Abstract Studies about the viability and vigor of seeds during storage, especially on the characterization of enzymatic changes, may increase the harvesting efficiency of immature seeds and guarantee their viability for a prolonged period. Therefore, this study aimed to evaluate the behavior of immature seeds of Tabebuia caraiba during storage. For this, thirty selected mother plants at the anthesis stage located in São João do Cariri and Sumé, Paraíba, Brazil were selected. Flowers of each tree were marked, and the fruits were harvested at 35, 42, and 49 days after anthesis (DAA) and characterized according to their maturation stages. The seeds from each maturation stage and city were packed in paper bags and stored in a refrigerator (6 ± 2 °C) for 360 days. The seed quality, seedling vigor, and enzymatic activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) were evaluated at the beginning of the storage period and intervals of 90 days. The seeds of T. caraiba harvested at 35, 42, and 49 DAA maintained high viability for 360 days of storage. T. caraiba seeds stored for 360 days withstood with high vigor when harvested at 42 DAA. The CAT, SOD, and POX activity was correlated to the deterioration process of the seeds under storage conditions.

RESUMO Erythrina velutina Willd. (Fabaceae) é tolerante à seca e com potencial para reflorestamento no semiárido, cuja resposta dessas sementes às condições ambientais de cada área de produção influenciam no seu tamanho, peso, potencial fisiológico e na sua sanidade. Desta forma, objetivou-se avaliar como as condições ambientais das diferentes regiões paraibanas influenciam nas características biométricas de sementes de E. velutina. Na pesquisa foram utilizadas sementes de 19 plantas matrizes coletadas em Juru, Sumé, Araçagi, Guarabira, São João do Cariri, Esperança, Queimadas, Cuité, Boa Vista e Areia, todas no estado da Paraíba, Brasil. Nas sementes de cada localidade foram determinados: o teor de água, peso de mil sementes e as características biométricas (comprimento, largura e espessura). O teor de água variou de 3,11 a 6,84% e o peso de mil sementes foi maior naquelas das plantas matrizes 2 (Sumé) e 14 (Cuité). O comprimento das sementes variou de 9,00 a 16,84 mm e foi maior naquelas da matriz 1, localizada no município de Juru. A espessura e largura das sementes variou de 5 a 12,99 mm e foram maiores na planta matriz 14 (Cuité). A temperatura, umidade, radiação solar, vento e precipitação causaram variação no comprimento, largura e espessura de sementes de Erythrina velutina Willd., com maiores médias na planta matriz 14 localizada no município de Cuité.

ABSTRACT Erythrina velutina Willd. (Fabaceae) is drought tolerant and has the potential for reforestation in the semi-arid region. The response of its seeds to the environmental conditions of each production area influences their size, weight, physiological potential, and health. Thus, this study aimed to assess how the environmental conditions of the different regions of Paraíba influence the biometric characteristics of E. velutina seeds. Seeds from 19 mother plants collected in Juru, Sumé, Araçagi, Guarabira, São João do Cariri, Esperança, Queimadas, Cuité, Boa Vista, and Areia, in the state of Paraíba, Brazil, were used in this study. Water content, thousand-seed weight, and biometric characteristics (length, width, and thickness) were determined in the seeds from each location. The water content ranged from 3.11 to 6.84%, while the thousand-seed weight was higher in mother plants grown in Sumé and Cuité. Seed length ranged from 9.00 to 16.84 mm, being higher in mother plants grown in Juru. Seed thickness and width ranged from 5 to 12.99 mm and were larger in mother plants from Cuité. Temperature, humidity, solar radiation, wind, and precipitation caused variations in the length, width, and thickness of E. velutina seeds, with higher means observed in mother plants grown in Cuité.

Abstract This study evaluate the effect of drought and heat stress on the quality of C. spectabilis seeds. A completely randomized design in a 4×4 factorial scheme, referring to four osmotic potentials based on Polyethylene glycol (PEG 6000 = 0.0, -0.2, -0.4 and -0.8 MPa) and four temperatures (25, 30 and 35 ºC constant and alternating between 25-35 ºC), with four replications of 50 seeds per plot was used. The germination percentage, first count germination, germination speed index, average germination time, average germination speed, length and dry mass of the root, shoot and seedlings were evaluated. C. spectabilis is sensitive to drought stress during germination and seedling establishment, tolerating up to -0.2 MPa. The physiological quality of seeds is reduced with the decrease of osmotic potentials. The temperature range between 25 and 30 ºC are the one that provide better conditions for the germination of the seeds of this species.

ABSTRACT: Seedling production is an important step in the lettuce production system. However, there is a tendency to apply excessive irrigation at this stage. The aim of this study was to test the use of the Simplified Irrigation Controller (SIC) under two conditions: first, with the sensor installed in the substrate (measuring the soil water tension) and second, in the atmosphere (“atmospheric” - responding to vapor demand in the atmosphere) to control the irrigation of lettuce seedlings. The performance of the SIC was evaluated by monitoring plant traits. The lettuce seeds of the Regina cultivar were sown in styrofoam trays with commercial organic substrate. Both experiments were conducted under greenhouse conditions and evaluated under different SIC activation tensions. Shoot fresh weight and dry weight, height, number of leaves, leaf length, leaf area, water use efficiency (WUE) (ratio between the dry mass of plant produced by the volume of water applied), chlorophyll content, stomatal conductance and chlorophyll a fluorescence were assessed. In the experiment with the substrate sensor, the tension of 11.5 kPa caused death in 94 % of the seedlings and was disregarded in the statistical analysis. All biometric and physiological traits evaluated decreased as the SIC tensions increased. Thus, tensions of 4.0 (substrate sensor) and 3.5 kPa (atmospheric sensor) showed greater potential for producing vigorous seedlings, with WUE average values of 1.86 and 1.37 g L−1, respectively. Cultivation of lettuce seedlings proved viable under both conditions when the SIC was used, with the emergence of a number of practical advantages of the atmospheric sensor over the substrate one.