Physical characteristics and chemical-nutritional composition of the castanheira-do-gurguéia fruit ( Dipteryx lacunifera Ducke ) 1

The castanheira-do-gurguéia is a native fruit tree with great regional importance, whose almond present pleasant flavor and exploration still limited. The objective of this research was to evaluate the physical and chemical-nutritional characteristics of 23 castanheira-do-gurguéia genotypes from natural occurrence areas of Piauí State southwestern savannah. A sample of 30 to 50 fruits per genotype was collected. The physical characteristics analyzed were: fruit mass, pericarp mass, fruit length, larger fruit thickness, fruit length/larger fruit thickness ratio, smaller fruit thickness, fruit length/smaller fruit thickness ratio, larger pericarp thickness, smaller pericarp thickness, longitudinal diameter of the pericarp cavity, vertical diameter of the pericarp cavity, almond mass, almond length, larger almond thickness, smaller almond thickness and almond length/larger almond thickness ratio. The following chemical-nutritional characteristics of almonds were analyzed: fat, crude protein, crude fiber, ash total carbohydrates, crude energy and minerals (P, K, Ca, Mg, Mn, Fe, Cu and Zn). The data were submitted to analysis of variance and genotypes means were compared by Scott-Knott’s test at 5%. There were differences among genotypes for all physical and chemical-nutritional characteristics evaluated, except Ca in the almonds. It was verified the presence of great phenotypic variability in the analyzed germplasm. The genotype G-3 is the most promising in terms of almond mass, almond length and larger almond thickness, and the genotypes G-7, G-10, G-13 and G-23 are the most promising in the chemical-nutritional composition.


Introduction
Brazil is one of the greatest repositories of the world's biodiversity, concentrating around 55000 species of superior plants, or 22% of the world's total, many of which are endemic (SILVA;BATES, 2002).Regarding native fruit species, the Central Brazil and the Northeast savannahs represent the country's second greatest genetic repository (RATTER; RIBEIRO, 1996).
Brazil's Northeast region presents a great diversity of native fruits, many of which have a good prospects for economic exploitation, such as hog plum (Spondias mombin L.), "pequi" (Caryocar coriaceum Wittm.), "bacuri" (Platonia insignis Mart.) and "baru" (Dipteryx alata Vog.), among others.There is also that species group which, despite its use potential, is known only locally, in some areas of the Northeast.This is the case of the "castanheira-do-gurguéia" (Dipteryx lacunifera Ducke), a species of natural occurrence in the savannah of the Southwest of Piauí State, where it is explored in an extractivist form by local's peoples, helping to supplement the family income.
The "castanheira-do-gurguéia" belongs to the Leguminoseae-Papilionoideae family and to the genus Dipteryx, which includes 14 species, all especially used as medicinal plants.In Brazil, these species can be found in the Amazon, Northeast, and Center-Western regions.Some are found in Venezuela and others in Central America, more specifically in Costa Rica and Panama (DUCKE, 1948).In turn, the species Dipteryx lacunifera Ducke is found in Brazil's Mid-North region, comprised by the states of Maranhão and Piauí, with a large occurrence in Piauí's Southwestern savannah.Vernacularly known as "garampara" and donkey's nut, the almond of "castanha-do-gurguéia" is a good source of energy, carbohydrate, crude protein and crude fiber; and this fact indicates, according to Carvalho et al. (2008), that this almond has potential use by the almond market.
However, the availability of information on this species is still scarce in the specialized literature (CARVALHO, 2005;CARVALHO, 2008;CARVALHO et al., 2008;VIEIRA JÚNIOR et al., 2007), and it is not enough to provide its sustainable management and use.Currently, it is exploited by the extractivism, with no reports on organized plantings.Thus, it is essential do researches that contribute to the increase of scientific knowledge about that species, and also to allow direct strategies favoring its conservation, advances in the domestication process, and its sustainable use.This research aimed to evaluate the physical characteristics of the fruit (pericarp and almond), and the nutritional composition of the pericarp and almond of 23 genotypes of castanheira-do-gurguéia.The chemical-nutritional characteristics of the almond analyzed were: fat, crude fiber, crude protein, ash, crude energy, total carbohydrate, and minerals (Ca, P, K, Mg, Cu, Mn, Zn and Fe).The mineral concentrations it were determined by atomic absorption spectrophotometry.
The total carbohydrate concentration it was obtained through the formula TC = 100 -(% crude protein + crude fiber + crude fat) and the crude energy was obtained by the formula: CE = crude protein (g) x 4 kcal + total carbohydrate (g) x 9 kcal + fat (g) x 4 kcal.All the concentrations it were determined by the methods described on the analytical guidelines of (IAL, 2005).

