Estimation of genetic parameter for growth of one year old Swietenia macrophylla King. progeny trial in Trenggalek, East Java

After being introduced to Indonesia, Swietenia macrophylla King. has since been widely planted for community and plantation forests in several locations. This study was carried out to ascertain the growth variation, heritability, and genetic correlation of the 1-year-old S. macrophylla progeny trial in Trenggalek, East Java. This progeny trial was designed of incomplete block design (IBD), and the plant materials are 50 families from Banjar-Ciamis, Samigaluh-Kulonprogo, Dlingo-Bantul, Bondowoso-East Java, and Lombok-West Nusa Tenggara. Three individuals were planted in line tree plot for each family, repeated 6 times with a spacing of 4m x 2m. According to the findings, the Bondowoso land race had the best growth with a height and stem diameter of 0.81 m and 1.12 cm, respectively. Families’ varying heights were divided into 14 groups, and the stem diameter was divided into 13 groups. The stem diameter has individual and family heritabilities of 0.23 (moderate) and 0.53 (moderate), respectively, whereas the height’s individual and family heritabilities are 0.39 (high) and 0.65 (high), respectively. Height and stem diameter showed a positive and strong of genetic correlation (0.90).


Introductions
The need for carpentry will likely rise as the population grows over time.As a result, there is an imbalance between the supply and demand.The occurrence is consistent with the findings of a study conducted in West Java [1], which identified a 4,872,673.93m 3 /year demand gap for carpentry.It is vital to create plantation trees that provide wood for woodworking in order to prepare for this issue.
One of the possible forest species for the establishment of woodworking plantations in Indonesia is Swietenia macrophylla King.(broadleaf mahogany).Despite being an exotic species, S. macrophylla has been widely planted in a number of Indonesian provinces.According to [2], the species has currently spread out quite a bit in Java, South Kalimantan, and Nusa Tenggara.This species is native to Latin America, but it has successfully adapted to a variety of environmental factors in Indonesia.This species has a good endurance for lengthy dry seasons, marginal soils, and locations up to 1,500 m above sea level [3].Previous studies report that the productivity of S. macrophylla plants varies considerably between sites and cycles.[4] informed that two types of sites in Northern Mindanao, Philippines, namely in Butuan and Cagayan de Oro, produced different S. macrophylla plant growth.In Butuan, the growth of plant height and stem diameter at the age of 50 months reached 9.4 m and 12.1 cm, respectively, while in Cagayan de Oro the growth of plant height only reached 3.8 m and stem diameter 4.5 cm.[2] reported that on sites with moderate fertility, the productivity of S. macrophylla plants aged 15 -30 years ranged from 7.7 -19.3 m 3 /ha/year.[5] informed that the volume increment of S. macrophylla plants with a rotation of 50 -60 years ranged from 15 -20 m 3 /ha/year.
The S. macrophylla Seedling Seed Orchard (SSO) in Parung Panjang, Bogor, which was planted from 95 families from West Java, Central Java, and East Java, exhibits great genetic diversity [6].The findings of this study are consistent with those of [7], who found that there were substantial differences in the growth of S. macrophylla seedlings from West Java, Central Java, East Java, and Lombok across families and land races.Additionally, the heritability value of individual and family of S. macrophylla progeny trial at 1-year-old in Kemampo, South Sumatra, was reported to be in the moderate category at the field level [8].These findings encourage the breeding efforts of S. macrophylla since there will be possibilities for selection because to the high genetic diversity and moderate to high heritability values.Based on the findings of the previous investigation, this study was carried out to determine the growth diversity, heritability and genetic correlation values of 1-year-old S. macrophylla progeny trial in Trenggalek, East Java.

Study site
The research was conducted at the S. macrophylla progeny trial in Dompyong Village, Bendungan District, Trenggalek Regency, East Java Province.The study site is located at an elevation of 729 m above sea level, latitude 7 o 55.483' S and longitude 111 o 43.221' E, soil type Litosol and total rainfall of 3,569 mm [9].

Researh materials and tools
The research materials used were 1-year-old S. macrophylla progeny trial.Fifty families from five land races (Banjar-West Java, Dlingo-Bantul, Samigaluh-Kulonprogo, Bondowoso-East Java and Lombok-West Nusa Tenggara) were involved in this study [10].The latitude, longitude and elevation positions of the five land races are presented in Table 1.The tools used in this study were galah meters to measure plant height, calipers to measure stem diameter and tally sheets to record measurement results.Sources: [11] and [12].

Research implementation
Research activities were carried out by measuring the height and stem diameter of plant with a sampling intensity of 100%.Plant height was measured from the base of the stem to the top of the plant, and stem diameter was measured at a height of ± 5 cm from the ground.To facilitate the implementation of measurements, tally sheets were printed and arranged following the design of trial.

