Sonia Cristina Juliano Gualtieri de Andrade Perez

Atividade alelopática de extratos aquosos de Aristolochia esperanzae O. Kuntze na germinação e no crescimento de Lactuca sativa L. e Raphanus sativus L.

This work analyzed the effects of aqueous extractsof Aristolochia esperanzae organs in the germination and initial growth of lettuce and radish. All the extracts were prepared using 100g of plant fresh material + 300mL of distilled water to produce the extract 100% concentrated. This extract was diluted with distilled water to produce a final concentrations of 75, 50 and 25%. The germination was evaluated by tests using the extracts of leaf, stem, root, fruit and flower, with concentration of 100, 75, 50, and 25%. In the seedlings growth, the extracts of leaf, stem, and root were used in the concentration of 100 and 50%. In the germination tests, four replicates of 30 seeds were distributed in Petri dishes with two filter paper moistened with 5mL of the extracts, dried during 12 hours and moistened again with 4,5mL of distilled water. In the first test, the rate and germination percentage were evaluated. In the growth test, the seeds were previously germinated (2-4mm radicle length) and transferred for plastic boxes containing the filter paper or coconut fiber, moistened with the extracts. The shoot height, radicle length, dry mass and the presence of abnormalities in the seedlings were evaluated. Both tests were maintained at constant temperature (27oC). The results showed that the leaf extracts affected strongly the germination percentage and all the extract, in different concentrations, delayed the germination of lettuce and radish seeds. In the growth tests could be verified that the stem and root extracts caused abnormality in the seedlings. The seedlings grown in filter paper presented bigger growth inhibition in relation to seedlings from coconut fiber. The extract concentration was the main responsible for the promotion or inhibition caused on lettuce and radish seedlings growth.

Efeito alelopático de Andira humilis Mart. ex Benth na germinação e no crescimento de Lactuca sativa L. e Raphanus sativus L.

Neste trabalho, objetivou-se avaliar o efeito alelopatico de caules e folhas de Andira humilis na germinacao de sementes e no crescimento de plântulas de rabanete e alface. Para os experimentos de germinacao foram preparados extratos aquosos de caules e folhas de A. humilis nas concentracoes de 0, 4, 8, 12 e 16% (p/v). Foram realizadas quatro replicas de trinta sementes de alface ou de rabanete, distribuidas em placas de Petri forradas com papel-filtro umedecido com 5mL dos extratos, mantidas a 27 oC e na ausencia de luz. As contagens das sementes germinadas foram realizadas a cada 12h, calculando-se a percentagem e a velocidade de germinacao. Extratos de caules e folhas reduziram significativamente a velocidade e a percentagem de germinacao, em relacao ao grupo controle. Os experimentos de crescimento foram realizados com quatro replicas de oito sementes germinadas de alface ou de rabanete, a 27 oC, na ausencia de luz e em papel-filtro como substrato, sendo avaliadas as concentracoes 0, 4 e 12% (p/v). Plântulas de alface e rabanete sofreram inibicao significativa em seus comprimentos, pelos extratos de folhas. Extratos de caules a 4 e 12% (p/v) nao causaram inibicao do crescimento em rabanete. A interferencia dos extratos na germinacao e no crescimento em alface e rabanete foi desassociada de qualquer efeito do potencial osmotico e do pH, indicando, portanto, atividade alelopatica.

Processo germinativo de sementes de paineira sob estresses hídrico e salino

Multiple stresses promoted by a changeable environment can limit germination process, seedling emergence and survival. The objective of this work was to determine the effect of water and salt stresses on the viability and vigour of paineira seeds (Chorisia speciosa St. Hil.) and the maximal tolerance limits. Water stress was evaluated using mannitol and PEGxa06000 solutions. Salt stress was evaluated using NaCl, KCl and CaCl2 solutions. After coat punction, four replicates of 50 seeds for each treatment were submitted to germination on filter paper moistened with test solutions at different osmotic potential and kept at 27oC. The lowest tolerance limit to water stress was observed when PEG solutions were used. The maximal tolerance limit was between -0,6 and -0.7 MPa for PEGxa06000 and between -1.4 and -1.6 MPa for mannitol solutions. The germination percentage decreased with the reduction of the osmotic potential of the environment, independently of the used salts. The same tolerance limits to different salts were observed between -1.0 and -1.2 MPa. Paineira may be considered a glycophyte with moderate tolerance to the salts NaCl, KCl and CaCl2.

