No abstract

The study of plant behavior in environments with different luminous intensities offers information about their ability to modify their growth and performance in response to light. The objective of this study was to evaluate the influence of shading on the development of Dimorphandra gardneriana Tul. Different levels of shading were used, with 0% shading (full sun)-(T 1), 30%-(T 2), 50%-(T 3) and 70% shading-(T 4). The different levels of shading were obtained by means of black polyolefin screens, sombre type, each treatment consisting of four replicates of 15 plants. The evaluated characteristics were: number of leaves, plant height, neck diameter, survival percentage, shoot length and primary root, green and dry mass of shoots and roots, total dry mass, Dickson quality index and (AP/MSPA), shoot height and diameter (A/DC), aerial part and root dry mass (MSPA/MSR), shoot height and dry mass (CPA/CR), as well as the percentage of roots (%R). The shading influenced negatively the quality of D. gardneriana seedlings, being those grown in full sun the ones that presented the best quality. Based on the morphological parameters studied, it can be affirmed that the D. gardneriana Tul., seedlings, produced in an open environment with high luminosity showed superior qualities in relation to the shaded seedlings.

ABSTRACT:The species Clitoria fairchildiana Howard, native to the Amazon region, by a rustic species and be of rapid growth, has been useful in heterogeneous reforestation for the reclamation of degraded areas, used in the planting of streets, public squares, roads and parking lots, due to its wide, leafy canopy and its rapid growth. The work was developed in the Laboratory of Analyses of Seeds of Centro de Ciências Agrárias of Universidade Federal da Paraíba. Thus, this study aimed to evaluate the physiological potential of C. fairchildiana seeds submitted to different drying times. The experimental design completely randomized, with treatments distributed in a factorial 4 x 5 (temperatures and periods of drying). It was evaluated to determine the water content after the drying processing for each period (0, 6, 12, 18 and 24 hours). For the evaluation of the effect of temperatures (35, 40, 45 and 50 °C) were performed the following tests: water content, germination, germination speed index (IVG), as well as length and dry mass of roots and aerial portion of seedlings. Drying of seeds of C. fairchildiana is recommended at the temperature of 35 °C, within drying 6 hours without compromising the physiological quality of seeds.

Spinach seeds are sensitive to high temperatures during germination and plant growth.It is known that seed priming with water or with seaweed extract (SWE) may enhance germination and seedling growth. The objective of this study was to evaluate the effects of seed priming with SWE (Ascophyllum nodosum) on the germination, seedling growth and antioxidant capacity of spinach seedlings under conditions of heat stress. Five concentrations of SWE (0.0, 0.15, 0.30, 0.60 and 1.2%) were used for priming the seeds under two temperatures (15 and 30 °C). Seeds primed with 0.3% SWE had the greatest activity of antioxidant metabolism and showed improved germination percentage, germination speed and seedling vigor under conditions of heat stress (30 °C) compared to nonprimed controls. Hydropriming and priming with 0.3% SWE resulted in lower contents of hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) under heat stress than control (nonprimed spinach seeds). This study showed that seed priming with SWE was effective to mitigate stress due to high temperatures and to improve spinach seed germination and seedling vigor.

O estudo da maturação de sementes é determinante no conhecimento do comportamento das espécies em relação à sua reprodução, possibilitando obter a época adequada de coleta para a obtenção de material genético de boa qualidade, sementes aptas para a conservação e produção de mudas. Objetivou-se estudar o processo de maturação de sementes de Sideroxylon obtusifolium, visando determinar o ponto de maturidade fisiológica. A pesquisa foi realizada com 30 árvores-matrizes localizadas na zona rural do município de Boa Vista - PB, as quais tiveram seus frutos coletados e conduzidos para estudo no Laboratório de Análise de Sementes do Centro de Ciências Agrárias da Universidade Federal da Paraíba, Areia - PB. Determinou-se as características físicas e fisiológicas. O delineamento estatístico empregado foi inteiramente ao acaso, com os resultados submetidos à análise de variância e regressão polinomial, em função dos períodos de coletas. O ponto de maturidade fisiológica de sementes de Sideroxylon obtusifolium ocorre entre 105 e 112 dias após a antese nas condições ambientais da área de pesquisa.

The objective of this study was to determine the elicitor potential of plant extracts from Caatinga biome by enzyme activity and epidemiological components of Alternaria brown spot (Alternaria alternate f. spp. citri). These were prepared ethanolic, dichloromethanic, and aqueous extracts from 14 plants (

Luffa operculata (L.) is a native Brazilian biome plant used for the treatment of respiratory diseases. Although Brazil’s flora comprises 67% of the world’s plants, only 8% of Brazilian plant species are studied each year. The studies indicate that climate change in tropical biomes intensifies the increase in salinized areas by about 10% per year for several reasons, including high temperatures, low rainfall and high evapotranspiration rates, due to surface water scarcity. Therefore, the aim of the present study was to evaluate the germination behavior and vigor of L. operculata seeds submitted to saline stress at different temperatures. To simulate salt stress conditions, sodium chloride was applied at 0.0; 3.0; 6.0; 9.0 and 12.0 dS m-1, at 25, 30, 35, 20-30 °C, with treatments distributed in a 5 x 4 factorial scheme (five levels of osmotic potential and four temperatures), using four replications. The seeds were then evaluated concerning water content, germination tests, first counts, germination speed index and seedling root and shoot lengths. At 30 and 35 °C, the seed germination and vigor of L. operculata were less affected up to an osmotic potential of 9.0 dS m-1, where it is considered a moderate salinity tolerance. At 35 ºC, the germination uniformity was reduced to 98 and 93% by applying the 6 and 9 dS m-1 solutions, respectively. For the same temperature, the germination velocity remained 6.09 (IVG) until the saline potential of 9.0 dS m-1

No abstract