Viable Seedlings Research Articles

Overcoming unilateral incompatibility in crosses with wild allotetraploid potato species Solanum stoloniferum Schldtl. & Bouchet

The germplasm of valuable for breeding wild allotetraploid potato species Solanum stoloniferum is rarely used because of pre- and postzygotic reproductive barriers with cultivated potatoes. One of the factors that complicate crosses between S. stoloniferum and S. tuberosum is unilateral incompatibility (UI). Here, we present the results of application of S. verrucosum and S v S v -lines for overcoming UI in crosses with S. stoloniferum and of generating male fertile hybrids derived from this species. S v S v -lines are F2 S. tuberosum dihaploid × S. verrucosum that are male fertile and have D/γ-type cytoplasm. Since they are homozygous for S v gene from S. verrucosum, they were expected to have the same ability for elimination of prezygotic incompatibility as this species. Three accessions of S. verrucosum and seven S v S v -lines were pollinated by 26 accessions of S. stoloniferum. The crosses with S. verrucosum failed or had low efficacy (1.5–2.4 seeds per pollination). On the other hand, use of S v S v -lines was more efficient: 15.8 seeds per pollination. In spite of low percentage of germination (1.9%), 40 seedlings of interspecific hybrids were produced. The experiment on hybridization between S v S v -lines and S. stoloniferum has been reproduced with the accession PI 205522 of the wild species, which had DNA markers of PVY and LB resistance genes and W/γ cytoplasm: 950 hybrid seeds and 12 viable seedlings were produced. The genome of the seedlings was doubled by colchicine treatment, which generated hexaploids that formed highly fertile pollen and set seeds from self-pollination. We were able to cross them as females with the variety Katahdin.

English

Castor bean (Ricinus communis L.) is an oleaginous of high economic value because its oil has numerous applications in the industry, such as in the manufacture of enamels and paints. Presently, its production is aimed at being used as a biodiesel. The main obstacle to a high production is the survival of the young plants in field in a no-tillage system. An alternative would be the production of seedlings. The objective of this research was to evaluate the initial growth of BRS Gabriela (R. communis L.) castor bean seedlings in function of different substrates and container volumes. The work was conducted at the nursery of the State University of Paraíba (UEPB), Catolé do Rocha, PB, Brazil. The experimental design was completely randomized (CRB) in a 4 × 2 factorial design with 6 replications. The factors consisted of 4 container volumes: 1, 0.5, 0.3, and 0.27 dm-3 and 2 substrates (S1 = 50% soil and 50% earthworm humus, and S2 = 40% soil, 30% earthworm humus and 30% sand). The analyzed variables were stem dry matter (SDM), root dry matter (RDM), plant leaf area (PLA), leaf biomass (LPM), stem biomass (SPM), water content (WC), plant height and stem diameter ratio (PHe/SD), root dry matter and dry shoot dry matter ratio (RDM/SDM), Dickson quality index (DQI) and succulence. The morphological characteristics were influenced by container volume and substrate. The largest container volume, together with the substrate S1 (50% soil and 50% earthworm humus), provided viable seedlings ready to be transplanted to the field.     Key words: Ricinus communis L., Initial growth, greenhouse, earthworm humus. &nbsp

