INFLUENCE OF WARM INTERVALS ON THE EFFECTS OF VERNALIZATION AND THE COMPOSITION OF PHOSPHOLIPID FATTY-ACIDS IN SEEDLINGS OF WINTER-WHEAT

Excised embryos of winter wheat were submitted to a different number of vernalization (2-degrees-C) and devernalization (20-degrees-C) cycles of different lengths. In all treatments sum of cold and warm intervals was 50 and 10 days, respectively. The influence of different temperature conditions of seedling growth on the effectiveness of vernalization and correlations between effectiveness of vernalization and final content of phospholipid fatty acids were analyzed. All indexes of generative development of plants (length of vegetative phase, % of generative plants, number of side shoots) showed the most effective was uninterrupted vernalization beginning immediately after excision of embryos. Increasing the number of 2-degrees-C/20-degrees-C cycles rapidly depressed effectiveness of vernalization, which reached the minimum with the 8.3 days at 2-degrees-C and 2 days at 20-degrees-C cycle and then improved again as cycles became shorter and more numerous. Correlations between indexes of generative plant growth and indexes describing composition of fatty acids in seedlings showed that from 50 % to 60 % of variability in the composition of phospholipid can be associated with changes in the degree of generative induction. A higher degree of generative induction was associated with a higher share of < 16, 16:0 and 18:2 acids and a lower share of 18:3 acid and also with a lower value of the 16:0/ < 16 ratio of phospholipids. The relation between the generative induction of plants and the composition of phospholipid fatty acids may however be blurred when induction proceeds under conditions of alternate short spells of vernalization and devernalization temperatures.