Analysis and Identification of Genes Associated with the Desiccation Sensitivity of Panax notoginseng Seeds.

Panax notoginseng (Burk.) F. H. Chen, a species of the genus Panax, radix has been traditionally used to deal with various hematological diseases and cardiovascular diseases since ancient times in East Asia. P. notoginseng produces recalcitrant seeds which are sensitive to desiccation and difficult to store for a long time. However, few data are available on the mechanism of the desiccation sensitivity of P. notoginseng seeds. To gain a comprehensive perspective of the genes associated with desiccation sensitivity, cDNA libraries from seeds under control and desiccation processes were prepared independently for Illumina sequencing. The data generated a total of 70,189,896 reads that were integrated and assembled into 55,097 unigenes with a mean length of 783 bp. In total, 12,025 differentially expressed genes (DEGs) were identified during the desiccation process. Among these DEGs, a number of central metabolism, hormonal network-, fatty acid-, and ascorbate-glutathione-related genes were included. Our data provide a comprehensive resource for identifying the genes associated with the desiccation sensitivity of P. notoginseng seeds.

Exogenous abscisic acid prolongs the dormancy of recalcitrant seed of Panax notoginseng.

The seeds of Panax notoginseng (Burk.) F. H. Chen are typically characterized by their recalcitrance and after-ripening process and exhibit a high water content at harvest as well as a high susceptibility to dehydration. Storage difficulty and the low germination of recalcitrant seeds of P. notoginseng are known to cause an obstacle to agricultural production. In this study, the ratio of embryo to endosperm (Em/En) in abscisic acid (ABA) treatments (1 mg·l-1 and 10 mg·l-1, LA and HA) was 53.64% and 52.34%, respectively, which were lower than those in control check (CK) (61.98%) at 30 days of the after-ripening process (DAR). A total of 83.67% of seeds germinated in the CK, 49% of seeds germinated in the LA treatment, and 37.33% of seeds germinated in the HA treatment at 60 DAR. The ABA, gibberellin (GA), and auxin (IAA) levels were increased in the HA treatment at 0 DAR, while the jasmonic acid (JA) levels were decreased. ABA, IAA, and JA were increased, but GA was decreased with HA treatment at 30 DAR. A total of 4,742, 16,531, and 890 differentially expressed genes (DEGs) were identified between the HA-treated and CK groups, respectively, along with obvious enrichment in the ABA-regulated plant hormone pathway and the mitogen-activated protein kinase (MAPK) signaling pathway. The expression of pyracbactin resistance-like (PYL) and SNF1-related protein kinase subfamily 2 (SnRK2s) increased in the ABA-treated groups, whereas the expression of type 2C protein phosphatase (PP2C) decreased, both of which are related to the ABA signaling pathway. As a result of the changes in expression of these genes, increased ABA signaling and suppressed GA signaling could inhibit the growth of the embryo and the expansion of developmental space. Furthermore, our results demonstrated that MAPK signaling cascades might be involved in the amplification of hormone signaling. Meanwhile, our study uncovered that the exogenous hormone ABA could inhibit embryonic development, promote dormancy, and delay germination in recalcitrant seeds. These findings reveal the critical role of ABA in regulating the dormancy of recalcitrant seeds, and thereby provide a new insight into recalcitrant seeds in agricultural production and storage.

Chayote Fruit (Sechium edule var. virens levis) Development and the Effect of Growth Regulators on Seed Germination.

