Pablo Gerzson Badinelli

Envelhecimento acelerado em sementes de azevém com e sem solução salina e saturada

The objective of the present study was to evaluate the methodology of the accelerated aging test to evaluate the physiological potential of s ryegrass seeds, as well as verify the possibility of the use of unsaturated and saturated solution of NaCl as an option for control of water uptake by seeds during the test without reducing its sensitivity. Four lots of ryegrass seeds were tested for germination, seedling emergence, speed emergence and accelerated aging (periods of 24, 48, 72 and 96h, with or without the use of saturated and saline solution of NaCl). The use of unsaturated and saturated solution of NaCl reduces water absorption by ryegrass seeds during the accelerated aging test, resulting in a rate of deterioration is less pronounced ,less drastic and more uniform results. Option 24h with unsaturated solution (SNS) was only able to stratify plots into two groups and should not be designated as promising. Thus, it should be used the 48h saturated NaCl solution (SSS), which stratified into three lots.

Influência dos diferentes períodos de colheita na expressão de isoenzimas em sementes de cevada

O objetivo foi avaliar os padroes isoenzimaticos de Esterase (EST - EC 3.1.1.1), Fosfatase Acida (ACP - EC 3.1.3.2), Malato Desidrogenase (MDH - EC 1.1.1.37), Alcool Deshidrogenase (ADH - EC 1.1.1.1) e Glutamato Oxalacetato Transaminase (GOT - EC 2.6.1.1), em sementes e plântulas de dois cultivares de cevada (MN 721 e Scarlett). As sementes foram fornecidas pela empresa Westermann, localizada no municipio de Piratini, Rio Grande do Sul, onde foi realizado o cultivo da cevada em 2007. Foram colhidas em tres epocas com diferentes percentuais de umidade, secas a 13% de umidade e armazenadas em câmara fria. Os cinco sistemas isoenzimaticos analisados apresentaram variacoes na expressao, principalmente quando comparados entre sementes e plântulas. Concluiu-se que ha variacao no padrao de expressao das enzimas EST, ACP, MDH, ADH e GOT entre sementes e plântulas. A expressao das enzimas EST e GOT foi pouco e muito influenciada pela epoca de colheita, respectivamente.

The effects of harvest periods on the seed quality of barley

The objective of this study was to evaluate the effect of different harvesting periods on the physiological quality of barley seeds. Seeds of cultivars MN 721 and Scarlett were used. The seeds were harvested at 118, 129 and 140 days after sowing. The humidity at the time of sampling was 25%, 18% and 13% in the first, second and third harvests respectively for the cultivar MN 721, and for the cultivar Scarlett it was 26%, 19% and 13%, respectively for the same periods. The seeds were oven-dried by forced air circulation down to 13% moisture content and then stored in a cold room (T 17 oC and RH 45-50%). Before analysis, the seed was subjected to pre-cooling of 5 to 10 oC for seven days to break dormancy. The seeds were evaluated by the standard germination tests, first count of germination, seedling length (shoot and root), dry weight (shoot and root), tetrazolium and accelerated ageing for each cultivar at the different harvest times after breaking dormancy. After harvesting, barley cultivars show a high level of dormancy. Depending on the cultivar, dormancy is most pronounced when seeds are harvested with a humidity content around 13%. The barley seeds with better physiological quality were obtained with moisture contents of 26% (118 days after sowing) and 18% (129 days after sowing) for the Scarlett and MN 721 cultivars, respectively.