Ploidy and Genome Size in Lilac Species, Cultivars, and Interploid Hybrids

Genome size variation can be used to investigate biodiversity, genome evolution, and taxonomic relationships among related taxa. Plant breeders use genome size variation to identify parents useful for breeding sterile or improved ornamentals. Lilacs (Syringa) are deciduous trees and shrubs valued for their fragrant spring and summer flowers. The genus is divided into six series: Syringa (Vulgares), Pinnatifoliae, Ligustrae, Ligustrina, Pubescentes, and Villosae. Reports conflict on genome evolution, base chromosome number, and polyploidy in lilac. The purpose of this study was to investigate genome size and ploidy variation across a diverse collection. Flow cytometry was used to estimate monoploid (1Cx) and holoploid (2C) genome sizes in series, species, cultivars, and seedlings from parents with three ploidy combinations: 2x x 2x, 2x x 3x, and 3x x 2x. Pollen diameter was measured to investigate the frequency of unreduced gametes in diploid and triploid Syringa vulgaris cultivars. Three triploids of S. vulgaris were observed: ‘Aucubaefolia’, ‘Agincourt Beauty’, and ‘President Grévy’. Across taxa, significant variations in 1Cx genome size were discovered. The smallest and largest values were found in the interspecific hybrids S. ×laciniata (1.32 ± 0.04 pg) and S. ×hyacinthiflora ‘Old Glory’ (1.78 ± 0.05), both of which are in series Syringa. Series Syringa (1.68 ± 0.02 pg) had a significantly larger 1Cx genome size than the other series. No significant differences were found within series Pubescentes (1.47 ± 0.01 pg), Villosae (1.55 ± 0.02 pg), Ligustrina (1.49 ± 0.05 pg), and Pinnatifoliae (1.52 ± 0.02 pg). For S. vulgaris crosses, no significant variation in 2C genome size was discovered in 2x x 2x crosses. Interploid crosses between ‘Blue Skies’ (2x) and ‘President Grévy’ (3x) produced an aneuploid population with variable 2C genome sizes ranging from 3.41 ± 0.03 to 4.35 ± 0.03 pg. Only one viable seedling was recovered from a cross combination between ‘President Grévy’ (3x) and ‘Sensation’ (2x). This seedling had a larger 2C genome size (5.65 ± 0.02 pg) than either parent and the largest 2C genome size currently reported in lilac. ‘Sensation’ produced 8.5% unreduced pollen, which we inferred was responsible for the increased genome size. No unreduced pollen was discovered in the other diploids examined. Increased ploidy may provide a mechanism for recovering progeny from incompatible taxa in lilac breeding.

Genome wide association analysis of cold tolerance at germination in temperate japonica rice (Oryza sativa L.) varieties.

A pool of 200 traditional, landraces and modern elite and old cultivars of rice, mainly japonica varieties adapted to temperate regions, have been used to perform a genome wide association study to detect chromosome regions associated to low temperature germination (LTG) regulation using a panel of 1672 SNP markers. Phenotyping was performed by determining growth rates when seeds were germinated at 25° and 15°C in order to separate the germination vigorousness from cold tolerance effects. As expected, the ability to produce viable seedlings varied widely among rice cultivars and also depended greatly on temperature. Furthermore, we observed a differential response during seed germination and in coleoptile elongation. Faster development at 15°C was observed in seeds from varieties traditionally used as cold tolerant parents by breeders, along with other potentially useful cultivars, mainly of Italian origin. When phenotypic data were combined with the panel of SNPs for japonica rice cultivars, significant associations were detected for 31 markers: 7 were related to growth rate at 25°C and 24 to growth rates at 15°. Among the latter, some chromosome regions were associated to LTG while others were related to coleoptile elongation. Individual effects of the associated markers were low, but by combining favourable alleles in a linear regression model we estimated that 27 loci significantly explained the observed phenotypic variation. From these, a core panel of 13 markers was selected and, furthermore, two wide regions of chromosomes 3 and 6 were consistently associated to rice LTG. Varieties with higher numbers of favourable alleles for the panels of associated markers significantly correlated with increased phenotypic values at both temperatures, thus corroborating the utility of the tagged markers for marker assisted selection (MAS) when breeding japonica rice for LTG.

