genetic variation and progeny x local ... international (1), piracicaba: p.45-54, 1990. genetic...

IPEF International (1), Piracicaba: p.45-54, 1990.

GENETIC VARIATION AND PROGENY X LOCAL INTERACTION IN Eucalyptus urophylla

EDSON SEIZO MORI

Instituto de Pesquisas e Estudos Florestais Caixa Posta, 530 – 13400 – Piracicaba-SP-Brazil

PAULO YOSHIO KAGEYAMA

e MARIO FERREIRA

ESALQ-USP, Depto. de Ciências Florestais 13400 – Piracicaba-SP-Brazil

The traits of tree growth were studied in open polinated progenies of wild populations of Eucalyptus urophylla from Flores Island in Indonesia. The objectives of the work were to study the genetic variation, effects of the interation progenies x localities, and to propose the use of these materials in genetic improvement programms. The experiments were established in Compact Family Blocks with 8 provenances and 63 progenies in Aracruz (ES), 94 in Belo Oriente (MG and 109 in Grão Mogol (MG). From the studies provenances, ilegele was superior in relation to all others. The greater difference between the provenances average and the control occurred at Aracruz (ES), the superiority being of the order of 457%. The individual analysis of variance presented significance for all characteristics and localities, with the exception of Belo Oriente (MG), where the F test was not significative for tree height. The joint analysis were highly significative for the interaction progenies x localities. The average heritabilities were far superior from the joint heritabilities, showing strong effects of the interaction progenies x localities. The losses occurred by the effects of the interaction achieved 26.73% for cilindric volume, 15.74% for d.b.h., and 8.14% for tree height. The greater losses occurred when, through simulation analysis, the selection of superior progenies was made in the locality of Grão Mogol (MG), whereas the trees were planted in Aracruz (ES). The phenotypic stability was evaluated by the method of EBERHART & RUSSELL (1966). Three strategies of improvement programs have been compared. �

INTRODUCTION Eucalyptus urophylla is a species that has a good potencial and productivity across several regions in Brazil. One of the best quality of this species is its resistance to canker (Cryphonectria cubensis) which usually occurs under tropical environmental conditions. The species, as every other of the Eucalyptus genus, is very sensitive to genotype x environment interaction (KAGEYAMA, 1983; MORI et alii, 1986; PATIÑO-VALERA, 1986 and MORAES, 1987). This phenomena , if mismanaged, can reduce substancially the genetic gains. To decrease these losses, the breeding strategy that has been utilized is the multiple populations. Thus, it has been considered the specificity of genetic materials, thought selection of individuals well adopted and productives on each ecological region.


To study the genetic and silvicultural performance of Eucalyptus urophylla in southern Brazil, the Institute of Forest Research and Study – IPEF though its cooperative program, is developing experimentation in its associated Companies and results are presented in this paper. The objectives of the investigation were:

a) To present the genetic variation of Eucalyptus urophylla tree selected in natural populations of Indonesia, across four locals, individually and jointly, aimed to orient breeding programs of the species;

b) To estimate the progeny x local interaction effects for growth traits; c) To propose the use of these materials in IPEF programs.

