Desiccation Of Seeds Research Articles

Breaking seed dormancy for sustainable food production: Revisiting seed priming techniques and prospects

Seed dormancy represents a pivotal challenge in seed germination, standing as a significant impediment to attaining SDG 2 - the zero-hunger goal. This dormancy arises from a range of environmental stressors, including restricted water conditions, temperature fluctuations, and light exposure. Consequently, the disruption of seed dormancy assumes paramount importance to ensure consistent germination and the cultivation of high-quality crops. Seed priming, an approach involving the treatment and desiccation of seeds, serves to augment pre-germination metabolism and expedite the germination process. Traditional priming methods encompass hydro-priming, halo-priming, hormonal-priming, and osmo-priming, each contributing to enhanced seed germination. Recent strides in priming technology have yielded even more effective outcomes concerning germination, germination timing, and seedling vigor. Novel approaches such as nano-priming (employing nanoparticle-infused solutions) and magneto-priming (involving magnetic fields) have surfaced, fostering uniform seed germination. Preeminent among these strategies is seed bio-priming, which not only alleviates seed dormancy but also augments nutrient uptake efficiency in germinating seedlings. This review paper delineates diverse priming methodologies applicable across a spectrum of crops, serving as an environmentally benign alternative to mitigate dormancy-linked predicaments and enhance plant growth. Additionally, we delve into the latest advancements in priming techniques and offer future perspectives. The central objective of this review article is to enhance comprehension of seed priming as a potent and invaluable tool for surmounting seed dormancy, consequently fostering sustainable global food production.

Physiological quality of seeds of Mimosa bimucronata (DC) O. KTZE. subjected to different types of drying

Despite its potential, to date, work has not been carried out to identify the ideal drying conditions for Mimosa bimucronata (DC) O. Kuntze. Considering the scarcity of information on the drying process of this species, this work was with the objective of evaluating the sensitivity to desiccation by means of drying on activated silica gel (fast) and under laboratory conditions (slow). Rapid drying with silica was performed. For slow drying, the seeds were placed in plastic containers without lids, both at room temperature. Every hour, the seeds were weighed until reaching the pre-established points (30, 25, 20, 15 and 10%). The variables analyzed were: water content, first germination count, germination, germination speed index, dry mass and seedling length. The seeds of M. bimucronata (DC) show orthodox behavior, withstanding desiccation at levels below 15%. The desiccation of seeds at very low levels impairs the formation of seedlings, preventing their normal development.

Integrative Metabolic and Transcriptomic Profiling in Camellia oleifera and Camellia meiocarpa Uncover Potential Mechanisms That Govern Triacylglycerol Degradation during Seed Desiccation.

Camellia seed oil is a top-end quality of cooking oil in China. The oil quality and quantity are formed during seed maturation and desiccation. So far, it remains largely unresolved whether lipid degradation occurs and contributes to Camellia oil traits. In this study, three different Camellia germplasms, C. oleifera cv. Min 43 (M43), C. meiocarpa var. Qingguo (QG), and C. meiocarpa cv Hongguo (HG) were selected, their seed oil contents and compositions were quantified across different stages of seed desiccation. We found that at the late stage of desiccation, M43 and QG lost a significant portion of seed oil, while such an event was not observed in HG. To explore the molecular bases for the oil loss In M43, the transcriptomic profiling of M43 and HG was performed at the early and the late seed desiccation, respectively, and differentially expressed genes (DEGs) from the lipid metabolic pathway were identified and analyzed. Our data demonstrated that different Camellia species have diverse mechanisms to regulate seed oil accumulation and degradation, and that triacylglycerol-to-terpenoid conversion could account for the oil loss in M43 during late seed desiccation.

Effect of desiccation damage on the seed viability of Hydnocarpus alpina Wight. of Western Ghats

