الفهرس 
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Abstract
In the present investigation, six maize genotypes namely Giza 2 open pollinated var., hybrids SC 10 and 128 and TWC 321, 323 and 324 as well as seven seed treatments which were control, soaking in water, GA3, ascorbic acid, osmopriming operation (PEG 8000), soaking in zinc solution and gamma irradiation treatments were used to study their effect on germination and seedling growth under field conditions and laboratory viability and vigour measurements of hybrids maize concerning local ecological conditions and genetic materials. Furtherthrough, evaluate several viability and vigour tests looking to determine the relationship between such laboratory tests and field emergence and in turn to identify vigour test which could predict field emergence for maize crop. Laboratory tests were conducted for two successive seasons during 2012 and 2013 years. Standard germination, tetrazolium and cold tests were carried out at Seed Laboratory, Agronomy Department, Faculty of Agriculture, Zagazig University, while Electrical conductivity test was conducted at Laboratory of Seed Technology Research Department at Giza ARC, Egypt.
Field emergence experiments were conducted during both testing seasons (2012 and 2013) at Kafr El-Hamam Research Station Zagazig district, Sharkia Governorate, Egypt, through three sowing dates i.e. 15th of April, May and June of 2012 and 2013. The results indicated that Giza 2 variety followed by hybrid TWC 321 recorded higher values of most viability and vigour measurements included germination (%), good seedlings (%), good+fair seedlings (%), first count %, speed germination index, germination index, seedling length, tetrazolium potential (1-5) (%), tetrazolium enrgy 1-3 (%), field emergence at 10th day (%), and emergence index. On the other hand, genotypes 128, TWC 323 and TWC 324 gave the lower values in that regard. However, hybrid SC 10 obtained higher germination (%) in cold test. EC results took the reverse direction of the forms presented seed viability and vigour results. This confirmed the potential differences in viability and vigour between genotypes and seed lots. Soaking corn seed in ascorbic acid appeared to be improved vigour and viability measurements whereas gave the higher good seedling (%), good+ fair seedling (%), first count %, speed germination index, germination index, seedling vigour index and seedling length as well as GA3 recorded longer seedling. The higher field emergence (%), was obtained by control treatment, soaking in zinc solution, soaking in GA3, osmopriming operation and soaking in ascorbic acid while seed soaking in water gave the higher field emergence index. otherwise, seed irradiated by gamma rays recorded lower values of most viability and vigour measurements as well as field emergence. Highly significant correlations were observed between field emergence of maize and each of germination (%), good seedlings (%), TZ-potential (%), TZ energy (1-2) (%) and field emergence index, on contrary, it was insignificantly correlated with electrical conductivity and cold tests. These results impressed the importance of maize seed viability and vigour measurements which could be used to predict field emergence and in turn determine the best seed quality and seeding rates required for planting under the different conditions as well as saving the seed and practical processes could be required after sowing to establish optimum plant density and good stand. Also, can be used TZ test to estimate seed viability and vigour as a quick test (24-36 hr.) to predict the field emergence in maize fields.