Number Of Latex Vessel Rings Research Articles

Relationships between yield and some anatomical and morphological traits in rubber tree progenies

The present work evaluated the relationship of rubber yield with morphological and structural traits of the laticiferous system in rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. Arg] open-pollinated progenies to understand the cause and effect relationships between traits in order to enable future early selection. The progenies were installed in Jaú, Pindorama and Votuporanga in a randomized block design, with five replications and 10 plants per plot at a spacing of 2.0 × 2.0 m. The traits evaluated at three years of age were rubber yield (Yld); girth (Grt), expressed by the stem perimeter; bark thickness (BT); number of latex vessel rings (RG); length (PL), diameter (PD) and petiole index (PI); leaflet length(LFL) and width (LFW); leaf width (LW), area (LA) and index (LI); and number of leaf storeys (NLS). Coefficients of the genotypic correlations were used for a graphical representation of the correlation network created in the Genes program. Subsequently, the diagnosis of multicollinearity, as well as the analysis of the direct and indirect genotypic correlations of bark anatomical traits, leaf morphological traits, girth, and rubber yield, were performed. The traits that showed significant genotypic correlations with rubber yield at the three evaluated sites were girth, bark thickness, and number of leaf storeys. The girth character had the largest direct effect on rubber yield. Canonical correlation analysis showed that selection for the number of leaf storeys may increase at least three of the traits (yield, girth, bark thickness, and number of latex vessel rings) for most locations studied. There is an association between the yield traits (yield, girth, and the laticiferous system) and the morphological traits.

Associations among rubber yield and secondary traits in juvenile rubber trees progeny

The reduction in the selection cycle for new rubber tree clones (Hevea brasiliensis) and the increase of rubber yield are sought continuously for crop breeding programs. Thus, the relation of rubber yield was assessed by morphological traits of the plant and structural laticiferous system of rubber trees in open pollinated progeny for indirect selection effect. The progeny was obtained from seeds of 22 selected clones according to yield and vigor of a population base established at the Agronomic Institute in Campinas. Progeny trials were installed in Jau, Pindorama and Votuporanga, in a randomized block design, five replications and ten plants per plot, spaced 2.0 × 2.0 m. The traits assessed at three years after planted were: rubber yield; girth; bark thickness; number of latex vessel rings; average distance between consecutive latex vessel rings; petiole length, petiole diameter and petiole index; leaflet length, leaflet width, leaf width, leaf area and leaf index and leaf storey. Coefficients were estimated by genotypic and phenotypic correlations between these traits. Overall the genotypic correlation coefficients had higher magnitudes compared to the phenotypic, indicating that genetic factors presented more influence on the association among traits. Rubber yield was correlated with traits related to vigor and laticiferous system, but did not correlate with morphological traits. The vigor and system laticiferous traits can be used for indirect selection in rubber tree breeding programs and possibility the shortening the breeding cycle. Girth showed highly significant correlation with bark thickness and leaf storey in Jau, Pindorama and Votuporanga, indicating that these traits can contribute to the secondary traits selection. Future studies with these progeny into adulthood will be important to verify whether the correlations persist, proving indirect selection at the age of three years old as effective.

Association among stability measurements in rubber tree traits

The simultaneous use of different methods of stability analysis is becoming more widely used in the selection of genotypes in breeding programs. Knowing how these different methods are associated can contribute to a more efficient selection. The objective of the present study was to assess association among different methods of stability analysis in the rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.], using different traits and different groups of genotypes for the same trait. Two open-pollinated progeny populations (POP1 and POP2) and a group of clones (Group 1) were analyzed. POP1 contained 22 progeny, assessed in the municipalities of Pindorama, Votuporanga and Jaú, São Paulo state, Brazil. POP2 included 30 progeny assessed in Selvíria, Mato Grosso do Sul state, Votuporanga and Colina, São Paulo state, Brazil. Group 1 consisted of 25 clones assessed in Votuporanga. The following traits were assessed in POP1: girth, rubber yield, bark thickness and number of latex vessel rings. Rubber yield was assessed in POP2 and Group 1 clones. The following methods of stability analysis were used: Wricke; Eberhart and Russell; Lin and Binns; AMMI (Principal Additive Effect and Multiplicative Interaction) and HMRPGV (Harmonic Mean of the Relative Performance of the Genetic Values) predicted by Blup (Best Linear Unbiased Prediction). The Spearman correlation was used to verify the association between the stability parameters. Three scenarios were observed; in the first, some parameters did not show significant association in any of the analyses: Eberhart and Russell with Lin and Binns; Eberhart and Russell with HMRPGV; Wricke with HMRPGV; AMMI with Lin and Binns and AMMI with HMRPGV. In the second, some parameters showed significant associations in all the analyses such as: Wricke with AMMI, Lin and Binns with HMRPGV. Finally, in the third, the significance of association varied according to the analysis: Eberhart and Russell with Wricke, Eberhart and Russell with AMMI and Wricke with Lin and Binns. Therefore, the association among some stability parameters varies according to the trait and/or the group of genotypes analyzed. The association observed in one analysis cannot be applied to another analysis. In this data analysis is possible to observe that the AMMI method can be used with HMRPGV or Lin and Binns. In addition, Eberhart and Russell can be used with HMRPGV or Lin and Binns, since they offer differentiation and provide additional approaches to the study of stability.