Hydnocarpus alpina Wight is an evergreen endangered medicinal tree species of Western Ghats. Several local names are available based on the distribution among the state in India that is Torathi (Kannada), Maravetti/Marotti (Malayalam), Attuchankalai (Tamil), Kastel (Hindi). Hydnocarpus alpina has very appreciated value in various medicinal properties like anti-larvicidal, anti-feedant, antimicrobial etc. due to the presence of significant chemical constituents. The seeds of this tree species are characterized with high moisture content and are intolerant to desiccation. They are under recalcitrant type seeds.Fully mature H. alpina seeds have 20% moisture content on harvest and recorded 80% germination. After 2 weeks of desiccation at open laboratory conditions (28±2 °C and 65% RH) their moisture content and percentage of germination decreased to 10.2% and 20 % respectively. Complete loss of viability occurred at 10% moisture level. This clearly indicates the recalcitrant nature of seeds. Different biochemical parameters such as lipid peroxidation, leachate conductivity, assay of free radical scavenging enzymes, analysis of primary metabolites like total soluble sugars, starch, total proteins, amino acids, lipids, phenols etc. were recorded for finding the biochemical basis of desiccation induced damage on seed viability. The results of the study reveals the metabolic disturbances associated with the desiccation of seeds and such parameters can be considered as markers for assessing the seed viability. Hence, safest low moisture content for the long term storage of seeds can be identified for the conservation of this endangered species of Western Ghats.

Fluidized Bed Seed Dewatering System

The aim of this work is to improve the efficiency of the dehydration process of seeds of agricultural plants by applying the fluidized bed treatment method. In order to achieve the aim of the work, an experimental plant for the dehydration of seeds in fluidized layer was developed, based on which the research was carried out. Convection and SHF were used as sources of fluidized bed seed treatment. The efficiency of the dehydration process with the application of the developed experimental plant was estimated for 3 types of seeds of agricultural alleaginous plants: grape seeds, flax seeds and white buckthorn seeds. These types of seeds were selected for research because at present their dehydration is a problem and they have a great potential for the food industry, traditional medicine, cosmetic industry, pharmaceutical industry, etc. The main results obtained in the application of the developed plant to the treatment of seeds of agricultural plants in a fluidized layer are: increase of the dehydration process speed, reduction of the treatment time, reduction of electricity consumption, increase of the seed quality and reduction of the processing costs. Again, the plant is simple in terms of construction, easy to use, low in cost and during operation has demonstrated a high level of operational safety. The significance of the results obtained lies in the efficiency of the process of dehydration of oilseeds of agricultural plants, based on fluidized bed treatment, mainly with a reduction in the cost of technological processing and an increase in the quality of these seeds, for subsequent use in the food industry, traditional medicine, cosmetics industry, pharmaceutical industry, etc.

Effects of desiccation of seeds in nine species with morphophysiological dormancy on germination and embryo growth

Abstract Aims In species with morphophysiological seed dormancy (MPD), little is known about the effects of desiccation of imbibed seeds on embryo growth and germination. We studied seed responses to dehydration in nine species with different levels of MPD. Methods For each species, a control test was conducted by keeping seeds permanently hydrated and exposed to the optimal stratification–incubation sequence to promote embryo growth. Simultaneously, tests were run in which seed stratification was interrupted for 1 month by desiccation at room temperature. Important Findings In Clematis vitalba and Ribes alpinum, with nondeep simple MPD, desiccation affected neither embryo growth nor seed viability, but the desiccation led to a decrease of germinative ability in R. alpinum by 16%. The seeds of Narcissus pseudonarcissus subsp. munozii-garmendiae, with deep simple epicotyl MPD, tolerated desiccation in different embryo growth stages, but their germinative ability decreased slightly. The response of species with complex levels of MPD to desiccation was more variable: Delphinium fissum subsp. sordidum, with intermediate complex MPD, and Anthriscus sylvestris and Meum athamanticum, both with deep complex MPD, tolerated desiccation. In contrast, Ribes uva-crispa with nondeep complex MPD, Lonicera pyrenaica with intermediate complex MPD and Chaerophyllum aureum with deep complex MPD, had diminished germination ability by desiccation. Although seeds of the species with simple levels of MPD tolerated desiccation, those of some species with complex levels were also highly tolerant. Thus, desiccation did not induce secondary dormancy in late embryo growth stages. The desiccation tolerance of imbibed seeds of most of the nine species may show their adaptability to climate change in the Mediterranean region.

Classification and quality of Acca sellowiana (O. Berg) Burret seeds as to tolerance to desiccation

The objective of this paper was to determine the physiological behavior and seed quality of five genotypes of Acca sellowiana regarding desiccation. Seeds were obtained from five plants of urban backyards in the cities of Dois Vizinhos - PR (A1, A2) and Vacaria - RS (A3, A4, A5). The experiment was conducted in a bifactor arrangement (5x3), with five genotypes and three levels of water content (28%, 15% and 5%), arranged into complete randomized block design, with four replicates of 50 seeds each. Seeds were germinated on absorbent paper soaked with water, being kept in BOD chamber under temperature of 25±3°C with photoperiod of 16 hours. Germination percentage, speed index and average time were assessed by counting seeds every two days for 50 days, starting from the moment of radicle emergence. No significant differences were observed for germination percentage and all genotypes surpassing 79% of germination. Desiccation of seeds had low influence on germination speed index and average time of germination, although genotype influence was verified due to genetic variability. Genotype A5 has seeds with superior quality from the others. Acca sellowiana seeds have orthodox behavior.