Intraspecific, Interspecific, and Interseries Cross-compatibility in Lilac

Lilacs (Syringa sp.) are a group of ornamental trees and shrubs in the Oleaceae composed of 22–30 species from two centers of diversity: the highlands of East Asia and the Balkan-Carpathian region of Europe. There are six series within the genus Syringa: Pubescentes, Villosae, Ligustrae, Ligustrina, Pinnatifoliae, and Syringa. Intraspecific and interspecific hybridization are proven methods for cultivar development. However, reports of interseries hybridization are rare and limited to crosses among taxa in series Syringa and Pinnatifoliae. Although hundreds of lilac cultivars have been introduced, fertility and cross-compatibility have yet to be formally investigated. Over 3 years, a cross-compatibility study was performed using cultivars and species of shrub-form lilacs in series Syringa, Pubescentes, and Villosae. A total of 114 combinations were performed at an average of 243 ± 27 flowers pollinated per combination. For each combination, we recorded the number of inflorescences and flowers pollinated as well as number of capsules, seed, seedlings germinated, and albino seedlings. Fruit and seed were produced from interseries crosses, but no seedlings were recovered. A total of 2177 viable seedlings were recovered from interspecific and intraspecific combinations in series Syringa, Pubescentes, and Villosae. Albino progeny were produced only from crosses with Syringa pubescens ssp. patula ‘Miss Kim’. In vitro germination was attempted on 161 seed from interseries crosses, resulting in three germinations from S. pubescens Bloomerang® x Syringa vulgaris ‘Ludwig Spaeth’. None survived, yet cotyledons produced callus for future efforts to induce embryogenic shoots. This study is a comprehensive investigation of lilac hybridization, and the knowledge gained will aid future efforts in lilac cultivar development.

Obtaining plant Miscanthus sacchariflorus (Maxim.) Hack and Miscanthus sinensis Andersson in vitro culture by indirect morphogenesis

Purpose. To obtain Miscanthus sacchariflorus (Maxim.) Hack and Miscanthus sinensis Andersson in vitro culture by indirect morphogenesis.Methods. Biotechnological procedures, mathematical and statistical analyses.Results. Composition of nutrient medium was developed intended for induction of callusogenesis from Miscanthus seeds with a poor germination and viability of seedlings – Murashige and Skoog (MS) medium was modified for the amount of macroelements (half-dose) that was supplemented with amino acids (300 mg/l of glutamic acid, 50 mg/l of aspartic acid, 5 mg/l of tyrosine, 3 mg/l of arginine, 2 mg/l of hydroxyproline) and plant growth regulators [2,5 mg/l of 2.4D (2.4-Dichlorophenoxyacetic acid), 0,6 mg/l of BAP (6-Benzyl-aminopurine) and 0,3 mg/l of ABA (Abscisic acid)]. Composition of nutrient medium was developed for regeneration of microplants from callus – agar MS medium was modified for the amount of macroelements (half-dose) supplemented with vitamins: 10 mg/l of thiaminum, 1,0 mg/l of pyridoxine, 1,0 mg/l of nicotinic acid (by White), 1,0 mg/l of ascorbic acid, 250 mg/l of glutamic acid, 2,0 mg/l of BAP, 0,3 mg/l of NAA (Naphthaleneacetic acid). On this medium, 100% regeneration of M. sacchariflorus (Maxim.) Hack and 50% regeneration of M. sinensis Andersson was obtained. Due to media modification aimed at initiating callusogenesis and microplants regeneration, reproduction factor of M. sinensis was increased 20 times at the average, M. sacchariflorus – 35–40 times.Conclusions. Plants of M. sacchariflorus (Maxim.) Hack and M. sinensis Andersson were obtained in vitro culture by initiation of callusogenes and microplants regeneration from the Miscanthus seeds with poor germination and viability on nutrient media of certain composition.

Biocontrol Potential of an Endophytic Streptomyces sp. Strain MBCN152-1 against Alternaria brassicicola on Cabbage Plug Seedlings.