The chayote fruit is a nontraditional vegetable belonging to the Cucurbitaceae family. The fruit has an endocarpic recalcitrant seed that emerges postharvest, drastically shortening its shelf life. In this study, the changes during fruit and seed development before and after harvest (ah) are reported. Additionally, in order to investigate how growth regulators (GRs) affect seed germination, 2-cloroethylphosphonic acid (CPA) (200 µL L-1), gibberellic acid (GA3) (100 and 200 mg L-1), auxin (2,4-D) (0.5 and 1.0 mM), and abscisic acid (ABA) (0.5 and 1.0 mM) were applied after harvest. The results showed that the chayote fruit reached horticultural maturity at 21 days after anthesis, with a sigmoid trend: phase I featured slow growth and high transpiration; in phase II, growth was accelerated and accumulation of endosperm was observed; and in phase III, both growth rate and transpiration were reduced, soluble sugars increased, and the seed showed 25% cotyledon development. At day 13 ah, CPA, GA3, and 2,4-D (0.5 mM) increased seed germination, with values between 10 and 15 mm of the embryonary axis, and the treatments with 2,4-D (1 mM) and ABA (0.5 and 1.0 mM) retarded their growth (2-6 mm). This research allowed us to reveal the phenological phases and the shelf life of the chayote fruit, as well as the results of possible postharvest treatment with GRs; our results suggest that strategies to delay viviparism and prolong the shelf life of the fruit should be applied before 10 days ah, when the embryonic axis of the seed has not developed.

Characterization of physiological traits during development of the recalcitrant seeds of Quercus serrata.

We investigated how developmental stage affects seed traits, including the relative level of desiccation tolerance of Quercus serrata. We tested the hypothesis that the relative level of desiccation tolerance is a quantitative trait associated with seed development and that a maximum relative level of desiccation tolerance is reached during development. Seed growth and physiological traits of Q. serrata from a subtropical forest were examined in detail during the developmental process. During seed development, the relative level of desiccation tolerance and other seed traits of Q. serrata varied. Dry matter accumulation in seed components increased rapidly beginning in mid-August, and moisture content declined. At the peak period of seed dispersal in late September, seeds were fully mature, with 100% germination. Relative level of desiccation tolerance increased up to the point of peak dispersal; however, at this time seeds were still recalcitrant. Post-mature development was accompanied by further increases in seed dry matter and decreases in moisture content, which led to a decrease in seed germination and relative level of desiccation tolerance. Our results suggest that in species with recalcitrant seeds, the relative level of desiccation tolerance and other seed traits are quantitative at the intraspecific level. The relative level of desiccation tolerance for recalcitrant seeds does not increase infinitely during phase II of development. There is a maximum relative level of desiccation tolerance in recalcitrant seeds within a species.

Anatomical and biochemical changes associated with thedevelopment and germination of Araucaria angustifolia seeds

This study aimed at assessing the cell cycle, and anatomical and biochemical changes that the embryonic axis of Araucaria angustifolia undergoes during development, focusing on the maturation stage. During all development, cells exhibited intense metabolic activity with an abundance of mitochondria, lipid bodies, and vacuolated cells. The continued accumulation of starch and protein was observed by LM and TEM and indicated by spectra of FTIR. Cell differentiation of the procambium was observed with a thickening of the cell wall and the formation of resiniferous ducts. At Stage III and IV, cells exhibited structural changes such as altered or elongated mitochondria and presence of plastoglobules. These results suggest that there is a gradual transition from developmental metabolism to germination metabolism. Such changes can contribute to the rapid germination of seeds right after their dispersion, making it an ecological strategy to reduce post-dispersal exposure to predators and to avoid damage from reduced moisture.

LC-MS data for metabolomics analysis of Garcinia mangostana L. seed germination.

Metabolic regulation is important during seed germination for the establishment of seedling. The germination strategy of mangosteen (Garcinia mangostana L.) seed is thought to be unique due to its recalcitrant characteristic (sensitive to coldness and drying). To investigate the metabolic changes during seed germination, we performed metabolomics analysis on germinating mangosteen seed sown after zero, one, three, five, seven and nine days. Sampled mangosteen seeds were subjected to methanol extraction prior analysis using Liquid Chromatography-Time of Flight-Mass Spectrometry (LC-TOF-MS). MS data were further analyzed using ProfileAnalysis (version 2.1). This is one of the earliest reports in metabolite identification and profiling of mangosteen seed at different germination stages. This data article refers to the article entitled "Metabolite profiling of mangosteen seed germination highlights metabolic changes related to carbon utilization and seed protection" (Mazlan et al., 2019) [1].