What Do We Know About the Genetic Basis of Seed Desiccation Tolerance and Longevity?

Long-term seed storage is important for protecting both economic interests and biodiversity. The extraordinary properties of seeds allow us to store them in the right conditions for years. However, not all types of seeds are resilient, and some do not tolerate extreme desiccation or low temperature. Seeds can be divided into three categories: (1) orthodox seeds, which tolerate water losses of up to 7% of their water content and can be stored at low temperature; (2) recalcitrant seeds, which require a humidity of 27%; and (3) intermediate seeds, which lose their viability relatively quickly compared to orthodox seeds. In this article, we discuss the genetic bases for desiccation tolerance and longevity in seeds and the differences in gene expression profiles between the mentioned types of seeds.

Сравнение посевных, урожайных и антиоксидантных свойств семян и проростков полевицы гигантской (Agrostis gigantea Roth) после воздушной сушки и термодегидратации

The study of the biological characteristics of feed crops and the use of modern methods in the study of the processes of their selection is relevant for the intensification of feed production. The article presents the results of a biochemical study of the giant VIK-2 (Agrostis gigantea Roth) field birch seed, their sowing and yield properties after thermal dehydration (drying of air-dried samples at 105 oС to constant weight), as well as their total antioxidant activity during germination in the dark. The total antioxidant activity of seeds and seedlings was studied using coulometric analysis and determined using electrogenerated bromine, the samples were analyzed on a certified couponometer Expert-006 (LLC Econix-Expert, Russia) using a certified method. The work shows that, compared with air drying after thermohydration, there is a decrease in the viability and yield properties of seeds. Seed germination decreased by 5.5%, the height of plants at the end of the germination period (on the 14th day after sowing) by 9.4%, the mass of 100 sprouts – by 21.3%, the yield of green mass (microgreen) also by 21.3%. The antioxidant activity of seeds after thermal dehydration also decreased by 21.4%. For the first time, data were obtained on the viability, formation of microgreen biomass and a change in the total antioxidant activity of the seeds of the VIK-2 giant cultivar after thermal dehydration (drying the initial seeds) in the test at 105 °C to constant weight. It was shown that thermal dehydration of seeds at 105 °C significantly affects the viability of seeds and seedlings of a bent field, which is associated with the characteristics of metabolism, forms and state of water activity in cells and tissues of plants.

Desiccation Tolerance, Germination and Moisture Sorption Isotherm of Garcinia afzelii seeds

The desiccation tolerance of Garcinia afzelii seeds was determined and sensitive vigour tests for assessing seed deterioration of this species were identified. Matured fruits were harvested in March 2009 from a small plantation at Ho in the Volta Region of Ghana. Depulped seeds were mixed with moistened sawdust and placed in white cotton sacks and quickly transported by air to the Seed Conversation Department of the Royal Botanic Gardens in the United Kingdom where a part of the experiment was carried out. The second season’s seeds was also harvested from the same plantation in April 2010 and used for another part of the studies in Ghana. Seed equilibrium relative humidity and moisture content on receipt in the United Kingdom were 93.3 % and 38.2 % respectively. Seed germination percentage decreased gradually with reduction in seed moisture content until after 25 % moisture content when germination percentage reduced drastically to 43 % at 23 % moisture content. The seeds of Garcinia afzelii are recalcitrant, with ‘critical moisture content’ about 25 %. Seedling dry weight, seed vigour index and speed of germination also decreased as seeds were dried. Electrical conductivity of leachate from seeds increased with desiccation of seeds. Water sorption isotherm curve for the species showed the typical sigmoid shape curve similar to that of orthodox species. Key words: Garcinia afzelii, vigour index, seedling dry weight, electrical conductivity, critical moisture content, moisture sorption isotherm.