In the present study, 77 strains of endophytic actinomycetes isolated from cabbage were screened in order to assess their biocontrol potential against Alternaria brassicicola on cabbage seedlings. In the first and second screening trials, cabbage seedlings pretreated with mycelial suspensions of each isolate were spray-inoculated with A. brassicicola. Strain MBCN152-1, which exhibited the best protection in screening trials and had no adverse effects on seedling growth, was selected for the greenhouse trial. In the greenhouse trial, cabbage seedlings, which had been grown in plug trays filled with soil mix containing spores of MBCN152-1 (1×108 spores g−1 of soil mix), were spray-inoculated with A. brassicicola and grown in greenhouse conditions. MBCN152-1 reduced disease incidence and significantly increased the number of viable seedlings. The efficacy of MBCN152-1 against damping-off caused by seed-borne A. brassicicola was then evaluated. Cabbage seeds, artificially infested with A. brassicicola, were sown in soil mix containing MBCN152-1 spores. The disease was completely suppressed when infested seeds were sown in a soil mix blended with MBCN152-1 at 1.5×107 spores g−1 of soil mix. These results strongly suggest that MBCN152-1 has the potential to control A. brassicicola on cabbage plug seedlings. MBCN152-1 was identified as a Streptomyces humidus-related species based on 16S rDNA sequencing. Scanning electron microscopy showed that the hyphae of MBCN152-1 multiplied on the surface of the seedlings and penetrated their epidermal cells. In conclusion, strain MBCN152-1 is a promising biocontrol agent against A. brassicicola on cabbage plug seedlings.

Biospeckle activity in coffee seeds is associated non‐destructively with seedling quality

AbstractSeeds age during storage, resulting in a decline in germination and seedling quality. Seed quality tests are important to monitor this decline. However, such tests are usually destructive and require large seed numbers and long time. For coffee seeds the standard germination test and assessment of seedling quality takes 30 days. Biospeckle has been used previously as a non‐destructive optical tool to monitor biological activity in a range of tissues. Biospeckle was applied 3–6 days after imbibition (DAI) to investigate an association with coffee seedling quality after 30 days. Two distinct areas of biospeckle activity were demonstrated, concurring with the locations of the embryonic axis and the cotyledons in the apical and central seed parts, respectively. Moisture content analysis revealed that embryos of imbibed seeds contained more water than endosperm. Different areas within the endosperm did not differ in moisture content, while the moisture content of the axis was higher than that of the cotyledons, and this did not change from 4 DAI. Therefore, it was concluded that high biospeckle activity was not the result of increased water content in any seed part, but more likely of growth and metabolism in the axis and cotyledons, which had been described previously. A threshold biospeckle ratio apical : central of 1.02 after 6 days distinguished between seeds that produced dead and viable seedlings after 30 days and provided similar results as a tetrazolium test, a widely acknowledged but destructive test for seed quality. Thus, biospeckle data provided a non‐destructive early parameter for seedling quality, based on embryo growth during germination.

Reduced germination success of temperate grassland seeds sown in dung: consequences for post-dispersal seed fate.

Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining plant populations of its constituents and enabling plants to colonize new habitats. Successful endozoochorous dispersal implies that seeds not only get consumed and survive the digestive tract but are also able to develop into viable seedlings in a dung environment. We experimentally assessed the germination probability and timing of 15 annual and perennial temperate European grassland species in cattle and horse dung and in different climatic conditions (greenhouse and outdoor conditions). Interspecific variation in germinability and germination timing are found, while life strategy had only an effect on germination timing. We found adverse effects of both cattle and horse dung on the germination characteristics of all tested grassland species, but the effects of cattle dung were more pronounced. In comparison with the control treatment, fewer seeds emerged in dung and more time was needed to germinate. Also, germination metrics clearly differed between the artificial greenhouse and outdoor conditions, with generally a lower germinability in outdoor conditions. According to our results, a large cost seems to be associated with endozoochorous dispersal in this stage of the life cycle, as seed dispersal effectiveness strongly depends on the quality of the deposition site with a lowered survival and germination probability when seeds are deposited in dung.

