BIOLOGICAL CHANGES OCCURED IN SOYBEAN SEED DURING EXPOSING TO SEVERAL TYPES OF SEED PRIMING

Biological experiments were carried out at Agronomy Seed Lab., Agronomy Dept., Faculty of Agriculture, Ain Shams University and Ain Shams Center For Genetic Engineering and Biotechnology ACGEB, Genetic Dept., Faculty of Agriculture, Ain Shams University during 2016/2017 season. Priming and its duration were investigated whereas different types of priming (hydro-priming, osmopriming and salt-priming) and different periods of each type (short- medium and long periods) were stuied. Newly harvested soybean seeds cultivar (Giza 111) were submitted from Field Crop Institute, Agricultural Research Center (ARC). It was found that type of priming enhanced germination percentage significantly from low performance of 40% to 51%, 68% and 75.5% for hydration, osmopriming and salt priming respectively. Extending exposing period to the longest period gave significantly maximum increment in seed germination. Maximum germination enhancement was achieved when calcium chloride solution was used for the longest period (48 hrs.) giving value of 96.0%. Such increment reached 140% as compared with control.  It was noticeable that increasing soaking period to the longest period examined in this investigation accelerated the rate of germination to a maximum level. Salt priming produced longest soybean seedling shoot when compared with control. Overall, for most results obtained in this trial,   seed primed with CaCl2 showed better perfor mance than those primed with water or PEG solution.  Seedling dry weight revealed a significant effect in a similar manner of seedling length. The longest exposing priming period showed a significant effect on seedling dry weight. Soybeans seeds proteins exposed to priming for all three periods used in this investigation varied from control, whereas number of protein bands on SDS gel increased from 10 bands separated on control pattern to 13, 11 and 12 for hydration treatment at periods of 6, 12 and 24 hrs., respectively. Also number of mono poly-uni. and unique bands varied as well as its intensive dye which reflect that amount of protein formed varied between treatments.  Considering exposing seeds to salt solution of CaCl2 for longest period (48 hrs.) less bands of separated protein were formed on SDS gel. Biological seed quality was assessed by extracting proteins on native polyacrylamide gel electrophoresis, whereas, all priming treatment at application periods caused on increasing in peroxidase activity compared to control (untreated seeds).  It was remarkably that the longest period of expose showed the highest peroxidase activity when compare to control and also for the short and medium exposing periods (6 and 12 hrs.). Also it was noticed that there were a unique diffuse band at the end of the lane, these bands were less intensive in staining color, meaning that their activities is less than those extracted from hydro-primed seeds for short and medium periods (6 and 12 hrs. respectively).  Seed esterase activity bands had two prolonged regions, these bands appeared as a diffuse bands. Esterase activity bands of PAGE gel showed less activity as subjected to all priming types at any period used in this investigation (long, medium and short) when compared to untreated seed (control). It was clear that increasing period of exposing seeds to priming reduced esterase activity since the intensive band diminished in their intensive color.