Environmental Correlates for Seed Desiccation Sensitivity of New Caledonian Plant Species1

Efficient in situ and ex situ conservation strategies are urgently needed in biodiversity hotspots, where high concentrations of endemic plant species are undergoing exceptional loss of habitat. In particular, determining seed desiccation sensitivity is a key prerequisite to design storage methods useful for ex situ programs. In this study, we explored seed desiccation sensitivity and its link with phenological and morphological traits as well as with the environmental variables for 45 New Caledonian plant species. Desiccation sensitivity was quantified through RH50, that is, the relative humidity at which 50% of initial viable seeds died. RH50 was found to be positively associated with the initial seed water content, seed mass, precipitation seasonality, precipitation of the warmest quarter, and presence in rainforest habitats. In contrast, the ability of species to endure desiccation increased in drier habitats such as dry forest. We also found that desiccation sensitivity was consistent at the genus level. These new data provide the basis to establish conservation plans for a large array of plant species in New Caledonia. Moreover, this study may help us to better understand the underlying mechanisms of desiccation sensitivity and to predict desiccation sensitivity of other taxa within the New Caledonian flora on the basis of taxonomy, functional traits and environmental features.

Factors Influencing in vitro Germination and Seed Storage Behavior of Couroupita guianensis Aubl. – A Useful Tropical Tree Species

Couroupita guianensis Aubl. popularly known as cannonball tree is widely distributed in the tropical regions. The tree parts are commonly used to treat wounds and tumors. Leaves, flowers, and fruits contain active phytochemicals with significant biological activity. In the recent years, destruction of natural habitats by mankind has reduced its distribution. Natural propagation of C. guianensis by seeds is greatly hindered by poor seed germination and viability. Therefore, the present study was undertaken to optimize the conditions for in vitro embryo germination and to investigate the seed storage behaviour. Mature seeds inoculated on MS basal medium germinated within 10 d with a frequency of 61.6%. Supplementation of plant growth regulators (PGRs) to MS medium improved the embryo germination frequency (100%). Seedlings with highest shoot length (8.10±0.11 cm) and root length (6.27±0.14 cm) were produced in MS medium supplemented with 1.0 mg/l kinetin and 0.1 mg/l indole-3-butyric acid. Among different strength liquid MS basal salts, quarter-strength produced a greater number of secondary roots (8.00±0.28) with average root length of 17.83±0.58 cm. Seed storage behaviour studies clearly proved the recalcitrant nature as only freshly harvested mature seeds retained the germination potential upon storage at 15 ºC for up to 45 d. Desiccation of seeds on exposure to air-dry storage resulted in rapid deterioration of germination. Pre-conditioning of germinated seedlings in liquid MS basal salts was required for their survival under field conditions. Plantlets with well-developed roots were successfully acclimatized to the field with 100% survivability. This protocol facilitates conservation, sustainable utilization and re-introduction of C. guianensis into its natural habitats.

Design, Construction, and Analysis of a Passive Indirect Solar Dryer With Chimney

The growing demand for alternative technologies, of clean and sustainable nature, has fostered the development and improvement of equipment that uses solar energy for the dehydration of seeds and fruits. Such equipment has been used worldwide for hundreds of years; however, it remains uncommon in Serra Gaúcha, a region of great production of grapes and apples for natura consumption in the state of Rio Grande do Sul—Brazil. In order to investigate the economic and technical viability of solar dryers in the Serra Gaúcha, this work has as target the design, simulation, construction, and experimental analysis of an Indirect Passive Solar Dryer with Chimney. The prototype, divided into three parts: solar collector, dehydration chamber, and chimney, was built prioritizing materials of low cost, but that did not compromise its performance. The device was submitted to experiments, which observed: solar collector behavior very close to the simulated one; obtaining a coefficient of performance of 87% in the equipment; satisfactory rise in temperature at the collector outlet comparing to its inlet; and dehydration of apples with a reduction of 89% in mass with 32.78 MJ of energy delivered to the system. The prototype payback period was estimated in two years.

Desiccation of Pachira aquatica Aubl. Seeds

The conservation of seed quality during storage is important to perform the maintenance and conservation of germplasm banks. Several native species of Brazil are intolerant to desiccation to desirable levels for conservation during storage is necessary to develop specific technologies for their conservation. The objective of this research was to evaluate the physiological quality of Paquira aquatica seeds submitted to drying periods. The study was carried out using seeds of P. aquatica dried at a temperature of 35 ºC, the following exposure times: 0 (no drying), 24, 48, 72 and 96 hours. Before and after each period of drying samples for the evaluations, the data were submitted to analysis of variance and regressionat level of 5%. The seeds of P. aquatica were dispersed with very high water content and a small reduction in its physiological value agrees quality, allowing the seeds to characterize this as a recalcitrant species. The drying temperature is 35 ºC until the viable 24 hours after this period the water content of seed reduced from 55% to 43%, which was considered the critical level for desiccation of seeds of P. aquatica. Because it reduces the values of first count, germination, rate of germination and growth of seedlings.The drying temperature the 35 ºC until the viable 24 hours, whit small reduction in its physiological quality seed P. aquatica.

