Heat-induced accumulation of proline and yield components in genetically divergent cereal varieties

Growth and development of cereals is affected by abiotic factors, particularly by high temperature. An important factor in plant adaptation to abiotic stress can be the proline accumulation. Proline is an amino acid involved in a series of metabolic processes and is important as a protein stabilizer, osmolyte and antioxidant. The aim of this experiment was to determine the effect of high temperature on the proline content and yield elements in different cereal varieties during two vegetative seasons. For the investigation, plant material of 8 genetically divergent winter wheat varieties, 1 variety of triticale and 1 oat variety were used. Samples were collected in days with moderate midday air temperatures of 24-26?C in the milk stage and after a few days in the same phenological stage, in conditions of high midday air temperatures of 34-36?C. Proline accumulation was determined spectrophotometrically. Statistical analyses of data were done in the SPSS program. The results during the first experimental year showed that under moderate air temperature conditions proline content was 0.661 ?mol g-1 fresh plant, and in the second experimental year 0.777 ?mol g-1 fresh plant. Under conditions of heat stress during the first year, the content of proline increased to 2.169 ?mol g-1 fresh plant, and in the second experimental year the average content was 2.510 ?mol g-1 fresh plant, which confirms the increase of proline accumulations under heat stress. Compared with other cereal varieties, wheat varieties Zvezdana, Pobeda, Simonida and Avenu were characterized by higher contents of proline in conditions of heat stress in both vegetative seasons. Statistical analysis and correlation of the results of proline accumulation and yield elements showed that more resistant varieties to heat stress conditions have higher yields.