engleski

The effect of germination temperature on seed dormancy in Croatian- grown winter wheats

The level of seed dormancy at harvest time is the main component of pre-harvest sprouting resistance in wheat and it is controlled by genetic as well as environmental factors. Temperature is an important environmental factor, influencing the induction of seed dormancy during seed development and maturation as well as the expression of seed dormancy during germination. The aim of this study was to determine genotype differences in expression of seed dormancy at different germination temperatures. Twenty five winter wheat genotypes including a highly dormant check RL4137, were grown in the field at two locations in Croatia during 2008/2009 growing season in a randomized complete block design with two replicates. From each plot 30 spikes were harvested at harvest maturity (approximately 14% moisture content on a wet weight basis). Three germination tests were conducted with hand threshed seeds under controlled environment at temperatures of 15, 20 and 25°C in darkness. The first germination test was started immediately after harvest (Time 1), whereas the second and third germination tests were conducted after 10 (Time 2) and 20 (Time 3) days of seed after-ripening at 20°C, respectively. Germination rate, expressed as weighted (by day) germination index (WGI), was calculated for each genotype by temperature combination. Combined ANOVA across locations revealed significant differences among genotypes (G) and locations (L) as well as significant G x L interaction for WGI for all three germination tests (Time 1, Time 2 and Time 3) and germination temperatures (15, 20 and 25°C). Genotypes responded with decreasing WGI mean values (increasing dormancy), as temperatures changed from 15 to 25°C in all three germination tests. The number of genotypes with the same level of seed dormancy as dormant standard RL4137 decreased from Time 1 to Time 3 at all three germination temperatures. In all three germination tests the number of genotypes ranking similar to standard RL4137 was lower at 25°C compared to other two germination temperatures. At 15°C the ranges of genotypic WGI mean values decreased from Time 1 to Time 3, at 20°C ranges of WGIs were similar for 15 and 20°C and lower at Time 3, whereas at 25°C ranges of WGIs increased from Time 1 to Time 3. This indicates that maximum differences in dormancy between genotypes included in the current study occurred at different stages of after-ripening depending on germination temperature.

seed dormancy ; germination temperature ; germination index (WGI) ;

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