Early harvest increases post-harvest physiological quality of Araucaria angustifolia (Araucariaceae) seeds

ResumenAraucaria angustifolia es una conífera nativa de Brasil y una especie en peligro de extinción. Sus semillas tienen un corto período de viabilidad, factor que contribuye a su vulnerabilidad. Este estudio tuvo como objetivo evaluar la calidad fisiológica durante el período de desarrollo y post-almacenamiento de semillas de A. angustifolia. Conos de A. angustifolia fueron recolectados en poblaciones naturales en Curitibanos, Santa Catarina, Brasil, en marzo, abril, mayo y junio y clasificados en los estadios de desarrollo cotiledonar i, ii y iii de acuerdo con el mes de recolecta. Un total de 10 conos fueron recolectados para cada estadio. Las semillas fueron almacenadas en refrigerador durante 60 y 120 días y posteriormente sometidas a pruebas de germinación (25 °C - fotoperiodo de 12 h) siendo evaluados el contenido de humedad, tetrazolio y el vigor (conductividad eléctrica [75 mL de agua destilada a 25 °C], índice de velocidad de germinación, y la longitud de la parte aérea y de la raíz). Durante el desarrollo de las semillas, el contenido de humedad se redujo desde el estadio cotiledonar (66.54 %) al estadio iii (47.44%), y el vigor aumentaron en el último estadio. Durante el almacenamiento, el contenido de humedad en el estadio cotiledonar y estadio i fue estable. Entretanto, las semillas almacenadas mostraron una reducción en el contenido de humedad después de 120 días en los estadios ii y iii. La calidad fisiológica en el estadio cotiledonar mostró un aumento de 86 % y 93 % de germinación después de 60 y 120 días de almacenamiento, respectivamente, a diferencia de los estadios ii y iii, los cuales mostraron una disminución en la viabilidad de las semillas y en el vigor después del almacenamiento. La conductividad eléctrica fue mayor para las semillas en estadio cotiledonar recién recolectadas que para aquellas almacenadas durante 60 y 120 días. Sin embargo, en otras estadios, el contenido de lixiviados después de 120 días de almacenamiento aumentó con el avance del período de recolecta. El índice de velocidad de germinación y la longitud de la parte aérea y raíz después del almacenamiento eran más altos para las semillas en el estadio cotiledonar y el estadio i, a diferencia del estadio ii y iii, los cuales tenían raíz y parte aérea de menor longitud durante el almacenamiento. Por lo tanto, el mantenimiento del contenido de humedad de la semilla durante el almacenamiento fue variable y depende del período de recolecta. Además, la calidad fisiológica de las semillas difiere entre los estadios más tempranos o tardíos. Una recolección precoz favoreció la calidad fisiológica de las semillas, y puede ser una estrategia para aumentar la conservación de semillas de A. angustifolia.

AbstractAraucaria angustifolia is a conifer native to Brazil and is an endangered species. Since this species seeds have a short period of viability, its vulnerability is higher. Thus the aim of this study was to evaluate the physiological quality of A. angustifolia seeds during the development and post-storage periods. For this, cones of A. angustifolia were collected from a natural population in Curitibanos, Santa Catarina, Brazil, in March, April, May and June 2012. The collected seeds were classified into developmental stages of cotyledonary, i, ii and iii according to the month of collection; a total of 10 cones were collected for each stage. Seeds were stored in a refrigerator for 60 and 120 days, and were submitted to a chamber germination test (25 °C-photoperiod 12 h). Additionally, seeds were tested for moisture content (105 °C for 24 hours), tetrazolium (0.1 % for 1 hour) and vigor (electric conductivity [75 mL distilled water at 25 °C], germination speed index, and shoot and root length). Our results showed that during seed development, moisture content decreased from the cotyledonary stage (66.54 %) to stage iii (49.69 %), and vigor increased in the last stage. During storage, moisture content at cotyledonary stage and stage i was stable. On the other hand, stored seeds exhibited a decrease in moisture content after 120 days at stages ii and iii. Physiological quality at the cotyledonary stage resulted in an increased germination rate of 86 % and 93 % after 60 and 120 days of storage, respectively; unlike stages ii and iii exhibited a decrease in seed viability and vigor after storage. Electrical conductivity was higher for fresh seeds at the cotyledonary stage, than for those stored for 60 and 120 days. However, in other stages, released leachate content after 120 days of storage, increased with the advance of the collection period. Germination speed index and shoot and root lengths after storage were highest for seeds at the cotyledonary stage and stage i; unlike stages ii and iii which had short root and shoot lengths during storage. Thus, the maintenance of seed moisture content during storage was variable and dependent on the period of collection. Furthermore, the physiological quality differed among earlier and later stages. Early collection favored seed physiological quality, and may be a strategy for better conservation of A. angustifolia seeds. Rev. Biol. Trop. 64 (2): 885-896. Epub 2016 June 01.