Genetic parameters in a rubber tree population: heritabilities, genotype-by-environment interactions and multi-trait correlations

Rubber tree breeding programs are mainly driven by selection of individuals with high yield and quality of rubber. Data from 51 open-pollinated progenies tested on six sites in Brazil were analyzed over several traits to estimate the following: genetic parameters such as narrow-sense heritability and additive genetic variance in single- and multi-site analyses, type B correlations to determine the relevance of genotype-by-environment interactions and its effects on alternative selection strategies, additive genetic repeatability correlation for rubber yield based on three consecutive yearly measurements, and type A correlations to evaluate trait-to-trait genetic associations for all measured traits. Average rubber yield (RYm) showed an estimated narrow-sense heritability of 0.31, with an estimated type B correlation of 0.84, indicating low levels of genotype-by-environment interaction. The trait survival and number of latex vessel rings (RG) showed larger genotype-by-environment interaction and the lowest heritabilites. High to moderate type B correlation was found for most traits, with a value of 0.85 between diameter (or girth) and RYm; therefore, it is possible to achieve interesting rubber yield genetic gains (over 3 years of measurements) from indirect selection based on diameter at age 2.

Estimation of genetic parameters in rubber progenies

This study was designed to evaluate the genetic variability, the potential for rubber yield and secondary traits of rubber tree progenies at three locations in the state of Sao Paulo. The experiments were conducted in a randomized block design with 22 progenies and 6 replications. At the age of three years, the progenies were evaluated for rubber yield, girth growth and total number of latex vessel rings. The results showed the existence of genetic variability among progenies for each location separately as well as between locations, with differences in the progeny performance for the traits. The individual heritabilities calculated for rubber yield, girth growth and total number of latex vessel rings (0.30, 0.63 and 0.29, respectively), associated with high genetic gains with selection for the traits studied at each site, showed that the populations can be considered suitable for the rubber breeding program, provided that an appropriate selection procedure is used.

Genetic parameters and correlation in early measurement cycles in rubber trees

Knowledge of the traits present in plant populations of a species is essential to carry out selection and breeding. The objective of the present study was to estimate the genetic parameters and correlate genetically and phenotypically the variables rubber yield, annual trunk girth increase, number of latex vessel rings and bark thickness in early measurement cycles. A total of 22 rubber tree progenies (Hevea brasiliensis) were assessed in three locations during three early measurement cycles. The bark thickness variable correlated significantly for the three increase measurements made in the locations of Jau, Pindorama and Votuporanga. The progeny mean based joint hereditability showed mean values greater than individual plants and within progeny plants of 0.848, 0.286 and 0.242, respectively. The variables annual trunk girth increase and bark thickness are genetically correlated variables. Rubber yield is correlated genetically with bark thickness that permits simultaneous selection for the two characteristics. The early measurement cycles were efficacious for finding genetic variability among the genotypes.

