Maternal environment and seed size are important for successful germination and seedling establishment of Pterocarpus erinaceus(Fabaceae)

Beda Innocent Adji ·Doffou Sélastique Akaffou·Philippe De Reffye·Sylvie Sabatier

Abstract Seed size and the growth environment are important variables that influence seed germination,growth and biomass of seedlings and future tree harvest and should thus be taken into account in agroforestry and reforestation programmes for endangered species like Pterocarpus erinaceus.In the present study,to assess seedling germination and vigour in P.erinaceus as a function of seed size in two environments,1080 seeds and 360 seedlings were evaluated at two separate sites in C?te d’Ivoire.The results show that large seeds had very high germination rates (up to 100%) and produced more vigorous plants better able to adapt to climate change.The maternal environment and seed size had a significant influence on seed germination(P <0.05) and seedling development (P <0.05) and biomass(P <0.05).Seedlings were most successful at the site with a humid tropical climate (Daloa).Seedling leaves had the same resistance regardless of seed size and study site,but leaf moisture content was more stable in seedlings grown from medium and small seeds.These results will help guide conservation strategies for the species and are key factors for rural populations,loggers,and forest management structures for the silviculture of this species.

Keywords Pterocarpus erinaceus ·Seed size·Germination performance·Seedling·Growth

Introduction

The vulnerability of forests to drought and continued anthropogenic pressures are major concerns worldwide (Choat et al.2012;Mbowa et al.2013;Segla et al.2016;Hérault et al.2020;Amani et al.,2015).In Africa,many species are overexploited and threatened with extinction because of their multiple uses (Ake,1999;Houndonougbo et al.2020;Adji et al.,2021).In particular,African rosewood (Pterocarpus erinaceusPoir.),native to arid and semi-arid areas of West Africa,is overexploited due to its highly valued wood for furniture and musical instruments,its sap for indigo dye,its amino-acid-rich leaves for livestock feed,and its leaves,bark,and roots are used to treat malaria and rheumatism and conditions such as fever,stomach aches,dental decay,general fatigue,,and high blood pressure (Kossi et al.2015;Rabiou et al.2015;CoP17-Prop.xx 2016;CITES-Secrétariat,2016;Dumenu 2019;Segla et al.2016,2020).Its exploitation is banned in many West African countries (in C?te d’Ivoire by decree n° 2013–508;MINEF 2013) because it has almost disappeared in its native range.

In the current context of climate change,rapid and effective reforestation and agroforestry strategies are needed to sustainably manage and conserve the remaining populations of this species.For conservation,an effective method is domestication using regeneration techniques that require the study of germination to determine the best conditions for germination and subsequent growth and selection of vigorous,resilient plants to establish permanent plots of plants that can best adapt to global changes (Walsh and Lord 1996;Mao et al.2019).For African rosewood,the fastest,most efficient techniques for optimizing its culture remains to be established.

Seed size is correlated with germination capacity and with several other plant characteristics,including dispersal pattern,growth form,biomass,specific leaf area (the main determinant of growth rate and an indicator of the quality of the species’ maternal site),and future harvest (Westoby et al.1996;Chacon et al.1998;Gunaga and Vasudeva 2011).Sowing mixed seeds of the same species leads to varying vigour and seedling size.In general,larger seeds germinate faster and produce more vigorous stress-resistant seedlings than smaller seeds (Chacon et al.1998;Gunaga and Vasudeva 2011).A possible explanation for this success is that large seeds contain more starch reserves and gibberellic acid,which stimulates germination by producing hydrolytic enzymes that weaken tissue barriers (i.e.,the endosperm or seed coat) than small seeds,which contain less starch reserves and accumulate more abscisic acid,which stimulates the induction and maintenance of dormancy during embryonic growth (Finkelstein et al.2008).In addition,in stressful environments,seedlings from large seeds develop roots that grow deeper and spread more widely than those from small seeds,which enable better survival and growth when resources are scarce (Gunaga and Vasudeva 2011).