Inoculação artificial de Fusarium oxysporum em sementes de Phaseolus vulgaris

Inúmeras doenças que afetam a cultura do feijão são transmitidas por sementes para tal, são importantes estudos com sementes infectadas que produzam plântulas viáveis. Dessa forma, o objetivo do trabalho foi testar diferentes métodos de inoculação de Fusarium oxysporum em sementes de feijão e verificar seu efeito no desenvolvimento das plântulas. Utilizaram-se sementes da cv. BRS Expedito, as quais foram inoculadas pelos métodos de suspensão de esporos, de contato com restrição hídrica e inoculação do substrato com discos de BDA contendo micélio do fungo. O delineamento experimental foi inteiramente casualizado com oito repetições. Foram feitas avaliações de emergência, comprimento e massa seca de parte aérea e incidência de sintomas da doença em caule e folha. A inoculação do patógeno Fusarium oxysporum em sementes de feijão influencia negativamente o desenvolvimento das plântulas. O método de suspensão de esporos produz sintomas da doença com o menor comprometimento do desenvolvimento das plântulas.

Propagación in vitro de Espeletia paipana S. Díaz y Pedraza, frailejón endémico en peligro de extinción

In this study we established a micropropagation protocol for Espeletia paipana S. Diaz and Pedraza, a critically endangered species with a current population size of 26 adult plants. The primary explants (seeds) used were superficially disinfected with sodium or calcium hypochlorite. The aseptic embryos were cultured on MS media with macroelements at different concentrations, with and without gibberellic acid (GA3), kinetin (KIN), and indole-3-butyric acid (IBA). The effects of temperature and light on germination also were examined. For multiplying shoots, we used MS supplemented with IBA and benzylaminopurine (BA). Shoot rooting was attempted by using IBA + BA, IBA, and 1-naphthalene acetic acid (NAA), and different mixtures of peat, mulch and sand were tested for hardening of the seedlings. The results showed that the highest percentage (66%) of aseptic embryos was obtained using 1% calcium hypochlorite. The highest percentage (50%) of germinated embryos was registered using the MS/4 supplement with 1 mg l-1 GA3, and the highest quantity of reactive embryos and viable seedlings were obtained at 24 oC with continual illumination. The best shoot proliferation results were achieved on MS with 0.5 mg l-1 IBA + 0.05 mg l-1 BA, while 85% rooting was achieved on MS with 5 mg l-1 IBA. The highest percentage (65%) of viable seedlings in a growing house was obtained using a mixture of soil enriched with organic matter and mulch in a 3:1 proportion. The proposed protocol may be employed to develop massive propagation programs, which could reverse the trend toward extinction of E. paipana.

Morphological and Biochemical Answer of the Wheat Seeds at Treatment with 2,4-Dinitrophenol and Potassium Iodate

Oxidative stress can be regarded as an imbalance between the amount of reactive oxygen species (ROS) and the ability of a biological system to eliminate the toxic species and repair the resulting damages. Since the germinating seeds and the resulted seedlings are rich in enzymes, whereas the treatment with chemicals affects much the seed germination, producing also ROS, we evaluate here the influence of 2,4-dinitrophenol (DNP) and potassium iodate (KIO3) on wheat germination (Triticum aestivum L.) and seedlings growth. Germination rate, the masses and heights of the 7 day old seedlings, as well as the activity of some enzymes involved in the oxidative stress such as peroxidase, catalase and superoxide dismutase were measured seven days after the chemical treatment. The treatment of the wheat seeds with 10-5 - 10-3 M solutions of DNP resulted in a relative concentration-dependent inhibition of the germination, with a concomitant stimulation of the weight and height of viable seedlings. The Gasparom variety treated with 10-5 M KIO3 showed a slight increase in the germination rate in comparison with the control batch. The two tested substances determined a significantly modified response of the oxidative stress enzymes, especially in the seeds treated with 10-4 and 10-3 M solutions.

Viability and susceptibility of propagation material from coffee plants to Colletotrichum sp.

