Imbibition, Germination and Vigor of Gymnanthes Klotzschiana Müll.Arg. Seeds Under Hypoxia

Émerson Couto da Rocha Luciana Magda de Oliveira Vinícius Spolaor Fantinel Romell Alves Ribeiro Dias About the authors

Abstract

The objective of this study was to assess hypoxia tolerance in Gymnanthes klotzschiana seeds harvested in two areas (Area 1 - subject to flooding; and Area 2 - not subject to flooding) by the imbibition curve, vigor and germination. Seeds of the two areas were submitted to: one (T-1d), three (T-3d), five (T-5d), ten (T-10d) and twenty days under hypoxia (T-20d); in addition to the control (T-0d). All treatments presented three germination stages. The highest germination was achieved in Area 1 T-1d (90%) and the lowest in Area 2 T-20d (31%). The Area 1 seeds required less time and water content to finish their germination, and they presented greater tolerance to hypoxia; a fact proven by the germination and vigor results. G. klotzschiana seeds harvested in an area subject to flooding are more tolerant to hypoxia and are recommended for restoration projects in this type of area.

Keywords:
environmental stress; submersion; flooding; branquilho

1. INTRODUCTION AND OBJECTIVES

Gymnanthes klotzschiana popularly known as branquilho, is a tree species that belongs to the Euphorbiaceae family, and it can be found in the Caatinga, Cerrado, and Atlantic Forest biomes (JBRJ, [2018?]Jardim Botânico do Rio de Janeiro - JBRJ. Gymnanthes klotzschiana Müll.Arg. Flora do Brasil 2020 [Internet]. [2018?] [cited 2018 Aug. 29]. Available from: Available from: https://bit.ly/2OWgXuW
https://bit.ly/2OWgXuW...
). Branquilho can occur naturally in wet and alluvial soils (Silva et al., 2012Silva AC, Higuchi H, van den Berg E, Nunes MH, Carvalho DA. Florestas inundáveis: ecologia, florística e adaptações das espécies. Lavras: Editora UFLA; 2012.), and this species has the potential to recompose degraded areas (Ferreira et al., 2013Ferreira PI, Gomes JP, Batista F, Bernardi AP, Costa NCF, Bortoluzzi RLC et al. Espécies potenciais para recuperação de áreas de preservação permanente no planalto catarinense. Floresta e Ambiente 2013; 20(2):173-182. 10.4322/floram.2013.003
https://doi.org/10.4322/floram.2013.003...
).

Many forest recomposition projects are unsuccessful (Brancalion et al., 2010Brancalion PHS, Rodrigues RR, Gandolfi S, Kageyama PY, Nave AG, Gandara FB et al. Instrumentos legais podem contribuir para a restauração de florestas tropicais biodiversas. Revista Árvore 2010; 34(3): 455-470. 10.1590/S0100-67622010000300010
https://doi.org/10.1590/S0100-6762201000...
; Rodrigues et al., 2009Rodrigues RR, Lima RAF, Gandolfi S, Nave AG. On the restoration of high diversity forests: 30 years of experience in the Brazilian Atlantic Forest. Biological Conservation 2009; 142(6): 1242-1251. 10.1016/j.biocon.2008.12.008
https://doi.org/10.1016/j.biocon.2008.12...
) due to the poor knowledge about seeds and seedlings behavior in the new colonization areas (Gattringer et al., 2017Gattringer JP, Donath TW, Eckstein RL, Ludewig K, Otte A, Harvolk-Schoning S. Flooding tolerance of four floodplain meadow species depends on age. Plos One 2017; 12(5): 1-15. 10.1371/journal.pone.0176869
https://doi.org/10.1371/journal.pone.017...
), among other factors. Considering this, the selection of matrices and seeds is fundamental in this process of reestablishing a new self-sustaining mature forest, especially in flooded areas.

Germination is the resumption of embryonic axis growth after the seed physiologically detaches from the mother plant and finds favorable conditions to develop (Bewley et al., 2013Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy. 3rd ed. New York: Springer; 2013.). Seeds usually have a three-phase imbibition pattern during the germination process (Carvalho & Nakagawa, 2012Carvalho NM, Nakagawa J. Sementes: ciência, tecnologia e produção. 5th ed. Jaboticabal: Funep; 2012.). The first phase is characterized by the reactivation of metabolism by water intake. The next phase is mainly differentiated by the low water intake in the seed. In the third phase more intense water reentry occurs, which culminates in forming a new seedling (Marcos-Filho, 2015Marcos-Filho J. Fisiologia de sementes de plantas cultivadas. 2nd ed. Londrina: Abrates; 2015.).

Tropical and subtropical environments subject to flooding vary greatly in terms of duration, frequency and amplitude of flooding (Ferreira et al., 2009Ferreira CS, Piedade MTF, Franco AC, Gonçalves JFC, Junk WJ. Adaptive strategies to tolerate prolonged flooding in seedlings of floodplain and upland populations of Himatanthus sucuuba, a Central Amazon tree. Aquatic Botany 2009; 90(3): 246-252. 10.1016/j.aquabot.2008.10.006
https://doi.org/10.1016/j.aquabot.2008.1...
). As such, they create places with different adaptive needs for species. According to Kozlowski (1997Kozlowski TT. Responses of woody plants to flooding and salinity. Tree Physiology Monograph 1997; 7(1): 1-29.), flooding can compromise germination by decreasing available oxygen in the substrate (hypoxia). However, this obstacles to germination depends on the species and also the flood time (Crawford & Brandle, 1996Crawford RMM, Brandle R. Oxygen deprivation stress in a changing environment. Journal of Experimental Botany 1996; 47(2): 145-159. 10.1093/jxb/47.2.145
https://doi.org/10.1093/jxb/47.2.145...
). Hypoxia decreases the energy produced by seeds during germination, as ATP synthesis is less efficient when the fermentative route is activated (Bailey-Serres et al., 2012Bailey-Serres J, Fukao T, Gibbs DJ, Holdsworth MJ, Lee SC, Licausi F et al. Making sense of low oxygen sensing. Trends in Plant Science 2012; 17(3): 129-138. 10.1016/j.tplants.2011.12.004
https://doi.org/10.1016/j.tplants.2011.1...
). This fact is explained for oxygen is the ultimate acceptor of electrons in the last phase of aerobic respiration. Thus, cells tend to use the fermentative route more often when oxygen is restricted or lacking for energy production (Kato-Noguchi, 2006Kato-Noguchi H. Pyruvate metabolism in rice coleoptiles under anaerobiosis. Plant Growth Regulation 2006; 50(1): 41-46. 10.1007/s10725-006-9124-4
https://doi.org/10.1007/s10725-006-9124-...
). Tolerance to lack of oxygen on germination was tested on Carapa guianensis Aubl. seeds, and germination was higher than 70% (Scarano et al., 2003Scarano FR, Pereira TS, Rôças G. Seed germination during floatation and seedling growth of Carapa guianensis, a tree from flood-prone forests of the Amazon. Plant Ecology 2003; 168(2): 291-296. 10.1023/A:1024486715690
https://doi.org/10.1023/A:1024486715690...
). In Himatanthus succubus (Spruce ex Müll.Arg.) Woodson seeds, a tree species typical of lowland areas, seedling formation reached 84% (Ferreira et al., 2006Ferreira CS, Piedade MTF, Bonates LC. Germinação de sementes e sobrevivência de plântulas de Himatanthus sucuuba (Spruce) Wood. em resposta ao alagamento, nas várzeas da Amazônia Central. Acta Amazonica 2006; 36(4): 413-418. 10.1590/S0044-59672006000400003
https://doi.org/10.1590/S0044-5967200600...
).

