Reproduction mode and apospory expressivity of selected hybrids of Paspalum notatum Flügge

Paspalum notatum Flüggé (bahiagrass) is the most important forage grass in the native grasslands of southern Brazil; the native germplasm is tetraploid and apomictic. Breeding to produce cultivars has been possible due to chromosome doubling of sexual diploid accessions, allowing hybridizations with apomictic genotypes, generating progenies with variability for agronomic traits and segregating for reproduction mode. The aim of this study was to determine the reproduction mode of selected hybrids derived from intraspecific crosses through cytoembryological analysis and to evaluate the level of apospory expres¬sivity. Eighty one tetraploid hybrids corresponding to 21 families of sexual and apomictic parents were generated and 28 most productive plants based on their superior agronomic performance in the field were evaluated. Sixteen hybrids were reproduced sexually and 12 of them were highly apomictic or facultative apomictic. Sexual hybrids may be used for further crosses in the breeding program while highly apomictic plants produce uniform progeny and become candidates of new cultivars to promote pasture diversification

Determination of the mode of reproduction of bahiagrass hybrids using cytoembryological analysis and molecular markers

The aim of this study was to determine the mode of reproduction of a hybrid progeny derived from intraspecific crosses of Paspalum notatum through cytoembryological analysis and use of RAPD (random amplification of polymorphic DNA) molecular markers. Cytoembryological analysis allowed identification of the mode of reproduction of 28 plants that were selected after agronomic productivity evaluations. Of these, 19 had embryo sac morphology compatible with an apomictic mode of reproduction and nine had embryo sac morphology compatible with a sexual mode of reproduction. Meanwhile, molecular marker analysis for 194 individuals showed 54 sexual and 140 apomictic plants; of the 28 plants analyzed by the two methods, ten results (35.7%) were in disagreement. In this paper, through cytoembryological analyses, a ratio of 1:2.1 of sexual to apomictic plants was found. The BCU 243 marker showed a stable pattern of amplification, but some results differed with cytoembryological analyses, demonstrating that these analyses are more reliable when determining the mode of sexual reproduction for the plants of P. notatum. Apomictic plants characterized in this work can be tested in the field to check their agronomic value and registration as plant varieties, while the sexual plants can be used as potential parents in future crosses

Reproductive analyses of intraspecific Paspalum notatum Flügge hybrids

Paspalum notatum is an important forage native to Southern Brazil and one of the most promising fodder species in terms of productivity, quality, resistance and growth speed. The objective of this study was to evaluate the reproductive mode and fertility of hybrid progenies resulting from artificial crosses among artificially duplicated sexual plants, selected intraspecific hybrids of the UFRGS breeding program and apomictic ecotypes of the species. The resulting F1 progenies were represented by 24 plants with high pollen viability (varying from 82.15 to 99.67%) and 1.2:1 segregation for the sexual: apomictic reproduction mode, indicating predominantly sexual hybrids, due to distorted segregation. In the apomictic plants, most chromosomes paired as bivalents in diakinesis. Since the low presence of abnormalities observed in the meiotic chromosome pairing and the high pollen viability of the hybrids, all plants were confirmed as promising parents for future crosses

Progênies híbridas de grama forquilha : avaliações agronômicas

Paspalum notatum Flüggeis one native forage grasses of southern Brazil. Through intraspecific hybridization, is possible generating progenies with variability for agronomic traits.The objective of this work was to evaluate 24 hybrids and select them for the superior agronomic traits, as well analyze correlations between forage traits that can assist in the selection of genotypes.The hybrids were obtained from crosses among sexual and apomictic clones, and were vegetative propagated in a greenhouse until the transplant to the field. The agronomic traits evaluated were: total green mass (TGM), leaf dry mass (LDM), stem dry mass (SDM), inflorescence dry mass (IDM), dead mass (DeM), total dry mass (TDM),growth habit (GH). Correlations between plant diameter (PD), number of tillers (NT), total dry matter (TDM), plant height (PH), total green matter (TGM), leaf dry matter (LDM), stem dry mass (SDM), number of inflorescences (NINF) and inflorescence dry matter (IDM) were performed using the Pearson correlation coefficient. The hybrids had great variability in all agronomic characteristics measured. Based on the three years of evaluation, hybrids KD9, KF1, KF4, and KD5 produced higher total dry mass than othergenotypes. The hybrid KF4 too had greater LDM; KF1 and KF4 were the colder tolerant. These genotypes were selected for evaluations, such as seed production, fertilizer use efficiency, animal performance, and for new crosses. The high correlation of the total dry mass with the other forage components will be useful for indirect select criteria in bahiagrass improving strategies.Paspalum notatumFlügge é uma gramínea forrageira nativa do sul do Brasil. Hibridizações intraespecíficas geram progênies com variabilidade para características agronômicas. O objetivo deste trabalho foi avaliar 24 híbridos e selecioná-los pelas características agronômicas superiores, bem como analisar correlações entre características forrageiras que possam auxiliar na seleção de genótipos. Os híbridos foram obtidos através dos cruzamentos entre clones sexuais e apomíticos, e foram propagados vegetativamente em casa de vegetação até o transplante para o campo. As características agronômicas avaliadas foram: massa verde total (MVT), massa seca das folhas (MSF), massa seca do caule (MSC), massa seca da inflorescência (MSI), material morta (MM), massa seca total (MST), hábito de crescimento (HC). As correlações entre diâmetro da planta (DP), número de perfilhos (NP), massa seca total (MST), altura da planta (Alt), massa verde total (MVT), massa seca das folhas (MSF), massa seca do caule (MSC), número de inflorescências (NINFL) e massa seca das inflorescências (MSINFL) foram realizados utilizando o coeficiente de correlação de Pearson. Os híbridos tiveram grande variabilidade em todas as características medidas. Em três anos de avaliações, os híbridos KD9, KF1, KF4 e KD5 produziram maior MST; KF4 apresentou maior MSF; KF1 e KF4 foram os mais tolerantes ao frio. Esses genótipos foram selecionados para avaliações de produção de sementes, eficiência no uso de fertilizantes, desempenho animal e para novos ciclos de cruzamentos. A alta correlação da massa seca total com outros componentes da forragem será útil para critérios de seleção indireta em estratégias de melhoramento da grama forquilha