Growth regulators and water stress in canafistula seed germination

Scarified selected seeds of the wood tree species canafistula were submitted to water stress at 27oC, with and without addition of putrescine and spermidine at concentrations of 5 and 10mM and gibberellin 0.1mM. The values of rate and germination percentage of all the experiments indicated that the seeds are resistant to water stress. When putrescine and spermidine were added to the germination media the performance under stress increased significantly. Gibberellin extended the maximal tolerance limit to water stress.

Ação do polietileno glicol na germinação de sementes de Adenanthera pavonina L. e o uso de poliaminas na atenuação do estresse hídrico sob diferentes temperaturas

O presente trabalho teve como objetivo avaliar a porcentagem e a velocidade de germinacao de sementes de Adenanthera pavonina L., previamente escarificadas com acido sulfurico, submetidas as solucoes de polietileno glicol nos potenciais osmoticos de 0,0; -0,1; -0,2; -0,3; -0,4; -0,5MPa e colocadas para germinar a 25, 30 e 35°C, observando, posteriormente, a atenuacao do estresse hidrico induzido pela adicao de poliaminas (100ppm) as solucoes de polietileno glicol. O aumento da concentracao de polietileno glicol no meio germinativo acarretou decrescimo na porcentagem e na velocidade de germinacao das sementes, mesmo com a adicao de poliaminas as solucoes. A atenuacao do estresse hidrico foi obtida em sementes submetidas as solucoes acrescidas de poliaminas, devido ao significativo aumento na porcentagem de germinacao dessas sementes; entretanto nao houve ampliacao do limite maximo de tolerância ao polietileno glicol.

Storage of ipê-branco and ipê-roxo seeds in different packagings and environments.

Storage plays a crucial role in maintaining the physiological quality of a seed lot. In this study, we aimed to identify an adequate condition for storage of ipe-branco (Tabebuia roseo-alba (Ridl.) Sand.) and ipe-roxo (Tabebuia impetiginosa (Mart.) Standl.) seeds, and to evaluate methods to estimate changes in the viability and vigor of those seeds. Different groups of seeds were placed in polyethylene bags, Kraft paper bags and cans. The seeds were then stored for up to 300 days under laboratory, refrigerator, and refrigerated chamber conditions. Seed water content, percentage and speed germination and electric conductivity were determined at the start of storage and thereafter at every 60 days. The best T. roseo-alba and T. impetiginosa seed conservation condition was obtained with cans maintained in the refrigerator. T. impetiginosa seeds can also be kept in polyethylene bags, paper bags, or cans when stored in a refrigerated chamber. Seed vigor changes in these species are initially identified by decrease in the speed germination.

INFLUÊNCIA DA LUZ NA GERMINAÇÃO DE SEMENTES DE CANAFÍSTULA SUBMETIDAS AO ESTRESSE HÍDRICO

This research aimed at recording the influence of light during germination of canafistula seeds under water stress. Seeds of Peltophorum dubium (Spreng.) Taub. were selected for this experiment. Four samples of 50 seeds were used in each test. The seeds were previously scarified with sulfuric acid during 20 minutes, rinsed and distributed in sterilized Petri dishes and incubated under optimal temperature. The dishes had a filter-paper moistened with test solution (PEG 6000 or manitol) in order to induce different osmotic potential values. The maximum tolerance limit under light or darkness, using PEG or manitol was between -1.4 and -1.6 MPa. When results of both osmotic treatments were compared, it was observed that seeds germinated faster in manitol than in PEG solutions. Under continuous light condition, the germination percentage was significantly reduced for seeds kept in manitol solutions. After 21 days under water stress (-1.6 to -2.0 MPa) the germination was suppressed. The seeds were rinsed in distilled water and maintained on 0.2% Captan solution, under the same light conditions. After 24 hours it was observed a recovery response. The seeds kept in manitol solutions presented lower values of germinability than those in PEG solutions. Continuous light conditions reduced the recovery response for seeds in manitol solutions.