Prediction of direct and indirect genetic gains and genotypic correlations in rubber tree progenies

The objective of this work was to estimate the genetic parameters, genotypic and phenotypic correlations, and direct and indirect genetic gains among and within rubber tree (Hevea brasiliensis) progenies. The experiment was set up at the Municipality of Jaú, SP, Brazil. A randomized complete block design was used, with 22 treatments (progenies), 6 replicates, and 10 plants per plot at a spacing of 3x3 m. Three‑year‑old progenies were assessed for girth, rubber yield, and bark thickness by direct and indirect gains and genotypic correlations. The number of latex vessel rings showed the best correlations, correlating positively and significantly with girth and bark thickness. Selection gains among progenies were greater than within progeny for all the variables analyzed. Total gains obtained were high, especially for girth increase and rubber yield, which were 93.38 and 105.95%, respectively. Young progeny selection can maximize the expected genetic gains, reducing the rubber tree selection cycle.

Correlações e análise de trilha em clones de seringueira

O conhecimento das características presentes nos genótipos é de extrema importância na condução de trabalhos de seleção e melhoramento. O objetivo foi avaliar as relações entre os caracteres agronômicos e anatômicos da casca, bem como seus efeitos diretos e indiretos sobre a produção de borracha seca da seringueira, mediante análise de trilha. Avaliaram-se seis clones de seringueira no delineamento experimental em blocos casualizados com quatro repetições, no Pólo Regional de Desenvolvimento Tecnológico dos Agronegócios do Centro Norte da Agência Paulista de Tecnologia dos Agronegócios, município de Pindorama, São Paulo, Brasil, no ano de 2005. Valor de correlação positivo e significativo foi observado apenas entre a produção de borracha seca e o número de anéis de vasos laticíferos (r = 0,88). Os caracteres perímetro do caule e número de anéis de vasos laticíferos apresentaram os maiores efeitos diretos sobre a produção de borracha seca. Por outro lado, a espessura da casca e o diâmetro dos anéis de vasos laticíferos mostraram efeitos diretos negativos e com altas magnitudes. A seleção indireta via número de anéis de vasos laticíferos proporcionará ganhos durante o processo de seleção em programas de melhoramento da seringueira.

Keragaan dan Hubungan Berbagai Komponen Hasil Tanaman Karet (Hevea brasiliensis Muell. Arg.) pada Dua Populasi Hasil Persilangan PB 260 dengan PN

Latex yield of rubber tree ( Hevea brasiliensis Muell. Arg.) is a complex trait influenced by external and internal factors. In this trial, F1 progenies of two populations (crossing PB 260 as high latex yielder x PN as low latex yielder) and their parents were used to study the characteristic of yield components, namely physiology, anatomy and growth characters which influence latex yield. Based on statistic analysis, it showed that latex yield of two populations had high variation among their F1 progenies. The other variables such as girth, bark thickness, number of latex vessel rings, plugging index, sucrose content and inorganic phosphate content also showed high variation. Based on path analysis and stepwise regression, it showed that the number of latex vessel rings and plugging index had bigger direct effect on determining latex yield of A population (PB 260 x PN 7111), while girth and plugging index variables had bigger direct effect on latex yield of C population (PB 260 x PN 7). Key words: Hevea brasiliensis Muell. Arg., latex yield, F1 progenies, physiology and anatomy characters

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 Jau, all in the Sao 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% for Pp while selecting best two plants within a progeny would result in a Pp genetic gain of 30.98%.

Estimation of variance components and prediction of breeding values in rubber tree breeding using the REML/BLUP procedure

The present paper deals with estimation of variance components, prediction of breeding values and selection in a population of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.] from Rio Branco, State of Acre, Brazil. The REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) procedure was applied. For this purpose, 37 rubber tree families were obtained and assessed in a randomized complete block design, with three unbalanced replications. The field trial was carried out at the Experimental Station of UNESP, located in Selviria, State of Mato Grosso do Sul, Brazil. The quantitative traits evaluated were: girth (G), bark thickness (BT), number of latex vessel rings (NR), and plant height (PH). Given the unbalanced condition of the progeny test, the REML/BLUP procedure was used for estimation. The narrow-sense individual heritability estimates were 0.43 for G, 0.18 for BT, 0.01 for NR, and 0.51 for PH. Two selection strategies were adopted: one short-term (ST - selection intensity of 8.85%) and the other long-term (LT - selection intensity of 26.56%). For G, the estimated genetic gains in relation to the population average were 26.80% and 17.94%, respectively, according to the ST and LT strategies. The effective population sizes were 22.35 and 46.03, respectively. The LT and ST strategies maintained 45.80% and 28.24%, respectively, of the original genetic diversity represented in the progeny test. So, it can be inferred that this population has potential for both breeding and ex situ genetic conservation as a supplier of genetic material for advanced rubber tree breeding programs.

