to increase the germination rate of seeds for following chilling, but acetone did not influence their germinability regardless of chilling. Washing the softened seeds in tap water increased the germination rate in comparison with no-washing. During desiccation of the seeds sequentially treated with the softening, washing and chilling, red light treatment showed higher germination rate than dark one, suggesting that red light treatment are necessary during desiccation.

The impact of freezing during maturation on storage products in canola seeds

Mature canoia (Brassica napus cv. Westar) seeds contain large quantities of the storage proteins cruciferin and napin and storage lipids rich in C18: 1 and C18:2 fatty acids. Both the quantity and quality of these products are altered by freezing during development. Further, the response to freezing changes during seed development. The effects include decreased fatty acid chain elongation, altered fatty acid unsaturation, higher lipid levels and lower protein levels. In addition, seeds in the pivotal moisture range (55%) may be predisposed to precocious germination, which is then inhibited by a lack of adequate seed moisture. The results indicate that freezing imparts its effect in two ways. Initially, there is a freezing (low temperature) component and this is followed by rapid desiccation of the seeds. Although most responses probably result from a combination of the stresses, it appears that inhibition of fatty acid chain elongation is caused by the freezing component and the gradual inhibition of storage protein accumulation is a result of accelerated seed desiccation.

Lipid-Sugar Interactions

The ability of seeds and other anhydrous plant forms to survive the withdrawal of water must involve a mechanism for protecting the integrity of cellular membranes. Evidence from animal systems implicates sugars as protective components, and we have tested the changes in mesomorphic phase state of phospholipid model membranes upon hydration and dehydration in the presence of sucrose and/or sucrose plus raffinose. X-ray diffraction studies of dry dimyristoylphosphatidylcholine (DMPC) indicate that the presence of sucrose lowers the chain order/disorder transition temperature to that of hydrated lipid; likewise, the lamellar repeat spacings showed the dry DMPC/sucrose mixture to be similar to that of the hydrated lipid. These results support the proposed potential of sugars to substitute for water in biomembranes. If sucrose is to serve as a protectant during desiccation of seeds, its tendency to crystallize would lessen its effectiveness. Raffinose is known to serve as an inhibitor of sucrose crystallization, and is abundant in seeds. The addition of raffinose to make DMPC/sucrose/raffinose mixtures (1/1/0.3 mass ratio) prevented sucrose crystallization, suggesting this as a possible in vivo role for raffinose.

Salt priming of muskmelon seeds for low-temperature germination

“Persia 202”, a muskmelon ( Cucumis melo L.) of Iranian origin, germinated well at 12–14°C. In contrast, the Israeli cultivar ‘Noy Yizre'el’ did not germinate at temperatures below 15°C. Both “Persia 202” and ‘Noy Yizre'el’ were subjected to salt priming pre-treatments in an attempt to improve their germinability at sub-optimal temperatures. Priming in 2–3% solutions of KH 2PO 4 + KNO 3 (1:1) for 1–5 days significantly increased the germination rate, synchronization and percentage. Enhancement of these effects was greatest at 10–11°C for “Persia 202” and at 15–16°C for ‘Noy Yizre'el’. Dehydration of seeds following treatments resulted in partial reversion of the positive effects of priming if incubation took place at the lower temperatures. Storage of dried primed seeds for up to 28 days at 10°C and 45% relative humidity further reversed the beneficial effects of priming in ‘Noy Yizre'el’ but not in “Persia 202”. Nitrate-containing salts were more efficient than nitrate-free salts in promoting low-temperature germination.