Climate Change in Himalayas: Research Findings and Complexities

Himalayas are important for its influence on the climate of much of Asia, and ecosystem services, which serve some 1.3 billion people living in 10 river basins that originate from the region. The region is warming rapidly and is highly vulnerable to climate change. This review (i) sheds light on some fairly well established facts about climate change in Himalayas, (ii) makes an attempt to give an integrated picture of its impact on various components, and (iii) discusses complexities in generalizing the findings. Himalayas are warming at 2-3 time higher rates than global average rate, at least in some areas. The rate of warming is increasing in time and with elevation. As for rainfall, uncertainty is high, but generally predictions are for more violent events. According to an analysis based on 75 glaciers, 63 glaciers are showing shrinkage and 12 growth, however, their (growing ones) measurements are of low confidence level. The contribution of glacier and snow melt to total river discharge varies from 5-60% from west to east. Violent extreme events and glacier melt lakes are predicted to generate more disasters. The intensification of pre-monsoon drought is likely to be a critical climate change factor, affecting several ecological processes and social behaviour. Its examples are drying of water springs, suppression of treeline and desiccation of seeds of the species in which seeds remain lying on ground for a relatively longer period before conditions for germination become favourable, and spread of forest fires. The intensified water shortage is a threat even to tourism supporting capacity of the region. Apple cultivation in the state of Himachal Pradesh is getting adversely affected by the lack of sufficient winter-chilling. Some interventions are possible to undertake to address climate change impact. They include addressing data gaps, particularly with regard to changes in glacier ice mass, volumes and timing of river flows, frequency and duration of extreme events, transboundary cooperation, and development of translational ecology research in which scientists work in a close partnership with stakeholders and administrators. The Himalayan region is disproportionately affected by climate change induced disasters and miseries, though the region's per capita fossil fuel consumption is ridiculously low, raising a issue of climate change justice.

Drying and reduction in sensitivity to desiccation of seeds of Alibertia edulis: the influence of fruit ripening stage.

The intense environmental degradation in tropical regions suitable for agriculture has decreased native forest populations of plants with important fruits and medicinal properties. Alibertia edulis is a native tree from the Brazilian Cerrado. Knowledge about the effects of drying and storage on the physiological behavior of its seeds may aid in its sustainable exploitation and conservation. The goal of the present study was to determine which fruit ripening stage results in A. edulis seeds with higher tolerance to desiccation, and to investigate the effectiveness of polyethylene glycol (PEG) induced osmotic stress in combination with abscisic acid (ABA) in increasing seed desiccation tolerance during storage. Seeds were dried in activated silica gel (fast) or under ambient conditions (slow). Seeds originating from mid-ripe or fully ripe fruits exhibited better physiological performance than those obtained from green fruits. Slow drying resulted in seeds with high physiological potential. Seeds may be stored for up to 180 days without losing viability when treated with -0.73 MPa PEG without ABA.

Taxonomic affinity, habitat and seed mass strongly predict seed desiccation response: a boosted regression trees analysis based on 17 539 species.

Seed desiccation response plays an important role in plant regeneration ecology, and has significant implications for species conservation. The majority of seed plants produce desiccation-tolerant (orthodox) seeds, whilst comparatively few produce desiccation-sensitive (recalcitrant) seeds that are unable to survive dehydration, and which cannot be conserved in traditional seed banks. This study develops a set of models to predict seed desiccation response in unstudied species. Taxonomy, trait, location and climate data were compiled to form a global data set of 17 539 species. Three boosted regression trees models were then developed to predict species' seed desiccation responses based on habitat and trait information for the species, and the seed desiccation responses of close relatives (either members of the same genus, family or order, depending on the model). Ten-fold cross-validation was used to test model predictive success. The utility of the models was then demonstrated by predicting seed desiccation response for two floras: Ecuador, and Britain and Ireland. The three models had varying success rates for identifying the desiccation-sensitive species: 89 % for the genus-level model, 79 % for the family-level model and 60 % for the order-level model. The most important predictor variables were the seed desiccation responses of a species' relatives, seed mass and annual precipitation. It is predicted that 10 % of seed plants from Ecuador and 1.2 % of those from Britain and Ireland produce desiccation-sensitive seeds. Due to data availability, prediction accuracy is likely to be higher for the British and Irish flora, where it is estimated that a desiccation-sensitive species had a 96.7 % chance of being correctly identified, compared with 80.8 % in the Ecuador flora. These models can utilize existing data to predict species' likely seed desiccation responses, providing a gap-filling tool for global studies of plant traits, as well as critical decision-making support for plant conservation activities.