This study aimed to verify the viability of propagation material from coffee plants descended from germplasm susceptible to blister spot disease as well as its susceptibility to Colletotrichum sp. relative to commercial coffee cultivars. In the first experiment, fruits were harvested from plants with and without symptoms of blister spot and sowed in trays containing a commercial sterilized substrate. The percentages of germinated seeds, viable plantlets and seedlings were evaluated. In diseased tissues, pathogens were isolated and identified though a pathogenicity test. In the second experiment, ten commercial cultivars and one cultivar originating from plants with blister spot were inoculated with the pathogens to assess the severity of anthracnose. Significant differences were not observed with respect to seed germination. However, the viability of plantlets and seedlings was reduced in the cultivar originating from plants with blister spot (Genotype Originated from Diseased Plants-GODP). These plants showed characteristic symptoms of blister spot, including necrosis in the leaves and hypocotyls, wilting and death. In the necrotic lesions, we observed characteristic sporulation of Colletotrichum sp. The cultivar most susceptible to anthracnose in cotyledonary leaves was Catuaí Vermelho (GODP), which presented the highest area under the disease progress curve (AUDPC). In conclusion, the viability of propagation material from coffee plants that had descended from plants with symptoms of blister spot (GODP) was reduced compared with plants from other genotypes, although seed germination was not affected. Moreover, GODP species are more susceptible to Anthracnose on the cotyledonary leaves relative to the other analyzed commercial cultivars. This work is the first to report on different symptoms exhibited by seedlings originating from the seeds of plants with symptoms of blister spot.

Mejoramiento de la germinación, control de la hiperhidricidad y formación de brotes en Vasconcellea stipulata Badillo

<p><strong>Título en ingles</strong>: Enhancement of germination, hyperhydricity control and in vitro shoot formation of Vasconcellea stipulata Badillo</p><p>Vasconcellea stipulata posee una gran importancia comercial debido a su actividad enzimática y como fuente para el mejoramiento genético de papaya, debido a su resistencia al virus de la mancha anular de esta especie. Sin embargo, debido a su baja regeneración por semillas y al limitado conocimiento de sus propiedades genéticas y farmacéuticas, esta especie no es cultivada ampliamente. La propagación a través del cultivo in vitro de semillas se ha usado para contrarrestar este tipo de problema, pero la hiperhidricidad, un trastorno fisiológico, expresado principalmente en los ejes embrionarios en desarrollo y asociado específicamente a esta especie, es una restricción significativa. Con el fin de obtener material de élite para el cultivo de V. stipulata, el objetivo de este trabajo fue incrementar la germinación, controlar la hiperhidricidad en embriones y evaluar el potencial para inducir respuestas morfogénicas, es decir, la formación de brotes. Nuestros resultados mostraron que es posible aumentar la germinación hasta un 53% en condiciones in vitro, dentro de un período más corto en presencia de peróxido de hidrógeno. Además, la hiperhidricidad se redujo significativamente (50%) en condiciones in vitro cuando se incluyó ácido giberélico en bajas concentraciones en el medio 1/2 Nitsch y Nitsch. Esto permitió recuperar hasta aproximadamente el 80% de plántulas viables. Finalmente, otros reguladores de crecimiento vegetal evaluados, indujeron la formación de brotes en yemas axilares y la formación de callos en secciones de hoja derivadas de plántulas.</p>

Foliage accumulation of aliphatic hydrocarbons in Solanum melongena grown on crude oil polluted and remediated agricultural soil.

Foliage accumulation of aliphatic hydrocarbon in Solanum melongena (garden egg) was studied using three different samples. Three plastic containers of equal sizes were filled with 10kg of humus soil and labeled sample A, B, C respectively. Sample B and C were polluted with 1 dm3 each of bonny light crude oil and 1.5 kg each of compost manure and chicken drops were added to sample C. After 8 weeks of crude oil biodegradation, viable seedlings of Solanum melongena were planted on the three soil samples and allowed to grow for 8 weeks. Plant leaves collected at the 8th week of growth were prepared for analysis. The result showed absence of aliphatic hydrocarbons in sample A (control). The highest concentration of aliphatic hydrocarbons observed in sample B was 9.44 ± 0.31mg/kg for C40 and 6.90 ± 0.37mg/kg for C26 while sample C had 6.21 ± 0.15 mg/kg for C40 and 5.54 ± 0.25mg/kg for C37. The lowest concentration of aliphatic hydrocarbons observed in sample B was 0.00 ± 0.00 mg/kg for C8 - C15 and 1.23 ± 0.06 mg/kg for C16 while sample C had 0.00 ± 0.00mg/kg for C8-C15 and 1.06 ± 0.07mg/kg for C27. The values of individual aliphatic hydrocarbons observed in Solanum melongena grown in soil sample B were higher when compared to the values of corresponding aliphatic hydrocarbons in those grown on soil sample C