LITERATURE REVIEW

Eucalyptus urophylla occurs in wild populations of Flores, Timor, Plantar , Adonara, Alor, Loblem and Wetar island in the Republic of Indonesia. In Flores island it is distributed across regions near Egon, Wokoh, Leworahang and Mandiri mount, usually on rich organic matter basaltic type of soil (MARTIN & COSSALER, 1976). Examining populations (provenances) and progenies of Eucalyptus urophylla in Belo Oriente-MG-Brazil, CAPTANI et alii (1987) found (until 4-year-old) a superiority for volume characteristic in Egon, Ilegele, Lewotobi, Ilimandiri and Longdangwyang provenances. The same provenances were studied by PINTO JUNIOR (1984) in four localities, and 3-year-old, who found a nean superiority in plants height for Ilegele and Egon provenances. Studying a mixed population of Ilegele, Lewotobi, Ilimandiri and Longdangwuang provenances across four localities distributed in São Paulo, Espirito Santo, Minas gerais and Distrito Federal States, PINTO JUNIOR (1984) obtained at the age of 3-year a narrow sense heritability at the plant level of 0.36 for plant height, 0.24 for d.b.h. and the joint heritability of 0.18 for plant height and 0.11 for d.b.h. MORAES (1987), studying progenies of 7-year old of Eucalyptus grandis, concluded that genetic gains estimation utilizing selection among and within progenies in each local and in a joint analysis for d.b.h., plant height and volume traits, were greater when the selection was realized in individual locals. Results with the same tendency were obtained for KAGEYAMA (1983) with the same species at the age of 5 years, and for MORI et alii (1986) and PATIÑO-VALERA (1986) with Eucalyptus saligna at the age of 3- and 2-years, respectively. MORAES (1987), studying progenies of 7-year old of Eucalyptus grandis, concluded that genetic gains estimation utilizing selection among and within progenies in each local and in a joint analysis for d.b.h., plant height and volume traits, were greater when the selection was realized in individual locals. Results with the same tendency were obtained for KAGEYAMA (1983) with the same species at the age of 5 years, and for MORI et alii (1986) and PATIÑO-VALERA (1986) with Eucalyptus saligna at the age of 3- and 2-years, respectively. These works demonstrated the importance of studies about genotype x environment interaction, that SHELBOURNE (1972) described as being the variation among genotypes in response to different environmental conditions.


The genotype x environment interaction, when its effects are not considered in tree breeding programs, may cause a reduction in genetic gains that a selection program would promote. Breeding programs with generalist objectives considereing individuals selected from broad environmental conditions can incorporate these losses (MORI et alii, 1986). NAMKOONG (1984) proposed a strategy for conducting tree improvement programs in multiple population for the maintenance of high genotypic variability in breeding populations, with possibilities to increase gains, return to the original variability, and to reduce he risks of inbreeding. There are several alternatives to investigate the phenomena of genotype x environment interaction. Through biometry, there are FINLAY & WILKINSON (1963) and EBERHART & RUSSEL (1966) models, among others, that are related to the studies of phenotypic stability of genetic materials. Using three models to estimates phenotypic stability of Eucalyptus spp hybrids clones, MORA (1986) observed that the highest gain through management of genotype x environment interaction would occur with the utilization of specific selection for each local, since the utilization of clones with mean stability would reduce the most part of gain in volume.

MATERIAL AND METHODS Half-sib progenies were obtained by open pollination seeds from wild populations of Eucalyptus urophylla from Flores island, Indonesia. Brazilian commercial control populations of the same species were also included in the experiment. Table 01 presents the list of utilized material and its respectives geographics origin. TABLE 01 – Provenances geographic origin used in experiments.

Provenances Latitude Longitude Altitude (m) Wukoh-Island Flores-Indonesia Ilegele-Island Flores-Indonesia Londangwuang-Island Flores-Indonesia Egon II-Aradetimg-Island Flores-Indonesia Saler Wukon-Island Flores-Indonesia Lewotobi-Island Flores-Indonesia Ilimandiri-Island Flores-Indonesia Egon I-Island Flores-Indonesia *Salesópolis-São Paulo-Brazil *Casa Branca-São Paulo-Brazil *Camaquã-São Paulo-Brazil *Linhares-Espirito Santo-Brazil

8º23’S 8º40’S 8º33’S 8º40’S 8º23’S 8º33’S 8º18’S 8º40’S

23º32’S 21º46’S 22º20’S 19º22’S

122º40’E 122º26’E 122º43’E 122º26’E 122º40’E 122º46’E 122º58’E 122º26’E 45º51’E 47º04’E 48º 09’E 40º 04’E

800 720-820 850-940 690-790

940 480-700 400-650 750-780

880 670 517 50

* commercial controls The characteristics of four experimental localities are presented in Table 02.


TABLE 02 – Characteristics of experimentation localities.

