Effects of temperature, chemical treatments and endogenous hormone content on peach seed germination and subsequent seedling growth

Abstract

Seeds of ‘Nemaguard’ and ‘Halford’ peaches were chilled and removed periodically for chemical treatment, estimation of abscisic acid and gibberellic acid and assessment of germination response. Non-chilled ‘Nemaguard’ seed treated with gibberellin germinated at 80%, and after 2 weeks' chilling at nearly 100%. ‘Halford’ seed germination was not enhanced by gibberellin at any stage prior to or during chilling. Only ‘Nemaguard’ seed germination was hastened by benzylamino purine. Both ‘Nemaguard’ and ‘Halford’ seed germination was reduced by abscisic acid. ‘Halford’ was far more sensitive to 100 mg l−1 abscisic acid, with zero germination even after 8 weeks' chilling; a similar treatment for ‘Nemaguard’ resulted in 70% germination. ‘Nemaguard’ seedling growth following giberellin treatment of non-chilled seed was similar to chilled controls; in contrast, ‘Halford’ seedlings grown from seed so treated did not compare favorably with controls. Abscisic acid seed treatment prior to germination restricted ‘Nemaguard’ seedling growth after germination and prevented ‘Halford’ seedling growth. There remains no clear primary role for these hormones applied exogenously, or their endogenous content, in regulating peach seed dormancy. We suggest their role, if any, to be in seedling growth subsequent to germination.