Hybrid progenies of Bahiagrass: agronomic evaluation

Paspalum notatum Flügge (bahiagrass) is one of the most common native grasses found in southern Brazil and have become one of the most promising forage species considering their value for beef cattle production in the tropics and subtropics. The breeding program has been possible through intraspecific hybridization among sexual and apomictic clones, generating progenies with variability for agronomic traits. Hybrid materials with superior agronomic performance can be selected, registered and protected to be made available as a commercial cultivar. The objective of this work was to evaluate 24 intraspecific hybrids and select them for the superior agronomic traits, as well analyze correlations between forage traits that can assist in the selection of genotypes. Based on the three years of evaluation, hybrids KD9, KF1, KF4, and KD5 produced higher total dry mass than other genotypes. The hybrid KF4 too had greater leaf dry matter; KF1 and KF4 were the more cold tolerant. These genotypes were selected for new cycles of hybridization and field evaluations, such as seed production, fertilizer use efficiency and animal performance. The high correlation of the total dry mass with the other forage components might be useful for indirect select criteria in bahiagrass improving strategies.Paspalum notatum Flügge is one native forage grasses of southern Brazil. Through intraspecific hybridization, is possible generating progenies with variability for agronomic traits. The objective of this work was to evaluate 24 hybrids and select them for the superior agronomic traits, as well analyze correlations between forage traits that can assist in the selection of genotypes.The hybrids were obtained from crosses among sexual and apomictic clones, and were vegetative propagated in a greenhouse until the transplant to the field. The agronomic traits evaluated were: total green mass (TGM), leaf dry mass (LDM), stem dry mass (SDM), inflorescence dry mass (IDM), dead mass (DeM), total dry mass (TDM), growth habit (GH). Correlations between plant diameter (PD), number of tillers (NT), total dry matter (TDM), plant height (PH), total green matter (TGM), leaf dry matter (LDM), stem dry mass (SDM), number of inflorescences (NINF) and inflorescence dry matter (IDM) were performed using the Pearson correlation coefficient. The hybrids had great variability in all agronomic characteristics measured. Based on the three years of evaluation, hybrids KD9, KF1, KF4, and KD5 produced higher total dry mass than other genotypes. The hybrid KF4 too had greater LDM; KF1 and KF4 were the colder tolerant. These genotypes were selected for evaluations, such as seed production, fertilizer use efficiency, animal performance, and for new crosses. The high correlation of the total dry mass with the other forage components will be useful for indirect select criteria in bahiagrass improving strategies

Dissimilaridade entre ecótipos de Andropogon lateralis submetidos a diferentes frequências de desfolha e alturas de corte

Andropogon lateralis Nees is a native grass of southern Brazil and is one of the most frequent specie found in native grasslands. The species is widely distributed and has a high degree of phenotypic plasticity, which makes it highly adaptable to different edaphoclimatic conditions and management. This study aimed to evaluate the behavior of twelve ecotypes of A. lateralis, collected in different regions of the state of Rio Grande do Sul and cut to three different heights and subjected to two different defoliation frequencies. From September to February, the ecotypes were evaluated for total dry matter, leaf and stem yields. In addition, total, vegetative and reproductive tillers and plant height were measured. These characteristics are important for the selection of superior genotypes in terms of genetic variability and forage production. Total dry matter and leaf dry matter are characteristics with agronomic importance and they showed the highest correlation (r = 0.77), enabling an indirect selection for one of these characteristics. The natural selection of plants resulted in distinct structural, morphological and productive characteristics with heterogeneity that allows the selection and grouping according to the characteristics, ecotypes with superior agronomic characteristics can be included in breeding programs.Andropogon lateralis Nees é uma gramínea nativa do sul do Brasil e uma das espécies mais frequentes na flora dos campos nativos da região. Possui ampla distribuição e alto grau de plasticidade fenotípica, tornando-o adaptável as condições edafoclimáticas e a práticas de desfolha. Este estudo teve como objetivo avaliar a dissimilaridade entre doze ecótipos de A. lateralis N., coletados em diferentes regiões do Rio Grande do Sul, submetidos a duas frequências de desfolha e três alturas de corte. No período de setembro a fevereiro, os ecótipos foram avaliados quanto à produção de matéria seca total, de lâminas foliares e de colmo. Além disso, foram medidos o número de perfilhos totais, vegetativos e reprodutivos e a altura das plantas. Essas características são importantes para a seleção de genótipos superiores em termos de variabilidade genética e produção de forragem. A matéria seca total e a matéria seca foliar são características com importância agronômica e apresentaram a maior correlação (r = 0,77), possibilitando uma seleção indireta para uma dessas características. A seleção natural das plantas resultou em características estruturais, morfológicas e produtivas distintas com uma heterogeneidade que permite a seleção e agrupamento de acordo com as características, ecótipos com características agronômicas superiores podem ser incluídos em programas de melhoramento

