Resumo: O estudo teve como foco aumentar a germinação de cultivares de alface sob condições de alta temperatura por meio de tratamentos de sementes. As sementes das cultivares de alface Yedikule, Iceberg, Iri Kıvırcık e BT Iri Kıvırcık com diferentes morfologias foliares foram submetidas a diferentes doses de ácido giberélico (GA3) (0, 250, 500 e 1000 ppm) e pré-condicionadas por resfriamento e aquecimento. As sementes foram germinadas em temperaturas ótima (20 °C) e alta (35 °C). Os resultados mostraram que a alta temperatura influenciou negativamente a porcentagem de germinação das cultivares de alface. A porcentagem média de germinação foi de 16,8% a 35 °C e 93,4% a 20 °C. Além disso, houve diferença significativa entre as cultivares de alface para germinação a 35 °C. Iri Kıvırcık e BT Iri Kıvırcık apresentaram termodormência severa e quase nunca germinaram a 35 °C. O pré-resfriamento e o pré-aquecimento promoveram a germinação a 35 °C em comparação com as sementes não condicionadas, mas o pré-resfriamento resultou em maior germinação do que o pré-aquecimento. GA3 foi considerado o tratamento mais útil para melhorar a germinação em comparação com os outros. A porcentagem de germinação de Iceberg, Yedikule e Iri Kıvırcık preparados com doses de GA3 atingiu mais de 80%. Os resultados sugeriram que o desempenho germinativo de cultivares de alface que sofrem de termodormência ou onde condições climáticas com altas temperaturas devem ser promovido pela aplicação de 500 ppm de GA3.

Abstract: The study focused on increasing the germination of lettuce cultivars under high-temperature conditions by seed treatments. The seeds of lettuce cultivars Yedikule, Iceberg, Iri Kıvırcık, and BT Iri Kıvırcık with different leaf morphology were primed by different doses of gibberellic acid (GA3) (0, 250, 500, and 1000 ppm) and preconditioned by chilling and heating. The seeds were germinated at optimal (20 °C) and high (35 °C) temperatures. The results showed that high temperature adversely influenced the germination percentage of lettuce cultivars. The mean germination percentage was 16.8% at 35 °C and 93.4% at 20 °C. Also, there was a significant difference among lettuce cultivars for germination at 35 °C. Iri Kıvırcık and BT Iri Kıvırcık showed a severe thermodormancy and hardly ever germinated at 35 °C. Prechilling and preheating promoted germination at 35 °C compared to unprimed seeds, but prechilling resulted in higher germination than preheating. GA3 was found to be the most useful treatment for improving germination compared to the others. The germination percentage of Iceberg, Yedikule, and Iri Kıvırcık primed with GA3 doses reached over 80%. The results suggested that the germination performance of lettuce cultivars suffering from thermodormancy or wherever climatic conditions with high temperatures should be promoted by the application of 500 ppm de GA3.

Sainfoin (Onobrychis viciifolia Scop.) is an important forage legume crop with 52 species adapted to dry and poor soils in Turkey, but little is known about the effects of salinity on germination and seedling growth in arid and semiarid regions suffering from salinity problem. The seeds and pollen of two species of sainfoin O. viciifolia and O. oxyodonta var. armena (Syn: O. armena) were exposed to 0, 5, 10, 20 and 30 dS m-1 of NaCl under in vivo and in vitro conditions and evaluated for germination under salt stress by comparing germination percentage, mean germination time, root and shoot length, fresh and dry seedling weight and dry matter. Increased salinity levels generally resulted in decrease in all traits except time to germination, dry seedling weight and dry matter, which increased at high salinity levels. O. viciifolia seeds germinated and grew more rapidly compared to O. armena seeds under NaCl stress. No decrease in germination and seedling growth up to 10 dS m-1 was recorded. On the other hand, there was a clear difference for germination and seedling growth between in vivo and in vitro conditions. Lower values were obtained from in vitro experiments; suggesting that mineral salts, sucrose and agar may have resulted in higher osmotic potential inhibiting germination and seedling growth of species compared in vivo conditions. Decrease in pollen germination with increasing salinities was very sharp, indicating that pollen germination had higher sensitive to salinity. But, pollen grains of O. armena germinated rapidly compared to O. viciifolia. The results emphasize that in vivo experiments could be used for screening of NaCl tolerance in sainfoin cultivars without expensive chemicals and sophisticated equipments, but pollen germination is more appropriate for its wild relatives.