Changes in abscisic acid levels in embryonic axis of Saraca asoca seeds during maturation and artificial dehydration

Abscisic acid (ABA) plays an important role in many cellular processes, including seed development, dormancy, germination and stress responses. Investigation on changes in endogenous ABA content of Saraca asoca seeds during development and artificial dehydration by indirect competitive ELISA method explains their influence on viability. The low ABA levels towards later stages of seed development validates non-orthodox nature of species. About 37% germination was observed in immature seeds of 60 days after anthesis onwards, which possess comparatively higher ABA content of 0.92 nmol g−1 fr. wt. In the course of seed maturation gradual loss of ABA was noticed with concurrent increase in germination. Artificial seed drying in open laboratory condition for five different periods, viz., 48, 96, 144, 192 and 240 h registered 49.7, 48.4, 46.9, 45.2 and 42.8% moisture contents, respectively, in fresh and mature seeds as control which possess moisture content of 51.6 with 100% germination. Dehydration of seeds results the significant increase of abscisic acid level in embryonic axis but the viability was declined simultaneously. So the present study deals with the influence of abscisic acid in desiccation tolerance during maturation and dehydration of recalcitrant seeds of Saraca asoca.

A Combination of Histological, Physiological, and Proteomic Approaches Shed Light on Seed Desiccation Tolerance of the Basal Angiosperm Amborella trichopoda.

Desiccation tolerance allows plant seeds to remain viable in a dry state for years and even centuries. To reveal potential evolutionary processes of this trait, we have conducted a shotgun proteomic analysis of isolated embryo and endosperm from mature seeds of Amborella trichopoda, an understory shrub endemic to New Caledonia that is considered to be the basal extant angiosperm. The present analysis led to the characterization of 415 and 69 proteins from the isolated embryo and endosperm tissues, respectively. The role of these proteins is discussed in terms of protein evolution and physiological properties of the rudimentary, underdeveloped, Amborella embryos, notably considering that the acquisition of desiccation tolerance corresponds to the final developmental stage of mature seeds possessing large embryos.

Dormancy induction by summer temperatures and/or desiccation in imbibed seeds of trumpet daffodils Narcissus alcaracensis and N.longispathus (Amaryllidaceae).

We analysed the effects of summer temperatures (28/14°C) and/or desiccation (from 48% to 8% humidity) on imbibed Narcissus alcaracensis and N.longispathus seeds with an elongating embryo. In the N.alcaracensis seeds that overcame dormancy (embryo elongation=27.14%), exposure to high temperatures induced secondary dormancy and reduced subsequent embryo growth. A further 3-month cold stratification (5°C) was required to break secondary dormancy. Desiccation in early embryo growth stages (elongation=11.42%) also reduced germination. Desiccation in the seeds in a more advanced growth stage (i.e. embryo elongation=27.14%) induced secondary dormancy, which the further 3-month cold stratification did not overcome. When desiccation was preceded by high temperatures, seeds better overcame secondary dormancy (i.e. longer embryo elongation and seed germination). Treatments did not affect seed viability. In the N.longispathus seeds that overcame dormancy (embryo elongation=59.21%), exposure to high temperatures induced secondary dormancy and they needed a further 1-month stratification at 15/4°C+2months at 5°C to reactivate the germination process. When embryo elongation was 42.10%, seed desiccation totally impeded subsequent germination. When embryo elongation reached 59.21%, desiccation induced secondary dormancy, which was not overcome by the above-described stratification treatment. When desiccation was preceded by high temperatures, seeds better overcame dormancy. Stress treatments killed 5-10% of seeds. This study suggests that the seeds of species with complex morphophysiological dormancy (MPD) levels are sensitive to desiccation in early embryo development stages, as opposed to the seeds of species with deep simple epicotyl MPD, which better tolerate water stress.