Colubrina glandulosa Perkins é uma espécie de importância ecológica e socioeconômica, porém, em risco de extinção. O presente trabalho teve como objetivo avaliar diferentes condições de armazenamento sobre a qualidade fisiológica de sementes de colubrina. As sementes foram acondicionadas em saco de papel e frasco de vidro, em ambiente de laboratório e em câmara seca, durante os períodos de 0, 3, 6, 9, 12 e 15 meses. Para cada período e condição de armazenamento foram avaliadas as seguintes variáveis: teor de água, germinação, velocidade de germinação, tempo médio e sincronia de germinação, comprimento total e massa seca de plântulas. O delineamento experimental foi inteiramente casualizado, em arranjo fatorial 2 x 6 (duas embalagens e seis períodos de armazenamento), com quatro repetições de 25 sementes. O teor de água das sementes variou de 8,0 a 17,8%, dependendo da embalagem e das condições ambientais do local de armazenamento, sendo fisiologicamente classificadas como ortodoxas. Em condições de laboratório, verificou-se diminuição no potencial fisiológico das sementes, a partir dos 6 meses, em embalagem de papel. Sementes acondicionadas em embalagem porosa ou impermeável, com teor de água de 8,0%, na condição de câmara seca, mantiveram a viabilidade quando armazenadas por 15 meses.

Colubrina glandulosa Perkins is a species of ecological and socioeconomic importance, but in danger of extinction. The present study aimed to evaluate different storage conditions to check the physiological quality of the colubrina seeds. The seeds were stored in a paper bag and glass bottle, in a laboratory environment and in a dry chamber, during 0, 3, 6, 9, 12, and 15 months. For each storage period and condition, the following variables were evaluated: water content, germination, speed of germination, mean time and germination synchrony, total length, and dry mass of seedlings. The experimental design was completely randomized, in a 2 × 6 factorial arrangement (2 packs and 6 storage periods), with 4 replicates of 25 seeds. The water content of the seeds ranged from 8.0% to 17.8%, depending on the packaging and environmental conditions of the storage site, being physiologically classified as orthodox. Under the laboratory conditions, seed physiological potential decreased from 6 months onward in the paper packaging. Seeds conditioned in a porous or impermeable packaging with a water content of 8.0%, in the dry chamber condition, remained viable when stored for 15 months.

Abstract A major challenge in sugarcane breeding program is the obtaining of enough number of seeds (caryopses) for the development of new improved cultivars. Genotypes differ in their function as pollen recipient and pollen donor, which also affect the seed performance. Thus, the aim of this study was to verify the production and performance of sugarcane seeds from different hybridizations involving RB92579 as pollen recipient and pollen donor. Twelve bi-parental crossings were carried out involving RB92579 and other different genotypes randomly chosen. Seed production potential was evaluated by percentage of fertile spikelets and caryopsis fresh weight. The seed physiological potential was determined by evaluating germination and vigor (index of germination rate, number of normal seedlings per gram of fuzz, and seedling dry weight). The results showed better performance for RB92579 as pollen donor for all characteristics studied. Therefore, RB92579 sugarcane cultivar should be used as pollen donor during hybridizations, condition that permits a greater production and physiological performance of seeds for the sugarcane breeding programs.

ABSTRACT Castor bean is one of the crops with potential to provide raw material for production of oils for biodiesel. This species possess adaptive mechanisms for maintaining the water status when subjected to drought stress. A better understanding these mechanisms under field conditions can unravel the survival strategies used by this species. This study aimed to compare the physiological adaptations of Ricinus communis (L.) in two regions with different climates, the semi-arid and semi-humid subject to water stress. The plants showed greater vapor pressure deficit during the driest hours of the day, which contributed to higher values of the leaf temperature and leaf transpiration, however, the VPD(leaf-air) had the greatest effect on plants in the semi-arid region. In both regions, between 12:00 p.m. and 2:00 p.m., the plants presented reduction in the rates of photosynthesis and intracellular CO2 concentration in response to stomatal closure. During the dry season in the semi-arid region, photoinhibition occurred in the leaves of castor bean between 12:00 p.m. and 2:00 p.m. These results suggest that castor bean plants possess compensatory mechanisms for drought tolerance, such as: higher stomatal control and maintenance of photosynthetic capacity, allowing the plant to survive well in soil with low water availability.

