Daiane Mugnol Dresch

Conservação pós-colheita de guavira (Campomanesia adamantium Camb.) sob diferentes revestimentos e temperaturas de armazenamento

Objetivou-se com este trabalho avaliar a conservacao pos-colheita de guavira (Campomanesia adamantium Camb.) em diferentes revestimentos e temperaturas de armazenamento. Os frutos receberam os seguintes tratamentos: imersao em 1) carboxi metilcelulose a 1% (m/v) (CMC); 2) pectina a 3%; 3) pectina + cloreto de calcio a 3% (m/v), e 4) sem tratamento (ST), todos embalados em polietileno de baixa densidade (PEBD) e armazenados por 0; 7; 14 e 21 dias em câmara B.O.D., nas temperaturas de 5; 10 e 15 oC. A menor perda de massa e acidez titulavel foram observadas a 5 oC e na cobertura pectina + calcio. O pH nao variou entre as coberturas e manteve-se maior a 5 oC. O teor de vitamina C foi maior sob efeito do revestimento de pectina + calcio, com valores semelhantes aos iniciais a 5 °C e 10 oC. Concluiu-se que as guaviras podem ser armazenadas por ate 21 dias em temperatura de 5 oC, revestidas com pectina + calcio a 3%.

Campomanesia adamantium (Cambess.) O. Berg seed desiccation: influence on vigor and nucleic acids

The aim of this study was to evaluate the sensitivity of Campomanesia adamantium seeds to desiccation by drying in activated silica gel (fast) and under laboratory conditions (slow). To assess the sensitivity of the seeds to desiccation, we used drying with silica gel and drying under laboratory conditions (25 °C), in order to obtain seeds with moisture content of 45, 35, 30, 25, 20, 15, 10 and 5%. The physiological potential of the seeds after desiccation was evaluated by measuring primary root protrusion, percentage of normal seedlings, germination seed index, seedling length, total seedling dry mass, electrical conductivity and DNA and RNA integrities. The C. adamantium seeds were sensitive to desiccation and to a reduction in moisture content to 21.1% or less by desiccation using silica gel, and to 17.2% or less by desiccation under laboratory conditions; impairment of the physiological potential of the seeds was observed at these low moisture content levels. The integrity of the seed genomic DNA was not affected after drying seeds in the two methods. However, drying in silica gel to 4.5% moisture content and drying under laboratory conditions to 5.4% moisture content resulted in the loss of seed RNA integrity.

Germinação e vigor de sementes de gabiroba em função do tamanho do fruto e semente

The knowledge on biometric aspects of fruits and seeds and their influence on germination are important for the production and properties of native species. This study aimed at evaluating the influence of fruit and seed size on the germination and vigor of Campomanesia adamantium seeds. For the biometric characterization, 120 fruits were randomly selected and visually divided into four classes, with predominance for size, in which longitudinal and transversal diameters and mass of seeds were measured. The seed characterization was carried out in 30 fruits of each class, by determining the number of whole, empty and total seeds of every fruit. The seeds physiological potential, according to fruit size, was evaluated with the aid of the following tests: imbibition curve, moisture content, germination percentage and speed index, seedling length, total fresh and dry matter of seedlings. A completely randomized design, with four treatments, was used. Fruits were respectively classified according to their longitudinal and transversal diameters as small (12.71 mm; 12.46 mm), medium small (15.38 mm; 15.01 mm), medium large (18.84 mm; 18.02 mm) and large (22.74 mm; 22.36 mm). The classes of small, medium small and medium large fruits presented seeds with higher germination percentage and speed index, while seedlings with higher biomass accumulation were observed for large fruits.