Characteristic Aracrus (ES) Belo Oriente (MG) Bom Despacho (MG) Grão Mogol (MG) Latitude Longitude Altitude Rainfall Temperature mean

19o48’S

40o17’W

50m

1360mm

23.6oC

19o10’S

42o20W

280m

1520mm

22.7oC

19o35’S

45o17’W

700m

1375mm

21.0oC

16o30’S

42o50’W

820m

1200mm

23.5oC

The experimental design was compact family blocks with 8 plots (provenances) and 63 subplots (progenies) in Aracruz (ES), 94 in Belo Oriente (MG), 66 in Bom Despacho (MG) and 109 in Grão Mogol (MG) – Brazil. Subplots consisted 10 plants row. Spacing among rows and among plants within rows was 3,0 x 2,0 m in all experiments. Traits measurement occurred at 7 years for d.b.h. plant height (H) and volume (d.b.h.2 x H x �/4): Experimental analysis was done in randon blocks for each local and in joint locals and the genetic parameters estimates were based in KAGEYAMA (1983) and MORAES (1987). For the joint analysis, common progenies of the following provenance were grouped: Ilegele (7 progenies), Longdangwuang (4), Lewotobi (8) and Ilimandiri (11), totalizing 30 progenies, according to the same methodology used by PINTO JUNIOR (1984). For genetic parameter estimates, they were considered as an unique population. The genetic gains estimates with progeny x local interaction effects were obtained by simulating of seeds utilization of selected plus trees from each local and they planted across other ones. Proportion of selection among progenies was 1:3. EBERHART & RUSSEL (1966) method was utilized for the study of progeny x local interaction.

RESULTS AND DISCUSSION

Provenance means for evaluated traits and localities at 7-year-old are presented in Table 03. Comparisons among average values of provenances and commercial controls demonstrated that all provenances were superiors. For volume, Ilegele provenance was 84% superior in relation to the control. Provenances average value was 58% superior. The major difference between provenances mean and controls (457%) occurred in Aracrus (ES) locality. The majority of studied provenances is represented by small number of progenies, what can be seen in Table 03. For the statistical analysis of the progenies and parameters estimates for each local and jointly, PINTO JUNIOR (1984) grouped the four provenances (Ilegele, Longdangwuang, Lewotobi and Ilimandiri) based on their closeness in the natural


region and also in relation of similar growth of this provenances in the locals of study. The same procedures were used in present paper.

Table 04 presents the results of variance analysis, averages and experimtnal variation coefficients envolving the 30 common progenies across four locals. TABLE 04 – Results of variance analysis, averages and experimental variation coefficients for traits and locals, envolving 30 progenies at 7-year-old.

Traits Locals Mean F prog C.V. exp (%)

d.b.h.

Aracruz (ES) Belo Oriente (MG) Bom Despacho (MG) Grão Mogol (MG)

14.36 13.73 11.15 10.57

3.53** 1.56*

1.86** 3.01**

8.74 13.40 13.70 12.70

Plant Height


21.50 15.77 13.96 11.97

2.95** 1.38ns 3.11** 2.86**

7.50 10.90 11.17 10.14

Cylindric volume (m3/plant)


0.4015 0.2932 0.1651 0.1312

2.99** 2.09** 2.14** 2.98**

22.81 37.75 30.37 32.10

F test values for progênies presented high statistical significance for all localities and traits, except for Belo Oriente (MG) locality where F test was significative at 5% level for d.b.h., and not significative for plant height. The experimental variation coefficients


presented similar values, as found by PINTO JUNIOR (1984) and CAPITANI et alii (1987) for the same provenances utilized in the present study. The average values, F test and experimental variation coefficient of analysis of four localities in groups are presented in Table 05. The highest mean productivities for d.b.h., plant height and volume were related to Aracruz (ES locality, with 14.36 cm, 21.50 m, and 0,4015 cm3, respectively. TABLE 05 – Results of joint variance analysis, averages and experimental variation coefficients for all traits and locals, envolving 30 progenies at 7-year-old.

F Test Characters Mean

Progenies (P) Locals (L) Interaction (PxL)

C.V. Exper. (%)

d.b.h. 12.46 1.03ns 26.16** 8.73** 11.80 Plant Height 15.80 2.03** 337.11** 3.67** 9.35 Cyl. Volume (m3) 0.2480 1.40ns 119.35** 3.97** 29.00 The F test for progenies, in joint analysis, presented statistical significance at the level of 1% for plant height. The same level occurred for the three traits on study for local and progeny x local interaction. The differences on the progenies performance in different localities have a high contribution on productivity response when different improvement strategies are applied (NAMKOONG et alii, 1980; MORI et alii, 1986 and MORAES, 1987). In this context, strategies considering the genotype x environment interaction effects are more appropriated. Variation coefficients were studied the three traits and for each local and in groups.


