Qualidade fisiológica de sementes de soja submetidas ao hidrocondicionamento = Soybean seed physiological quality after hydro-conditioning

A técnica de hidratação controlada de sementes vem sendo utilizada como método de condicionamento fisiológico, tanto para sementes deterioradas como para sementes altamente sensíveis à embebição rápida, ou a interação entre ambas, objetivando melhorar o desempenho destas no campo. A hidratação pode ser seguida por secagem, se assementes não tiverem atingido a fase III da germinação, facilitando, assim, o subseqüente manuseio, armazenamento e semeadura no campo. O objetivo do presente trabalho foi avaliar os efeitos do hidrocondicionamento na qualidade fisiológica de sementes de soja,sendo estas sementes hidrocondicionadas por períodos de 0, 20 e 24h, secas e armazenadas por 0, 90, 180 e 270 dias em câmara seca, com umidade e temperatura controladas. O hidrocondicionamento teve efeito benéfico na qualidade fisiológica das sementes de soja,suas vantagens se tornaram mais evidentes com o envelhecimento natural das sementes durante o armazenamento.<br><br>Controlled hydration of seeds has been used as a physiological conditioning method, both for deteriorated seeds as well as seeds that are highly sensitive to soaking, or an interaction among both, aiming to improving their performance after sowing in the field. Thehydration must be followed by drying, in case the seeds have not reached yet phase III of germination, thus facilitating subsequent handling, storage and sowing operations. This work aimed to evaluate the hydro-conditioning effect (0, 20 and 24 hours, followed by seeddrying) on the physiological quality of soybean seeds, stored in dry chamber under controlled conditions (relative humidity and temperature) during 0, 90, 180 and 270 days. Hydro-conditioning has revealed positive effects on the physiological quality of those seedsand its advantage became more evident according to natural aging of the seeds during the storage

Efeito da época de colheita e da espessura do tegumento sobre a viabilidade e o vigor de sementes de soja Effects of harvest epoch and seed coat thickness on viability and vigor of soybean seeds

Esta pesquisa foi desenvolvida no Núcleo Experimental de Ciências Agrárias da UFMS, em Dourados, MS, com o objetivo de avaliar a viabilidade e o vigor das sementes de nove genótipos de soja, dos quais, cinco cultivares (EMBRAPA-64, EMBRAPA-4, BR-16, FT-Abyara e IAC-100) e quatro linhagens (BRD-9527, BRD-9561, BRD-9507 e BRD-9502), com diferentes colorações e espessuras de tegumento, colhidas no estádio R8 e com 14 dias após este estádio. Após a colheita, determinaram-se a espessura do tegumento das sementes, a porcentagem de embebição de água pelas sementes, a viabilidade das sementes, pelos testes de germinação e de tetrazólio e o vigor, pelos testes de emergência em areia, teste de tetrazólio e pelo envelhecimento acelerado. As sementes das linhagens BRD-9561 (tegumento preto), BRD-9527 (tegumento marrom), BRD-9502 e BRD-9507 (tegumento amarelo) apresentam maior espessura de tegumento, mas a espessura não é uma característica que per si assegura melhor qualidade fisiológica das sementes, independente da época de colheita. O retardamento de colheita reduziu a germinação e o vigor das sementes e ainda aumentou a porcentagem de embebição de água pelas sementes.The research was conducted at the Núcleo Experimental de Ciências Agrárias of the Federal University of Mato Grosso do Sul(UFMS), in Dourados, MS. The objectives were to evaluate seed viability and vigor of nine soybean genotypes (five cultivars: EMBRAPA-64, EMBRAPA-4, BR-16, FT-Abyara, and IAC-100; and four lines: BRD-9527, BRD-9651, BRD-9507, and BRD-9502), with different seed coat colors and coat tickness, harvested at stage R8 and 14 days later. After harvest, seed coat thickness and water uptake (%) was determined. Seed viability was evaluated trough germination and tetrazolium tests, and seed vigor was evaluated through emergence in sand, tetrazolium and through accelerated aging tests. Lines BRD-9561 (black coat), BRD-9527 (brown coat), BRD-9507 and BRD-9502 (yellow) had thicker teguments, but this characteristic per se does not guarantee greater plant vigor and viability. Delaying harvest resulted in low seed vigor and viability and increased imbibitions percentage in water

α-Tocopherol levels in natural and artificial aging of soybean seeds - doi: 10.4025/actasciagron.v34i3.12660

Tocopherols are well known constituents of vitamin E, and the main antioxidants in soybean. Are natural antioxidants and stabilizers that can inhibit lipid degradation, reducing non-enzymatic oxidation of these compounds during storage of seeds, germination and initial development of seedlings. The objective of this work was to determine the level of α-tocopherol in four soybean seeds cultivars naturally and artificially aged. Seeds of four soybean cultivars stored from 0 to 180 days in a dry chamber (natural aging) and subjected to high temperature and humidity (artificial aging) were analyzed for α-tocopherol content. The quantification of α-tocopherol in the soybean seeds was performed by high performance liquid chromatography (HPLC) combined with the Soxhlet extraction method. Significant differences in α-tocopherol levels in seeds were observed for all cultivars and storage times. The α-tocopherol contents of the soybean seeds showed linear correlations with an increasing period of storage for all the cultivars studied. However, the artificially aged seeds had a higher content of α-tocopherol than those naturally aged