Given the promising results of research on seed size in other species and the urgent need for rapid regeneration protocols to compensate for the drastic loss ofP.erinaceusstands in C?te d’Ivoire and elsewhere,studying the germination and seedling growth inP.erinaceusin different environments should lead to strategies to ensure its conservation.Here we thus evaluated germination and seedling vigour inP.erinaceusas a function of seed size in two different maternal environments to guide the choice of seed type to achieve vigorous seedlings for reforestation programmes and agroforestry systems in new environments that differ from its native zone.

Material and methods

Plant material

Two types of plant material were used.The first comprised 1080 shelled seeds ofP.erinaceuscollected from ripe fruits of seed trees in good physiological condition from four locations in C?te d’Ivoire (Table 1) in March 2020.The second type of material comprised 360 4-month-old seedlings resulting from the germination of the seeds ofP.erinaceuswe collected.These seedlings were reared in a nursery in two locations in C?te d’Ivoire.The dendrometric characteristics,the number of seed trees,and number of healthy seeds selected after hulling according to their provenance are listed in Table 1.The plant material belongs to the rural village communities whose plots we surveyed at each location;we received oral authorization to use the material.We vouchered a specimen of this material in the public herbarium (N° UCJ010935) at the National Centre for Floristics(Centre National de Floristique) in C?te d’Ivoire (Koffiet al.2018) and at the Swiss Scientific Research Centre (Centre Suisse de Recherche Scientifique,CSRS) in C?te d’Ivoire(Bakayoko et al.2020).

Methods

Experimental sites

The experiments ran from March to July 2020 in nurseries in two locations with different climate characteristics (Daloa and Korhogo) in C?te d’Ivoire (Fig.1).The characteristics of the two study sites are listed in Table 2.

Fig.1 Geographical location of the study sites

Table 1 Dendrometric characteristics and location of Pterocarpus erinaceus seed trees used

Table 2 Geographical location and characteristics of study sites (Guillaumet et al.1971;Louppe and Ouattara 1996;Akaffou et al.2019;Hérault et al.2020)

Collecting and sorting seeds

Ripe fruits were randomly collected from seed trees in good physiological condition in the four locations mentioned above.The thorny seed shell of each fruit was removed so the seed could be extracted (Fig.2 a).All the seeds from the trees sampled at each origin were mixed in a large container so that their exact origin (mother tree) could not be distinguished.A random batch of 100 seeds was removed from the container to weigh each seed and measure length,width,andthickness and calculate a seed shape index (ratio of width to length) (Millogo 2014).

Fig.2 Husking (a),sorting seeds into large,medium,and small categories from left to right (b) and distribution of seeds number and frequency according their size (c)

Batches of 100 seeds were removed,weighed and measured until the container was empty for a total of 13.46 batches (124 seeds to Katiola+529 seeds to Niakara+611 seeds to Korhogo+82 seeds to Ferké=1346 seeds/100 seeds per batch=13.46 batch).

The seeds were sorted into three size categories (large,medium and small) (Fig.2 b) based on the results of an analysis of variance (ANOVA) of all the dimensions (mass,length,width and shape index) recorded (Table 3).

Table 3 Means±SE for seed characteristics for each seed size of Pterocarpus erinaceus

Setting up nursery trials

Black polyethylene bags (20 cm×10 cm) with drainage holes were filled with local potting soil,then grouped to form three subblocks.In each nursery,each subblock contained 90 polyethylene bags filled with local soil containingone each of the three seed-size classes (i.e.,one subblock of large seeds,one subblock of medium seeds and one subblock of small seeds).Subsequently,180 seeds per size category were selected at random,soaked in water to break seed dormancy,then sown at a depth of 2 cm at a rate of two seeds per black bag in each subblock giving 2 seeds×90 black bags×3 size categories of seeds or 180 large seeds+180 medium seeds+180 small seeds=540 seeds per nursery.The same design was used at the two study sites.The seeds were treated with granulated FURADAN against rodents.After the emergence of the seedlings,the pre-leaves were treated with DECIS to limit insect attack.Maintenance in the nurseries consisted of daily watering and manual weeding.

