Germination of Phoenix roebelenii Seeds

The Phoenix roebelenii O'Brien is one of the most used plants in the Brazilian landscape. The work aimed to study the effect of different fruit harvesting locations, associated with seven temperature conditions, on the germination of P. roebelenii seeds. The fruits were collected from two different locations: Ilha Solteira, western Sao Paulo State and Jaboticabal in the middle East of the same State. The disseminules (seeds with stucked endocarp) were placed in plastic boxes (gerbox), and the experimental design was entirely randomized in a factorial scheme of 7x2 (seven temperatures conditions: room temperature, constant at 20, 25, 30 and 35 degrees C and alternated at 20-30 and 25-35 degrees C; and two fruit harvesting locations: Ilha Solteira and Jaboticabal, with four replications with 25 seeds each. The disseminules that emitted the germinative intumescence were daily noted until the germinative process got steady, in about 90 days. The germination rate (G%), the germination speed index (GSI), and the means were extracted and compared by the Tukey test. The highest values of germination rate were obtained at 30, 25-35 degrees C and room temperatures. The seeds showed a higher GSI at room temperature. The fruit harvesting locations influenced the germination.

GERMINATION OF EUCALYPTUS SEEDS UNDER WATER AND SALT STRESS

The knowledge of the physiology of Eucalyptus spp. germination may contribute significantly to the development of management and choice of suitability of the deployment areas. The aim was to evaluate the effects of water and salt stress on seed germination of Eucalyptus camaldulensis, E. citriodora, E. grandis, E. robusta and E. urophylla. The seeding was done with four replicates of 0.05 g of seeds in paper moistened with solutions at potentials of 0.0, -0.2, -0.4, and -0.8 MPa, induced with polyethylene glycol (PEG 6000) and NaCl. The germination test was in 25 degrees C in the presence of light. Were evaluated the first test score seven days after sowing, and weekly germination (normal seedlings) until 28 days. Were also calculated the germination speed index. Water stress causes a greater reduction in the rate of germination and accumulated germination of E. camaldulensis and E. citriodora seeds than salt stress, and the seeds of E. robusta are more adapted to germinate under salt stress moderate, between -0.2 and -0.4 MPa. Regardless of the substance used to induce stress, the threshold for germination was -0.8 MPa. The E. camaldulensis is the most sensitive specie to water stress and E. urophylla most sensitive to salt stress.

Short-term effect of alginate-biochar microbeads in corn germination

Biochar is the solid by-product of biomass pyrolysis. It is a promising soil conditioner and can be a material with high aggregate economic value, since its performance can improve plant’s nutrient utilization and reduce the usage of conventional fertilizers. Biochar can be used in the formulation of new types of fertilizers as polymeric microbeads. These microbeads can be enriched with biochar and nutrients in its matrix to form fertilizers of slow release of nutrients. Thus, as a promising agricultural material, it is important to assess the environmental hazards caused by the implementation of these microbeads. In this context, seeds were sown in a soil-less Petri dish with microbeads produced with biochar from sugarcane enriched with or without phosphate. The seeds germination and its vitality were evaluated by the first germination count (FGC) and the germination speed index (GSI). The short-term effects showed that the microbeads, in general, assessed by the means of FGC, GSI and mass gain showed the best performance, suggesting that the environment created by these materials provided the best chemical and physical interaction with the embryonic axes.

Phytotoxicity of Tagetes erecta L. and Tagetes patula L. on plant germination and growth

This study evaluated the phytotoxic potential and antioxidant activity of Tagetes patula and Tagetes erecta, and total phenols and flavonoids of the extracts were quantified. Laboratory bioassays for both pre- and post-emergence were performed in Lactuca sativa L. seeds and in the Allium cepa seeds test. The antioxidant activity was evaluated by DPPH radical scavenging and reducing power of iron, besides total phenols and flavonoids quantification in the extracts. Thus, was observed a reduction in the mitotic index when in compared with the negative control. Was observed also a reduction the germination and development of tested seedlings and was verified a considerable antioxidant potential and presence of flavonoids and phenolic compounds in the extracts. According to these results, it is possible to conclude that T. erecta and T. patula have phytotoxic compounds that may enhance and expand their use in the management of organic agriculture, mainly in vegetables.