Selection and genetic gains for juvenile traits in progenies of Hevea in São Paulo State, Brazil

Five yield traits were investigated in three-year-old progenies from open-pollinated rubber trees [Hevea brasiliensis (Willd. ex Adr. de Juss) Muell.-Arg.]. Twenty progenies were evaluated in a randomized, complete block design replicated three times using 10 plants per linear plot at the North Central Experimental Station in Pindorama, São Paulo State, Brazil. The characters evaluated included the average yield of rubber, growth vigor, bark thickness, total number of latex vessel rings and latex vessel size. Highly significant (p < 0.01) genetic differences were observed among progenies for most traits. The genotypic variance components accounted for 13.2%, 12.3%, 9.4%, 3.4% and 0.23% of the phenotypic variance for yield, growth vigor, bark thickness, total number of latex vessel rings and latex vessel size, respectively. Heritabilities, as well as genotypic and phenotypic correlations among traits, were estimated. Heritabilities for the above traits at the individual plant level (<img border=0 id="_x0000_i1026" src="../../../../img/revistas/gmb/v27n2/a14img01.gif" align=absmiddle>) were 37%, 35%, 69%, 10% and 16%, respectively. Significant positive genotypic and phenotypic correlations were found between the yield of rubber and growth vigor (r g = 0.73, r p = 0.70), bark thickness (r g = 0.70**, r p = 0.75**) and the total number of latex vessel rings (r g = 0.64, r p = 0.80). There was no relationship between yield and latex vessel size, growth vigor or total number of latex vessel rings. Based on these data, selecting the best two out of 20 progenies would result in a genetic gain of 12.3% and 6.8% for yield of rubber and growth vigor, respectively. The two best individual ortets within each progeny would result in a genetic gain of 27.7% and 9.1%, with a total gain of 40% and 16% for these two traits, respectively.

Relationships between yield and some structural traits of the laticiferous system in Hevea clones resistant to South American leaf blight

Latex yield and six anatomical bark traits were measured in a five-year-old rubber tree clonal trial planted in Itubera (Bahia, Brazil), on forty-nine different clones. The clones were pre-selected for resistance to SALB (South American Leaf Blight) caused by the fungus Microcyclus ulei (P.Henn.) v. Arx. The studied traits were : average yield (AY), girth (SC), virgen bark thickness (BT), total number of latex vessel rings (NR), average density of latex vessel per ring (DV), average diameter of latex vessels (DL) and average distance between consecutive latex vessel rings (AD). Phenotypic, genotypic and environmental correlations, and coefficient of genetic prediction (CGP) were calculated for all characters. There were considerable genetic variations between clones for AY, NR and BT, as indicated by high values of CGP. The genetic correlations were significant between AY and NR. The possibility to use NR as predictor of AY is discussed and the expected gains in percent of several references for AY are computed. FDR 4575, FDR 6099, FDR 5240, FDR 2010, FDR5597, CDC308, FDR 4151, CDC 943, MDX 608 clones were retained for their potential yield and recommended for multilocation large scale trials.

Seleção combinada univariada e multivariada aplicada ao melhoramento genético da seringueira

Este trabalho objetivou estimar os coeficientes de herdabilidade e de predição genética, pelo método multivariado, e comparar os ganhos genéticos obtidos por meio da seleção entre e dentro de progênies, individual e combinada, em seringueira (Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. Arg.). Vinte e duas progênies de meios-irmãos foram plantadas na Estação Experimental de Votuporanga, SP, no delineamento de blocos ao acaso, com cinco repetições e dez plantas por parcela. Aos três anos de idade foram avaliados os caracteres: número de anéis de vasos laticíferos (NA), produção de borracha seca (PB), espessura de casca (EC) e circunferência do caule (CC). Os resultados demonstraram haver variabilidade significativa entre progênies quanto aos caracteres PB, EC e CC. As estimativas de coeficientes de herdabilidade e de predição genética foram mais elevadas nas progênies, com valores mais expressivos quanto aos coeficientes de predição genética. Ganhos genéticos adicionais foram obtidos pela seleção combinada. Embora os referidos ganhos tenham sido de pequena magnitude, recomenda-se o uso do método, por propiciar maior acurácia e ganho genético. Os valores mais expressivos de acurácia e ganho genético foram estimados pelo método multivariado.