Variables assessed

Germination

germination was tested for the three seed categories and the following variables evaluated:(1) Germination time or latency:the time until first seed germinated after sowing(Amani et al.2015;Douma et al.2019);(2) germination delay:time from sowing until germination for each seed(N’golo et al.2018;Douma et al.2019);(3) germination speed:average time until 50% of the seeds had germinated(Berka and Abdelkader 2001;Diatta et al.2009;Douma et al.2019);(4) duration of germination:period between the time that the first seed germinated until the last seed germinated (Amani et al.2 015;Douma et al.2019);(5) germination rate:the percentage of germinated seeds among the total number of seeds sown (Zerbo et al.2010;Souza and Fagundes 2014;Gorgon et al.2015);and,(6) germination dynamics:cumulative number of seeds that germinated daily and periodically throughout the germination period (Samreen and Shahid 2000;Akaffou et al.2019).

Seedling growth

After germination,60 seedlings were randomly selected from each subblock (provenance of seed category) and each study site for a 4-month follow-up:60 from the germination of large seeds,60 from the germination of medium seeds,and 60 from the germination of small seeds per nursery (60 seedlings×3 size categories×2 study sites=360 seedlings).

Growth was assessed for 4-month-old seedlings according to the seed provenance category in two phases.First,seedling development and,second,dry biomass of the organs of each seedling (organs were dried in the oven at 60 °C for 72 h stored in silica gel until measurement).The developmental variables measured were height,diameter,number of single and compound leaves on the main stem,root length and root diameter (Samreen and Shahid 2000;Matheus and Marcilio 2014).The variables used to evaluate dry organ biomass were total seedling dry mass,total leaf dry mass,dry mass of the main stem,and dry mass of the roots of each seedling.All developmental variables were measured using a ruler graduated in centimetres and an electronic calliper graduated in millimetres.All dry biomass was measured using an electronic scale with 0.001 g precision.Next,the dry matter of the leaves was evaluated as the ratio of the oven-dried matter of a leaf in milligrams to its watersaturated fresh mass in grams (Garnier and Navas 2012).This functional leaf trait enables the evaluation of leaf resistance to physical hazards and the recognition of species or individuals associated with productive or highly disturbed environments.

Statistical analyses

Statistical analyses were first performed using one-dimensional descriptive statistics,linkage analysis (correlation,regression,and covariance) and multidimensional analysis (PCA) in XLSTAT 2020 version 7.5 (Addinsoft,Paris,France).All variables were compared using analysis of variance in SAS version 9.4 (SAS Institute,Cary,NC,USA).A Student–Newman–Keuls and a LSD test at the 5% threshold were used for post hoc comparison.

Results

Influence of seed size and study site on seed germination

Our results showed that seed size and site properties had a significant effect on the germination variables.All variables were better in the large seeds grown in the nurseries at the two study sites.However,the large seeds sown in Daloa performed better than the large seeds sown in Korhogo:latency of the large seeds was 3 days in Daloa versus 4 days in Korhogo.The germination delay for each large seed varied between 3 and 20 days (average 7.69 ± 5.52 days) in Daloa and between 5 and 25 days (average 9 ± 4.54 days) in Korhogo.Their germination speed was 6 days in Daloa compared to 8 days in Korhogo.The germination delay for large seeds was 17 days in Daloa versus 21 days in Korhogo.The germination rate was 100% for large seeds sown in Daloa and 82% for large seeds sown in Korhogo.The Daloa site was more favourable for germination of all three seed size classes than the Korhogo site (Fig.3).For each seed-size category,the daily germination dynamics were more pronounced at the Daloa site (Fig.4 a) than at the Korhogo site(Fig.4 b).