The objective of this study was to evaluate the hypoxia tolerance of G. klotzschiana seeds harvested in two areas (Area 1 - subject to flooding; and Area 2 - not subject to flooding) by the imbibition curve, vigor and germination.

2. MATERIALS AND METHODS

2.1. Matrix selection, harvesting, extraction and seed processing

Ripe fruits (dark brown in color) were harvested from selected mother trees without phytosanitary issues, with diameter at breast height ≥ 15 cm and at least 30 m apart, in two areas (lots).

Area 1, where 20 matrices were selected (Lat.: −27.841221° and Long.: −50.234878°), is classified as an Alluvial Mixed Ombrophilous Forest (IBGE, 2012Instituto Brasileiro de Geografia e Estatística - IBGE. Manual Técnico da Vegetação Brasileira: Sistema fitogeográfico Inventário das formações florestais e campestres Técnicas e manejo de coleções botânicas procedimentos para mapeamentos. Rio de Janeiro; 2012.), and it is located in the municipality of Lages, SC. Area 1 is characterized by being an environment subject to periodic flooding, being in a lowland, following a river course. Area 2, where eight matrices were selected (Lat.: −28.196411° and Long.: −50.752545°), is classified as Montana Semi-deciduous Seasonal Forest (IBGE, 2012Instituto Brasileiro de Geografia e Estatística - IBGE. Manual Técnico da Vegetação Brasileira: Sistema fitogeográfico Inventário das formações florestais e campestres Técnicas e manejo de coleções botânicas procedimentos para mapeamentos. Rio de Janeiro; 2012.), and it is located in Capão Alto, SC. This area is upstream from the Barra Grande hydroelectric dam, and it is not subject to periodic flooding because it is steep and higher. A larger number of matrices were selected in Area 1 as it presents high relative density of branquilho, aiming at greater sample representativeness. Approximately 350 g of seeds were collected per selected matrix in both areas.

After harvesting, the fruits were placed in plastic bags and sent to the Seed Laboratory of Santa Catarina State University to extract the seeds under shade of a canvas. The processing was performed using sieves and manually. The seeds were subsequently placed in glass containers, properly closed, and stored in a cold chamber (10 °C and RH = 65%) for a maximum of five days.

2.2. Hypoxia treatment

In order to simulate water stress by flooding, 100 seeds were divided into four repetitions and placed in plastic cups with 60 mL of distilled water, which was renewed every 72 hours (h). Six treatments were defined: one day (T-1d), three days (T-3d), five days (T-5d), ten days (T-10d) and twenty days of hypoxia (T-20d), in addition to the treatment without the effect of simulated flooding (T-0d). The treatment definition was based on the study developed by Barddal (2006Barddal ML. A influência da saturação hídrica na distribuição de oito espécies arbóreas da floresta ombrófila mista aluvial do rio Iguaçu, Paraná, Brasil [dissertation]. Curitiba: Universidade Federal do Paraná; 2006.).

2.3. Obtaining imbibition curves

The imbibition curves were established during the germination process to verify the water absorption behavior in the different proposed treatments. The curves were obtained by the Equation 1 for each treatment:

F i n a l w e i g h t = I n i t i a l w e i g h t × 100 i n i t i a l w a t e r l e v e l 100 - F i n a l w a t e r l e v e l (1)

Weighing was performed within the first 24 h every 6 h, and thereafter every 12 h. Each curve was completed when at least 40% of the seeds of each repetition presented a 3 mm primary root.

2.4. Physical and physiological analyses

The following method was determined according to the rules for seed analysis (Regras para Análise de Sementes - RAS) (Brasil, 2009Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Regras para análise de sementes. Brasília, DF; 2009.): the dry mass before hypoxia treatments, in four replications of 50 seeds; and the water content of the seeds before and after each treatment, in two repetitions of five grams each. An electronic scale accurate to 0.001 g was used for weighing the samples, and an oven at 60 °C for 24 h for drying to determine dry mass and an oven at 105 °C for 24 h was used to obtain initial and final seed water content. After the drying period, the containers were placed in a desiccator containing silica gel for 10 minutes until they reached room temperature.

After exposure to hypoxia, the seeds were placed to germinate in plastic boxes (11.0 × 11.0 × 3.5 cm) on a blotter substrate and they were moistened to 2.5 times their weight. Germination was performed in a growth chamber containing four 25 W lamps, alternating temperature (20/30 °C) and 12 h photoperiod (Santos & Aguiar, 2005Santos SRG, Aguiar IB. Efeito da temperatura na germinação de sementes de Sebastiania commersoniana (Baillon) Smith & Downs separadas pela coloração do tegumento. Scientia Forestalis 2005; 69: 77-83.). Only seeds that generated normal seedlings were considered for the sum of the final germination percentage (Brasil, 2009Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Regras para análise de sementes. Brasília, DF; 2009.).

