Hybrid H1 Research Articles

Physiological and Biochemical Characterization of Jiló Seeds (Solanum gilo) in Different Harvest Times

The evaluation of seed quality during the development process is important for the definition of the moment of harvest. In this context, the objective in this study was to evaluate the quality of Jilo seeds during development through physiological, biochemical and electrophoretic tests of enzymes. Six genetic materials, JIL white, JIL 001, JIL 005, JIL 006, H1 and H2 were used. Fruits were harvested at 35, 40, 45 days after anthesis (DAA). A total of 50% of all fruits harvested at 45 DAA remained at rest for seven days which were labeled as 45 DAAr. The seeds at each maturation stage were extracted from the fruits and evaluated by water content, weight of one thousand seeds, electric conductivity, germination, germination speed index, seedling emergence, and seedling emergence rate index. The chemical composition of the seeds was also evaluated, as well as the expression of the enzymes esterase, isocitrate lyase, malate dehydrogenase, alcohol dehydrogenase, superoxide dismutase, catalase, peroxidase and endo-β-mannanase. The highest values of germination and vigor were found in seeds harvested at 45 DAA and 45 DAAr, mainly for hybrids H1 and H2. The highest values of lipids and proteins and lower carbohydrates were found in the most immature seeds of Jilo. The enzymes analyzed showed higher expression in the initial stages of development, however reduced with the advancement of the maturation stage. Endo-β-mannanase expression increased with seed development. Jilo seeds harvested at 45 DAAr presented the highest of germination and vigor values. This “being” considered as the ideal harvest point.

Estimates of heterosisparameters in elephant grass (Pennisetumpurpureum Schumach.) for bioenergy production

With a high growth rate and a DM yield of up to 80 t ha-1 yr1, elephant grass (Pennisetum purpureum Schumach.) has been utilized as an alternative source of energy. However, genotypes adapted to and productive in the different regions of Brazil need to be developed. Thus, the objectives of the present study were to estimate and evaluate heterotic effects in elephant-grass hybrids obtained in a partial diallel cross (5 x 5), with the aim of assisting the superior hybrids selection for bioenergy production. The experiment was conducted in Campos dos Goytacazes, Rio de Janeiro, Brazil. The following traits were evaluated: plant height (HGT), stem diameter (SD), leaf blade width (LBW), number of tillers per linear meter (NT), percentage of DM (%DM), and DM yield (DMY). The experiment was conducted in a randomized block design, with 35 treatments (five female parents, five male parents, and 25 hybrid combinations) and three replicates. The adopted statistical model was that of Miranda Filho and Geraldi, in an adaptation of Gardner and Eberhart. Significant heterosis was observed for most traits in the rainy and dry seasons. Hybrid combinations H1 ('Cubano Pinda' x 'Mercker'), H7 ('Cameroon-Piracicaba' x 'Tres Rios'), H8 ('Cameroon-Piracicaba' x 'Mercker 86-Mexico'), H17 ('IAC-Campinas' x 'Tres Rios'), H18 ('IAC-Campinas' x 'Mercker 86-Mexico'), and H25 ('Guacu/IZ.2' x 'Roxo') showed potential for use in breeding programs that aiming at develop clones with a energy biomass production capacity high.