Fig.3 Effect of seed size and study site on germination rate of three sizes of seeds of Pterocarpus erinaceus

Fig.4 Germination dynamics of three sizes of seeds of Pterocarpus erinaceus at Daloa(a) and Korhogo (b)

Analysis of the relationship between germination variables showed that regardless of seed type and study site,the germination rate was strongly but negatively correlated with the latency (r=?0.9043) and the germination delay(r=?0.9375) of all seeds (Table 4).The correlation matrix also showed a strong positive correlation between germination delay and germination latency (r=?0.9701).

Influence of seed size and study site on seedling development

Influence of seed size

Comparison of seedling development variables (Table 5)by seed classes showed that all seedlings from the large seeds differed significantly among themselves (P<0.05)but were all significantly more developed than seedlings from the other two seed classes (Table 5).

Influence of study site

The seedlings obtained after 4 months in the nursery in Daloa were more vigorous and well developed than those in the Korhogo nursery (Table 6 and Fig.5).All the developmental variables differed significantly from one nursery to another (P<0.05).

Fig.5 Vigour of 4-month-old seedlings from large (1),medium(2) and small seeds (3) of Pterocarpus erinaceus at Daloa (a) and Korhogo (b)

Table 4 Pearson correlation matrix for germination variables for Pterocarpus erinaceus

Table 5 Effect of seed size on the development of 4-month-old Pterocarpus erinaceus seedlings

Table 6 Effect of study site on development of 4-month-old seedlings of Pterocarpus erinaceus

Aerial parts of the seedling were taller in Daloa than in Korhogo (Fig.6 a),and roots were longer in Korhogo than in Daloa (Fig.6 b).

Fig.6 Height of stems (a) and length of roots (b) of 4-month-old plants from different seed sizes of Pterocarpus erinaceus at Daloa and Korhogo according to the size of original seed

Influence of seed size and study site on seedling dry biomass

Influence of seed size

Table 7 shows the dry biomass of the organs of the young seedlings from the three sizes of seed.The organ dry biomass of all the seedlings originating from all three seed sizes differed statistically from one another (P<0.05) except for leaf resistance (leaf dry matter content),which was statistically identical in the three size classes (P>0.05).All seedlings from large seeds weighed more than the other seedlings from the two other seed sizes,and the smaller the seed size,the lower the organ dry mass.

The models in Fig.7 illustrates the relationships between fresh and dry leaf biomass of seedlings and the seed sizes indicate that the amount of water in the leaves is more stable in seedlings from medium and small seeds than the more variable water content in leaves of seedlings from large seeds.In addition,the higher the fresh leaf mass of the leaves of seedlings from medium and small seeds,the higher is the corresponding dry leaf mass,whereas this is not often the case of leaves of seedlings grown from large seeds (non-linear regression).

Fig.7 Relationship between leaf fresh mass and leaf dry mass of 4-month-old plants grown from large (a),medium (b) and small seeds (c) of Pterocarpus erinaceus

Fig.8 Projection of nursery seedling categories and organ biomass types on axes 1 and 2 of the principal component analysis

Figure 8 shows the projection of the location of the three categories of seedlings and biomass types on axes 1 and 2 of the PCA (biplot).Analysis of the weight factor matrix enabled extraction of two components that explain 99.59% of total variability,and consequently the total variation among the three categories of seedlings and their corresponding organ biomasses.Plane 1–2 is characterised by eigenvalues of 98.75% for the F1 axis and 0.85% for the F2 axis.The different descriptors contributing to the formation of the first (F1) and second component (F2) form a single group consisting of seedlings germinated from large seeds in the Daloa nursery,and were characterised by greater fresh and dry biomass than all other categories of seedlings.