Seeds that did not generate normal seedlings were classified as abnormal seedlings (rootless and/or without cotyledons and necrotized hypocotyl) and empty seeds as dead and non-germinated seeds. Seeds were sectioned longitudinally and immersed in a solution of 2,3,5 triphenyl chloride 0.1% tetrazolium for 2 h at 30 °C to verify the viability of ungerminated seeds, according to the methodology suggested by Cosmo et al. (2010Cosmo NL, Nogueira AC, Lima JG, Kuniyoshi YS. Morfologia de fruto, semente e plântula de Sebastiania commersoniana, Euphorbiaceae. Revista Floresta 2010; 40(2): 419-428. 10.5380/rf.v40i2.17837
https://doi.org/10.5380/rf.v40i2.17837...
). The seeds that fully colored the hypocotyl radicle axis and the cotyledons were considered viable. Unstained seeds were classified as unviable.

Germination was monitored daily and the following tests were used to determine seed vigor: first germination count - FGC (five days after the end of each treatment period); and germination speed index (GSI), which assessed as germinated the seeds that expanded the first pair of cotyledonary leaves. The GSI calculation was performed according to the equation proposed by Maguire (1962Maguire JD. Speed of germination: aid in selection and evaluation for seedling emergence and vigor. Crop Science 1962; 2(2): 176-177.). All physiological analyzes were completed at 21 days after the submersion period.

2.5. Statistical analysis

Germination and vigor data were initially submitted to normality analysis by the Shapiro-Wilk Test, and then the factor analysis was performed (six treatments × two areas). The values generated were assessed by the F-Test and the means by the Scott-Knott Test (1974), both at a sig α = 0.05 nificance level of Regression analysis was used to adjust the imbibition curves (α = 0.05) The Sisvar statistical program was used for statistical analyzes.

3. RESULTS AND DISCUSSION

The seeds collected in Area 1 (subject to periodic flooding) presented initial water content of 8.9% and germination of 85%. Seeds from Area 2 (not subject to periodic flooding) had 9.2% initial water content and 84% germination. Water content and control germination did not differ statistically between areas. The dry mass at both collection sites was 0.085 g/50 seeds.

The seeds of all treatments followed the three-phase imbibition pattern for both collection areas (Figure 1). Considering only Area 1, the seeds reached 30% of water content in approximately 30 h at the end of the germination Phase I. The seeds presented low water uptake during Phase II. This phase was proportionally longer in treatments exposed to oxygen restriction for a longer period. The seeds of all treatments started Phase III germination with water content near to 35%. Seeds that were not exposed to hypoxia (T-0d) began Phase III at approximately 70 h (radicle emission) after germination began. In seeds that remained for one day (T-1d), three days (T-3d), five days (T-5d), ten days (T-10d) and twenty days (T-20d) under hypoxia, Phase III started at approximately 84, 132, 160, 252 and 580 h, respectively, after the beginning of the germination process.

Figure 1
Imbibition curves during germination of G. klotzschiana seeds collected in Area 1 (area subject to periodic flooding) and in Area 2 (area not subject to periodic flooding), when submitted to different hypoxia periods.

The seeds collected in Area 2 completed germination Phase I with around 40% of water content, which was reached in approximately 24 h in all treatments. The seeds had a low water uptake during Phase II (similar behavior to Area 1 seeds). The seeds of all treatments presented water content close to 45% at the beginning of Phase III. Seeds that were not exposed to controlled flooding (T-0d) reached Phase III in approximately 100 h. Phase III began at 124, 172, 220, 300 and 540 h, for the T-1d, T-3d, T-5d, T-10d and T20d treatments, respectively (Figure 1).

The imbibition curve showed that seeds collected in Area 1 germinated faster and at the same time needed a lower water content to start and finish their germination process, regardless of the treatments assessed, compared to seeds harvested in Area 2. This is probably an adaptation developed by the species to flooding, because the faster the germination and formation of a seedling, the greater their chances to tolerate a flooded environment, as well as oxygen restriction. Seeds in this stress condition tend to increase the activity of some anaerobic respiration-related enzymes, such as alcohol dehydrogenase and pyruvate decarboxylase (Magneschi & Perata, 2009Magneschi L, Perata P. Rice germination and seedling growth in the absence of oxygen. Annals of Botany 2009; 103(2): 181-196. 10.1093/aob/mcn121
https://doi.org/10.1093/aob/mcn121...
). Metabolic and molecular reprogramming becomes critical to generate energy necessary for rapid germination and stretching of plants under hypoxic conditions (Narsai & Whelan, 2013Narsai R, Whelan J. How unique is the low oxygen response? An analysis of the anaerobic response during germination end comparison with abiotic stress in rice and Arabidopsis. Frontiers in Plant Science 2013; 349(4): 1-14. 10.3389/fpls.2013.00349
https://doi.org/10.3389/fpls.2013.00349...
).

In relation to the germination stages, Phase I is a physical process, independent of seed viability (Wang et al., 2015Wang WL, Liu SJ, Song SQ, Moller IM. Proteomics of seed development, desiccation tolerance, germination and vigor. Plant Physiology and Biochemistry 2015; 86(1): 1-15. 10.1016/j.plaphy.2014.11.003
https://doi.org/10.1016/j.plaphy.2014.11...
). The water intake in the seeds at this stage was fast in all treatments and in the two lots assessed - possibly because the large difference in water potential between the seed and the substrate. This accelerated water intake did not affect the seed germination of either collection area, since they presented similar germination to the treatment without the influence of simulated flooding (T-0d) as shown in Table 1.

Table 1
Germination, first germination count and germination speed index in G. klotzschiana seeds submitted to different hypoxia periods, originating from two areas after 21 days of germination testing.

This may show a positive ability of G. klotzschiana seeds to efficiently rearrange their membrane structures. According to Bewley et al. (2013Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy. 3rd ed. New York: Springer; 2013.), seeds that support low water contents at the end of the maturation process (orthodox), such as branquilho, present reducing sugars and oligosaccharides that interact with proteins and hydrophilic functional groups in the membranes, maintaining compartmentalization and cellular functionality. Maintaining cell integrity is associated with the ability of seeds to reorganize more efficiently and thus preserve their physiological quality (Villa-Hernández et al., 2013Villa-Hernández JM, Dinkova TD, Aguilar-Caballero R, Rivera-Cabrera F, Sánchez de Jiménez E, Pérez-Flores LJ. Regulation of ribosome biogenesis in maize embryonic axes during germination. Biochimie 2013; 95(10): 1871-1879. 10.1016/j.biochi.2013.06.011
https://doi.org/10.1016/j.biochi.2013.06...
; Weitbrecht et al., 2011Weitbrecht K, Müller K, Leubner-Metzger G. First off the mark: early seed germination. Journal of Experimental Botany 2011; 62(10): 3289-3309. 10.1093/jxb/err030
https://doi.org/10.1093/jxb/err030...
).

