The evaluation and improvement of seed quality and storage potential in cauliflower and cabbage seeds
This study aimed to improve seed quality in cauliflower and cabbage, firstly though the development of rapid methods for the evaluation of germination and seed storage potential using measurements of seed leachates conductivity and secondly, through the application of seed treatments both as pre-storage treatments and to improve germination under stress conditions. Significant negative correlations between germination and the conductivity of seed leachate were observed both when seed had high germinations after ageing and when a range of germinations resulted from either combinations of dead plus living seeds, or ageing. This suggested that conductivity measurements could be applied to predict seed germination. Seed quality declined during storage at two moisture contents (12% and 6.5%) and two temperatures (25oC and 35o C) as reflected by the increase in seed leachate conductivity and decline in germination and vigour. Differences in seed storage potential were best predicted by the controlled deterioration (CD) test and by CD followed by measurements of leachate conductivity. Other pre-storage assessments (laboratory germination, Ki, conductivity) were less consistent in prediction of storage potential. The second approach used to improve seed quality was to apply pre-storage seed treatments to improve seed storage potential. The most striking improvements in seed storage potential occurred after pre-storage hydration treatments, aerated hydration (AH) for 12h or 18h and water soaking for 3h or 6h, with smaller improvements after antioxidant treatments (0.1% a-tocopherol and 0.1% ascorbic acid). Halogenation (I2) treatment had no effects on storage potential. Improved seed quality was also revealed after AH treatment by both the increased ability of seed to germinate at high temperature (35oC) and more rapid germination at reduced water potential and under salinity stress. AH treatment also increased the ability of seeds to recover from exposure to higher temperature (40oC) and reduced water potential (-1.90 MPa).