Seleção genética em progênies de Eucalyptus camaldulensis em área de cerrado matogrossense / Genetic selection in Eucalyptus camaldulensis progenies in savanna area of Mato Grosso State, Brazil

O presente trabalho objetivou estimar parâmetros, correlações e ganhos genéticos para caracteres de crescimento e forma, em um teste de progênies deEucalyptus camaldulensisna região centro-oeste do Brasil. Aos três anos de idade, as progênies foram avaliadas quanto aos caracteres: altura total (ALTT), altura comercial (ALTC), diâmetro à altura do peito (DAP) e forma de fuste (FF). A análise de deviance detectou diferenças significativas para os caracteres ALTC, DAP e FF. As estimativas das herdabilidades individuais foram de baixa magnitude para ALTT (0,10) e DAP (0,16), porém, ALTC (0,18) e FF (0,25) apresentaram valores de média a alta magnitude. Os coeficientes de variação genética individual (CVgi%) variaram de 8,59% para FF a 15,91% para ALTC. As correlações fenotípicas e genéticas preditas foram positivas e de alta magnitude entre ALTT e ALTC (0,80 e 0,82, respectivamente) e ALTT e DAP (0,85 e 0,86, respectivamente), indicando que a seleção indireta pode ser utilizada para essas associações. A seleção individual se mostrou superior, quando comparada à seleção entre e dentro. Os valores encontrados indicaram perspectivas de progressos genéticos com seleção baseada nos caracteres avaliados.

This study aimed to estimate parameters, correlations and genetic gain for growth and shape traits in a progeny trial using Eucalyptus camaldulensisin Central Brazil. When it was three years old, progenies were evaluated for the following traits: total height (ALTT), commercial height (ALTC), diameter at breast height (DAP) and stem form (FF). Deviance analysis detected significant differences for ALTC, DAP and FF. Estimates of individual heritability showed low magnitude for ALTT (0.10) and DAP (0.16). However, ALTC (0.18) and FF (0.25), showed median to high magnitude values. Individual genetic variation coefficients (CVgi%), ranged from 8.59% (FF) to 15.91% (ALTC). Predicted phenotypic and genetic correlations were positive and of high magnitude between ALTT and ALTC (0.80 and 0.82) as well as between ALTT and DAP (0.85 and 0.86), indicating that indirect selection can be used for these associations. Individual selection showed to be superior when compared to selection between and within. Found values indicated perspectives of genetic progress with selection based on the evaluated characters.

Variabilidade genética para caracteres morfométricos de matrizes de castanha-do-brasil da Amazônia Mato-grossense / Genetic variability for morphometric characteristics in Brazilian nut parent trees from northern Mato Grosso, Amazon rain forest

O presente estudo objetivou estudar a variabilidade genética de matrizes de Bertholletia excelsa através da estimação de parâmetros e ganhos genéticos para os caracteres peso/ouriço (g), peso de sementes/ouriço (g) e número de sementes/ouriço no pré-melhoramento da espécie. Foram utilizadas 90 matrizes de polinização aberta, sendo 30 matrizes de cada tipo, denominadas localmente de rajada, mirim e rosa, no município de Cotriguaçu, noroeste de Mato Grosso, região amazônica. O experimento foi estabelecido sob delineamento inteiramente ao acaso, com 90 tratamentos (matrizes) e seis ouriços por matriz, com suas respectivas sementes. As variáveis foram analisadas usando-se a metodologia de modelo linear misto do software SELEGEN-REML/BLUP. Os coeficientes de herdabilidades individuais no sentido amplo dos efeitos genotípicos totais (0,21, 0,14 e 0,34) para os caracteres peso/ouriço (g), peso de sementes/ouriço (g) e número de sementes/ouriço, respectivamente, são considerados moderados para os dois primeiros caracteres e alto para o caráter número de sementes/ouriço, sugerindo expressivo controle genético. A seleção das 10 melhores matrizes revelou predominância da procedência do tipo rosa, proporcionando ganhos genéticos expressivos de pelo menos 24,16% para peso/ouriço (g), 27,44% para peso de sementes/ouriço e 16,92% para o caráter número de sementes por ouriço. Os valores expressivos das matrizes do tipo rosa estimulam a utilização desses germoplasmas em programas de melhoramento genético da espécie, na seqüência das avaliações, bem como apontando para a possibilidade de obtenção de híbridos intraespecíficos para caracteres desejáveis.