The higher water content presented by seeds collected in Area 2 at the end of Phase I and until the end of germination could be explained by the lower restriction to water entry by the seed coat, probably due to the lower vigor of these seeds (Table 1) (Bewley et al., 2013Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy. 3rd ed. New York: Springer; 2013.; Li et al., 2014Li J, Wang Y, Pritchard HW, Wang X. The fluxes of H2O2 and O2 can be used to evaluate seed germination and vigor of Caragana korshinskii. Planta 2014; 239(6): 1363-1373.).

Stability in the water absorption during Phase II is common in species that have well-defined three-phase germination (Bewley et al., 2013Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy. 3rd ed. New York: Springer; 2013.). It was observed that seeds remaining for a longer period under oxygen restriction extended this phase proportionally. Seeds from treatment T-20d had the highest mortality rates (flaccid and yellowish internal tissues) and the lowest germination (Table 1). In this case, the death of some seeds could have started by lipid peroxidation caused by free radicals (Palermo et al., 2015Palermo FF, Risso WE, Simonato JD, Martinez CBR. Bioaccumulation of nickel andits biochemical and genotoxic effects on juveniles of the neotropical fish Prochilodus lineatus. Ecotoxicology and Environmental Safety 2015; 116: 19-28. 10.1016/j.ecoenv.2015.02.032
https://doi.org/10.1016/j.ecoenv.2015.02...
; Sevcikova et al., 2011Sevcikova M, Modra H, Slaninova A, Svobodova Z. Metals as a cause of oxidative stress in fish: a review. Veterinarni Medicina 2011; 56(11): 537-546.), which possibly caused the loss of cell turgor by induced death. Biological membranes are semipermeable barriers and the maintenance of their functions depends on their integrity (Kraffe et al., 2007Kraffe E, Marty Y, Guderley H. Changes in mitochondrial oxidative capacities during thermal acclimation of rainbow trout Oncorhynchus mykiss: Roles of membrane proteins, phospholipids and their fatty acid compositions. Journal of Experimental Botany 2007; 210: 149-165.).

The onset of root protrusion (Phase III) is basically a physical process (Bewley et al., 2013Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy. 3rd ed. New York: Springer; 2013.) and water ingress is essential for cell expansion. Later, the higher water absorption is justified by the need to transport previously hydrolyzed compounds to the embryonic axis, which are necessary for forming a new seedling.

Seeds from both areas had different behaviors in the control treatment regarding Phase III, whereas those from Area 1 started this phase 30 h before seeds from the other area. This is an indication of the higher quality and probably greater tolerance to hypoxia of the seeds in this lot (Area 1). Considering all treatments, seeds collected in Area 1 generally reached Phase III before those collected in Area 2, showing greater vigor of Area 1 seeds. Vigor involves energy biosynthesis and associated metabolic compounds to cellular activity and membrane integrity (AOSA, 1983Association of Official Seed Analysts - AOSA. Seed vigour testing handbook. East Lansing; 1983.), which are critical in tolerating environmental stresses during germination (Xiaolin et al., 2017Xiaolin W, Fen N, Xiuli H, Wei W. Genetic modification for improving seed vigor is transitioning from model plants to crop plants. Frontiers in Plant Science 2017; 8(8): 1-7. 10.3389/fpls.2017.00008
https://doi.org/10.3389/fpls.2017.00008...
).

Germination showed significant differences between treatments in the same area and between areas. For Area 1, only treatment T-20d was inferior to the others (45%), and T-1d seeds had the highest index (90%). For Area 2, seed germination of treatments T-0d and T-1d were higher, with 84% and 81%, respectively; T-3d, T-5d and T-10d were statistically equal and higher than T-20d, for which 31% germination was verified. Considering the same treatment between areas, only the control (T-0d) and T-1d did not differ statistically (Table 1).

Seeds from the two collection areas submitted to the treatments also presented different results regarding vigor. For Area 1, the FGC was significantly higher for T-0d (80%), T-1d (86%), T-3d (80%) and T-5d (75%) treatments from stress due to hypoxia; these differed from T-10d (66%) and T-20d (5%). For Area 2 seeds, only seeds that remained for 20 days under oxygen restriction (T-0d) presented different results from the others. When FGC from the same treatments in relation to the two areas was compared, seeds from Area 1 were superior to those from Area 2 in most treatments, except for T-20d (Table 1).

The GSI of seeds from Area 1 was higher than in T-1d (2.78), and they were statistically different from the others only in T-20d. This test showed higher values for T-0d (1.61) and T-1d (1.62) seeds in Area 2, and the lowest index was found for T-20d (0.58), which was inferior to the others. When the GSI was compared between the same treatments in relation to the areas, only T-20d seeds showed values which did not differ statistically (Table 1).

Germination was similar in both areas when there was no stress effect, but slower for Area 2 seeds. Higher germination values and mainly seed vigor for most treatments applied to Area 1 seeds indicated that germination velocity, especially revealed by the FGC, is the most important factor to be considered in branquilho’s adaptability to flooding (Table 1). Seeds with greater vigor are more tolerant to environmental stresses, because these seeds need to germinate rapidly after dispersal under a probable oxygen restriction condition. Greater tolerance to flooding in germination is genetically regulated (Colmer et al., 2013Colmer TD, Armstrong W, Greenway H, Ismail AM, Kirk GJD, Atwell BJ. Physiological mechanisms of flooding tolerance in rice: transient complete submergence and prolonged standing water. Progress in Botany 2013; 75: 255-307. 10.1007/978-3-642-38797-5_9
https://doi.org/10.1007/978-3-642-38797-...
), and it includes the ability to initiate and maintain the carbohydrate catabolism required for anaerobic respiration and thus sustain energy supply and maintenance (Colmer et al., 2013Colmer TD, Armstrong W, Greenway H, Ismail AM, Kirk GJD, Atwell BJ. Physiological mechanisms of flooding tolerance in rice: transient complete submergence and prolonged standing water. Progress in Botany 2013; 75: 255-307. 10.1007/978-3-642-38797-5_9
https://doi.org/10.1007/978-3-642-38797-...
; Kirk et al., 2013Kirk GJD, Greenway H, Atwell BJ, Ismail AM, Colmer TD. Adaptation of rice to flooded soils. Progress in Botany 2013; 75: 215-253.). The importance of carbohydrate utilization during germination under hypoxia condition was addressed by Ferreira et al. (2009Ferreira CS, Piedade MTF, Franco AC, Gonçalves JFC, Junk WJ. Adaptive strategies to tolerate prolonged flooding in seedlings of floodplain and upland populations of Himatanthus sucuuba, a Central Amazon tree. Aquatic Botany 2009; 90(3): 246-252. 10.1016/j.aquabot.2008.10.006
https://doi.org/10.1016/j.aquabot.2008.1...
) in Himatanthus succubus seeds, a typical tree species of periodically flooded areas.