Conservation and fruit biology of Sichou oak (Quercus sichourensis, Fagaceae) - A critically endangered species in China.

Several conservation programs have been started for the critically endangered Sichou oak (Quercus sichourensis) since 2007. These programs include detailed field investigations, seedling cultivation and research on the fruit biology of the species. In this study, we first report on the five mature individual trees found in our 9-year field investigation. Thus far, a total of 10 mature individuals have been recorded. All Q. sichourensis trees are healthy and most produce healthy acorns. Acorns of Q. sichourensis are large with dry masses of 8.0-14.0 g. These acorns had high moisture contents at collection and died shortly after (7-28 d) when dried with silica gel. Characteristics of Q. sichourensis acorns varied between populations. Compared with the acorns from Funing, the acorns collected from Ceheng were bigger, more viable (germination percentage was up to 96%), less sensitive to desiccation, and germinated faster. Q. sichourensis occurs in regions with a distinct 5-6 month dry season. Habitat degradation is largely responsible for the rareness of Quercus sichorensis, but desiccation sensitivity of the acorns may also limit the regeneration of the species and potentially lead to its continued rareness. As a species with extremely small populations (PSESP), Q. sichourensis is facing high risk of extinction and should be defined as a Critically Endangered species in the global IUCN Red List.

[Effect of different water conditions on Panax notoginseng seeds after-ripening and germination physiology].

Effect of different water conditions on the physiological indexes (e.g.seed water content, vigor, antioxidase activities)of Panax notoginseng seeds were studied under process of after-ripening and germination.The results showed show that compared with 2.5% treatment, under the treatment of 5%, P.notoginseng seeds possessed stable seed water content, the seed vigor was exceed by 51%,variation of antioxidant enzyme (SOD, POD, CAT) activity and malondialdehyde (MDA) content were small, crude fat and total sugar content decreased significantly.With the increase of PEG 6000 concentration, the germination characteristic indexes obviously decreased, antioxidase activities increased firstly and decreased afterwards, content of MDA, soluble protein and total sugar increased obviously.There were significant positive correlation between germination characteristic indexes and osmotic substance content(r>0.900, P<0.01), and significant negative correlation with MDA (r>0.900, P<0.01).In conclusion, because the characteristic of dehydration intolerance of P.notoginseng seeds, 5% water content of sand burying stratification treatment was the best for after-ripening, 15% concentration of PEG 6000 treatment was the highest tolerance limit of germination process.

Effect of different water conditions on Panax notoginseng seeds after-ripening and germination physiology / 中国中药杂志

Effect of different water conditions on the physiological indexes (e.g.seed water content, vigor, antioxidase activities)of Panax notoginseng seeds were studied under process of after-ripening and germination.The results showed show that compared with 2.5% treatment, under the treatment of 5%, P.notoginseng seeds possessed stable seed water content, the seed vigor was exceed by 51%,variation of antioxidant enzyme (SOD, POD, CAT) activity and malondialdehyde (MDA) content were small, crude fat and total sugar content decreased significantly.With the increase of PEG 6000 concentration, the germination characteristic indexes obviously decreased, antioxidase activities increased firstly and decreased afterwards, content of MDA, soluble protein and total sugar increased obviously.There were significant positive correlation between germination characteristic indexes and osmotic substance content(r>0.900, P<0.01), and significant negative correlation with MDA (r>0.900, P<0.01).In conclusion, because the characteristic of dehydration intolerance of P.notoginseng seeds, 5% water content of sand burying stratification treatment was the best for after-ripening, 15% concentration of PEG 6000 treatment was the highest tolerance limit of germination process.

Global 5-methylcytosine alterations in DNA during ageing of Quercus robur seeds.