Design and data analysis
The research design used was the Incomplete Block Design (IBD) due to the study sites had high differences in slope.In this study, the family was nested within the land race.The land race factor consisted of 5 levels and the families factor consisted of 50 levels.For each family, 3 tree plots were planted, repeated 6 times with a spacing of 4 x 2m.Tree plot planting followed the direction of the contour with a distance of 2 m between plants.
To determine the diversity, the data were analyzed using the following model [13] : Notes: (1) Yijklm = observation of the i th block, the j th row nested in the i th block , the k th column nested in the i th block, the l th land race and the m th mother tree nested in the l th land race; µ = average of the general observations; Bi = effect of the i th block; Rj(Bi) = effect of the j th row nested in the i th block; Ck(Bi) = effect of the k th column nested in the i th block; Pl = effect of the l th land race; Fm(Pl) = effect of the m th family nested in the l th land race; Bi*Fm(Pl) = effect of the interaction between the i th block with the m th family nested in the l th land race; Ɛijklm = random residual error.
Duncan Multiple Range Test (DMRT) to determine differences within each treatment was conducted if the variance analysis results were significant at a maximum test level of 5%.
Individual heritability and family heritability values for height and stem diameter characters were estimated using the following formula [13]: Notes : Due to the potential for self-pollination and/or pollination within families that may occur in S. macrophylla, the family variance component (σ 2 f) in the individual heritability equation was estimated to be ⅓ of the additive genetic variance (σ 2 A) [14].The following formula was used to obtain the estimated value of genetic correlation between characters [13].
Notes : rg = genetic correlation, f(xy) = covariance component of family for characters x and y, = variance component of family for character x, σ 2 f(y) = variance component of family for character y.

Growth variability
The growth of S. macrophylla progeny trial was quite diverse, with an average height of 70.02 ± 18.16 cm and stem diameter of 9.95 ± 3.3 mm.To determine the diversity between land races and families, an analysis of variance was conducted with the results presented in Table 2. One-year-old S. macrophylla progeny trial in Trenggalek, East Java, grew in height and stem diameter significantly differently depending on how the land race, family, and interaction between the block and the family nested in the land race were treated (Table 2).A DMRT significant difference test was performed to ascertain the variations in growth between families and land races.The results are shown in Figures 1 and 2, for the variations in growth between land races and families, respectively.
Table 2. shows that the treatment of land race, family and the interaction between blocks with family nested in land race had a very significant effect on the growth of plant height and stem diameter.This shows that there is diversity in the growth of height and stem diameter among land races, families and the interaction between blocks with families nested in land races.The results of the analysis of variance are in line with the results of research by [7] on 5-month-old S. macrophylla seedlings in the nursery, whose genetic material source is the same as the trial plot in Trenggalek, East Java.This shows that the growth of height and stem diameter of S. macrophylla at the nursery level and 1-year-old plants still varies.
In this study, the significant effect of the interaction treatment between blocks and families on plant growth (height and stem diameter) is likely to occur because the test site has a high difference in slope, so the growing conditions are quite diverse.At the field level, analysis of variance with significant results for the treatment of families and the interaction between blocks and families in 1-year-old S. macrophylla plants was also reported in the research of [8] in Kemampo, South Sumatra.In another study conducted in Butuan, Northern Mindano, Philippines on 50-month-old S. macrophylla progeny trial plants, it was informed that the origin of the seed source (land race) had a significant effect on the growth of height and stem diameter [4].
The diversity of S. macrophylla growth in this study is supported by the results of [6].The RAPD marker-based research informed that the genetic diversity of S. macrophylla in SSO in Parung Panjang, Bogor, which was built from 95 families from West Java, Central Java and East Java, had high genetic diversity, which amounted to 0.3255.
The value of mahogany genetic diversity in this study is higher when compared to the average isozyme-based genetic diversity in meranti tembaga (Shorea leprosula) from several populations in Kalimantan, namely Ho of 0.247 [15], kulim (Scorodocarpus borneensis) in Riau with RAPD markers of 0.226 [16], Gyrinops verstegii in Kebar, Papua of 0.294 and Manokwari, Papua of 0.236 with RAPD [17], and sengon (Paraserianthes falcataria) with RAPD markers in Java at 0.235 [18].However, the genetic diversity value of S. macrophylla (Ho 0.3255) is lower when compared to the genetic diversity value of mindi (Melia azedarach) with microsatellite markers in Padasari, West Java with Ho of 0.454 [19] and Diospyros rumphii with isoenzyme markers in North Sulawesi of 0.59 [20].The DMRT results (Figure 1) showed that plant growth of the Bondowoso land race was better than that of the Banjar-Ciamis, Lombok, Dlingo-Bantul and Samigaluh-Kulonprogo land races.Variability in growth between seed sources also occurs in progeny trial manglid (Manglietia glauca Bl.) at 4.5 year old [21], gmelina (Gmelina arborea Roxb.) at 1 year old [22] and araukaria (Araucaria cunninghamii) at 7 year old [23].This is possible because the elevation of the Bondowoso land race (Table 1) is almost the same as the elevation of the trial site in Trenggalek, so the plant growth of the Bondowoso land race is more optimum than the other land races.This phenomenon is in line with the results of [24], which informed that oil palm plants grow optimally when planted on land with elevation < 600 m above sea level, so that when planted on land with elevation > 600 m above sea level, the photosynthesis rate decreases.In 1-year-old pulai darat (Alstonia angustiloba) in Wonogiri, Central Java, elevation differences in seed source origin also significantly affected plant growth between populations [25].Growth diversity among seed sources (land races) was also observed in provenance trial of S. macrophylla grown in two locations in Northern Mindano, Philippines [4].Growth diversity among seed sources (provenances) also occurred in Neolamarckia cadamba (Roxb.)species grown in progeny trial in Guangdong, China [26].The DMRT showed that the diversity of plant height growth among families in the S. macrophylla progeny trial at the age of 1 year was divided into 14 groups (Figure 2a), and stem diameter was divided into 13 groups (Figure 2b).The best height growth was occupied by 11 parent trees with a range of 80.36 -96.06 cm, and the best stem diameter growth was occupied by 16 parent trees with a range of 10.71 -13.65 mm.Based on the results of research at the age of 6 months, it turned out that the height growth of S. macrophylla offspring trial plants in the same trial plot was also divided into 14 groups, and the stem diameter was divided into 13 groups [10].This phenomenon indicates that the trend of diversity in plant growth at 1 year of age is still the same as when the plants are 6 months old, or has not changed.