Investigation on the s of guava (Psidium guajava L.) infusions on germination, root tips and meristematic cells of Latuca sativa

Guava (Psidium guajava L.) is a plant often employed in popular medicine. Recently several studies have alerted about the toxicity of substances present in medicinal plants, which can pose risks to the human health. In this sense, the present work aimed to investigate the phytotoxic, cytotoxic and genotoxic action of three guava varieties - Paluma, Pedro Sato and Roxa (purple) - on the plant test system Lactuca sativa L. Thus, macro- and microscopic evaluations were carried out for five infusion concentrations (2.5, 5.0, 10.0, 20.0 and 40.0 g.L-1) prepared from each variety. Distilled water was used as negative control. Chromatographic and spectroscopic analysis by HPLC-PAD indicated that the chemical composition of the infusion of Roxa is different than that of the infusions of the varieties Paluma and Pedro Sato. It was observed that seed germination and root growth in L. sativa exposed to infusions decreased with increasing infusion concentration, regardless of the tested cultivar. For the mitotic index, no statistical differences were observed. On the other hand, a significant increase in the frequency of cell cycle alterations was verified, especially for the highest concentrations tested. The cytogenotoxic was significant. Therefore, guava should not be used indiscriminately in popular medicine.

Seed quality, chlorophyll content index and leaf nitrogen levels in maize inoculated with Azospirillum brasilense

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Allelopathic potential of Equisetum giganteum L. and Nephrolepis exaltata L. on germination and growth of cucumber and lettuce

Nephrolepis exaltata L. Schott "Bostoniensis" family Davalliaceae and Equisetum giganteum L. family Equisetaceae, Phylum Pteridophyta, exhibit a strong mechanism of dominance in the areas in which they live. Have secondary compounds with allelopathic activity. The objective of this article was evaluate allelopathic potential of two ferns species, using bioassay applying aqueous extracts of dried fronds, in cucumber and lettuce seeds, and observing germination and initial development. To observe the influence on germination was analyze the percentage of germinated seeds and germination speed index (GSI). To observe initial development was analyzed shoot and root growth of the seedlings. The bioassays revealed that no concentration significantly inhibited the germination, but germination speed was delayed gradually in two species tested, as increased the extract concentration. In initial development, all the extracts showed a tendency to inhibit the growth, and an increase in extract concentration decreasing growth of radicle and hypocotyl axis. We conclude that the aqueous extract has inhibitory activity more pronounced in early development than in seed germination, affecting the primary structures of the tested plants, corroborating with the observations of occurrences of the species in natural places where dominate and suppress the growth of other species.

Osmotic potentials on water uptake and germination of Guazuma ulmifolia Lam. (Sterculiaceae) seeds

Osmotic potentials on water uptake and germination of Guazuma Ulmifolia Lam. (Sterculiaceae) seeds. This work was carried out in the Germination Lab. of the Department of Botany, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, São Paulo State, Brazil. The aims of this work were to determine the water uptake curve and to evaluate the germination of Guazuma ulmifolia seeds subjected to different water potentials. For the water uptake curve, seven replicates of 50 pre-scarified seeds were placed onto paper moistened with 15 mL PEG 6000 solution under the potentials 0 (control), -0.3 and -0.6 MPa at 25o C in the darkness. For the germination assay, four replicates of 50 seeds were subjected to the same above-described conditions; however, one lot of seeds was modified when there was variation in the refractometric index, whereas the remaining ones were kept in the same solutions until the end of the experiment. All three phases of water uptake were detected under 0 and -0.3 MPa; however, phase II was prolonged under -0.6 MPa and germination was not observed. For 0 and -0.3 MPa, the adopted statistical models consisted of asymptotic (phases I and II) and exponential (phase III) functions, y = a*[1 - b*exp (-c*t) + exp (-d + e*(t - t0)]. For -0.6MPa, only the asymptotic function y = a* [1 - b* exp (-c*t)] was used since there was no evidence of germination. The germination final percentage and speed index were lower under -0.3 MPa, mainly when solutions were not replaced; besides, germination was not detected under -0.6 MPa, with or without solution replacement.