Biometry , Emergence and Initial Growth of Accessions and Mangaba Progenies

Mangaba (Hancornia speciosa Gomes) is a native fruit of great economic, cultural, and environmental importance in its areas of occurrence. Due to extractive activities and real estate pressure, the number of natural populations has considerably decreased. The propagation of the species is still one of the primary obstacles for orchard implantations, thus, studies that provide a better understanding of the dynamics of the species’ growth should be developed. This work aimed to evaluate the biometry, emergence, and initial growth of mangaba progenies (Hancornia speciosa Gomes), using the plant material from the Active Germplasm Bank of Embrapa Coastal Tablelands, located in Itaporanga d’Ajuda, SE, Brazil. Treatments consisted of progenies from 17 accessions. The experiment was carried out in a completely randomized design with four replications of 25 seeds. Number of seeds per fruit, as well as fruit and seed weight (g), length (mm), width (mm), and thickness (mm) were evaluated. For emergence and initial growth, the following variables were analyzed: percentage of emergence (PE%), emergence speed index (ESI%), survival rate (SR%), height (H), stem diameter (SD), and the number of leaves (NL). Biometric analyses of fruits and seeds revealed significant phenotypic variability among mangaba accessions. Progenies of the accessions LGP1, LGP3, LGP4, PTP4, TCP2, TCP6, ABP1, ABP2, ABP4 and BIP4 showed better results for all emergence and initial growth variables. The progenies of accessions TCP1, BIP4, CAP5 and PRP5 expressed lower emergence and survival percentages, and low vigor.


Introduction
Hancornia speciosa Gomes (family Apocynaceae) is a tree fruit native to Brazil, found in the coastal tablelands, coastal lowlands, and in the Cerrado Biome.Its fruit is used as raw material for the manufacture of several by-products, such as jelly, ice cream, juice, jam, sauce, wine, and vinegar (Costa, Silva, Ledo, Santos, & Silva Júnior, 2011).For this reason, this specie has aroused the interest of the food industry sector.
Despite its agroindustrial potential, this specie is mostly exploited by an extractive way.The areas of natural occurrence have undergone accelerated genetic erosion due to great real estate pressure, mainly in the coastal lowland of the Brazilian northeast.
Mangaba is usually sexually propagated.However, the species presents recalcitrant seeds, and its pulp contains inhibitory substances, which may prevent or hinder germination (Vieira Neto, Silva Junior, & Ledo, 2009).These facts contribute to the low germination rate and slow and uneven seedling growth.Therefore, propagation is one of the major bottlenecks for the species production.
Aiming at the conservation and future improvement of this plant, the Mangaba Active Germplasm Bank (AGB) of Embrapa Coastal Tablelands was implemented in 2009 at the Experimental Field of Itaporanga d'Ajuda-SE, in a Restinga area, in Brazil.The AGB currently contains 271 accessions, propagated by open-pollinated seeds from the States of Bahia, Paraíba, Sergipe, Pernambuco, Alagoas, Ceará, Pará and Minas Gerais.The characterization of accessions is fundamental to the knowledge of their potential and the identification of the variability among them (Lima et al., 2012).Moreover, information on the propagation is essential and must precede orchards implantation.
The physiological quality of seeds is influenced by the genotype, and the maximum seed quality potential, such as germination and vigor, is genetically controlled (Prete & Guerra, 1999).Therefore, research involving the divergence and genetic relationships for traits related to physiological quality assist in creating selection strategies for the improvement of seed physiological quality (Cardoso, Silva, Pereira, Viana, & Araújo, 2009).In selection programs, diversity can be early verified by the seed quality, using germination and vigor tests (Dias & Marcos Filho, 1995).
Plant breeding programs usually aim at high-quality cultivars.Studies on seeds, using physiological tests, may contribute to developing methods for the selection of high-quality-seeds genotypes (Moura, Chaves, Naves, Aguiar, & Sobierajski, 2013).Growth analyses can also be used to describe plant morphophysiological conditions, phenotypic differences, and effects of ecological phenomena on the growth and adaptability of species to different ecosystems (Magalhães, 1986).
Fruit and seed biometry is another relevant tool to detect genetic variability in populations of the same species and the relationships with environmental factors (Gonçalves et al., 2013).Tropical tree species have a great variety of traits, such as fruit size, number of seeds per fruit, seeds size, and seeds dimension.Thus, the biometric characterization can be a relevant subsidy for species differentiation (Cruz, Carvalho, & Leão, 2001).Despite the economic, social, and environmental importance of mangaba, research involving fruits and seeds biometry is still incipient, requiring further studies.
Understanding the development is crucial to creating management strategies for mangaba in its region of origin.Furthermore, some genetic resources with potential traits can be incorporated into the productive process (Vieira, Souza, Belo, & Camilo, 2013).However, there is a lack of studies on the several aspects involved in mangaba propagation.Works addressing this topic are paramount for future breeding programs that aim at better conservation and utilization of this fruit.This work aimed to evaluate the biometry, and emergence and initial growth of accessions and progenies from the Mangaba Active Germplasm Bank of Embrapa Coastal Tablelands.