Table 06 – Coefficnets of variation for traits and locals studied

Variation Coefficients Characters Localities pCV CVp CVw CVg CVexp CVp1 CVg/CVexp


9.07 9.34

10.32 12.48

25.87 39.27 31.37 33.97

24.99 38.98 29.57 31.77

7.76 4.35 7.14

10.11

8.84 13.40 13.70 12.73

- - - -

0.89 0.32 0.52 0.79 d.b.h.

Mean Join

10.30 9.56

32.62 37.20

31.33 32.02

7.34 1.80

11.39 11.80

- 18.27

0.64 0.15


7.10 7.24

10.95 9.88

19.49 26.04 23.25 23.52

18.50 25.32 19.95 21.11

5.89 4.20 9.17 8.14

7.50 10.90 11.17 10.14

- - - -

0.79 0.39 0.82 0.80

Plant Height

Mean Join

8.79 7.12

23.08 24.31

21.22 21.44

6.85 4.92

9.93 9.35

- 8.92

0.69 0.53


20.34 29.96 23.09 33.70

63.02 131.22 65.79 74.98

61.36 131.08 61.18 67.71

16.52 13.87 16.61 24.71

22.81 37.75 30.37 32.10

- - - -

0.72 0.37 0.55 0.77

Cylindric volume

Mean Join

26.77 17.86

83.75 96.13

80.33 95.97

17.93 10.57

30.76 29.00

- 26.77

0.58 0.36

Note: pCV = phenotypic variation coefficient at average level. CVp = phenotypic variation coefficient at plant level. CVw = within progenies variation coefficient. CVg = genetic variation coefficient. CVexp = experimental variation coefficient CVp1 = progeny x local interaction variation coefficient In general, plant height presents the smallest averages and joint variation coefficients, and volume presents the highest values. The phenotypic variation coefficients within progenies (CVw) was about three times higher than phenotypic variation coefficients in averages level of progenies (CVp). This fact induces to conclude that for Eucalyptus urophylla the strategy of superior individual selection within progenies tests must be conduced with higher intensity within progenies. The genetic gain is also directly correlated with the heritability of considered material. Table 07 contain the heritability coefficient for the different traits and localities.


TABLE 07 – Narrow sense heritability coefficients at plant level (h2), at progenies mean level (h2) and at within progenies level ( 2

mh ) and at within progenies level ( 2wh ).

Character

Locality Parameter d.b.h. Plant height Cylindric

volume h2 0.34 0.37 0.27

2mh 0.73 0.69 0.66 Aracruz (ES) 2wh 0.29 0.30 0.22

h2 0.05 0.10 0.04 2mh 0.22 0.34 0.21 Belo Oriente

(MG) 2wh 0.04 0.08 0.03

h2 0.21 0.62 0.26 2mh 0.48 0.70 0.52 Bom Despacho

(MG) 2wh 0.18 0.63 0.22

h2 0.35 0.48 0.43 2mh 0.66 0.68 0.53 Grão Mogol

(MG) 2wh 0.30 0.45 0.40

h2 0.24 0.39 0.25 2mh 0.52 0.60 0.48 Mean 2wh 0.20 0.37 0.22

h2 0.01 0.19 0.05 2mh 0.04 0.54 0.35 Joint 2wh 0.01 0.18 0.04

Highest average heritability coefficients were obtained for plant height, being 0.39 in narrow sense at plants level, 0.60 in average progenies level and 0.37 within progenies. The same tendency occurred for the joint coefficients. The heritability coefficients for average level of progenies for each local and in joint, for three traits, were higher than coefficients at plants level, showing that selection can be more effective at average level of progenies than within progenies. The variation coefficients values multiplied by heritability among ( pCV x mh2 ) and within (CVw.h2w) progenies for the localities and traits are presented in Table 08.


TABLE 08 – Variation coefficient multiplied for heritability, among and within progenies.

