The aim of this study was to evaluate the quality of sunflower cultivars with different oleic/linoleic acid ratio, germinating under low temperature conditions through seedling growth tests (shoot and root dry weight, and root/shoot index) and mean germination time. The results showed that the mean germination time and root and shoot dry weight did not have any relation with the oleic/linoleic ratio in either temperature condition. In seedling growth tests High Linoleic cultivars performed better than High Oleic cultivars, but the variation within each cultivar group did not permit association of that result to the oleic/linoleic ratio. These variables were related to the dry weight of the seeds. There were a differential response of the shoot and root portions at low temperature, changing the dynamics of growth, with the corresponding modification of the root/shoot Index, without relation to the oleic/linoleic ratio.

El objetivo de este trabajo fue estudiar el vigor a baja temperatura de semillas de girasol con diferente proporción de los ácidos oleico/linoleico, a través de la evaluación del crecimiento de plántulas (pesos secos aéreo y radicular y indice raíz/aéreo) y el tiempo medio de germinación. La proporción oleico/ linoleico de las semillas no se relacionó con el tiempo medio de germinación ni con las variables de crecimiento medidas, ni a temperatura óptima ni a baja temperatura. Los pesos secos aéreo y radicular fueron mayores, en general, en el grupo Alto Linoleico. Sin embargo la variación dentro de cada grupo no permitió asociar la respuesta a la baja temperatura con la composición acídica de los cultivares. Dichas variables se relacionaron con el peso seco de las semillas. Se evidenció respuesta diferencial a la bajas temperatura de las porciones aérea y radicular, con la consiguiente modificación del indice raíz aéreo, variable que tampoco mostró asociación con la composición acídica de los cultivares.

Soybean seeds show high sensitivity to climatic conditions and to management before and during harvesting. In the crop season 1997/1998, the "El Niño" phenomenon produced copious rains causing seed damage. The aim of this study was to evaluate the differential germination response between soybean seeds harvested on time and seeds submitted to weathering, and to verify the possible existence of genetic variability in germination of deteriorated seeds. Twenty varieties belonging to Maturation Group III were studied. From each variety, two seed lots were processed: seed harvested on time, under favorable agro climatic conditions ("good"), and seed deteriorated by a long permanence in the field before harvesting ("bad"). The germination, Tetrazolium tests and conductivity for viability and vigor analysis, and a field emergence test were carried out. In "good" seed lots, germination attained the highest values (between 70 and 80%) only in 55% of varieties and vigor ranged between 32% and 67% and seedling emergence between 31% and 49 %. Vigor by the Tetrazolium test showed the best relationship with field emergence. There was significant correlation among all tests. "Bad" seed lots presented very low germination (2-27%). No variability was detected in the germination behavior of different varieties in relation to unfavorable harvest conditions.

Las semillas de soja muestran una alta sensibilidad a las condiciones climáticas y al manejo durante y después de la cosecha. En el ciclo agrícola 1997/1998 el fenómeno de "El Niño"produjo copiosas lluvias, afectando la calidad de las semillas. La finalidad de este trabajo fue estudiar el comportamiento germinativo diferencial entre semilla de soja cosechada a término y semilla sometida a deterioración a campo (por humedad) y la posible existencia de variabilidad genética, para ese parámetro, en la semilla de soja deteriorada. Se utilizaron veinte variedades pertenecientes al Grupo de Maduración III. De cada variedad se procesaron dos lotes: semilla cosechada a término, bajo condiciones agro climáticas favorables ("buena") y semilla deteriorada por condiciones agro climáticas desfavorables durante el retraso de su cosecha ("mala"). Se realizaron ensayos de germinación, Tetrazolio y conductividad eléctrica para análisis de viabilidad y de vigor y emergencia a campo. En las semillas "buenas"la germinación alcanzó los valores más altos, entre 70% y 80%. Sólo en el 55% de los lotes, el vigor varió entre 32 y 67% y la emergencia a campo entre 31% y 61%. La prueba de vigor por Tetrazolio fue la que mejor evaluó la implantación a campo. Hubo correlación significativa entre todas las pruebas. Los lotes "malos" presentaron germinación muy baja, entre 0 y 27%. No se detectó variabilidad en la respuesta germinativa de las diferentes variedades a condiciones de cosecha desfavorables.

A produção de girassol, até a pouco tempo baseava-se no uso de cultivares com alto teor de ácido linoleico, mas, nos últimos anos, a procura por óleo com conteúdo mais alto de ácido oleico tem aumentado. A produção de girassol se estabeleceu com a semeadura de cultivares de alto teor de ácido oleico, em regiões mais quentes, mas tem se tornado conveniente o cultivo em áreas temperadas, como o Sudeste de Província de Buenos Aires. Nesta região são recomendadas semeaduras antecipadas, para que o enchimento dos grãos coincida com épocas de disponibilidade hídrica e luminosidade suficientes para a obtenção de maiores rendimentos. Porém, a antecipação da semeadura pode ser prejudicada pela baixa temperatura do solo, retardando a emergência das plântulas e resultando em um estande heterogêneo. A finalidade deste trabalho foi avaliar o desempenho de sementes de quatro cultivars com alto teor de ácido oleico na área ao sul da Província de Buenos Aires, através de testes de vigor e ensaios de campo. Foram conduzidos testes de germinação, frio, tetrazólio a duas temperaturas, envelhecimento acelerado e três ensaios de campo, em condições climáticas distintas. Os dados foram analisados através de Anova usando modelos lineares generalizados e foram comparados os testes entre si e os cultivars entre si por medio de contrastes. A emergência das plântulas a temperatura ótima e sub-ótima para cultivars de alto teor de ácido oleico e de alto linoleico foi semelhante. O sucesso do estabelecimento do estande não aparenta estar relacionado à composição de ácidos graxos.

Sunflower crop was based, as yet, on high linoleic cultivars, but in the last years request for oil with higher content of oleic acid has increased, due to their dietary characteristics. At the beginning, high oleic cultivars were used to be sown in warm regions, but then the concern about growing it in temperate areas, as the south-east of Buenos Aires Province, was posed. In this region, early sowings are recommended, so that grain filling matches with a period of appropriate hydric and light conditions, as to result in greater yields. However, early sowings are limited by low soil temperature, that delays seedling emergence, resulting in heterogeneous stand establishment. The aim of this work was to evaluate seed performance of four high oleic cultivars in the southern area of Buenos Aires Province, by means of vigor tests and field trials. Germination, cold, tetrazolium viability, tetrazolium viability with cold, accelerated ageing tests and three field sowings at different soil temperatures were performed. Data were analyzed by Anova using generalised linear models, and tests and cultivars were contrasted among themselves. Similar seedling emergence under optimal and suboptimal temperatures for high oleic and high linoleic cultivars was recorded. The success of seedling establishment does not appear to be related to the acidic composition of seeds.