Natural establishment of indigenous trees under planted nuclei: A study from a clear-felled pine plantation in an afrotropical rain forest

Applied nucleation has been proposed as a cost-effective reforestation alternative to large-scale re-planting or establishing plantations with exotic tree species. We tested applied nucleation in a regenerating clear-cut pine plantation in Kibale National Park, Uganda, where natural succession had been slow. We planted Neoboutonia macrocalyx, a relatively common indigenous pioneer tree species with animal dispersed seeds and a wide crown, in the pine plantation clear-cuts as seeds and transplanted seedlings. After six years of monitoring the growth of the nucleus trees we identified all naturally recruited seedlings under the nuclei and adjacent control sites without planted nuclei. We monitored the growth and turnover of the recruited seedlings for one year and examined the ground vegetation structure under the nuclei and control sites. We found that the N. macrocalyx nucleus trees had survived equally well if planted as seeds or transplanted seedlings and had attained heights up to ten meters tall. Understory vegetation structure under the established nuclei was less dense (P=0.001) and shorter (P=0.039) compared to control sites. We also found that natural recruitment of indigenous tree species under the nuclei was higher compared to control sites. The seedling density under the nuclei was significantly higher (P=0.035), and there was a significant difference in the composition of seedling communities (P=0.0001) with a larger number of different tree species found under the nuclei. We found that a viable seedling community had been established with a good potential to take over when planted nucleus trees eventually die. Our results show that planting nucleus trees can increase recruitment of indigenous tree species in locations where natural succession is otherwise slow.

Iivestigations on hybrids in the genus Trifolium L. V. Fertility and cytogenetics of the hybrid Trifolium nigrescences Viv. x T. isthomocarpum Brot.

<i>T.nigrescens</i> (2n = 16) crosses with <i>T .isthomocarpum</i> (2n = 16) reciprocally. The viability of hybrid seedlings depend from the direction of the cross. At the time of diakinesis and metaphase I the average chromosome figures per PMC's was 7.014<sub>II</sub>, 0.005<sub>III</sub>, 0.435<sub>IV</sub> and 0.209<sub>I</sub>. For one half of the PMC's in the metaphase I the typical chromosome arrangement was 8<sub>II</sub>. The F<sub>1</sub> plants was almost completly sterile. The causes of viability of hybrid seedlings depending on the direction of the cross, and the sterility of hybrid plants, are discussed.

Investigation of Coffee Seed Physical Purity, Seed Health and Effect of Storage Time on Viability

High seed quality is essential for optimum stand establishment in Coffee. As a result, it is necessary to have seed physical, germination percent, physiological and health tests that permit rapid, objective and accurate evaluation of seed quality. This study evaluated the effect of storage time on physical, physiological, germination percent and health quality of seed lots of five coffee varieties obtained from research and commercial company. This test is conducted under ideal laboratory conditions and in the nursery site. After sample collected pure, pea-beery, cracked and shriveled seeds were measured before determining standard germination and vigor. The highest pea berry was recorded at JARC on the variety 75227(18.63), and the lowest was at LCP on the variety 74165 (8.81). In parchment coffee seed, the percentage of physical defects during seed processing affects germination and seedling viability. The standard germination test in the moisten-soft paper continues to be the most common measure of seed quality in coffee. In addition, this test requires more than two weeks before a determination of seed germination was possible. Ideally, seed quality tests efficiently differentiate between poor and good seed lots in a short period. There was high germination percent in the first planting time were recorded after one month storage than other two consecutive storage time. Normal germinated seedling reduced with in increases seed storage time and the incidence of seed/ soil -born pathogenic fungi. The germination test of seeds from laboratory under petri-dish with moist soft paper and at the nursery site also had low vigour and did not produce suitable seedlings for planting evaluated after three month storage. If after one month storage time of coffee seeds germinated more than older seeds (as our study indicates), then seedlings derived from younger may have a competitive advantage over seedlings derived from older one. In the present study, pre-emergence seedling mortality (Rotten) was greater in third month storage than in first month old seeds. This mortality partially accounted for the lower germination percentage in three month old seeds because only seeds that emerged above the soil surface were considered to have germinated is an indication of reduced vigor. In my study, in coffee seeds, seedlings from relatively low stored seeds were generally better able to withstand environmental stress than those from old seeds. Coffee seed sample from two sources stored safely to optimize coffee seedling production at the appropriate time and season with ideal climatic conditions for planting in the field.