C.V.xh2 d.b.h. Planting Height Cylindric Volume Locality

Among Within %(**) Among Within %(**) Among Within %(**) Aracruz (ES) Belo Oriente (MG) Bom Despacho Grão Mogol (MG)

6.64 2.02 4.94 8.18

7.32 1.45 5.18 9.65

109 72

105 118

4.89 2.43 7.67 6.71

5.63 2.09

12.61 9.42

115 86

164 140

13.41 6.42

11.95 18.12

13.34 4.40

13.53 27.06

99 69

113 149

Mean 5.45 5.88 108 5.43 7.44 137 12.48 14.58 117 Joint 0.38 0.32 84 3.84 3.86 100 6.25 3.84 61

** Relative percentage between among and within progenies Although phenotypic variation coefficient in the progenies means level ( pCV ) presented inferior values than within progenies variation coefficients (CVw), heritability coefficients presented an opposite behaviour. Thus, the multiplications CV.h2 for among and for within progenies presented similar values. However, CV.h2 values within progenies for all traits and localities, except Belo Oriente (MG) that presented inverse results. The importance of the multiplication values of these coefficients can be observed in the genetic gain estimate formula of FALCONER (1981), modified for percentage, in testing for selection among and within progenies. The coefficients are basic component of the formula that are presented as follow: GSm% = i1 . pCV . 2

mh , GSw% = i2 . CVw . 2

wh , GS% = GSm% + GSw% , Where: GSm%, GSw% and GS% are respectively, the genetic gains in percentage among progenies, Within progenies and total; . i1 and i2 are standardized selection differential among and within progenies, respectively; . pCV and CVw are phenotypic variation and within progenies variation coefficients, respectively. 2

mh e 2wh are average heritability and within progenies heritability coefficients,

respectively. The CV.h2 values are properties of the population and locals, being possible to the breeder only the handling of theses components through the standardized selection differential (i). In a progeny test, the increase of number of treatment to permite increasing possibilities of selection among progenies becomes limited to the physical size of the test to be established. On the other hand, the number of individuals can be considerably increased within progenies, by establishing larger plots near the experiment, but out of it. In that way,


possibilities for selection within progenies and, consequently, the standardized selection differential is increased. This procedures was presented by MORI et alii (1989). Therefores, the total genetic gain in a generation can be increased, by amplifying the standardized selection differential (i) within progenies. In this paper the genetic gains were obtained through a proportion of selection of 1:3 among progenies and 1:10 within progenies. The results for the three traits and four localities are show in Table 09. TABLE 09 – Genetic gains (%) for differents traits, locals and in joint analysis.

Localities Characters

Aracurz (ES) Belo Oriente (MG)

Bom Despacho (MG)

Grão Mogol (MG)

Mean Joint Losses by Interaction

(PxL) d.b.h. Plant Height Cylindric Volume

20.42

15.58

39.04

4.91

6.50

15.20

14.84

31.10

37.68

26.47

24.37

68.64

16.66

19.39

40.14

0.92

11.25

13.41

15.74

8.14

26.73 Proportion of selection: 1:3 among progenies 1:10 within progenies The best gains were obtained for volume (40.14%), followed by plant height (19.39%) and by d.b.h. (16.66%). The joint gains were inferior, with values of 13.41% for cylindric volume, 11.25% for plant height and 0.92% for d.b.h. If the best individuals of the four localities are grouped in a same seed orchard and seeds are collected for planting in the same locals, the joint genetic gains for volume would be 13.41%. On the other hand, if four seed orchard with the best individuals of each locality were established and the collected seeds were planted in the same locals, the mean expected gains for volume would be 40.14%. This means that if the first procedure is followed, a loss of 26.73% of expected gains would occur for not considering the effects f progeny x local interaction (Table 09). Figure 1 presents histograms of the percentages of average genetic gains of the four localities and of the percentages of joint gains for the three studied traits.


FIGURE 1 – Histograms of average and joint genetic gains for different traits.

Table 10 presents the percentage of expected genetic gains decreased by progeny x local interaction. A raiot of 1:3 was utilized for selection among progenies.


TABLE 10 – Expected genetic gains percentage reduced by progeny x local interaction.