When analyzing the T-1d treatment in relation to the T-0d, it was observed that the application period of seed stress occurred during Phase I and consequently the effect of this adverse factor was low or null. The controlled flooding stress effect reached a longer period in Phase II germination for the T-3d, T-5d and T-10d treatments. Although Phase II is characterized as a physiological rest period, it is important in the physiological response of seeds, since in this period begins the hydrolysis of the reserves and the fight against free radicals (Wang et al., 2015Wang WL, Liu SJ, Song SQ, Moller IM. Proteomics of seed development, desiccation tolerance, germination and vigor. Plant Physiology and Biochemistry 2015; 86(1): 1-15. 10.1016/j.plaphy.2014.11.003
https://doi.org/10.1016/j.plaphy.2014.11...
). The low hypoxia effect on seeds from Area 1 for these treatments (T-3d, T-5d and T-10d) was possibly due to the greater efficiency in controlling reactive oxygen species (ROS) present in the cells during the treatment period with lower oxygen availability in the environment. However, cellular damage due to the lower efficiency in controlling ROS may have occurred in the seeds of these same treatments from Area 2, and mainly in the T-20d treatment of both areas, where the lowest germination and vigor indices occurred.

Thus, maintaining cellular integrity throughout the stress period in which Area 1 seeds were exposed is possibly related to the time when this adverse effect was present during germination and the ability of the seeds to counteract this adverse condition. As Phase II is a preparatory step for germination (Bewley et al., 2013Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy. 3rd ed. New York: Springer; 2013.), the lack of oxygen only delayed this process. Maintaining seed quality during this period is probably linked to the synthesis of antioxidant compounds (López et al., 2011López MA, Vicente J, Kulasekaran S, Vellosillo T, Martínez M, Irigoyen ML et al. Antagonistic role of 9-lipoxygenase-derived oxylipins and ethylene in the control of oxidative stress, lipid peroxidation and plant defence. The Plant Journal 2011; 67(3): 447-458. 10.1111/j.1365-313X.2011.04608.x
https://doi.org/10.1111/j.1365-313X.2011...
; Sharma et al., 2012Sharma P, Jha AB, Dubey RS, Pessarakli M. Reactive oxygen species, oxidative damage, and antioxidative defense mechanism in plants under stressful conditions. Journal of Botany 2012; 1-26. 10.1155/2012/217037
https://doi.org/10.1155/2012/217037...
), such as superoxide dismutase and catalase enzymes (Iannone et al, 2012Iannone MF, Rosales EP, Groppa MD, Benavides MP. Reactive oxygen species formation and cell death in catalase-deficient tobacco leaf discs exposed to paraquat. Biological Trace Element Research 2012; 146(2): 246-255. 10.1007/s12011-011-9244-1
https://doi.org/10.1007/s12011-011-9244-...
; Luo et al., 2013Luo X, Wu J, Li Y, Nan Z, Guo X, Wang Y et al. Synergistic effects of GhSOD1 and GhCAT1 overexpression in cotton chloroplasts on enhancing tolerance to methyl viologen and salt stresses. Plos One 2013; 8(1): 1-11. 10.1371/journal.pone.0054002
https://doi.org/10.1371/journal.pone.005...
).

Abnormal seedling formation was low, ranging from 0 to 9%, with the maximum being recorded for T-10d (Area 1) and T-3d (Area 2). The number of dead seeds (DS) was highlighted for the treatments in which the seeds remained up to twenty days under hypoxia (T-20d). The number of non-germinated seeds (NGS) in this treatment represented 24% and 22% (DS) for Area 1. In Area 2, T-20d presented 22% NGS and 37% DS. The amount of empty seeds was similar in all treatments in both areas. Seed viability was between 0 and 4% of total germination. Thus, the number of dormant seeds had little influence on the distinction between treatments and lots (Table 2).

Table 2
Percentage of abnormal seedlings, dead seeds, empty seeds, non-germinated seeds, and viable G. klotzschiana seeds harvested in two areas under different flooding regimes and submitted to six periods of hypoxia.

The number of non-germinated and dead seeds increased overall in both evaluated areas as stress was more pronounced, especially for T-20d. Seeds in this oxygen-restricted condition may limit cell division and elongation due to energy scarcity (Takahashi et al., 2011Takahashi H, Saika H, Matsumura H, Nagamura Y, Tsutsumi N, Nishizawa NK et al. Cell division and cell elongation in the coleoptile of rice alcohol dehydrogenase 1-deficient mutant are reduced under complete submergence. Annals of Botany 2011; 108(2): 253-261. 10.1093/aob/mcr137
https://doi.org/10.1093/aob/mcr137...
), as well as damage by the presence of reactive oxygen species (Andrade et al., 2010Andrade ER, Melo-Sterza FA, Senada MM, Alfieri, AA. Consequências da produção das espécies reativas de oxigênio na reprodução e principais mecanismos antioxidantes. Revista Brasileira de Reprodução Animal 2010; 34(2): 79-85.).