Impacto de la introducción de la abeja doméstica (Apis mellifera, Apidae) en el Parque Nacional del Teide (Tenerife, Islas Canarias)

Valido, A., Rodriguez Rodriguez, M.C., Jordano, P. 2014. Impact of the introduced honeybees ( Apis mellifera , Apidae) on Teide National Park (Tenerife, Canary Islands). Ecosistemas 23(3): 58-66. Doi.: 10.7818/ECOS.2014.23-3.08 Each spring, the introduction of up to 3000 beehives is permitted in the Teide National Park (Tenerife, Canary Islands). This introduction implies that around 100 millions of Apis mellifera (Apidae) bees compete with the native fauna (insects, but also birds and lizards) for floral resources (nectar/pollen). Since A. mellifera is not considered an effective pollinator (qualitatively), its massive presence can also reduce fruit and seed production, and the viability and vigour of seeds and seedlings by inbreeding depression. We document the ecological consequences of massive honeybee introduction on the native pollination network of this protected area (with a high frequency of Canarian endemic species) and also to review examples worldwide about their impact on insular flora and fauna. Our results indicate that both the structure and functionality of the pollination network were negatively, and significantly affected under the massive presence of A. mellifera . When beehives were installed into the Park, the diversity of native flower visitors decreased. Besides, the reproductive performance of highly visited plant species by honeybees ( Echium wildpretii and Spartocytisus supranubius ) was significantly reduced. According to these results, we recommend the complete suppression of introduced beehives in Teide National Park in order to protect its endemic flora and fauna.

Influência do sistema de corte basal de miniestacas na propagação clonal de híbrido de Eucalyptus urophylla x Eucalyptus globulus subsp. maidenii

A técnica de miniestaquia permitiu o estabelecimento de florestas clonais em larga escala. Porém, pouco se avançou no seu manejo em viveiro para genótipos recalcitrantes. Assim, esse estudo teve como objetivo avaliar a influência do sistema de cortes na base de miniestacas na produção de mudas de um clone híbrido de Eucalyptus urophylla x Eucalyptus globulus subsp. maidenii. Desta forma, foram realizadas três avaliações: 1) sobrevivência aos 30 dias em casa de vegetação; 2) enraizamento aos 45 dias em casa de sombra; e 3) aproveitamento final aos 60 dias na área de rustificação. O índice de enraizamento foi determinado com base no percentual de sobrevivência. O delineamento experimental utilizado foi em blocos casualizados constituído de três tratamentos: 1) miniestacas com corte na base perpendicular (testemunha); 2) miniestacas com corte na base em bisel (corte diagonal) e 3) miniestacas cortadas perpendicularmente, com três incisões longitudinais na base. Foram avaliadas quatro blocos de 228 plantas por bloco. Os resultados de enraizamento foram superiores a 80% nos melhores tratamentos e indicam que a propagação do clone via miniestaquia é viável, não apresentando comportamento recalcitrante. Os sistemas de corte basal das miniestaca em bisel e as incisões não favoreceram a formação de raízes.