Planting Local Trait Selection Local

Aracruz (ES) Belo Oriente (MG)

Bom Despacho (MG) Grão Mogol (MG)

d.b.h. Aracruz (ES) Belo Oriente (MG) Bom Despacho (MG) Grão Mogol (MG)

5.95* -1.42 1.17 -1.68

-0.05 2.20* 0.29 0.06

1.59 1.08

4.61* 2.15

1.75 1.87 4.62

8.30* Height Aracruz (ES)

Belo Oriente (MG) Bom Despacho (MG) Grão Mogol (MG)

4.62* -0.80 0.80 1.93

0.32 2.52* 0.43 0.58

0.60 0.95

7.17* 4.61

1.36 0.40 3.81

6.76* Cyl. Volume


12.69* 0.02 2.24 -3.65

1.63 6.05* 0.73 -0.39

3.15 1.51

1.40* 3.46

2.29 0.72 4.21

17.33* Proportion of selection among progênies 1:3 * genetic gains without progeny x local interaction From applied point of view, if a selection in Grão Mogol (MG) locality is practiced and, based on these results, seeds of the best plus trees (that originated the progeny test) are collected and planted across the four localities the highest gains in the same locality would occur (17.33%). If the same seeds lot is planted in Bom Despacho (MG), the gains would be 3.46% (with losses of 7.94% of its local performance). For the Belo Oriente (MG) and Aracruz (ES) localities, no genetic gain would be observed, and volume productivity mean for each local would be diminished for 0.39% and 3.65%, respectively. The response to the expected genetic gain would be negative. Table 11 assembles the results of the phenotypic and genetic variation coefficients among the traits from the different locals. TABLE 11 – Phenotypic (rF) and genetic (rG) correlation coefficient.

Planting Local Locality Selection Local

Height x d.b.h. Height Cyl. Vol.

d.b.h. Cyl. Vol.

Aracruz-ES rF rG

0.80 0.80

0.80 0.81

0.97 0.98

Belo Oriente – MG rF rG

0.75 1.14

0.67 1.18

0.89 1.85

Bom Despacho – MG rF rG

0.91 0.98

0.92 0.99

0.96 0.98

Grão Mogol – MG rF rG

0.77 0.78

0.74 0.82

0.88 1.01

Mean (*) rF rG

0.83 0.85

0.82 0.87

0.93 0.99

* Without Belo Oriente (MG) locality.


The genetic correlations were highest than the phenotypic one for all cases. For the Belo Oriente (MG) locality, the values of genetic correlation coefficients estimates were superior than 1.00, denoting low precision of the estimatings. Therefore, estimates were based on the average account for localities. One of the strategies that can be utilized to conduct breeding programs in the use of progenies with higher adaptation hability to different localities. EBERHART & RUSSEL (1966) method is very utilized to determine the phenotypic stability to different environments. It consists of estimating the regression coefficient ( b̂ ), the deviation variances of b̂ and the average volume per progeny, the regression coefficients and it respective deviation. These values are shown in Figure 2 and Table 12. TABLE 12 – Progeny average values for cylindric volume (m3), regression coefficient ( b̂ ) and b̂ deviation variance obtained by EBERHART & RUSSELL (1966) methodology.

Progeny Mean b̂ S2 Deviation (b) 1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

0.24 0.28 0.24 0.29 0.27 0.25 0.34 0.27 0.24 0.24 0.24 0.22 0.26 0.27 0.25 0.24 0.22 0.24 0.33 0.15 0.22 0.19 0.22 0.24 0.24 0.22 0.26 0.23 0.28 0.27

0.95 0.71 0.48 1.04 1.09 0.87 1.42 0.87 0.83 1.08 0.92 0.79 1.32 0.98 1.16 0.86 0.97 1.27 2.00 0.57 1.17 1.26 1.19 1.05 1.08 0.55 0.90 0.26 1.47 0.88

-0.001 0.012 -0.001 -0.001 -0.002 -0.001 0.025 0.000 -0.002 0.001 0.010 0.002 -0.002 -0.001 0.000 -0.001 -0.001 -0.001 -0.002 -0.002 0.000 0.000 -0.002 -0.001 0.001 -0.001 -0.001 0.009 0.006 -0.002