The goal of the study was to detect genetic variability in Brazilian nuts parent trees through parameters estimation and genetic gains for the following indexes: fruit weight (g) seed weight per fruit (g) and number of seeds per fruit at species pre-improvement. Ninety (90) open pollination parent trees were used, 30 of which being of each type, locally called "rajada", "mirim" and "rosa" at the Cotriguacu municipality, Northeastern of Mato Grosso State. A completely randomized design was used, with 90 treatments (parent trees) and six fruits per parcel with their respective seeds. Variables were analyzed using the method of mixed univariate additive linear model from the software SELEGEN-REML/BLUP. Individual heritability coefficients in the broad sense for total genotypic effects (0,21, 0,14 e 0,34) for fruit weight (g) seed weight per fruit (g) and number of seeds per fruit (g) respectively, are considered moderate for the two first indexes and high for number of seeds per fruit, suggesting substantial genetic control. Selection of the 10 best provenances and parent trees showed predominance of the "rosa" type, allowing substantial genetic gains of at least 24,16% for fruit weight (g), 27,44% for seed weight per fruit and 16,92% for the number of seeds per fruit. The remarkable values for the "rosa" type suggest utilization of such germoplasms in genetic improvement programs of this species in the following evaluations. The results also point out the possibility of obtaining intraspecific hybrids for desirable characteristics.

Prediction of Hevea progeny performance in the presence of genotype-environment interaction

Twenty two open-pollinated Hevea progenies from different parental clones of the Asian origin were tested at five sites in the Northwestern São Paulo State Brazil to investigate the progeny girth growth, rubber yield, bark thickness and plant height. Except for the rubber yield, the analysis of variance indicated highly significant (p<0.01) genotype x environment interaction and heterogeneity of regressions among the progenies. However, the regression stability analysis identified only a few interacting progenies which had regression coefficients significantly different from the expected value of one. The linear regressions of the progeny mean performance at each test on an environmental index (mean of all the progenies in each test) showed the general stability and adaptability of most selected Hevea progenies over the test environments. The few progenies which were responsive and high yielding on different test sites could be used to maximize the rubber cultivars productivity and to obtain the best use of the genetically improved stock under different environmental conditions.

Vinte e duas progênies de Hevea de polinização aberta obtidas de diferentes clones fenotipicamente selecionados de uma população de origem asiática Hevea brasiliensis (Willd. Adr. ex Juss.) Muell-Arg. durante três anos foram testadas em cinco locais. As variáveis perímetro do caule, produção de borracha, espessura da casca e a altura de planta foram determinadas em todos locais no Estado de São Paulo, Brasil. De acordo com as análises de variância, com exceção a produção de borracha, observou-se a existência de interações significativas entre genótipo x ambiente (p<0.01) e heterogeneidade de regressões entre as progênies. Porém, a análise de estabilidade de regressão identificou a interação de poucas progênies cujos coeficientes de regressão foram significativamente diferentes do valor esperado de um. Regressões lineares do desempenho médio das progênies para cada teste em um índice ambiental (média de todas as progênies em cada local) mostrou a estabilidade e adaptabilidade da grande maioria das progênies de Hevea nos diferentes locais. As poucas progênies que foram superiores e altamente produtivas nos diferentes testes de progênies podem ser utilizadas para maximizar a produtividade de cultivares de seringueira e determinar a melhor utilização do ganho genético dos grupos sob as diferentes condições ambientais de cultivo.

Genetic variation in growth traits and yield of rubber trees (Hevea brasiliensis) growing in the Brazilian state of São Paulo

Analysis of variance and covariance was preformed on growth traits (stem girth, bark thickness, total height gain and rubber yield) of 22 open-pollinated progenies of the rubber tree Hevea brasiliensis from an Asian Hevea collection introduced to Agronomic Institute (Instituto Agronômico, Campinas, São Paulo, Brazil; IAC) in 1952. This progeny trial was replicated at three sites in São Paulo state and it was found that at three years from sowing there was statistically significant variation for girth, bark thickness, height and rubber yield. An individual test sites, values of individual plant heritability for girth ranged from h= 0.36 to h= 0.89 whereas values for heritability for progeny means ranged from h= 0.77 to h= 0.87. These moderate and high heritabilities suggest that a combination of progeny and within-progeny selection would be effective at increasing girth in this population at individual sites. Across sites, values of individual-plant heritability for girth ranged from h= 0.36 to h= 0.47, whereas values for heritability of progeny means girth ranged from h= 0.77 to h= 0.87. There were high positive genetic correlations between increased girth and bark thickness suggesting that breeding aimed at increasing girth would also increase bark thickness and possibly height

Age-age correlation for early selection of rubber tree genotypes in São Paulo State, Brazil