ABSTRACT Maturation is a characteristic of sugarcane plant (Saccharum spp.) and even when grown under the same soil and climate conditions the varieties differ on the maturation curve. Thus, studies that allow establishing maturation curves of different sugarcane genotypes in the local soil and climate may indicate the proper harvesting period to ensure better quality of the raw material. This study aimed to analyze the levels of soluble sugars during the maturation phase and assess the technological and productivity indexes of four irrigated sugarcane genotypes in the region of Rio Largo, Alagoas. The experiment was conducted in randomized blocks in a 4 x 2 x 5 factorial: four genotypes (RB92579, RB98710, RB99395 and RB961003), two stem portions (internodes 1-4 and internodes 5-8) and five seasons (82, 49, 25, 13 and 3 days before harvesting), each treatment with three replications. Internodes 1-4 showed the highest levels of reducing sugars, while the largest accumulation of sucrose and total soluble solids occurred in internodes 5-8. RB99395 genotype showed more stability in the sugar levels during sugarcane maturation, which can indicate early maturation and high agricultural yield.

Tabebuia aurea (Benth. & Hook. f. ex S. Moore) (Bignoniaceae) é uma espécie arbórea comum no Brasil, utilizada para fins ornamentais de calçadas e parques cuja madeira é usada para fabricação de móveis. O objetivo deste estudo foi avaliar o efeito do sombreamento no crescimento e na fotossíntese de mudas de T. aurea e sua adaptação fotossintética após transferência ao sol pleno. As plântulas de T. aurea foram cultivadas sob 0, 50, 70 e 95% de sombreamento. Sob cada condição de sombreamento foram avaliadas a radiação fotossinteticamente ativa e as trocas gasosas das folhas aos 51 (plântulas jovens) e após 70 dias após a semeadura das sementes sem o uso de luz artificial; logo em seguida as plântulas foram transferidas para o sol pleno e nova medidas foram feitas após 15 min e 3 dias da transferência para a nova condição. As plântulas de T. aurea apresentaram crescimento satisfatório até o nível de 50% de sombreamento no viveiro que pôde ser verificado tanto pelo crescimento como pelo acúmulo de biomassa total. O sombreamento acima de 70% reduziu o número de folhas, área foliar e o diâmetro do coleto em relação às plantas expostas ao pleno sol. Os resultados sugerem que plântulas de T. aurea devem ser cultivadas em sol pleno ou com sombreamento de até 50% para maximizar o crescimento no viveiro e minimizar o estresse de transferência das mudas para o local de plantio definitivo.

Tabebuia aurea (Benth. & Hook. f. ex S. Moore) (Bignoniaceae) is a boreal species common in Brazil. It is used for ornamental parks and along sidewalks. Its timber is also used for furniture. The objective of this study was to evaluate the effect of nursery shading on the growth and photosynthesis of T. aurea and their photosynthetic adaptation after being transferred to direct sunlight. The T. aurea seedlings were grown under 0, 50, 70 or 95% shade. The photosynthetic active radiation and leaf gas exchange were measured over two distinct periods: 51 (young seedlings) and 70 days after having been sown under each shade treatment. Immediately after the measurements were taken, the seedlings were transferred into full sunlight and the measurements were repeated two times after 15 min and 3 days under ambient sunlight. T. aurea seedlings showed satisfactory growth up to 50% shade in the nursery, which could be verified both by growth measurement and by total biomass accumulation. Shading greater than 70% reduced the number of leaves, the leaf area and the stem diameter in relation to plants exposed to full sunlight. The results suggest that T. aurea seedlings should be grown under full sunlight or under shading up to 50% to maximize their growth in the nursery and to minimize stress when transferring the seedlings to their final planting sites.

O estresse hídrico afeta grande parte da agricultura mundial, razão por que se propôs, através deste trabalho, avaliar o comportamento, em casa-de-vegetação, de quatro variedades de cana-de-açúcar (SP79-1011, RB72454, RB98710 e RB92579) submetidas a déficit hídrico durante a fase inicial de crescimento vegetativo. As plantas foram cultivadas em vasos plásticos contendo 15 kg de solo. O estudo foi um fatorial (4 variedades x 3 níveis de água disponível no solo), em delineamento inteiramente casualizado, com cinco repetições. Os níveis de água no solo foram baseados na capacidade de água disponível (CAD) ficando assim definidos: controle (80 a 100% da CAD), estresse hídrico moderado (40 a 60% da CAD) e estresse hídrico severo (0 a 20% da CAD). A deficiência hídrica provocou reduções significativas na condutância estomática (gs), transpiração foliar (E), fotosíntese líquida (A) e na eficiênca de uso da água de produção (EUAp), independente da variedade. As variedades SP79-1011 e RB98710 apresentaram maior sensibilidade estomática, reduzindo gs e E aos 71 dias após início do estresse, mesmo sob condições controle; entretanto, em tais condições A foi pouco afetada, indicando que as plantas são capazes de manter a taxa fotossintética, mesmo com os estômatos parcialmente fechados. O estresse hídrico provocou pouca redução na eficiência fotoquímica potencial das variedades estudadas.