FIGURE 2 – Phenotypic stability for cylindric volme trait by BERHART & RUSSELL (1966) MODEL

Progenies that presented highest volume were 7 ( b̂ = 1.42), 19) b̂ = 2.00), 4 ( b̂ = 0.71) and 29 ( b̂ = 1.47). The progeny 4, besides habing high volume, has a regression coefficient of about 1.00, meaning a more predictable performance across differents locals. It is very desirable, especially, to have variance of deviations from regression fo b̂ close to zero, indicating confidence of regression. On the other hand, the progeny 19, with highest volume and b̂ equal 2.00 is more specific for environments more productive. It is the best progeny in Aracruz (ES), the third in Belo Oriente (MG) and one of the worst in Grão Mogol (MG) and Bom Despacho (MG). For studies of phenotypic stability, it would be advisable to work with a great number of progenies to increase the possibilities to choose individuals with larger capacity of adaptation.


For the comparison of genetic gains among three breeding strategies it was necessary the utilization of the selection ratio of 1:6 among progenies to make possible to choose progenies more responsive with production superior to average. Five progenies were selected among thirty. Table 13 presents percentage of genetic gains in volume as an average for progenies, according to the breeding strategies of multiple population(with selection of specific progenies for each localities), of conduction of stable phenotypes (with selection of individuals with major adaptation ability in the local in study) and traditional (with selection of progenies not considering the environments difference and the progeny x local interaction). TABLE 13 – Genetic gains (%) at progeny level.

Locality

Strategy Aracurs (ES) Belo Oriente

(MG)

Bom Despacho

(MG)

Grão Mogol (MG) Mean

Multiplus population Stable Traditional

18.81 5.09 1.15

10.18 0.79 1.93

14.18 10.72 1.09

26.10 13.25 1.94

17.32 7.46 1.53

Proportion of selection 1:6 among progeny. Applying the procedure of the traditional strategy, the gains were small with average of 1.53% in volume. Using the superior and better adapted progenies in different localities, the gains were 7.46%. Selecting the best progenies at each locals (multiple populations strategies), the gains were the largest with average value of 17.32%. The differences were large among the multiple population and the conduction of stable progenies (9.86%) and of 15.79% for the traditional. Between the strategy of the stable progenies and the traditional, the difference was 5.93%. Based on the gains, it is observed an avantage to use the multiple populations over the others. However, its conduction is more complex and with higher cost than the two other. It must have a technical-economical-operational equilibrium for making its establishment feasible. The best proposal would be the utilization of a mixed strategy, with conduction of the more generalistic genotypes in determined stages. At first, a population with specific adaptation would be established, for the best utilization of progeny x local interaction. As a second step, a selection of more stable progenies would be made.

CONCLUSION a) Progenies variation among locals: For d.b.h., plant height and volume traits, at the age of 7 years there was variation among progenies in different localities and the phenomenum of progeny x local interaction was present.


b) Heritability values: Plant height trait presented the best narrow sense heritability coefficients at plant level (h2), at progeny mean level (h2) and within progenies ( 2

wh ), showing more genetic control than the others traits studied, which implicates in smaller influence of the progeny x local interaction effects over the trait. c) Expected genetic gains and losses inherents of the progeny x local interaction effects: The best genetic gains with selection among and within progenies for d.b.h. and volume were shown from Grão Mogol (MG) and, for plant height, from Bom Despacho (MG). Highest losses inherents of the progeny x local interaction effects occurred for volume (26.73%). The highest reduction in genetic gain for volume was 3.65% in Aracruz (ES), when selection was made in Grão Mogol (MG). d) Breeding strategies: Comparing the three strategies for conducting breeding programs, it is concluded that multiple populations strategy is more indicated than the other ones. However, there is a possibility for conducting mixed programs with selection of stable progenies for all regions.

ACKNOWLEDGEMENTS The authors wish to thank the forest Companies Aracruz Florestal S.A., Cenibra Florestal S.A., CAF Florestal S.A. and Florestas Rio Doce S.A. and Professor Norberto da Silva, University of São Paulo, for collaborating in the accomplishment of this study.

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