BACKGROUND AND AIMS: Epigenetic regulation plays an important role in the management of plant growth, development and response to stress factors, and several reports have indicated that DNA methylation plays a critical role in seed development and viability. This study examines changes in 5-methylcytosine (m(5)C) levels in the DNA of seeds during ageing, a process that has important implications for plant conservation and agriculture. METHODS: Changes in the global level of m(5)C were measured in mature seeds of oak, Quercus robur. The extent of DNA methylation was measured using a protocol based on two-dimensional thin-layer chromatography. Viability of seeds was determined by germination and seedling emergence tests. KEY RESULTS: An ageing-related decrease in total m(5)C during storage of recalcitrant seeds was highly and significantly correlated with a decrease in seed viability, as reflected by a reduction in germination (r = 0·8880) and seedling emergence (r = 0·8269). CONCLUSIONS: The decrease in viability during ageing of Q. robur seeds is highly correlated with a global decline in the amount of m(5)C in genomic DNA, and it is possible that this may represent a typical response to ageing and senescence in recalcitrant seeds. Potential mechanisms that drive changes in genomic DNA methylation during ageing are discussed, together with their implications for seed viability.

Why is intracellular ice lethal? A microscopical study showing evidence of programmed cell death in cryo-exposed embryonic axes of recalcitrant seeds of Acer saccharinum.

BACKGROUND AND AIMS: Conservation of the genetic diversity afforded by recalcitrant seeds is achieved by cryopreservation, in which excised embryonic axes (or, where possible, embryos) are treated and stored at temperatures lower than -180 °C using liquid nitrogen. It has previously been shown that intracellular ice forms in rapidly cooled embryonic axes of Acer saccharinum (silver maple) but this is not necessarily lethal when ice crystals are small. This study seeks to understand the nature and extent of damage from intracellular ice, and the course of recovery and regrowth in surviving tissues. METHODS: Embryonic axes of A. saccharinum, not subjected to dehydration or cryoprotection treatments (water content was 1·9 g H2O g(-1) dry mass), were cooled to liquid nitrogen temperatures using two methods: plunging into nitrogen slush to achieve a cooling rate of 97 °C s(-1) or programmed cooling at 3·3 °C s(-1). Samples were thawed rapidly (177 °C s(-1)) and cell structure was examined microscopically immediately, and at intervals up to 72 h in vitro. Survival was assessed after 4 weeks in vitro. Axes were processed conventionally for optical microscopy and ultrastructural examination. KEY RESULTS: Immediately following thaw after cryogenic exposure, cells from axes did not show signs of damage at an ultrastructural level. Signs that cells had been damaged were apparent after several hours of in vitro culture and appeared as autophagic decomposition. In surviving tissues, dead cells were sloughed off and pockets of living cells were the origin of regrowth. In roots, regrowth occurred from the ground meristem and procambium, not the distal meristem, which became lethally damaged. Regrowth of shoots occurred from isolated pockets of surviving cells of peripheral and pith meristems. The size of these pockets may determine the possibility for, the extent of and the vigour of regrowth. CONCLUSIONS: Autophagic degradation and ultimately autolysis of cells following cryo-exposure and formation of small (0·2-0·4 µm) intracellular ice crystals challenges current ideas that ice causes immediate physical damage to cells. Instead, freezing stress may induce a signal for programmed cell death (PCD). Cells that form more ice crystals during cooling have faster PCD responses.

LEA polypeptide profiling of recalcitrant and orthodox legume seeds reveals ABI3-regulated LEA protein abundance linked to desiccation tolerance.