Water stress affects a great part of the world's agriculture. Thus, this work was conducted to evaluate photosynthetic traits in four varieties of sugarcane (SP79-1011, RB72454, RB98710 and RB92579) submitted to water stress during the early stage of the vegetative period. The plants were cultivated in plastic pots (15 kg of soil). The study was a factorial (4 varieties x 3 levels of soil water content based on available water capacity (AWC)), in a completely randomized design with 5 replications. The levels of water content in the soil were as follows: control (80 to 100% of AWC), moderate water stress (40 to 60% of AWC) and severe water stress (0 to 20% of AWC). Water stress provoked a significant reduction in stomatic condutance (gs), foliar transpiration (E), net photosynthesis (A) and in the water use efficiency of production (WUEy), irrespective of varieties. The varieties SP79-1011 and RB98710 showed greater stomatal sensitivity, reducing gs and E by the 71 days after the beginning of the water stress treatments, even in the control. However, under such conditions A was little affected, indicating that the plants are capable to fixing CO2 with stomata partially closed. Water stress caused a small reduction in the potential photochemical efficiency (Fv/Fm ratio) in the studied varieties.

O mercado brasileiro de flores tropicais encontra-se em franco crescimento, com uma importante participação da região Nordeste, destacando-se o estado de Alagoas. Dentre as flores tropicais de corte para exportação, a alpínia (Alpiniapurpurata (Vieill) K. Schum) ocupa posição de destaque. Visando retardar a senescência das hastes florais de alpínia, cultivar Pink Ginger, foram conduzidos dois experimentos em laboratório no CCA da Universidade Federal de Alagoas. No primeiro, foram testados três tempos (30; 60 e 120 minutos) de exposição ao tiossulfato de prata 1 mM, seguido ou não de pulsing em sacarose a 20%, por 12 horas. No segundo experimento foram verificados os efeitos nas relações hídricas e longevidade das hastes da adição de sulfato de cálcio a 50 e 100 mM, silicato de sódio a 1,25 e 2,50 mM, além da interação sulfato de cálcio a 50 mM + silicato de sódio a 1,25 mM, em solução de manutenção. Nos dois experimentos, a testemunha consistiu da manutenção das hastes em água destilada. A massa fresca e a qualidade das hastes foram determinadas a cada dois dias. O tiossulfato de prata, aplicado na forma de pulsing por 60 minutos ou mais, promoveu desidratação das hastes. O uso de sulfato de cálcio promoveu aumento da durabilidade comercial e melhoria da hidratação das hastes.

The Brazilian market of tropical flowers has been growing broadly with a strong participation of the Northeast Region, where the State of Alagoas stands out. Among the exporting tropical cut flowers, pink ginger (Alpinia purpurata (Vieill) K. Schum) has been one of the most promising species. Aiming at delaying senescence in floral stems of pink ginger, two laboratory experiments were carried out at the Agricultural Science Center of the Federal University of Alagoas. In the first experiment, three different exposure periods (30; 60, and 120 minutes) to silver thiosulphate 1 mM were tested, followed or not by pulsing in a 20% sucrose solution, for 12 hours. In the second experiment, we evaluated the effect of adding calcium sulphate 50 and 100 mM, sodium silicate 1.25 and 2.5 mM, and the combination of calcium sulphate 50mM + sodium silicate 1.25mM on the hydric status and longevity of floral stems. In both experiments, the control treatment consisted of keeping stems in distilled water. Fresh biomass and quality of floral stems were determined every other day. Silver thiosulphate applied in pulsing for 60 minutes or more led to stem dehydration, whereas calcium sulphate improved both stem hydration and commercial durability.