Influence of the study site

Young plants raised in the Daloa nursery had the highest organ masses (Table 8).All dry masses of all organs of seedlings growing in Daloa differed significantly (P<0.05) from the dry masses of seedlings grown in Korhogo.In contrast,leaf resistance did not differ significantly between the sites,and leaves had similar dry matter content regardless of the site and seed size class.

Table 7 Effect of seed size on the biomass of 4-month-old Pterocarpus erinaceus seedlings

Table 8 Effect of the study site on the biomass of 4-month-old Pterocarpus erinaceus seedlings

Figure 9 shows differences in the moisture content of leaves on the stem of seedlings grown in Daloa (Fig.9 a),Korhogo (Fig.9 b) and in the two study sites (Fig.9 c),and the relationship between total fresh mass and total dry mass of the seedlings (Fig.9 d).Figure 9 also shows that the moisture content of the leaves was more stable in Korhogo than in Daloa and that the higher the fresh mass of the seedlings,the higher the corresponding dry mass.

Fig.9 Relationship between leaf fresh mass and leaf dry mass in Daloa (a),in Korhogo (b),between total leaf fresh mass and total leaf dry mass (c) and between total fresh plant mass and total plant dry mass (d)

Discussion

The shape and mass of seeds are essential characteristics that can affect the regeneration of plant stands.In this study,the different seed sizes led to significant differences in the germination and the 4-month growth of the young seedlings.

Seed germination

The germination rates of the three seed sizes ranged from 42 to 100% in 20 days in Daloa (Guinean-humid zone) and from 34 to 82% in 33 days in Korhogo (Sudano-dry zone).In the studies of Adou et al.(2013) and N’golo et al.(2018),the maximum germination rates of seeds ofP.erinaceuswere 29% in the south and 68.5% in the north of the C?te d’Ivoire.In contrast,in Togo,Johnson et al.(2020) obtained moderately high rates ranging from 77 to 92% for the different provenance of this species over 15 days (82% in the Sudano-dry zone,92% in the Guinean-humid zone,and 77%in Sudano-Guinean semi-humid zone).The results of the studies in Togo are comparable with our results because the study areas are practically the same.

The larger the seed size the higher was the germination rate at all study sites since larger seeds have greater starch reserves in the embryo.The same phenomena has been reported in studies by Chacon et al.(1998) onCryptocarpa albain Chile,by Mao et al.(2019) onPinus thunbergiiin China,by Gunaga et al.(2007) onPongania pinnataandVateria indicaand by Pommel (1990) in a greenhouse study of maize in France.In addition,Gunaga and Vasudeva(2011) showed that large seeds ofMannea surigahave a dormancy break and a rapid,very high germination rate due to the high concentrations of carbohydrates,gibberellic acid(GA) and other nutrients compared with medium and small seeds.The induction and release of primary or secondary dormancy are controlled by different mechanisms including complex interactions between the environment and abscisic acid (ABA),and gibberellins such as gibberellic acid (GA).ABA promotes the induction and maintenance of dormancy during embryonic maturation (Finkelstein et al.2008).Gibberellins,on the other hand,promote the breaking of dormancy and germination (Finkelstein et al.2008) in several plant species.This group of hormones stimulate germination by producing hydrolytic enzymes that weaken the barriers formed by tissues like the endosperm or seed coat by mobilizing seed storage reserves and by stimulating the development of the embryo.Consequently,the greater the carbohydrate reserves in big seeds,the more the development of the embryo is stimulated leading to germination of the seed.The hormonal balance theory has been proposed that dormancy and germination depend on the accumulation and balance of ABA and GA (N’Dri et al.,2011).Environmental signals regulate this balance by altering the expression ofcatabolic and biosynthetic enzymes (Finkelstein et al.2008).Germination is therefore characterised by an increase in GA biosynthesis and the degradation of ABA (Finch-Savage and Leubner-Metzger 2006).

