The effect of accelerated aging (AA) and seed priming on specific seed enzymes was studied in soybeans. Aging seeds for 48 and 96 h at 41°C and 100% humidity reduced germination from 92% to 68% and 0%, respectively. Malate dehydrogenase (MDH) glutamate dehydrogenase (GDH), and esterase were assayed in extracts from dry and imbibing seeds. Malate dehydrogenase activity was the least affected by AA treatments. Certain GDH isozyme activity was reduced by 17% after 48 h of AA and almost completely lost after 96 h. Imbibing for 24 h increased GDH activity in 48 h-accelerated-aged seeds but not the 96 h-aged seeds. Two esterase isozymes in dry seeds showed a 77% loss of activity after 48 h of AA. This treatment increased the total esterase activity, with the greatest activity observed after 96 h of AA. This was due to the appearance of a diffuse high molecular weight (HMW) region of activity observed on native polyacrylamide gels and specifically induced in the embryonic axes. Imbibing 48-h-accelerated-aged seeds for 48 h caused a reappearance of the two esterase enzymes lost during aging. The HMW esterase staining region also appeared after imbibing unaged seeds for 24 h. Seed priming, caused a response similar to imbibition for each enzyme except the HMW esterase activity. Priming 48-h-accelerated-aged seeds reduced the HMW esterase activity. This was not observed during imbibition of aged seeds and indicates the first identification of a specific enzymatic response unique to a seed priming treatment.

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 1842 Mohamed; Zaki; Olfat El-Bagoury and Rania Younis Arab Univ. J. Agric. Sci., Special Issue, 26(2C), 2018 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.

F 1 and F 2 seeds of four crosses were formed during 2001 and 2002 growing seasons. The F 2 population's plants were evaluated during 2003 growing season under the two planting dates (14 th May and 29 th June) to estimate the phenotypic correlation coefficients among eight plants characters and their contributions in the variation of grain yield/ plant at the Agric. Res.

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Six population's seeds of four yellow maize crosses were formed during 2001 and 2002 growing seasons. Their plants were evaluated during 2003 growing season under two planting dates (14 th May and 29 th June) for six agronomic traits at the Agric. Res. Stat. of Fac. of Agric., Ain Shams Univ., Shalakan, Kalubia Governorate, Egypt. The present work aimed to determine the genetic parameters and their interactions with planting dates for grain yield per plant, 100-kernel weight, number of kernels per row, ear length, ear diameter, and days to silking in the six populations (P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2). Mean values of the six populations for all studied traits in all crosses were higher under normal planting date than those under late one. Therefore, normal planting date seemed to be non-stress environment. The potence ratio for all traits in the four crosses exceeded (+1) except days to silking where it was less (-1). The highest heterosis percentage relative to mid and better parent reached 192.06% and 152.01% in cross 1 for grain yield per plant under late planting date. Inbreeding depression values were not-significant in all studied traits except ear diameter and 100-kernel weight in crosses 1 and 3 as well as grain yield per plant in all crosses also, it was positive for most studied characters in the four crosses except days to silking trait. Dominance occupied the first rank, additive or dominance type of epistasis occupied the second or the third contributor to the genetic effects in order of importance according to cross with exception of days to silking, where additive and additive occupied the first and the second ranks. Narrow sense heritability was relatively high for yield attributes whereas it was low for grain yield per plant. Meantime, expected genetic advance was relatively moderate or low for all traits. Therefore, it could be suggested that selection for most studied traits in the subsequent generations will be relatively more effective than in the early generations.