Seeds eventually enter into dormancy when some environmental stress occurs (Finch-Savage & Leubner-Metzger, 2006Finch-Savage WE, Leubner-Metzger G. Seed dormancy and the control of germination. New Phytologist 2006; 171(3): 501-523.), at least until environmental conditions become favorable (Huang et al., 2010Huang X, Schmitt J, Dorn L, Griffith C, Effgen S, Takao S et al. The earliest stages of adaptation in an experimental plant population: strong selection on QTLS for seed dormancy. Molecular Ecology 2010; 19(7): 1335-1351. 10.1111/j.1365-294X.2010.04557.x
https://doi.org/10.1111/j.1365-294X.2010...
). However, stress due to lack of oxygen for the seeds of this species, especially for a period longer than ten days, represented a loss in viability for most seeds. Hypoxia stress can influence seed germination (Ferreira et al., 2009Ferreira CS, Piedade MTF, Franco AC, Gonçalves JFC, Junk WJ. Adaptive strategies to tolerate prolonged flooding in seedlings of floodplain and upland populations of Himatanthus sucuuba, a Central Amazon tree. Aquatic Botany 2009; 90(3): 246-252. 10.1016/j.aquabot.2008.10.006
https://doi.org/10.1016/j.aquabot.2008.1...
; Gonçalves et al., 2012Gonçalves JFC, Melo EGF, Silva CEM, Ferreira MJ, Justino GC. Estratégias no uso da energia luminosa por plantas jovens de Genipa spruceana Steyerm submetidas ao alagamento. Acta Botanica Brasilica 2012; 26(2): 391-398. 10.1590/S0102-33062012000200014
https://doi.org/10.1590/S0102-3306201200...
), and depending on the flooding time seedlings may lose their viability (Medina et al., 2009Medina CL, Sanches MC, Tucci MLS, Sousa CAF, Cuzzuol GRF, Joly CA. Erythrina speciosa (Leguminosae-Papilionoideae) under soil water saturation: morphophysiological and growth responses. Annals of Botany 2009; 104(4): 671-680.) and/or its development may be compromised (Pisicchio et al., 2010Pisicchio CM, Bianchini E, Pimenta JA, Sert MA, Davanso-Fabro VA, Medri ME. Heliocarpus popayanensis (Malvaceae) tolera a hipóxia do substrato? Acta Scientiarum - Biological Sciences 2010; 32(2): 201-209.).

Species adapted to periodically flooded environments, such as G. klotzschiana, develop strategies that allow them to establish and survive at environments with low oxygen concentrations (Jackson & Ram, 2003Jackson MB, Ram PC. Physiological and molecular basis of susceptibility and tolerance of rice plants to complete submergence. Annals of Botany 2003; 91(2): 227-241.). Seeds need to take advantage of the short and unpredictable periods when the water level drops to germinate (Marques & Joly, 2000Marques MCM, Joly CA. Germinação e crescimento de Calophyllum brasiliense (Clusiaceae), uma espécie típica de florestas inundadas. Acta Botanica Brasilica 2000; 14(1): 113-120. 10.1590/S0102-33062000000100010
https://doi.org/10.1590/S0102-3306200000...
). Therefore, high seed vigor becomes essential in plant establishment, especially for branquilho that has autochoric dispersion, in which seeds can remain in a flooded site for some days. Note that seeds are first released by “bursting” of fruits (spring/summer) and may eventually colonize by hydrochory in other places less prone to flooding.

In projects to recompose flood-prone areas, such results suggest that selecting seeds from oxygen-restricted sites may be fundamental for branquilho plants to grow. Schmiede et al. (2009Schmiede R, Donath TW, Otte A. Seed bank development after the restoration of alluvial grassland via transfer of seed-containing plant material. Biological Conservation 2009; 142(2): 404-413. 10.1016/j.biocon.2008.11.001
https://doi.org/10.1016/j.biocon.2008.11...
) and Gattringer et al. (2017Gattringer JP, Donath TW, Eckstein RL, Ludewig K, Otte A, Harvolk-Schoning S. Flooding tolerance of four floodplain meadow species depends on age. Plos One 2017; 12(5): 1-15. 10.1371/journal.pone.0176869
https://doi.org/10.1371/journal.pone.017...
) highlight that the restoration of flooded areas should contain seeds and/or seedlings adapted to this condition. Moreover, flooding may intensify in the next years due to climate change (Frigerio et al., 2018Frigerio S, Schenato L, Bossi G, Mantovani M, Marcato G, Pasuto A. Hands-on experience of crowdsourcing for flood risks. An android mobile application tested in Frederikssund, Denmark. International Journal of Environmental Research and Public Health 2018; 15(9): 1-19. 10.3390/ijerph15091926
https://doi.org/10.3390/ijerph15091926...
), further increasing the importance of this strategy of matrix selection for rebuilding these environments.

4. CONCLUSION

Gymnanthes klotzschiana seeds harvested from areas subject to flooding are more tolerant to hypoxia, thus, they are recommended for reforestation projects in this area.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the Centro de Ciências Agroveterinárias of Universidade do Estado de Santa Catarina for making available the equipment and inputs used in this research. The authors also would like to acknowledge the research group of the Laboratório de Sementes Florestais for their supports in both exams and collection of seeds in the field work.