Data analysis
For physical characteristics, it was considered a completely randomized statistical design with 23 treatments (genotypes), in which fruits and kernels per genotype were used as replications.For chemical-nutritional characteristics, it was also considered a completely randomized statistical design with 23 treatments (genotypes), but in this case with three replications per genotype of almonds.
Initially, it was performed residual analysis of the data with the aim of verifying the existence of differences and heterocedasticity of variances, adjustment of errors to the normal distribution, assumption of independence and additivity of the errors in the mathematical model.
Afterwards, the physical measurements and chemical-nutritional data were submitted to the variance analysis, with their means compared by Scott-Knott's test, at 5% of significance.

Results and discussion
The mean squares obtained from the analysis of variance for the physical characteristics of fruit and almonds, and for the chemical-nutritional characteristics of the almond are presented in Table 2.The F test indicated significant differences among genotypes, evidencing the existence of genetic variability in the populations studied, as well as the perspective of genetic gain by selection for one or more of these characteristics.The coefficients of variation were mostly lower, evidencing precision in the measurements.With the exception of Ca, the F test also indicated significant differences of the mean squares for the chemical-nutritional characteristics of almonds, evidencing the presence of genetic variability those characteristics among individuals and, therefore, the possibility to identify desirable individuals for using in future breeding programs in this species.
There were significant differences among genotypes for all physical characteristics of fruits (TAB.3) and almonds (TAB.4).The fruit mass (FM) and the pericarp mass (PM) showed the highest amplitude of variation.FM ranged from 6.36 g to 22.49 g and PM ranged from 5.76 g to 21.56 g, and for both traits the Physical characteristics and chemical-nutritional composition of the castanheira-do-gurguéia fruit (Dipteryx lacunifera Ducke) and G-5 (18.37 mm) presented the largest means for the vertical diameter of the pericarp cavity (VDPC).For the remaining characteristics, the differences observed, although significant, were of small range.
The genotype G-3 exhibited the highest value for almond mass (AM), with 1.66 g, while the genotype G-13, with 0.57 g of AM, exhibited the lowest mean for this trait.The genotypes G-2 (1.45 g) and G-5 (1.33 g) are also interesting, especially from the standpoint of future use in breeding programs of the species.Carvalho et al. (2008), working with almonds from a mixture of individuals, obtained 0.73 g of AM, a little smaller than the overall mean of 0.95 g obtained in this research.In general, there was the tendency that fruits with larger values of FM also had larger AM's values (TAB.5).The genotypes G-17, G-3, G-16 and G-7 showed the largest means of almond length (AL), while the genotype G-3 showed the largest mean for the larger almond thickness (LAT).
Estimates of phenotypic correlation coefficients among nine fruit physical characteristics are shown in Table 5.Most of these correlation coefficients were positive and of high magnitude (r p > 0.70), indicating that there should be no major problems in the selection process to improve agronomically important traits, such as FM.The highest phenotypic correlation was found between FM and smaller fruit thickness (SFT) (r p = 0.97).FM showed high correlation coefficients with most of the physical characteristics studied, indicating that it can be of great importance in the selection process.Corrêa et al. (2008), in a study with baru walnut, also obtained high phenotypic correlations involving FM [r p = 0.83 between FM and fruit length (FL); r p = 0.92 between FM and larger fruit thickness (LFT); and r p = 0.81 between FM and SFT], which confirms the importance of FM, especially when one has in mind indirect genetic gain by selection.In this research, high phenotypic correlations were also obtained between FL and larger fruit thickness (LFT) (r p = 0.91); FL and AL (r p = 0.90); FL and longitudinal diameter of the pericarp cavity (LDPC) (r p = 0.91); LFT and SFT (r p = 0.93); LFT and AL (r p = 0.89); AM and larger almond thickness (LAT) (r p =0.89); and FM and AM (r p = 0.82).In the specific case of the FM and AM, the high phenotypic correlation coefficient between them is an indication that it is possible to increase the AM by indirect selection for larger or heavier fruit.Relatively low negative correlations were found for FL and smaller almond thickness (SAT) (r p = -0.17)and for SAT and LDPC (r p = -0.23),indicating that larger fruits tend to show less thicker almonds, and less thicker almonds tend to result in larger longitudinal pericarp cavities.
There were significant differences among genotypes for all chemical-nutritional characteristics analyzed, except for calcium (TAB.6 and 7).The genotypes G-7 and G-23 prevailed in the crude protein concentration, with means of 18.03 and 17.24%, respectively, and significantly differed from the other genotypes.On the other hand, the genotype G-5 showed the smallest mean for this characteristic (TAB.6).The mean concentration of crude protein (15.41%) found in this work is equivalent to the Physical characteristics and chemical-nutritional composition of the castanheira-do-gurguéia fruit (Dipteryx lacunifera Ducke)