In contrast to orthodox seeds that acquire desiccation tolerance during maturation, recalcitrant seeds are unable to survive drying. These desiccation-sensitive seeds constitute an interesting model for comparative analysis with phylogenetically close species that are desiccation tolerant. Considering the importance of LEA (late embryogenesis abundant) proteins as protective molecules both in drought and in desiccation tolerance, the heat-stable proteome was characterized in cotyledons of the legume Castanospermum australe and it was compared with that of the orthodox model legume Medicago truncatula. RNA sequencing identified transcripts of 16 homologues out of 17 LEA genes for which polypeptides are detected in M. truncatula seeds. It is shown that for 12 LEA genes, polypeptides were either absent or strongly reduced in C. australe cotyledons compared with M. truncatula seeds. Instead, osmotically responsive, non-seed-specific dehydrins accumulated to high levels in the recalcitrant cotyledons compared with orthodox seeds. Next, M. truncatula mutants of the abscisic acid insensitive3 (ABI3) gene were characterized. Mature Mtabi3 seeds were found to be desiccation sensitive when dried below a critical water content of 0.4 g H2O g DW(-1). Characterization of the LEA proteome of the Mtabi3 seeds revealed a subset of LEA proteins with severely reduced abundance that were also found to be reduced or absent in C. australe cotyledons. Transcripts of these genes were indeed shown to be ABI3 responsive. The results highlight those LEA proteins that are critical to desiccation tolerance and suggest that comparable regulatory pathways responsible for their accumulation are missing in both desiccation-sensitive genotypes, revealing new insights into the mechanistic basis of the recalcitrant trait in seeds.

Effects of desiccation on Euterpe edulis Martius seeds

Information on desiccation sensitivity of Euterpe edulis seeds under two drying rates is presented. The sensitivity was studied during the course of germination and normal germination. The water content was evaluated for both seeds and embryos. Results showed the following: (a) For both drying treatments and for both germination and normal germination, desiccation sensitivity values were higher for measurements based on the water content of the embryo than for those of the seed. (b) For both drying treatments, desiccation sensitivity were higher for normal germination than for germination based on both the embryo and seed water contents. (c) Under the slow drying treatment and for measurements based on the seed water content, critical water content was visible for normal germination but not for germination; (d) Critical water contents for germination and normal germination were more clearly established in the fast drying treatment than they were in the slow drying method based on both the embryo and seed water contents. Critical water contents were not associated with changes in electrolyte leakage, which suggests that conductivity is not a good indicator of physiological seed quality. From the beginning of both drying treatments, changes in nuclei and vacuoles were observed, but, when seed water content was reduced to below critical values, the cells became severely plasmolyzed, the vacuoles highly distorted, and the nuclei formed an almost homogeneous mass with the chromatin and the nucleoplasm, which suggests irreversible DNA damages.

Effects of desiccation on Euterpe edulis Martius seeds

Information on desiccation sensitivity of Euterpe edulis seeds under two drying rates is presented. The sensitivity was studied during the course of germination and normal germination. The water content was evaluated for both seeds and embryos. Results showed the following: (a) For both drying treatments and for both germination and normal germination, desiccation sensitivity values were higher for measurements based on the water content of the embryo than for those of the seed. (b) For both drying treatments, desiccation sensitivity were higher for normal germination than for germination based on both the embryo and seed water contents. (c) Under the slow drying treatment and for measurements based on the seed water content, critical water content was visible for normal germination but not for germination; (d) Critical water contents for germination and normal germination were more clearly established in the fast drying treatment than they were in the slow drying method based on both the embryo and seed water contents. Critical water contents were not associated with changes in electrolyte leakage, which suggests that conductivity is not a good indicator of physiological seed quality. From the beginning of both drying treatments, changes in nuclei and vacuoles were observed, but, when seed water content was reduced to below critical values, the cells became severely plasmolyzed, the vacuoles highly distorted, and the nuclei formed an almost homogeneous mass with the chromatin and the nucleoplasm, which suggests irreversible DNA damages.(AU)

Germination of Aesculus hippocastanum seeds following cold-induced dormancy loss can be described in relation to a temperature-dependent reduction in base temperature (Tb ) and thermal time.

• The effect of moist stratification at cool temperatures on Aesculus hippocastanum (horse chestnut) seed dormancy release and subsequent thermal time requirement for germination has been investigated. • Germination performance following over 50 different treatments, each varying in time and temperature of stratification and germination to a total test time of over 3 yr, was used to develop a predictive model for dormancy release and germination. • Stratification at 2-16°C caused a reduction in base (minimum) temperature for germination (Tb ), being fastest at the colder temperatures. Using the sigmoid relationship between rate of reduction in Tb and stratification temperature, seed germination can be predicted in relation to thermal time accumulation above a gradually reducing Tb . Newly shed unstratified seeds, seeds with reduced viability, and seeds on the brink of germination because of Tb being close to stratification temperature, did not conform to the model. • T b is not constant during dormancy release in horse chestnut seeds. A reduction in Tb in response to cold stratification may be characteristic of summer annuals, suggesting future applications for this approach in seed ecology studies.

