O mogango (Cucurbita pepo) apresenta multiplicação por sementes, via semeadura direta ou em bandejas para posterior transplante, sendo indispensável a utilização de sementes com elevado vigor. Para que as sementes germinem é necessário que existam condições favoráveis de oxigênio, temperatura e disponibilidade de água, mas nem sempre essas condições são adequadas, especialmente em solos salinos. O objetivo desta pesquisa foi avaliar a influência de diferentes concentrações salinas na manifestação da qualidade fisiológica de sementes e na expressão dos sistemas isoenzimáticos em plântulas de mogango. Foram utilizadas sementes de mogango, cv. Sul Mineiro, submetidas às concentrações salinas de 0, 25, 50, 75 e 100 mM no substrato. A resposta das sementes a essas variações foi avaliada pelos testes de germinação (computando-se a primeira contagem de germinação e porcentagem de plântulas normais e anormais), comprimento de parte aérea e sistema radicular, índice de área foliar, fitomassa seca (parte aérea e raiz) e isoenzimas (superóxido dismutase, peroxidase e esterase). Sob condições de estresse salino, sementes de mogango, cultivar Sul Mineiro, apresentam dificuldades para a germinação e desenvolvimento de plântulas; estas ativam mecanismo de defesa com maior expressão no sistema radicular.

Schinus terebinthifolius is a native forest species which may be used in recuperating degraded areas and in urban afforestation. In order to evaluate the efficiency of methods for separating lots of S. terebinthifolius seeds into vigor levels, five lots of seeds were qualitatively evaluated for their moisture content, germination, first count, accelerated aging (the traditional and the saturated salt methods), germination speed index, average time of germination and seedling length and dry weight. The results showed that the tests of first germination count, accelerated aging at 41 ºC for 72 hours, average time of germination, seedling length and dry matter permitted the separation of S. terebinthifolius seeds into different vigor levels.

CALCIUM AND SILICON ON PRODUCTION AND QUALITY OF SOYBEAN SEEDSABSTRACT -The use of natural products in plant protection constitutes an important tool for the farmers to organic production. The study aimed to evaluate the efficiency of the calcium and silicon in the production and quality of soybean seeds. We used seeds of organic soybeans (Glycine max L.) cultivar BR36, from such cooperative in the 2004/2005 harvest. The experimental design used was randomized blocks with five treatments (calcium 40, calcium 50, silicon 40, silicon 50 and control). The treatments were compared by Duncan test at 5% probability. The variables of yield components were: number of pods per plant, seed number per pod, productivity and yield. The physiological quality of seeds was determined by tests: germination, first count germination, cold test, electrical conductivity and accelerated aging. Conclude that soybean plants treated with calcium and silicon produce seeds of higher physiological quality; treatments with application of Ca and Si reduce the seed yield per unit area.

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The aim of this study was to evaluate the performance of sunflower seed lots under different osmotic potentials. Four lots of sunflower seeds, cv. Paraíso 33 were used, submitted to different water restrictions 0 (control), -0.10 MPa (1.310 g L -1 of NaCl), -0.20 MPa (2.620 g L -1 of NaCl), -0.30 MPa (3.930 g L -1 of NaCl) and -0.40 MPa (5.240 g L -1 of NaCl), through the use of saline solutions in conducting the tests. The physiological quality was evaluated by: germination, emergence rate index, cold, emergence, accelerated aging, seedling length and seedling dry weight, as well as the enzymatic activity. The results obtained showed that the physiological potential of sunflower seeds is negatively affected in water restrictions -0.30 and -0.40 MPa, and the enzymes superoxide dismutase (SOD) and peroxidase (PO) are activated when sunflower seeds are submitted to saline stress. Key words: Helianthus annuus L., salinity, stressDesempenho fisiológico e bioquímico em sementes de girassol submetidas a diferentes potenciais osmóticos RESUMO O objetivo neste estudo foi avaliar o desempenho de lotes de sementes de girassol submetidas a diferentes potenciais osmóticos. Para isto foram utilizados quatro lotes de sementes de girassol, cv. Paraíso 33, submetidos a diferentes restrições de água 0 (controle); -0,10 MPa (1,310g L -1 de NaCl); -0,20 MPa (2,620 g L -1 de NaCl); -0,30 MPa (3,930 g L -1 de NaCl) e -0,40 MPa (5,240 g L -1 de NaCl) através da utilização de soluções salinas na condução dos testes. A qualidade fisiológica foi avaliada pelos testes: germinação, índice de velocidade de emergência, frio, emergência, envelhecimento acelerado, comprimento e massa seca de plântulas, como também a atividade enzimática. O potencial fisiológico de sementes de girassol é afetado negativamente em restrições de água -0,30 e -0,40 MPa e as enzimas superóxido dismutase (SOD) e peroxidase (PO) são ativadas quando as sementes de girassol são submetidas ao estresse salino.

In the present study, the objective was to evaluate the production and quality of rice seeds of four cultivars under conditions of saline stress caused by irrigation water. The work was carried out at the EliseuMaciel Agronomy College of the Universidade Federal de Pelotas, with four rice cultivars, IRGA 417, Avaxi CL, Inov CL and IAS 12-9 (Formosa). In the experiment, the following saline concentrations were used: 0; 12.5; 25; 37.5; 50; 75 and 100mM. After completing the crop cycle, the following agronomic characteristics were evaluated in each of the plants: number of panicles, total weight of panicles, percentage of full seeds, percentage of seedlings and weight of a thousand seeds. The physiological quality of the seeds harvested from the plants maintained under conditions of salinity stress was evaluated by germination and first count tests. Saline stress reduced the productivity and physiological quality of rice seeds, with different responses from the four cultivars used.