Feeding preference of Plutella xylostella for leaves treated with plant extracts

Plutella xylostella L. is one of the main agents to cause damages to plants of Brassica genus, provoking negative impacts in cultures. The use of botanical extracts in plants protection has been related in literature, however, their use in the species analyzed in this study is not yet reported. We assessed the effect of aqueous and methanolic extracts of the species: Schinus terebinthifolius Raddi (Pink Pepper), Annona coriacea Mart. (Araticum), Duguetia furfuracea (A. St.-Hil.) Benth. & Hook. (Pindaúva do campo) and Trichilia silvatica C. DC. (Catiguá-branco), occuring in the state of Mato Grosso do Sul and whose feeding preference of P. xylostella larvae of 3rd instar. We intend to answer the following questions: (1) Are the plant species analyzed fagodeterrentes? (2) what type of extract produces the least food preferrence? To answer these questions, we treated cabbage disks with aqueous extracts stored in a refrigerator in periods of 0, 7, 14 and 21 days and the methanolic extracts were treated at concentrations of 0.5 mg/mL, 1.0 mg/mL, 2.0mg/mL. The aqueous and methanolic extracts of T. silvatica presented the lowest values of feeding preference, 0.113 and 0.06, respectively, compared to other extracts.

Drying and reduction in sensitivity to desiccation of seeds of Alibertia edulis: the influence of fruit ripening stage

The intense environmental degradation in tropical regions suitable for agriculture has decreased native forest populations of plants with important fruits and medicinal properties. Alibertia edulis is a native tree from the Brazilian Cerrado. Knowledge about the effects of drying and storage on the physiological behavior of its seeds may aid in its sustainable exploitation and conservation. The goal of the present study was to determine which fruit ripening stage results in A. edulis seeds with higher tolerance to desiccation, and to investigate the effectiveness of polyethylene glycol (PEG) induced osmotic stress in combination with abscisic acid (ABA) in increasing seed desiccation tolerance during storage. Seeds were dried in activated silica gel (fast) or under ambient conditions (slow). Seeds originating from mid-ripe or fully ripe fruits exhibited better physiological performance than those obtained from green fruits. Slow drying resulted in seeds with high physiological potential. Seeds may be stored for up to 180 days without losing viability when treated with -0.73 MPa PEG without ABA.

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.

Gas exchange and antioxidant activity in seedlings of C opaifera langsdorffii Desf. under different water conditions

The aim of this study was to evaluate gas exchange, efficiency of the photosynthetic apparatus, and antioxidant activity in Copaifera langsdorffii Desf. The seedlings were cultivated under different conditions of water availability, in order to improve the utilization efficiency of available water resources. The seedlings were cultivated in four different water retention capacities (WRC- 25%, 50%, 75%, and 100%), and evaluated at four different time (T- 30, 60, 90, and 120 days). During the experimental period, seedlings presented the highest values for carboxylation efficiency of Rubisco (A/Ci), intrinsic water use efficiency (IWUE = A/gs), chlorophyll index, and stomatal opening, when grown in the substrate with 75% WRC, but the stomatal index (SI) was less the 25% WRC. The efficiency of photosystem II was not significantly altered by the treatments. Comparison between the extreme treatments in terms of water availability, represented by 25% and 100% WRC, represent stress conditions for the species. Water availability causes a high activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) in the plant.

Effect of storage in overcoming seed dormancy of Annona coriacea Mart. seeds.

The aim of this study was to evaluate the effect of pre-treatments on overcoming dormancy of A. coriacea seeds. Seeds were processed and stored in polyethylene bags at temperatures of at -18°C (42% RH), 5°C (34% RH), 15°C (60% RH) and 25°C (34% RH), during 0, 30, 60, 90, 120 and 150 days. After storage, seeds were immersed in 350 mg.L-1 gibberellic acid for 144 hours. Sowing was carried out in plastic bags containing Red Latosol + Bioplant®. Moisture content, emergence percentage, emergence speed index, length and dry mass of seedlings, were evaluated. The experimental design was completely randomized in a factorial with four replications of 50 seeds each. The seed storage at 5°C and subsequent immersion in gibberellic acid was efficient to reach high percentage, emergence speed and plant growth. A. coriacea seeds showed non-deep simple morphophysiological dormancy wherein the physiological component can be overcome after the seeds are storage at 5°C for a maximum period of 53 days and subsequent immersed in exogenous GA (350 mg.L-1 for 144 hours).