English

Plants are frequently exposed to various biotic and abiotic stresses that impair their growth, development and limit the productivity. In the present work the objective was to evaluate the effect of saline stress on the germination and biochemical alterations by the expression of enzymatic systems in corn seeds treated with different concentrations of NaCl. Hybrid maize seeds (H1, H2, H3) were used during 2013 cropping season and solutions of sodium chloride (NaCl) to simulate the saline stress. The respective concentrations of NaCl (mol.m-3) were zero (0.0 g/L); 25 (1.46 g/L); 50 (2.93 g/L); 75 (4.39 g/L) and 100 mol.m-3 (5.85 g/L), diluted into water. In order to evaluate the physiological potential of these seeds, we realized the germination test with four replications of 50 seeds, distributed between three germitest papers moistened with NaCl solutions, described above. The evaluation was performed on the seventh day, with the first count realized determining the percentage of normal seedlings on the fourth day after planting. The biochemical evaluation was performed by the expression of isoenzymes superoxide dismutase (SOD), esterase (EST), catalase (CAT), alcohol dehydrogenase (ADH), malate dehydrogenase (MDH) and alpha amylase. Seeds of the three tested hybrids have lower germination when placed in conditions of greater concentration of salinity. The hybrid H3 that presents higher tolerance to salinity and hybrid H1 are most susceptible during the germination process. The hybrid with higher vigor, H3 had higher activity of alpha amylase and catalase enzyme groups. Esterase and alcoholic dehydrogenase were not effective in measuring the quality of maize grains under salt stress conditions. Key words: Zea mays, physiological quality enzyme.

Pathogenicity inPlasmopara halstedii(Sunflower downy mildew) races 710, 714 and 704

Pathogenicity including virulence and aggressiveness characteristics was studied on three Plasmopara halstedii (the causal agent of downy mildew) isolates of races 710, 714 and 704 using five single zoosporangium isolates per pathogen isolate. Based on the reaction for the P. halstedii isolates to four sunflower hybrids H1 to H4 varying only in their downy mildew resistance genes, there were differences in virulence spectrum in pathogen isolates. Analysis of five single zoosporangium isolates for P. halstedii isolates showed significant variability within pathogen isolate for all aggressiveness criteria. There were no significant differences among pathogen isolates for all aggressiveness criteria. There were significant differences in the morphology of zoosporangia and sporangiophores for pathogen isolates. Genetic relationships were detected between pathogen isolates using 12 EST-derived markers. There was no intra-race genetic variation, but three genetically-identified groups were detected among pathog...

Interaction between sunflower plants and five isolates of Plasmopara halstedii on the level of pathogenicity

The interaction between sunflower plants showing a high level of quantitative resistance and five Plasmopara halstedii (the causal agent of downy mildew) isolates of several races were studied using five single zoosporangium isolates per pathogen isolate. Aggressiveness criteria were analyzed for 25 P. halstedii single zoosporangium isolates. Based on the reaction for the P. halstedii isolates to four sunflower hybrids H1–H4 varying only in their downy mildew resistance genes, there were differences in virulence spectrum in pathogen isolates. Analysis of five single zoosporangium isolates for P. halstedii isolates showed significant variability within pathogen isolate for all aggressiveness criteria but not for all pathogen isolates. The hypothesis explaining the interaction between P. halstedii and its host plant was discussed on the level of pathogenicity.

Pathogenic variability in Plasmopara halstedii (sunflower downy mildew)

Pathogenic variation was studied in 19 Plasmopara halstedii isolates belonging to races 100, 300, 710 and 714. Based on the reaction for the P. halstedii isolates to four sunflower hybrids H1 to H4 differing only in their downy mildew resistance genes, there were differences in virulence spectrum in pathogen isolates. All sunflower hybrids were resistant to isolates of races 100 and 300 and sensible to isolate of the race 714, H1 was only sensible to isolates of race 710. Regarding aggressiveness criteria on two sunflower inbred lines showing different levels of quantitative resistance, there were significant differences in aggressiveness for P. halstedii isolates. The index of aggressiveness (sporulation density/latent period) varied between 8.1 and 23.6. There was a significant correlation (r = −0.456) between the two aggressiveness criteria at p < 0.05.

