Effects of water supply methods and seed moisture content on germination of China aster (Callistephus chinensis) and tomato (Lycopersicon esculentun Mill.) seeds

Uniform and fast germinating seeds are of prime importance for agriculture. To improve the germination properties of seeds, different treatments called priming are used. These methods generally involve the controlled uptake of water by the seeds. To be able to understand the processes involved in different priming methods the aim of the research was to study the relationship between the methods of water supply, water uptake rate by seeds. seeds moisture content and germination of China aster 'Jolanta' and tomato 'Janosik' seeds. Seeds of these species were primed by: (i) soaking in excessive amount of distilled water for 0-1440 min in the ratio of seeds to water (v:v) of 1:3; (ii) soaking in limited amount of distilled water 10-1280 ml kg(-1) of seeds; (iii) matriconditioning in the ratios of 1:0.4:0.2-2.0 (w:w:w) for seeds, Calflo and water, respectively. The imbibed seeds were incubated for I day at 20 degrees C and seed moisture content was measured after incubation. Additionally, in seeds moistened up to 37% (China aster) and 35% (tomato), dynamics of water uptake were examined. Seeds, after imbibition and incubation, were dried to the initial moisture content (m.c.). Percentage of the germinated seeds, maximum germination (G(max)), time for the first seed to germinate (T-1), time to reach 50% germination (T-50), time between 10 and 90% of G(max) (T-90-T-10), at 5, 20 or 35 degrees C for the China aster seeds and at 15, 20 or 35 degrees C for tomato were evaluated. The results showed that water supply methods significantly affected seed imbibition rates and dynamics of seed germination, although these depended on plant species. It was found that water uptake was fastest in seeds soaked in excessive water amount and also that China aster took water faster than tomato. Imbibition of seeds during matriconditioning in Calfo and in limited water amounts was slower. Imbibition of seeds up to 37% m.c. for China aster and 35% m.c. for tomato, irrespective of the conditioning method, was the most favorable for germination. The earliest germination was observed in seeds soaked in excessive amount of water and incubated for 1 day. Germination of seeds matriconditioned, and those conditioned in limited water amount for 1 day was slower. We conclude that although the optimal final moisture content is independent of the different water supply methods used, the water supply method itself strongly affect the germination properties (T-1, T-50 and T-90-T-10 dynamics of germination). (c) 2005 Elsevier B.V. All rights reserved.