REFERENCES

  • Andrade ER, Melo-Sterza FA, Senada MM, Alfieri, AA. Consequências da produção das espécies reativas de oxigênio na reprodução e principais mecanismos antioxidantes. Revista Brasileira de Reprodução Animal 2010; 34(2): 79-85.
  • Association of Official Seed Analysts - AOSA. Seed vigour testing handbook East Lansing; 1983.
  • Bailey-Serres J, Fukao T, Gibbs DJ, Holdsworth MJ, Lee SC, Licausi F et al. Making sense of low oxygen sensing. Trends in Plant Science 2012; 17(3): 129-138. 10.1016/j.tplants.2011.12.004
    » https://doi.org/10.1016/j.tplants.2011.12.004
  • Barddal ML. A influência da saturação hídrica na distribuição de oito espécies arbóreas da floresta ombrófila mista aluvial do rio Iguaçu, Paraná, Brasil [dissertation]. Curitiba: Universidade Federal do Paraná; 2006.
  • Bewley JD, Bradford K, Hilhorst H, Nonogaki H. Physiology of development, germination and dormancy 3rd ed. New York: Springer; 2013.
  • Brancalion PHS, Rodrigues RR, Gandolfi S, Kageyama PY, Nave AG, Gandara FB et al. Instrumentos legais podem contribuir para a restauração de florestas tropicais biodiversas. Revista Árvore 2010; 34(3): 455-470. 10.1590/S0100-67622010000300010
    » https://doi.org/10.1590/S0100-67622010000300010
  • Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Regras para análise de sementes Brasília, DF; 2009.
  • Carvalho NM, Nakagawa J. Sementes: ciência, tecnologia e produção 5th ed. Jaboticabal: Funep; 2012.
  • Colmer TD, Armstrong W, Greenway H, Ismail AM, Kirk GJD, Atwell BJ. Physiological mechanisms of flooding tolerance in rice: transient complete submergence and prolonged standing water. Progress in Botany 2013; 75: 255-307. 10.1007/978-3-642-38797-5_9
    » https://doi.org/10.1007/978-3-642-38797-5_9
  • Cosmo NL, Nogueira AC, Lima JG, Kuniyoshi YS. Morfologia de fruto, semente e plântula de Sebastiania commersoniana, Euphorbiaceae. Revista Floresta 2010; 40(2): 419-428. 10.5380/rf.v40i2.17837
    » https://doi.org/10.5380/rf.v40i2.17837
  • Crawford RMM, Brandle R. Oxygen deprivation stress in a changing environment. Journal of Experimental Botany 1996; 47(2): 145-159. 10.1093/jxb/47.2.145
    » https://doi.org/10.1093/jxb/47.2.145
  • Ferreira CS, Piedade MTF, Bonates LC. Germinação de sementes e sobrevivência de plântulas de Himatanthus sucuuba (Spruce) Wood. em resposta ao alagamento, nas várzeas da Amazônia Central. Acta Amazonica 2006; 36(4): 413-418. 10.1590/S0044-59672006000400003
    » https://doi.org/10.1590/S0044-59672006000400003
  • Ferreira CS, Piedade MTF, Franco AC, Gonçalves JFC, Junk WJ. Adaptive strategies to tolerate prolonged flooding in seedlings of floodplain and upland populations of Himatanthus sucuuba, a Central Amazon tree. Aquatic Botany 2009; 90(3): 246-252. 10.1016/j.aquabot.2008.10.006
    » https://doi.org/10.1016/j.aquabot.2008.10.006
  • Ferreira PI, Gomes JP, Batista F, Bernardi AP, Costa NCF, Bortoluzzi RLC et al. Espécies potenciais para recuperação de áreas de preservação permanente no planalto catarinense. Floresta e Ambiente 2013; 20(2):173-182. 10.4322/floram.2013.003
    » https://doi.org/10.4322/floram.2013.003
  • Finch-Savage WE, Leubner-Metzger G. Seed dormancy and the control of germination New Phytologist 2006; 171(3): 501-523.
  • Frigerio S, Schenato L, Bossi G, Mantovani M, Marcato G, Pasuto A. Hands-on experience of crowdsourcing for flood risks. An android mobile application tested in Frederikssund, Denmark. International Journal of Environmental Research and Public Health 2018; 15(9): 1-19. 10.3390/ijerph15091926
    » https://doi.org/10.3390/ijerph15091926
  • Gattringer JP, Donath TW, Eckstein RL, Ludewig K, Otte A, Harvolk-Schoning S. Flooding tolerance of four floodplain meadow species depends on age. Plos One 2017; 12(5): 1-15. 10.1371/journal.pone.0176869
    » https://doi.org/10.1371/journal.pone.0176869
  • Gonçalves JFC, Melo EGF, Silva CEM, Ferreira MJ, Justino GC. Estratégias no uso da energia luminosa por plantas jovens de Genipa spruceana Steyerm submetidas ao alagamento. Acta Botanica Brasilica 2012; 26(2): 391-398. 10.1590/S0102-33062012000200014
    » https://doi.org/10.1590/S0102-33062012000200014
  • Huang X, Schmitt J, Dorn L, Griffith C, Effgen S, Takao S et al. The earliest stages of adaptation in an experimental plant population: strong selection on QTLS for seed dormancy. Molecular Ecology 2010; 19(7): 1335-1351. 10.1111/j.1365-294X.2010.04557.x
    » https://doi.org/10.1111/j.1365-294X.2010.04557.x
  • Iannone MF, Rosales EP, Groppa MD, Benavides MP. Reactive oxygen species formation and cell death in catalase-deficient tobacco leaf discs exposed to paraquat. Biological Trace Element Research 2012; 146(2): 246-255. 10.1007/s12011-011-9244-1
    » https://doi.org/10.1007/s12011-011-9244-1
  • Instituto Brasileiro de Geografia e Estatística - IBGE. Manual Técnico da Vegetação Brasileira: Sistema fitogeográfico Inventário das formações florestais e campestres Técnicas e manejo de coleções botânicas procedimentos para mapeamentos Rio de Janeiro; 2012.
  • Jackson MB, Ram PC. Physiological and molecular basis of susceptibility and tolerance of rice plants to complete submergence. Annals of Botany 2003; 91(2): 227-241.
  • Jardim Botânico do Rio de Janeiro - JBRJ. Gymnanthes klotzschiana Müll.Arg. Flora do Brasil 2020 [Internet]. [2018?] [cited 2018 Aug. 29]. Available from: Available from: https://bit.ly/2OWgXuW
    » https://bit.ly/2OWgXuW
  • Kato-Noguchi H. Pyruvate metabolism in rice coleoptiles under anaerobiosis. Plant Growth Regulation 2006; 50(1): 41-46. 10.1007/s10725-006-9124-4
    » https://doi.org/10.1007/s10725-006-9124-4
  • Kirk GJD, Greenway H, Atwell BJ, Ismail AM, Colmer TD. Adaptation of rice to flooded soils. Progress in Botany 2013; 75: 215-253.
  • Kozlowski TT. Responses of woody plants to flooding and salinity. Tree Physiology Monograph 1997; 7(1): 1-29.