Biometria de frutos e sementes e germinação e curupixá (Micropholis cf. venulosa Mart. & Eichler - Sapotaceae) / Fruit and seed biometry and germination of Micropholis cf. venulosa Mart. & Eichler (Sapotaceae)

Micropholis cf. venulosa Mart. & Eichler, conhecida como curupixá, é uma espécie arbórea que vem sendo explorada pelas industrias madeireiras do Estado do Pará. O objetivo do trabalho foi estudar as características biométricas de frutos e sementes de curupixá e avaliar o efeito do dessecamento na germinação das sementes. Determinou-se o comprimento e o diâmetro dos frutos, o número de sementes por frutos, a porcentagem de sementes danificadas por insetos e o comprimento, a largura e a espessura das sementes. No controle (sementes frescas) e nas sementes submetidas ao dessecamento em sílica gel durante 72 e 96 horas, foram quantificadas as porcentagens de germinação, de plântulas anormais, de sementes mortas, tempo médio de germinação e o número de dias para iniciar a germinação. A semeadura foi realizada em substrato de areia e serragem curtida (1:1), em quatro repetições de 50 sementes. O fruto de curupixá é uma baga oblonga cujo comprimento e diâmetro dos frutos variaram de 32,5 a 72,9 mm e de 29,1 a 58,0 mm, respectivamente. O número de sementes por fruto variou de um a três, com 53,3 por cento delas danificadas por insetos. O comprimento, a largura e a espessura das sementes variaram de 15,5 a 41,4 mm, de 8,0 a 18,7 mm e de 4,7 a 12,6 mm, respectivamente. Nas sementes frescas observou-se que a germinação foi lenta e com acentuada desuniformidade, iniciando 24 dias após a semeadura e atingindo a germinação final de 55 por cento aos 96 dias após a semeadura. Registrou-se reduções significativas na germinação das sementes submetidas ao dessecamento e, aumento no número de dias para iniciar a germinação e na porcentagem de sementes mortas. A redução do grau de umidade de 42,6 por cento para 28,9 por cento reduziu a germinação de 55 por cento para 24,7 por cento e aumentou a porcentagem de sementes mortas de 40,5 por cento para 70 por cento, indicando que sementes dessa espécie apresentam sensibilidade ao dessecamento.

Micropholis cf. venulosa Mart. & Eichler, knwon as curupixá, is a tree largely used in forest exploitation in the State of Pará. The objective was to study the biometrics features of fruit and seeds and the effect of desiccation on seed germination. It was measured the length and diameter of fruits, number of seeds per fruits, percentage of seeds damaged by insects, length, width and thickness of seeds. For control (fresh seeds) and desiccated seeds, the percentage of germination, of abnormal seedlings, of dead seeds, mean time germination and number of days to first germination were also measured. Seeds were desiccated by storage on silica gel for 72 and 96 hours. Sowing was carried out on a substrate containing sand and sawdust (1:1), in four replicates of 50 seeds. Length and diameter of the fruits ranged from 32.5 to 72.9 mm and 29.1 to 58.0 mm, respectively. Fruits had one to three seeds, and 53.3 percent of them were damaged by insects. The M. cf. venulosa fruit is a bacca with length, width and thickness of seeds ranged from 15.5 to 41.1 mm, 8.0 to 18.7 mm and 4.7 to 12.6 mm, respectively. For control seeds germination was slow and non-uniform, and started 24 days after sowing. Total germination (55 percent) was recorded 96 days after sowing. It was observed a significant reduction on germination of desiccated seed and an increase on the number days to first germination and on the percentage the dead seeds. Moisture reduction in seeds from 42.6 percent to 28.9 percent reduced germination to 24.7 percent and increased the percentage of dead seeds to70 percent, indicating that seeds of this species are sensitive to desiccation.