Rhizosphere properties of maize genotypes with contrasting phosphorus efficiency

An experiment was conducted in a growth chamber to evaluate characteristics of the rhizosphere of maize genotypes contrasting in P-use efficiency, by determining length and density of root hairs, the rhizosphere pH and the functional diversity of rhizosphere bacteria. A sample of a Red Oxisol was limed and fertilized with N, K and micronutrients. In the treatment with the highest P level, 174 mg kg-1 P was added. Each experimental unit corresponded to a PVC rhizobox filled with 2.2 dm-3 soil. The experiment was completely randomized with three replications in a 5 x 2 factorial design, corresponding to five genotypes (H1, H2 and H3 = P-efficient hybrids, H4 and H5 = P-inefficient hybrids) and two P levels (low = 3 mg dm-3, high = 29 mg dm-3). It was found that 18 days after transplanting, the nodal roots of the hybrids H3 and H2 had the longest root hairs. In general, the pH in the rhizosphere of the different genotypes was higher than in non-rhizosphere soil, irrespective of the P level. The pH was higher in the rhizosphere of lateral than of nodal roots. At low P levels, the pH variation of the hybrids H2, H4 and H5 was greater in rhizospheric than in non-rhizospheric soil. The functional microbial activity in the rhizosphere of the hybrids H3 and H5 was highest. At low soil P levels, the indices of microbial functional diversity were also higher. The microbial metabolic profile in the rhizosphere of hybrids H1, H2, H3, and H5 remained unaltered when the plants were grown at low P. The variations in the rhizosphere properties could not be related to patterns of P-use efficiency in the tested genotypes.

Germination energy as a parameter of seed quality in different sunflower genotypes

Using the standard method, we studied the germination energy of seed of seven different sunflower genotypes (five hybrids and two cytoplasmically male sterile female lines) developed at the Institute of Field and Vegetable Crops in Novi Sad. The seed was treated with the fungicides benomil, metalaxyl and fludioxonil and the insecticides thiamethoxam and imidacloprid and kept for a year in a storage facility. Analysis of variance showed that there were highly significant differences among the genotypes, chemical treatments, and storage periods. Highly significant differences were also recorded for all the interactions among the factors studied. On average, the highest germination energy was found in the hybrid H2 (93.45%), whose values of this parameter were highly significantly higher than those of the rest of the genotypes, except for the hybrid H1. Also, each of the hybrids had highly significantly higher germination energy than either of the two lines, and the differences among the hybrids themselves were highly significant. Looking at the chemical treatments, the control had the highest germination energy by a highly significant margin (80.39%). The largest difference was observed in relation to the treatments with insecticides (5.48 and 9.56%). These treatments had highly significantly lower values of germination energy than those involving fungicides. Germination energy increased in the first nine months of storage, peaking at 81.29%. After that, there was a sharp drop to 68.94% after 12 months of storing. Differences among the different storage periods were all highly significant except for that between six and nine months of storage, which was not statistically significant.

Production and genetic analysis of partial hybrids from intertribal sexual crosses betweenBrassica napusandIsatis indigoticaand progenies

With the dye and medicinal plant Isatis indigotica (2n = 14) as pollen parent, intertribal sexual hybrids with Brassica napus (2n = 38, AACC) were obtained and characterized. Among a lot of F1 plants produced, only five hybrids (H1-H5) were distinguished morphologically from female B. napus parents by showing low fertility and some characters of I. indigotica, and also by having different chromosome numbers. H1-H4 had similar but variable chromosome numbers in their somatic and meiotic cells (2n = 25-30), and H5 had 2n = 19, the same number as the haploid of B. napus. GISH analysis of the cells from H1 and H5 detected one I. indigotica chromosome and one or two chromosome terminal fragments. New B. napus types with phenotypic and genomic alterations were produced by H1 after pollination by B. napus and selfing for several generations, and by H5 after selfing. A progeny plant (2n = 20) was derived from H1 after pollination by I. indigotica twice and had a phenotype similar to a certain type of B. rapa, showing that hybrid H1 likely retained all chromosomes of the A genome and lost some of the C genome in parental B. napus. The reasons for the formation of the partial hybrids with unexpected chromosomal complements and for the chromosome elimination are discussed.