  • Kraffe E, Marty Y, Guderley H. Changes in mitochondrial oxidative capacities during thermal acclimation of rainbow trout Oncorhynchus mykiss: Roles of membrane proteins, phospholipids and their fatty acid compositions. Journal of Experimental Botany 2007; 210: 149-165.
  • Li J, Wang Y, Pritchard HW, Wang X. The fluxes of H2O2 and O2 can be used to evaluate seed germination and vigor of Caragana korshinskii Planta 2014; 239(6): 1363-1373.
  • López MA, Vicente J, Kulasekaran S, Vellosillo T, Martínez M, Irigoyen ML et al. Antagonistic role of 9-lipoxygenase-derived oxylipins and ethylene in the control of oxidative stress, lipid peroxidation and plant defence. The Plant Journal 2011; 67(3): 447-458. 10.1111/j.1365-313X.2011.04608.x
    » https://doi.org/10.1111/j.1365-313X.2011.04608.x
  • Luo X, Wu J, Li Y, Nan Z, Guo X, Wang Y et al. Synergistic effects of GhSOD1 and GhCAT1 overexpression in cotton chloroplasts on enhancing tolerance to methyl viologen and salt stresses. Plos One 2013; 8(1): 1-11. 10.1371/journal.pone.0054002
    » https://doi.org/10.1371/journal.pone.0054002
  • Magneschi L, Perata P. Rice germination and seedling growth in the absence of oxygen. Annals of Botany 2009; 103(2): 181-196. 10.1093/aob/mcn121
    » https://doi.org/10.1093/aob/mcn121
  • Maguire JD. Speed of germination: aid in selection and evaluation for seedling emergence and vigor. Crop Science 1962; 2(2): 176-177.
  • Marcos-Filho J. Fisiologia de sementes de plantas cultivadas 2nd ed. Londrina: Abrates; 2015.
  • Marques MCM, Joly CA. Germinação e crescimento de Calophyllum brasiliense (Clusiaceae), uma espécie típica de florestas inundadas. Acta Botanica Brasilica 2000; 14(1): 113-120. 10.1590/S0102-33062000000100010
    » https://doi.org/10.1590/S0102-33062000000100010
  • Medina CL, Sanches MC, Tucci MLS, Sousa CAF, Cuzzuol GRF, Joly CA. Erythrina speciosa (Leguminosae-Papilionoideae) under soil water saturation: morphophysiological and growth responses. Annals of Botany 2009; 104(4): 671-680.
  • Narsai R, Whelan J. How unique is the low oxygen response? An analysis of the anaerobic response during germination end comparison with abiotic stress in rice and Arabidopsis. Frontiers in Plant Science 2013; 349(4): 1-14. 10.3389/fpls.2013.00349
    » https://doi.org/10.3389/fpls.2013.00349
  • Palermo FF, Risso WE, Simonato JD, Martinez CBR. Bioaccumulation of nickel andits biochemical and genotoxic effects on juveniles of the neotropical fish Prochilodus lineatus Ecotoxicology and Environmental Safety 2015; 116: 19-28. 10.1016/j.ecoenv.2015.02.032
    » https://doi.org/10.1016/j.ecoenv.2015.02.032
  • Pisicchio CM, Bianchini E, Pimenta JA, Sert MA, Davanso-Fabro VA, Medri ME. Heliocarpus popayanensis (Malvaceae) tolera a hipóxia do substrato? Acta Scientiarum - Biological Sciences 2010; 32(2): 201-209.
  • Rodrigues RR, Lima RAF, Gandolfi S, Nave AG. On the restoration of high diversity forests: 30 years of experience in the Brazilian Atlantic Forest. Biological Conservation 2009; 142(6): 1242-1251. 10.1016/j.biocon.2008.12.008
    » https://doi.org/10.1016/j.biocon.2008.12.008
  • Santos SRG, Aguiar IB. Efeito da temperatura na germinação de sementes de Sebastiania commersoniana (Baillon) Smith & Downs separadas pela coloração do tegumento. Scientia Forestalis 2005; 69: 77-83.
  • Scarano FR, Pereira TS, Rôças G. Seed germination during floatation and seedling growth of Carapa guianensis, a tree from flood-prone forests of the Amazon. Plant Ecology 2003; 168(2): 291-296. 10.1023/A:1024486715690
    » https://doi.org/10.1023/A:1024486715690
  • Schmiede R, Donath TW, Otte A. Seed bank development after the restoration of alluvial grassland via transfer of seed-containing plant material. Biological Conservation 2009; 142(2): 404-413. 10.1016/j.biocon.2008.11.001
    » https://doi.org/10.1016/j.biocon.2008.11.001
  • Sevcikova M, Modra H, Slaninova A, Svobodova Z. Metals as a cause of oxidative stress in fish: a review. Veterinarni Medicina 2011; 56(11): 537-546.
  • Sharma P, Jha AB, Dubey RS, Pessarakli M. Reactive oxygen species, oxidative damage, and antioxidative defense mechanism in plants under stressful conditions. Journal of Botany 2012; 1-26. 10.1155/2012/217037
    » https://doi.org/10.1155/2012/217037
  • Silva AC, Higuchi H, van den Berg E, Nunes MH, Carvalho DA. Florestas inundáveis: ecologia, florística e adaptações das espécies Lavras: Editora UFLA; 2012.
  • Takahashi H, Saika H, Matsumura H, Nagamura Y, Tsutsumi N, Nishizawa NK et al. Cell division and cell elongation in the coleoptile of rice alcohol dehydrogenase 1-deficient mutant are reduced under complete submergence. Annals of Botany 2011; 108(2): 253-261. 10.1093/aob/mcr137
    » https://doi.org/10.1093/aob/mcr137
  • Villa-Hernández JM, Dinkova TD, Aguilar-Caballero R, Rivera-Cabrera F, Sánchez de Jiménez E, Pérez-Flores LJ. Regulation of ribosome biogenesis in maize embryonic axes during germination. Biochimie 2013; 95(10): 1871-1879. 10.1016/j.biochi.2013.06.011
    » https://doi.org/10.1016/j.biochi.2013.06.011
  • Wang WL, Liu SJ, Song SQ, Moller IM. Proteomics of seed development, desiccation tolerance, germination and vigor. Plant Physiology and Biochemistry 2015; 86(1): 1-15. 10.1016/j.plaphy.2014.11.003
    » https://doi.org/10.1016/j.plaphy.2014.11.003
  • Weitbrecht K, Müller K, Leubner-Metzger G. First off the mark: early seed germination. Journal of Experimental Botany 2011; 62(10): 3289-3309. 10.1093/jxb/err030
    » https://doi.org/10.1093/jxb/err030
  • Xiaolin W, Fen N, Xiuli H, Wei W. Genetic modification for improving seed vigor is transitioning from model plants to crop plants. Frontiers in Plant Science 2017; 8(8): 1-7. 10.3389/fpls.2017.00008
    » https://doi.org/10.3389/fpls.2017.00008

  • 1
    Associate editor: Juliana Müller Freire 0000-0002-4758-2533

Publication Dates

  • Publication in this collection
    01 July 2020
  • Date of issue
    2020

History

  • Received
    04 Sept 2017
  • Accepted
    12 Aug 2019
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