In a field trial involving 68 rubber tree (Hevea spp.) clones calculation of genotypic correlation coefficients revealed significant age-age correlation from age 1 to 6 (immature period) for girth A and for age 7 to 12 (mature period) for girth B and for age 7 to 12 (production of latex) for yield. Rank correlation coefficients between all immature ages of girth (girth A), all ages of mature girth (girth B) and all annual rubber production (yield) were significant for the three traits, with the coefficients decreasing with increasing age. Selection of the sets of best 30, 15, 10 and 5 clones from the available 68 clones at a given age was generally accompanied by a descending order of percentage success. It was suggested: (a) to have the best 30 clones of age 6, select the set of best 36 clones at age 2, (b) to have the best 15 clones of age 6, select the set of best 20 clones at age 3, (c) to have the best 5 clones of age 6, select the set of best 8 clones at age 4, and (d) to have the best 3 clones of age 6, select the set of best 3 clones at age 5. More than 80% of the targeted clones on girth A or girth B basis and more than 76.7% clones on yield basis were found to get selected at steps (a) through (d). For achieving early multiplication of the most productive clone for deployment, multiplication should be started with the best 36 (i.e. 60%) clones selected at age 2.

Variabilidade genética e estimativas de herdabilidade para o caráter germinação em matrizes de Albizia lebbeck / Genetic variability and heritability estimates for the germination trait in Albizia lebbeck parent trees

Em áreas rurais, buscam-se espécies arbóreas que apresentem rápido crescimento, habilidade para fixar nitrogênio e melhorar a estrutura do solo, especialmente em locais degradados, tendo usos múltiplos e facilidade para consórcio com culturas agrícolas. A Albizia lebbeck apresenta essas características. O presente estudo avaliou a variabilidade genética e estimou parâmetros genéticos em progênies de albizia para o caráter germinação. Sementes de 26 matrizes da espécie foram coletadas no município de Campo Grande, MS. Os testes de superação da dormência e germinação foram realizados no laboratório de Botânica da Universidade Católica Dom Bosco. O delineamento experimental foi o de blocos ao acaso, com cinco repetições e 15 plantas. As estimativas de herdabilidade no sentido amplo foram de 0,43 para indivíduos e 0,79 para média de matrizes, sugerindo expressivo controle genético. A seleção das 10 melhores matrizes proporcionou ganho genético de, pelo menos, 8,1 por cento. Este germoplasma pode ser usado em programa de melhoramento genético para a espécie.

Genetic variability and selection for laticiferous system characters in Hevea brasiliensis

Six laticiferous system characters were investigated in 22 three-year-old, half-sib rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.] progenies, evaluated at three sites (Votuporanga, Pindorama and Jaú, all in the São Paulo State, Brazil). The traits examined were: average rubber yield (Pp), average bark thickness (Bt), number of latex vessel rings (Lv), average distance between consecutive latex vessel rings (Dc), density of latex vessels per 5 mm per ring averaged over all rings (Dd) and the diameter of the latex vessels (Di). The joint analysis showed that site effect and progeny x sites interaction were significant for all traits, except Lv. Estimates of individual heritabilities across the three sites were high for Bt; moderate for Lv, Pp and Dc; low for Dd and very low for Di. Genetic correlations in the joint analysis showed high positive correlations between Pp and the other traits. Selecting the best five progenies would result in genetic gains of 24.91 percent for Pp while selecting best two plants within a progeny would result in a Pp genetic gain of 30.98 percent.

Genotype-environment interaction and phenotypic stability for girth growth and rubber yield of Hevea clones in São Paulo State, Brazil

The best-yielding, best vigour and most stable Hevea clones are identified by growing clones in different environments. However, research on the stability in Hevea brasiliensis (Willd. Adr. ex Juss.) Muell.-Arg. is scarce. The objectives of this work were to assess genotype-environment interaction and determine stable genotypes. Stability analysis were performed on results for girth growth and rubber yield of seven clones from five comparative trials conducted over 10 years (girth growth) and four years (rubber yield) in São Paulo State, Brazil. Stability was estimated using the Eberhart and Russell (1966) method. Year by location and location variability were the dominant sources of interactions. The stability analysis identified GT 1 and IAN 873 as the most stable clones for girth growth and rubber yield respectively since their regression coefficients were almost the unity (beta = 1) and they had one of the lowest deviations from regressions (S2di). Their coefficient of determination (Rý) was as high as 89.5 percent and 89.8 percent confirming their stability. In contrast, clones such as PB 235, PR 261, and RRIM 701 for girth growth and clones such as GT 1 for rubber yield with regression coefficients greater than one were regarded as sensitive to environment changes.