However,there may be exceptions to the rule,because large seeds do not guarantee the highest germination rates with good seedling vigour for all species.Dar et al.(2002) showed that medium-sized seeds produced better germination and high seedling vigour than larger seeds and smaller seeds inAcacia catechu,Pinus roxburghii,Albizia lebbekandRobinia pseudoacacia.Under the same climate and soil conditions,experimental conditions,Malavasi and Malavasi (1996) and Agboola (1996) showed that,in certain tropical tree species,seed size had no influence on germination and seedling vigour.In Daloa,germination rates were higher in all seed size groups than in Korhogo.We believe this difference is due to the type of potting soil used in the bags and the local climate in Daloa and Korhogo;the soil at Korhogo is poor in organic matter and subject to an arid tropical dry climate that can increase soil salinity,whereas Daloa is a forested area with humus-rich soil and a humid tropical climate.The beneficial effects of soil type on germination have been shown in several studies,such as that of Aparicio et al.(2002).In the same context,Alaoui et al.(2013) and Tian et al.(2014) showed that saline stress had a negative effect on seed germination.The results showed that the germination latency time (germination of the first seed among a batch of sown seeds) was positively correlated with the germination delay (time between planting and germination for each seed of the considered batch)(r=0.9701).This means that for a given seed lot,the faster the germination of the first seed,the faster all the seeds in that lot germinate.The correlation matrix also showed that the germination rate was negatively correlated with latency(r=?0.9043) and with germination delay (r=?0.9375).Thus,the higher the seed germination rate,the shorter were the germination latency germination delay for each seed.Indeed,Mao et al.(2019) showed that the vigour index and germination rate were negatively correlated with the average germination time.

Seedling growth

Our results showed that,regardless of the size of the original seed,none of the seedlings grown in Korhogo (Sudano-dry zone) had any compound leaves after four months.In contrast,the seedlings grown in Daloa (Guinean-humid zone)were more vigorous,regardless of the size of the seed,but the roots were longer in Korhogo than in Daloa.In our opinion,these facts are also due to the different types of soil and climate at the two sites.The rich soils and wet climate of Daloa produced larger,more vigorous,mature seedlings.In their studies,Maranz and Wiesman (2003) and Soloviev et al.(2004) reported that the climate and/or the ecological gradient had an effect on seedling morphology.Similarly,Salazar and Quesada (1987) and Assogbadjo et al.(2005,2006) showed that the origin of differences in seedling morphology included soil type,and the age and genetic characteristics of the mother trees.Salt-rich acidic soils also can have a negative effect on plant growth (Alaoui et al.2013).However,Dianda and Chalifour (2002) reported that the climatic zone of origin had no impact on seedling growth;only the age and genetic background of the mother tree had a significant effect on seedling morphology.It should be noted that although the seedlings appeared to be more vigorous at Daloa than at Korhogo,the seedlings at Korhogo had longer roots than the seedlings at Daloa,regardless of the size of the original seed,which can be explained by differences in the water regime.In Korhogo,the soil dries out rapidly after the seedlings have been watered due to lower relative humidity,higher temperatures,and higher sand content in the soil.A few hours after watering,the water evaporates by evapotranspiration or infiltrates into the deeper soil layers by percolation;the roots are therefore forced to extend deeper into the soil.Douma et al.(2019) already reported this phenomenon inParkia biglobosa.As we mentioned earlier,not all young plants that germinated from small seeds developed compound leaves,but young plants that germinated from large seeds were better developed than seeds that germinated from other seed categories,regardless of the study site.Results of studies by Aparicio et al.(2002),Chacon et al.(1998),Mao et al.(2019),Gunaga and Vasudeva (2011),Gunaga et al.(2007),Rahman and Bourdu (1986) and Pommel (1990) are similar.However,Dar et al (2002) reported contradictory results;seedlings from medium-sized seeds were larger and more vigorous than seedlings from small and large seeds.On the other hand,Malavasi and Malavasi (1996) and Agboola(1996) reported that seed size does not influence seedling shape and vigour in certain tropical tree species.