Acacia polyphylla é uma espécie arbórea característica dos estádios iniciais da sucessão secundária, de grande utilidade na recuperação de áreas degradadas. O presente trabalho teve como objetivo estudar a germinação de suas sementes sob diferentes condições de temperatura e luz. Avaliaram-se os efeitos das temperaturas constantes de 15, 20, 25 e 30 ºC e alternada de 20-30 ºC, sob fotoperíodo de oito horas de luz branca. A temperatura constante de 25 ºC foi a mais adequada para a germinação e o estudo de luz foi realizado nessa temperatura. As sementes foram submetidas à ausência de luz e a fotoperíodos de 1 a 12 horas sob luz branca (alta relação vermelho/vermelho-extremo), além de fotoperíodos sob luz branca iniciados e finalizados com luz de sombreamento (baixa relação vermelho/vermelho-extremo). A porcentagem de germinação não foi afetada pelos diferentes fotoperíodos sob luz branca testados, mas fotoperíodo igual ou superior a quatro horas favoreceu o desenvolvimento inicial das plântulas. A germinação não foi afetada pela luz com baixa relação vermelho/vermelho-extremo, mas na ausência de luz as sementes germinaram em menores porcentagem e velocidade.

Acacia polyphylla (Leguminosae-Mimosoideae) is a typical tree species of secondary succession in Brazil, important for restoration of degraded areas. The purpose of this work was to evaluate the seed germination under different temperatures and light conditions. Constant (15, 20, 25 and 30 ºC) and alternating (20-30 ºC) temperatures were evaluated, at an eight hours photoperiod under white light. Constant temperature of 25 ºC was optimal and the light experiments were conducted at that temperature. Seeds were incubated in darkness and at photoperiods from 1 to 12 hours under white light (high red/far-red ratio), as well as at photoperiods under white light initiated and concluded with shade light (low red/far-red ratio). Germination percentage was not affected by the photoperiods under white light tested, but a photoperiod similar or higher than four hours was required for better initial seedling growth. Both germination percentage and speed was not affected by light of a low red/far-red ratio, but they decreased in darkness.

Guazuma ulmifolia Lam., conhecida como mutamba, é uma espécie arbórea característica dos estádios iniciais da sucessão secundária, com ampla ocorrência natural no Brasil. Possui grande potencial para recuperação ambiental de áreas degradadas. Neste trabalho, conduziram-se dois experimentos, nos quais as sementes foram extraídas e escarificadas antes da instalação dos testes de germinação. O primeiro experimento foi desenvolvido com sementes colhidas em outubro de 1995 e teve por objetivo definir as temperaturas cardeais para a germinação das sementes. Foram testadas as temperaturas de 10, 15, 20, 25, 30, 35, 40 e 45 ºC, sob fotoperíodo de oito horas. Os resultados mostraram que a temperatura mínima é próxima de 10 ºC, a máxima se situa entre 35 e 40 ºC e as temperaturas de 25 e 30 ºC encontram-se dentro da faixa ótima. No segundo experimento, visou-se avaliar o requerimento fotoblástico de sementes recém-colhidas (colheita de outubro de 1996) e armazenadas em câmara seca por um ano (colheita de outubro de 1995). Os testes de germinação foram conduzidos a 30 ºC e as sementes recém-colhidas tiveram a germinação promovida pelas luzes branca e vermelha, mas inibida pela luz vermelha-extrema e ausência de luz. As sementes armazenadas, entretanto, revelaram-se insensíveis à luz.

Guazuma ulmifolia Lam. (Sterculiaceae) is a typical tree species of the initial stages of secondary succession in Brazil, with potential for use in restoring degraded areas. Two experiments were carried out in this work, in which seeds were extracted and scarified before conducting the germination tests. The first experiment was conducted with seeds harvested in October 1995 and aimed to determine the cardinal temperatures for seed germination. Constant temperatures of 10, 15, 20, 25, 30, 35, 40 and 45 ºC were tested under an eight hour photoperiod. The results showed that the minimum temperature is around 10 ºC, the maximum between 35 and 40 ºC, while 25 and 30 ºC temperatures are within the optimum range. The second experiment aimed to evaluate the photoblastic requirement of both freshly harvested (October 1996) and one year dry stored (harvested in October 1995) seeds. Germination tests were conducted at 30 ºC. The results showed that germination of freshly harvested seeds was promoted either by white or by red light, but inhibited by infra-red light or by darkness. Stored seeds, however, were insensitive to light.