Carla Regina Baptista Gordin

Salt stress on seeds germination and seedlings development of niger (Guizotia abyssinica (L.f.) Cass.)

The soil, and subterranean and superficial water saltiness process is one of the most important environment degradation problems. Niger is an annual herbaceous with biodiesel production potential, which seeds behavior is unknown in saline conditions. In this way, this work aimed to evaluate the niger seeds germination and initial seedlings growth submitted to different salt solutions. The treatments used constituted of three types of salts: NaCl, KCl and CaCl2 at four osmotic potentials (-0.3; -0.6; -0.9 e -1.2 MPa). The niger seeds sowed directly on substrate water moistured constituted the control treatment. The saline effects on seeds germination were evaluated though germination percentage, germination medium time and germination speed index. The Niger seedlings were analyzed through the shoot and root length and fresh and dried mass seedlings. The statistic design used was entirely casualized, constituted by a factorial 3x5 (salts x osmotic potentials) with four repetitions of 50 seeds. The Niger seeds are salinity sensitive. Seeds exposition to NaCl, KCl and CaCl2 reduces the germinative ability and the seedlings growth at -0.3 MPa. The salt solutions inhibit the Niger seeds germination at -1.2 MPa.

Germinação, biometria de sementes e morfologia de plântulas de Guizotia abyssinica Cass

The niger plant (Guizotia abyssinica Cass.) is a herbaceous annual with a potential for biodiesel production but information on seed quality is scarce. The objective of this study was to determine the temperatures and substrates for seed germination and initial seedling development, besides characterizing niger seed and seedling morphology. One thousand seed weight, moisture content, weight, length, width and thickness of seeds were determined. The seed germination test was done at a constant temperature in continuous light (15 °C, 20 °C, 25 °C and 30 °C) and with an alternating temperature (20-30 °C) with 10 h dark and 14 h of white light for the highest temperature and two substrates (on paper and between paper). The seed imbibitions curves germination percentage, germination speed index, mean germination time, seedling length and dry weight were determinated. The niger seeds had similar dimensions: 4.54 mm long, 1.39 mm wide, 1.15 mm thick and a mean weight of 0.0043 g. The 20-30 °C and 25 °C temperatures and the two substrates tested are suitable for the niger seed germination test.

Armazenamento de sementes de Crambe abyssinica Hochst. ex R.E.Fr. em diferentes embalagens e ambientes

O interesse pelo crambe (Crambeabyssinica) surgiu em virtude da sua superioridade, em relacao a soja e as demais oleaginosas, na producao de oleos vegetais, e por adaptar-se com facilidade ao plantio direto. Objetivou-se, com este trabalho, avaliar o armazenamento de sementes de crambe, em diferentes embalagens e ambientes. Foram testadas as embalagens de saco de polietileno e embalagens de plastico rigido com fechamento hermetico, nas seguintes condicoes: ambiente (25 ± 2 oC e 60% de UR) e câmara fria e seca (15 ± 2 oC e 45 % de UR), durante 0, 30, 60, 90, 120, 150 e 180 dias (periodo de maio a novembro de 2010), sendo avaliados, mensalmente, o teor de agua, a germinacao, na primeira contagem, o indice de velocidade de germinacao e o tempo medio de germinacao das sementes. O experimento foi conduzido em DIC, com quatro repeticoes de 50 sementes para cada tratamento. Inicialmente, as sementes apresentaram germinacao media de 60% e teor de agua de 7,0%. As embalagens e ambientes empregados permitiram alteracoes no teor de agua que desencadearam o inicio da deterioracao das sementes, evidenciado pela reducao de germinacao na primeira contagem, indice de velocidade e aumento do tempo medio de germinacao das sementes. Entretanto, a germinacao nao foi influenciada pelos tratamentos e periodos de armazenamento. De maneira geral, as sementes de crambe podem ser acondicionadas em embalagem impermeavel durante 180 dias de armazenamento, em condicao de15 ± 2 oC e 45% de UR. Palavras-chave: Crambeabyssinica, oleaginosa, potencial fisiologico, teor de agua.

Photosynthetic and enzymatic metabolism of Schinus terebinthifolius Raddi seedlings under water deficit

Schinus terebinthifolius Raddi is a tree species that can be used in the recovery of degraded areas, as it exhibits rapid growth and has a very expansive root system, facilitating water uptake from the deeper layers of the soil. The objective of this study was to evaluate photosynthesis and enzymatic activity in S. terebinthifolius seedlings under conditions of water deficit and their potential to recover following re-irrigation. The experiment was conducted in a greenhouse under a plastic covering where plants were distributed into two groups: Group 1 – control plants, where irrigation was maintained at 70% of the water retention capacity, and Group 2 – stressed plants, where irrigation was suspended until the photosynthetic rate neared zero, followed by rehydration for 12 days, then a further suspension of irrigation. At the beginning of the experiment and during the suspension of irrigation and rehydration, plants were evaluated for gas and antioxidant enzyme exchanges. Hydric stress significantly reduced photosynthesis, stomatal transpiration conductance, carboxylation efficiency of Rubisco, and the chlorophyll content of the S. terebinthifolius plants. Following rehydration, plants recovered the carboxylation efficiency of Rubisco, but not the photosynthetic rate. Antioxidant enzyme activity increased in both the aerial part and the root in response to water deficit.

Emergence and initial growth of Hancornia speciosa (Gomes) seedlings with different substrates and water availability

Hancornia speciosa is a promising fruit species due to the high protein content of its fruit. However, there is little information about its production, with a lack of information concerning the germination of its seeds and initial seedling growth. The aim of this study was to evaluate water availability and suitable substrates for its seedling emergence and production. The seeds were deposited in tubes, containing the following substrates: Distroferric Red Latosol (L); Latosol+Sand (L+A); Latosol+Bioplant® (L+B); Sand+Latosol+Poultry Litter in the following proportions 2:2:1 (L+A+C1) and 2:4:1 (L+A+C2) associated with water retention capacities of 25%, 50%, 75% and 100%. The substrates L+A, L+B and L and a water availability of 75% to 100% are recommendable for seedling emergence and early seedling growth. Substrates that consisted of poultry litter and water availability of 25% and 50% were prejudicial to growth and quality of Hancornia speciosa seedlings.