Abscisic acid and kinetin seed treatments improved germination characteristics of aged seeds in canola cultivars (Brassica napus) under water stress

摘要

The use of high-quality seed is essential for good stand establishment and yield in any crop. A major concern of seed business and rape seed growers alike is that deterioration of some seed lots leading to loss of vigour. Seed germination, seedling emergence and crop establishment are important aspects of rape seed production. In Iran, water is the most common abiotic stress to which rape seeds are exposed. The objectives of this study was to assess the effects of exogenous application of abscisic acid (ABA) and cytokinin (CYT) seed treatment on improvement of germination characteristics of aged seeds of rape cultivars under drought stress. The experiments were carried out at seed and biotechnology laboratories of College of Agriculture, University of Tehran during 2004-2005. A completely randomized design with three replications was conducted. The rape seed cultivars Licord (winter variety) and Option 500 (spring variety) were included. The seeds were aged using the accelerating-aging test.Characteristics such as germination percentage (%), germination index and germination speed were measured in all experiments.The results revealed that seed aging or deterioration and drought stress reduced the seed vigor, germination %, and speed of germination. Under the accelerate-aging test and drought stress, rape seed cultivars differed significantly. For accelerate-aging and drought stress treatments, germination percentage, germination index, and speed of germination of Licord cultivar was significantly higher than Option cultivar. The treatment of these various aged seeds with ABA and CYT hormones improved drought tolerance. Higher concentrations of these two hormones increased the level of tolerance. Aged seeds performed better under ABA treatments.