Research on the nature of recalcitrance in temperate tree seeds: GC and FTIR examinations of stored and desiccated seeds
Abstract
Quercus alba L., Q. durandii Buckl., and Q. virginiana Mill. acorns were collected, stored at +4oC and -2oC,and tested monthly to examine the physiological, biochemical, and moisture changes taking place during storage. Aesculus pavia L. seeds were similarly stored but tested only every three months, while those of Q. nigra L. and Q. pagoda Raf. were tested on a yearly basis. While all these seeds are classified as recalcitrant, not all deteriorate at the same rate nor does the lower storage temperature always enhance seed longevity. In addition, while gas chromatographic and Fourier transform infrared spectrometer (FT-IR) analyses revealed that amounts of sucrose change dramatically in stored acorns, we found that there are interspecific differences observed in carbohydrate mobilization and also differences between cotyledon and embryonic axis tissue within a species. Also, any moisture loss prior to storage was fatal; and proper handling of seeds could be of greater significance than storage temerature. FT-IR studies have also found changes in membrane lipids and secondary protein structure in desiccating and stored acorns, emphasizing that low storage temperatures do not deter metabolic activity in hydrated, recalcitrant seeds.