Heritability and genetic correlation
Heritability and genetic correlation are two genetic factors that hold a crucial key to breeding activities.According to [27], the heritability value represents the component of the ratio between the value of additive variance and the value of phenotypic variation.In the meantime, pleiotrophy (genes that control more than one traits) is the main cause of genetic correlation, which is the correlation value between the breeding values of two different traits [13].Table 3 provides more information on the estimated heritability and genetic correlation values for the height and stem diameter features in this study.According to the estimated heritability values (Table 3), stem diameter characters had individual and family heritabilities of 0.23 and 0.53 respectively, while plant height characters had individual and family heritabilities of 0.39 and 0.65, respectively.The moderate criterion for stem diameter characteristics and the high criteria for plant height characters both include these heritability values [28].When compared to findings from a study conducted on the same plant species and age in Kemampo, South Sumatra by [8], the individual and family heritability values in this study are greater.The genetic material employed in this study had a pretty wide distribution (West Java, Central Java, East Java, and Lombok), whereas the genetic material used in the study by [8] comes from Bogor, Lampung, and South Sumatra.
Given that the plant was only a year old when this study was conducted, changes in the heritability value of S. macrophylla may still take place.According to [29], as plants get older, the heritability value may fluctuate due to changes in gene regulation.According to some research findings, some plant species, such as Acacia mangium [30], Araucaria cunninghamii [31], and pulai gading (Alstonia scholaris) [32; 33] experience changes in heritability values as plants age.
In addition to age, the heritability value of a plant species is also influenced by the trial location [14].This is supported by the results of research by [4] in Northern Mindanao, Philippines and [34] in Mexico.In the study of [4], trial plots were established on two different sites, namely fertile and marginal land.On fertile land, 50-month-old S. macrophylla plants had a high heritability value of 0.37; while on marginal land the heritability value was 0.43.Meanwhile, in the research of [34], S. macrophylla plants aged 5 years on fertile land had a high heritability value of 0.31 while on marginal land it was 0.26.
The genetic correlation between height growth and stem diameter of 1-year-old S. macrophylla plants has a strong positive value (0.90).Like the heritability value, the genetic correlation value in this study is greater than the genetic correlation value in the research of [8] on the same plant species and age, which amounted to 0.79.Although it is an introduced species, the genetic correlation value in this study is also higher than the genetic correlation value of several other tropical plant species, including sandalwood (Santalum album) aged 8 months at 0.87 [35], and nyawai (Ficus variegata) aged 1 year at 0.8 [36].However, the genetic correlation value is expected to change with increasing age, because the plants are still very young.In its application, the genetic correlation value can be used as information for selection.If the positive genetic correlation value is strong, then selection can be based on one character only.

Conclusion
The growth of S. macrophylla that was one year old was significantly influenced by the land race, the family, and the interaction between the block and the family.Land race Bondowoso, East Java, holds the top rank in terms of height and stem diameter growth.There are 13 groups for stem diameter growth and 14 groups for the variability of height growth among families.Height traits have a high level of individual and family heritability, whereas stem diameter traits have a moderate level of heritability.Height and stem diameter traits exhibit a substantial positive genetic correlation (0.90).

of family, σ 2
fb = variance component of family and block interraction, σ 2 e = variance component of error, B = harmonic mean of the number of blocks, N = harmonic mean of the number of individuals per plot.

Figure 2 .
Figure 2. (a) DMRT for plant height between family and (b) DMRT for stem diameter between family

Table 2 .
Variance analysis in plant height and stem diameter

Table 3 .
Estimation of heritability and genetic correlation in plant height and stem diameter