Genetics of anthracnose panel canker disease resistance and its relationship with yield and growth characters in half-sib progenies of rubber tree (Hevea brasiliensis)

Rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell-Arg] anthracnose panel canker disease resistance, caused by Colletotrichum gloeosporioides (Penz.) Sacc., and growth and yield characters were assessed at three years old in the nursery, in 18 half-sib progenies. There were highly significant (P &lt; 0.01) genetic differences among progenies for most characters. The genetic component of variance accounted for 3.37, 6.07, 12.74, 12.13, 19.82 and 3.58% of the phenotypic variance for anthracnose-infected area, anthracnose lesion stripe length, yield, girth, virgin bark thickness and total number of latex vessel rings, respectively. Narrow-sense heritability estimates for the above characters were 13.45, 24.30, 50.97, 48.52, 79.30 and 14.30%, respectively. No significant genetic correlations were found among anthracnose panel canker resistance, yield and growth characters. The frequency distribution of anthracnose-infected area and anthracnose lesion stripe length suggests polygenic control. Selecting the best three progenies out of 18 progenies would result in a genetic gain of 12.87 and 24.24% for infected area and lesion stripe length, respectively. The best five selected individuals out of 50 individuals within each progeny would result in a genetic gain of 9.47 and 24.62%, with a total gain of 22.34 and 48.87% for these two characters, respectively.

Growth trends, genotype-environment interaction and genetic gains in six-year-old rubber tree clones (Hevea) in São Paulo State, Brazil

Budwood from seven different clones of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. Arg.] was planted in replicated trials in four different test sites in the plateau region of the state of São Paulo, Brazil. The clones represented a range of imported germplasm, whereas the locations were selected to represent a range of rubber growing areas. Girths were measured for six years consecutively, before the initiation of tapping for latex. Total number of latex vessel rings (lvr) and bark thickness (bt) were measured at six years. The largest average for all characters was observed in Matão. Overall means for girth, total number of latex vessel rings and bark thickness at six years were 35.26 cm, 11.30 units and 4.83 mm, respectively. Both the test sites and clones showed statistically significant differences in girth, lvr and bt values. There were significant clone x site interactions. Girth at one year was not a reliable predictor of future field performance. Broad sense heritability for girth was 0.16, and for lvr and bt it was 0.28 and 0.40, respectively, at six years. Repeatability was quite high, from 0.52 to 0.75 for all characters in all years. When two clones out of seven were selected, expected genetic gain in girth was about 2.0%; for lvr and bt it was 7.0% and 14.6%, respectively.

Relação entre diferentes caracteres de plantas jovens de seringueira

O presente trabalho foi realizado com o objetivo de determinar a existência e as magnitudes de correlações e regressões lineares simples em plântulas jovens de seringueira (Hevea spp.), para melhor condução de seleção nos futuros trabalhos de melhoramento. Foram utilizadas médias de produção de borracha seca por plântulas por corte, através do teste Hamaker-Morris-Mann (P); circunferência do caule (CC); espessura de casca (EC); número de anéis (NA); diâmetro dos vasos (DV); densidade dos vasos laticíleros (D) e distância média entre anéis de vasos consecutivos (DMEAVC) em um viveiro de cruzamento com três anos e meio de idade. Os resultados mostraram, entre outros fatores, que as correlações lineares simples de P com CC, EC, NA, D, DV e DMEAVC foram, respectivamente, r =t 0,61, 0,34, 0,28, 0,29, 0,43 e -0,13. As correlações de CC com EC, NA, D, DV e DMEAVC foram: 0,65, 0,22, 0,37, 0,33 e 0,096 respectivamente. Estudos de regressão linear simples de P com CC, EC, NA, DV, D e DMEAVC sugerem que CC foi o caráter independente mais significativo, contribuindo com 36% da variação em P. Em relação ao vigor, a regressão de CC com os respectivos caracteres sugere que EC foi o único caráter que contribuiu significativamente para a variação de CC com 42%. As altas correlações observadas da produção com circunferência do caule e com espessura de casca evidenciam a possibilidade de obter genótipos jovens de boa capacidade produtiva e grande vigor, através de seleção precoce dessas variáveis.