Method
This study used the plant material from the Active Germplasm Bank of Embrapa Coastal Tablelands, located at the Experimental Field of Itaporanga d'Ajuda, Sergipe, Brazil (lat.11°06′40″ S and long.37°11′15″ W) (Table 1).Twenty-five fruits per accession were collected in June 2015.Afterward, fruits were taken to the Seed Analysis Laboratory of Embrapa Coastal Tablelands, where the biometric analyses and seed processing were carried out.The exper seeds per were subje Analysis S   The present results demonstrated high levels of phenotypic variability for fruits and seeds of mangaba accessions, requiring an in-depth study to identify important traits for the production of fruits and genotypes of commercial interest.

Emergence and Initial Growth
The studied accessions showed differences for percentage of emergence, emergence speed index, and survival rate (Table 3).The progenies of the accessions from the states of Bahia (LGP1, LGP3, and LGP4), Sergipe (PTP4, PTP5, TCP2, and TCP6), and Pará (ABP1 and ABP2) obtained higher percentages of emergence.Note.PE% = Percentage of Emergence; ESI = Emergence Speed Index; SR% = Survival Rate.
The vigor of the plants verified by the percentage of emergence was better expressed in plants from the accessions LGP1, LGP3, LGP4, PTP2, PTP4, TCP2, ABP1, and ABP2.The progenies of the accessions PTP2, TCP1, BIP4, CAP5, and PRP5 had the lowest survival rates.Most of the accessions that obtained better results for percentage of emergence were also more vigorous.Thus, it is inferred that percentage of emergence correlates to ESI and that it is possible to select progenies that express faster establishment.
Emergence and plant vigor are target traits in breeding programs (Oliveira, Lopes, Chaves, Martins, & Alves, 2013).Thus, seeds genetic attributes have considerable importance since the seedlings originated from them will certainly reflect their capacity to form superior individuals (Vechiato & Parisi, 2013).The relative contribution of each trait to genetic variability is essential for the selection of traits of greater interest, as well as for the discard of those that little contribute to genotypes differentiation (Correa & Gonçalves, 2012).
The determination of adequate propagation procedures can be a primordial factor for the domestication and commercial cultivation of a species, aiming to obtain high-quality seedlings that comply with the commercial standard (A.V. Pereira, E. B. C. Pereira, Junqueira, & Fialho, 2002).In mangaba, the study of genotypes to obtain propagation material is crucial for the future introduction of this species to commercial fields.
Variations in the percentage of emergence, ESI, and survival rate were detected in other studies, such as that of Silva, Mota, and Farias Neto (2009), who reported percentage of emergence ranging from 27.9% to 98.9% among progenies of bacabi (Oenocarpus mapora Karsten) and bacaba (Oenocarpus distichus Mart.).Freitas and Costa (2015) verified differences in the emergence speed index in progenies of Eugenia calycina, ranging from 0.160 and 0.289.Studies with pequi seeds (Caryocar brasiliense Camb) revealed a variation in survival rate between progenies, ranging from 50 to 100%, with a mean of 93.4% (Moura et al., 2013).
A continuous growth was observed throughout the evaluations, and significant variations were detected among the progenies for the analyzed traits (Table 4).The progenies of the ABP4 access obtained higher height (45.10 cm); (4.43 mm) and the TCP6 and BIP4 accessions, with the highest number of leaves.For all initial growth variables the progenies of the CAP5 accessions reached lower values, being lower than the others.
The study on plant growth is fundamental to increase the field of knowledge regarding genotypes behavior.The morphological parameters are widely used to determine seedlings quality standard.Thus, the knowledge of morphological variability allows selecting materials with better possibilities of domestication.Understanding the plant development is essential for the management of mangaba due to materials that have potential traits to be introduced to the production chain (Vieria et al., 2013) in mangaba seedlings.
The variation in the germinative behavior of progenies may be associated with the genetic information of each accession since they have different origins.This fact reinforces the hypothesis that plants originating from geographically distinct regions may present high variability.Thus, the knowledge about this genetic material is fundamental to the selection of the best parents in order to obtain genotypes with superior traits.

Table 3 .
Percentage of emergence, emergence speed index and survival rate of progenies of mangaba accessions of the Active Germplasm Bank of Embrapa Coastal Tablelands, Itaporanga d'Ajuda, SE, Brazil