Analysis of variance of the dry biomass of the organs evaluated in our study revealed significant differences between the two study sites as well as between the seedlings resulting from germination of the three sizes of seeds.Overall,our results showed that the seedlings at Daloa had higher organ masses than those at Korhogo.Once again,the soil and climate at Daloa allowed the seedlings to store more dry matter regardless of whether the seedling germinated from seeds of different sizes.At both study sites,seed size did influence the biomass of the seedlings;the larger the seeds,the greater was the biomass.However,the seedlings that germinated from large seeds at Daloa weighed more than the seedlings from large seeds at Korhogo.Several other studies have confirmed the positive effect of seed size on seedling vigour and biomass,e.g.,Aparicio et al.(2002) on durum wheat in Spain,Chacon et al (1998) onCryptocarya albain Chile,Mao et al (2019) onPinus thunbergiiin China,and Gunaga and Vasudeva (2011) onMannea surigain India,Gunaga et al.(2007) onPongania pinnataandVateria indicain India,Alaoui et al.(2013) on wheat in Morocco,Rahman and Bourdu (1986) on maize seedlings and Pommel (1990) on maize seedlings in greenhouses in France.In our study,leaf water content showed a linear regression with good fit between fresh and dry leaf mass of seedlings from medium and small seeds for the set of leaves,whereas the leaf water content of the seedlings from the large seedlings had a poor fit.These results imply that seedlings from medium and small seeds germination had more stable water quantities,and less water was wasted through evaporation during photosynthesis than from the large seeds,explaining why seedlings from medium and small seeds were smaller and less vigorous than seedlings from large seeds.In fact,the more water lost through the leaves,the higher the photosynthetic activity,the more starch (dry matter) produced and stored and hence,the more vigorous the plants.Similarly,our results showed a linear regression in water content between fresh and dry leaves of all the seedlings at Korhogo,in contrast to the seedlings at Daloa (non-linear adjustment).Thus,Daloa seedlings had a highly variable and unstable water content and therefore stored less water in their leaves,in contrast to the leaves of seedlings grown in Korhogo,where the hydric stress on seedlings forces them to conserve more water,photosynthetic activity is therefore,resulting in stressed and less vigorous seedlings than at Daloa.Evaluation of the leaf dry matter content (LDMC) showed that the leaves of all the seedlings we evaluated had identical resistance regardless of the size of the original seed or the study site.This phenomenon can be explained by the seedlings being the same species.The LDMC evaluated in this study is very important as it provides clues to productive or disturbed environments and to the decomposition of leaf litter.Indeed,Garnier and Navas (2012) indicated that leaves with high LDMC tend to be relatively resistant and are assumed to be more resistant to physical hazards (e.g.,herbivory,wind)than leaves with low LDMC.They also mentioned that some aspects of the relationship between leaves and water and flammability also depend on LDMC.Low LDMC species tend to be associated with less productive,often highly disturbed environments.In addition,leaf litter from high-LDMC leaves tends to decompose more slowly than litter from low-LDMC leaves.

Conclusion

This study confirmed that large seeds are both a tool and a selection criterion for sexual regeneration and the establishment of permanent plots to rapidly and effectively safeguard certain endangered species such asPterocarpus erinaceus.We showed that large seeds ofP.erinaceushave very high germination rates (up to 100%) and produce more vigorous plants better able to adapt to and resist climate change.The maternal environment and seed size had a significant influence on germination (P<0.05) and seedling development (P<0.05) and biomass (P<0.05).Seedlings from large seeds were more resistant to water and environmental stress,especially in an environment with rich soil and a humid tropical climate.The leaves had the same resistance regardless of the size of the seeds and the study site,but leaf moisture content was more stable in seedlings grown from medium and small seeds.These results are decision support tools and key factors for rural populations,loggers,state forest management structures for silviculture of the speciesP.erinaceus.This study should now be extended to other threatened species (CITES or the IUCN Red List).