Avaliação qualitativa de frutos de tangerineiras híbridas (Citrus deliciosa x C. nobilis)

18

Freqüência de embriões nucelares em híbridos de citrus

24

Produção de forragem de híbridos tetraploides de grama forquilha

In Southern Brazil, much of the livestock activity is developed in native grasslands. Studies about forage traits, frost tolerance and nutritional value of native forage species there has been increasing with better results of productive efficiency (animal gain). The objective of this work was to evaluate forage yieldof forty-five intraspecific hybrids of segregating progenies of bahiagrass (Paspalum notatumFlügge) from agronomic analyses under greenhouse conditions and determine the reproduction mode of selected hybrids. The hybrids had great variability in all agronomic characteristics measured. The plants with the highest total dry mass production were 17PN10P3 and 17PN29P1 (sexualreproduction), 17PN10P5, 17PN16P3 and 17PN28P4 (apomicticreproduction). The high correlation of the total dry mass with tillers numberand with the root dry mass demonstrate that the hybrids can be used as forage and also to reduce the effects of soil erosion in degraded areas. The evaluations of agronomic characteristics and the determinationof the mode of reproduction of the selected hybrids allowed the identification of promising genetic materials for forage yield and to soil cover, selecting them for additional stages in the breeding program.No sul do Brasil, boa parte da atividade pecuária é desenvolvida em pastagens nativas. Estudos sobre caraterísticas agronômicas, tolerância ao frio e valor nutritivo das espécies forrageiras nativas têm aumentado, e melhores resultados de eficiência produtiva (ganho animal) são alcançados. O objetivo deste trabalho foi avaliar a produção de forragem de 45 híbridos intraespecíficos de progênies segregantes de grama-forquilha (Paspalum notatumFlügge), através de análises conduzidas em casa de vegetação e determinar o modo de reprodução dos híbridos selecionados. Os híbridos tiveram grande variabilidade para as características analisadas. As plantas com a mais alta produção total de matéria seca foram 17PN10P3 e 17PN29P1 (reprodução sexual), 17PN10P5, 17PN16P3 e 17PN28P4 (reprodução apomítica). A alta correlação da matéria seca total com o número de perfilhos e com a massa seca total das raízes indica que as plantas híbridas podem ser usadas como forrageiras e para recuperação de áreas degradadas, reduzindo os efeitos da erosão do solo. As avaliações das características agronômicas e adeterminação do modo de reprodução dos híbridos selecionados permitem a identificação de materiais genéticos promissores para produção de forragem e para coberturade solo, selecionando-os para as próximas fases do programa de melhoramento

Overexpression of the mitochondrial MT-sHSP23.6 gene during antioxidant activity in tomato cv. Micro-Tom subjected to flooding

Plants grown under flooding stress conditions form reactive oxygen species, both during oxygen deficiency and after reoxygenation. The tolerance of plants under these conditions depends on an efficient antioxidant system, which may be influenced by the higher expression of heat shock proteins, such as mitochondrial MT-sHSP23.6. The objective of the present study was to determine whether the overexpression of this gene increases the antioxidant activity in tomato cv. Micro-Tom plants subjected to flooding during the vegetative stage of four fully expanded leaves. The experiment was performed with three genotypes of tomato plants (Solanum lycopersicum Mill. cv. Micro-Tom), one non-transformed denominated “WT” and two modified for high and low expression of the MT-sHSP23.6 gene, subjected to normal irrigation conditions, 72 hours of flooding, and 24 and 192 hours of recovery after the removal of flooding, consisting a 3x4 split-plot factorial design with four replications. Plants were collected at the vegetative stage of 4 fully expanded leaves to determine superoxide dismutase, ascorbate peroxidase and catalase activities, hydrogen peroxide accumulation and lipid peroxidation. Overexpression of the mitochondrial MT-sHSP23.6 gene in the evaluated plants resulted in higher antioxidant system activity. However, it did not necessarily lead to less damage caused by oxidative stress. Low expression of this gene resulted in lower antioxidant system activity and greater damage caused by reactive oxygen species