Table 1 -
Geographical location of the castanheira-do-gurguéia genotypes collected in Piauí's southwestern savannah

Table 2 -
Summary of the analysis of variance for physical characteristics of fruits and almonds, and for chemical-nutritional characteristics of almonds in 23 genotypes of castanheira-do-gurguéia **Significant at 1% by F test.NS No significant; MQ: mean square; FM: fruit mass; FL: fruit length; LFT: larger fruit thickness; SFT: smaller fruit thickness; PM: pericarp mass; LDPC: longitudinal diameter of the pericarp cavity; VDPC: vertical diameter of the pericarp cavity; AM: almond mass; AL: almond length; LAT: larger almond thickness; SAT: smaller almond thickness

Table 3 -
Fruit physical characteristics of 23 castanheira-do-gurguéia genotypes collected in the southwestern savannah of Piauí State 1 Means followed by the same letter in columns do not differ from each other by the Scott-Knott's test at 5%.FM: fruit mass; FL: fruit length; LFT: larger fruit thickness; SFT: smaller fruit thickness; PM: pericarp mass; LDPC: longitudinal diameter of the pericarp cavity; VDPC: vertical diameter of the pericarp cavity Genotypes 1 FM (g) FL (mm) LFT (mm) FL/LFT ratio SFT (mm) FL/SFT ratio PM (g) LDPC (mm) VDPC (mm)

Table 4 -
Physical characteristics of almonds of 23 castanheira-do-gurguéia genotypes collected in the southwestern savannah of Piauí State

1
Means followed by the same letter in columns do not differ from each other by the Scott-Knott's test at 5%.AM: almond mass; AL: almond length; LAT: larger almond thickness; SAT: smaller almond thickness

Table 5 -
Estimates of the phenotypic correlation coefficients among physical characteristics of fruit and almond of 23 castanheira-do-gurguéia genotypes collected in the southwestern savannah of Piauí State *,* Significant coefficients to 1% and 5% by t test, respectively.NS No significant; FM: fruit mass; FL: fruit length; LFT: larger fruit thickness; SFT: smaller fruit thickness; LDPC: longitudinal diameter of the pericarp cavity; VDPC: vertical diameter of the pericarp cavity; AM: almond mass; AL: almond length; LAT: larger almond thickness; SAT: smaller almond thickness *

Table 6 -
Chemical-nutritional characteristics of almonds of 23 castanheira-do-gurguéia genotypes collected in the southwestern savannah of Piauí State 1 Means followed by the same letter in columns do not statistically differ from each other by the Scott-Knott's grouping test at 5% Genotypes 1 Crude protein (%) Fat (%) Crude fiber (%) Ash (%) Total carbohydrate (%) Crude energy (kcal 100 g -1 )