الفهرس | Only 14 pages are availabe for public view |
Abstract Four field experiments were conducted at the Agriculture Experiments and Research Station at Giza, Faculty of agriculture, Cairo University, Egypt during 2018, 2019 and 2020 seasons. The objective of this work are: study the effect of water stress, air temperature during seed formation as well as field weathering stress after physiological maturity on seed constituents, physical and physiological seed traits as well as seedling establishment in the field of Soybean variety Giza 111. According to the obtained results from water stress study exposing irrigated soybean crop to water stress during seed formation up to harvest maturity reduced the normal seeds of the total yield by 20%and increased t h e defective seeds,greenseeds andseedswithcrackedseedcoat percentage. This was in parallel with reduction in germination percentage, normal seedling, seedling length, seedling dry weight and seedling vigor index. Also, when water stress started at R5 stage (seed formation) or earlier at R3 stage (pod formation) caused significant reduction in oil and protein content, but carbohydrate and fiber contents were increased. Also saturated fatty acids (palmitic & stearic) of the extracted oil did not gr e at l ychanged, while oleic (18:1) increased by 4.76 percent point, while linoleic (18:2) decreased by 4.51 percent points and linolenic (18:3) decreased by 2.11 percent points when the parental plants exposed to water stress at R3 stage up to harvest maturity compared to non-stressed plants. According to field weathering study, harvesting at 7 days after physiological maturity produced greatest normal seeds but delaying harvesting after that increased defective seed%, EC value and decreased seed weight. Highest seed germination % and normal seedling%, longest and heaviest seedling were recorded from the seed harvested at PM which showed highest oil and protein content and highest values of seedling vigor index. According to heat stress study little temperature increase (1.0 C° ) of the air around the soybean plants during seed formation reduced seed oil content by 1.0- 1.5 %and increased protein content by 0.5-1.0%, with small change in other components. In context, the oleic fatty acid tended to increase and lenolenic acid tended to decrease under the condition of high air temperature |