Interspecific hybridization of Cucumis anguria and C. zeyheri via embryo-rescue

Embryo-rescue was used to facilitate interspecific hybridization of Cucumis anguria L. and C. zeyheri Sond. Embryos were excised from developing fruits at one week intervals for six weeks after hand pollination. Medium containing coconut water was the most suitable for initial germination, and a medium with ascorbic acid was the best for embryo development and plant recovery. Viable plants were obtained from embryos and these plants showed morphological characteristics different from both parents. The analysis of the leucine aminopeptidase (LAP) locus revealed three hybrid types, H1.1, H1.2 and H2.

Crescimento e produção do melão cultivado sob cobertura de solo e diferentes freqüências de irrigação

Objetivou-se, com este trabalho, avaliar índices de crescimento, fisiológicos e de produção, de quatro híbridos de meloeiros cultivados com e sem cobertura do solo e três freqüências de irrigação. Utilizaram-se dois experimentos conduzidos no período de junho a setembro de 2001, em Mossoró, RN. Num se cultivou usando solo nu e noutro, usando cobertura com filme de polietileno. Adotou-se o delineamento experimental em blocos completos casualizados com duas repetições por bloco. Utilizaram-se três freqüências de irrigação, com cada uma aplicada num bloco experimental. Estudaram-se os híbridos de melão cantaloupe, denominados PX3912947 (H1), Vera cruz (H2), Trusty (H3) e Torreon (H4). Maior área foliar foi obtida nos híbridos H1 e H2, independente da cobertura e freqüência de irrigação. No sistema de plantio com cobertura do solo, a cultura do meloeiro aumentou o peso seco da parte vegetativa sem os frutos e suportou turno de regas maiores. Os híbridos H2 e H4 obtiveram, juntos, maior taxa de crescimento absoluto no solo descoberto, enquanto apenas o híbrido H4 alcançou maior taxa de crescimento relativo, neste solo. Os híbridos H1 e H3 produziram frutos grandes fora do padrão. A cobertura do solo proporcionou maior produtividade e peso médio dos frutos.

Atividade de enzimas pectinametilesterase e poligalacturonase durante o amadurecimento de tomates do grupo multilocular

Mediu-se a atividade das enzimas pectinametilesterase (PME) e poligalacturonase (PG) em frutos de tomate do grupo multilocular em diferentes estádios de maturação e correlacionou-se com mudanças na textura, pectinas e licopeno. Os tomates foram colhidos no estádio verde-maturo e colocados a amadurecer em recinto com umidade relativa de 85-90% e temperatura ambiente de 20(0)C±2. Durante o armazenamento, foram retiradas amostras nos estádios verde-maturo, "de vez", maduro e vermelho-maduro para determinar a atividade enzimática. As outras características foram analisadas somente quando os frutos atingiram o estádio vermelho-maduro. Dentre os genótipos avaliados, três híbridos, H3: F1 (BPX 308B hv x Stevens), H8: F1 (BPX 308B hv x Piedmont) e H1: F1 (BPX 308B hv x BPX-127H) sobressaíram-se com melhores características para o consumo ao natural, quando comparado às testemunhas, por apresentarem menor atividade das enzimas PME e PG, o que reduziu a despolimerização e solubilização das pectinas resultando em maior textura. As maiores espessuras da polpa e menores números de lóculos também contribuíram para aumentar a textura do fruto melhorando a vida-de-prateleira e a qualidade dos frutos. A baixa atividade da enzima PG não influenciou o desenvolvimento da cor, atributo considerado importante na aceitação do fruto pelo consumidor. O híbrido H1: F1 (BPX 308B hv x BPX- 127H), que contém o gene alc em heterozigose, o qual condiciona maior conservação pós-colheita, foi o terceiro melhor híbrido para consumo, não apresentando efeito detrimental na coloração, sugerindo que o gene alc em heterozigose pode ser uma alternativa viável para o melhoramento genético do tomateiro visando a melhor conservação pós-colheita.