Influência do armazenamento, substrato, envelhecimento precoce e profundidade de semeadura na germinação de canafístula

Peltophorum dubium is a tree species native from the Brazilian semideciduous forest considered to be in extinction. It is a 15-25m high perennial tree, often used in recomposition programs or as ornamental. Its wood has a long lifespan and multiple uses. This work aimed at to determine the storage effect on seed germination rate and vigour, using different substrates and the field performance on different sowing depths. After the scarification, the seeds were distributed on different substrates as paper, xaxim, sand and cotton. No significant difference was observed among the substrates in relation to the germination rate. The viability and vigour were not affected after two years in a glass container under 10oC. The seeds were resistant to the induced aging (45oC - 100% relative humidity) until 144 hours, after what a decrease in the final percentage of seedlings was observed, but not on the dry matter. Several groups of seeds (intact, scarified, scarified and imbibed with GA3) were sowed in the field (1, 3 and 5 cm of depth) and in vermiculite (1cm depth - room temperature). For all treatments, a significant reduction on the initial population was observed with the increase in sowing depth. Scarified seeds resulted in a higher initial population and the use of GA3 increased seed germination in the field at 3 and 5 cm depth.

Allelopathic potential of bark and leaves of Esenbeckia leiocarpa Engl. (Rutaceae)

Allelopathic potential of bark and leaves of Esenbeckia leiocarpa Engl. (Rutaceae)). We investigated the inhibitory potential of aqueous extracts of bark and leaves of Esenbeckia leiocarpa Engl. on lettuce germination and early seedling growth. We compared the effects of four concentrations (100, 75, 50 and 25%) of each extract to water and polyethylene glycol (PEG 6000) solution controls for four replicates of 50 seeds for germination and four replicates of ten seedlings for seedling growth. The inhibitory effects of E. leiocarpa extracts on the percentage of germination and on the germination speed seemed to be more than simply an osmotic effect, except for the percentage of seeds germinated in bark extracts. When compared to water control, both bark and leaf extracts delayed germination, and leaf extracts also affected the percentage of germinated seeds. Leaf extracts of all concentrations strongly inhibited the development of seedlings and caused them some degree of abnormality; bark extracts also caused abnormalities and reduced seedling growth. Root development was more sensitive to the extracts than hypocotyl growth. The negative effects of leaf extracts on germination and seedling growth were more pronounced than those of bark extracts, and the overall effects of both extracts were positively correlated with extract concentrations.

Efeito do estresse hídrico e envelhecimento precoce na viabilidade de sementes osmocondicionadas de paineira (Chorisia speciosa)

The objective of this work was to evaluate the efficiency of osmotic conditioning on the tolerance increase of seeds of Chorisia speciosa St. Hil. to water stress and accelerated aging. The seeds previously scarified (punction) were primed in KNO3 (0.1M) solutions at 20oC during 24 hours. After that, the seeds were dried (at 27oC) until the initial moisture level, presented before the pre-imbibition, was reached. Primed and non primed seeds were exposed to water stress simulated with PEG 6000 solutions, with 0.0, -0.1, -0.2, -0.3, -0.4, -0.5, -0.6 and -0.7 MPa of osmotic potentials and to accelerated aging at 45oC and 100% of RU during 0, 24, 48, 72, 96 and 120 hours. The mean values of rate and germination percentage were higher in primed seed than in non primed ones. The tolerance limit to water stress was extended for primed seed. Primed seeds were more sensible to accelerated aging.