Effect Of Water Stress During Seed Formation On Seed Quality Of Irrigated Soybean

Abstract

These experiments were carried out at Agricultural experiments and Research Station, Faculty of Agric., Cairo University, Giza, Egypt during 2018 and 2019 summer seasons to study the effect of water stress during seed formation on seed quality of soybean. Four treatments were used: 1-non-stress, mild stress, moderate stress and high stress. The present study indicated that 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 the defective seeds, green seeds and seeds with cracked seed coat 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 change while, oleic (18:1) increased by 4.76 percent point, while linoleic (18:2) decreased by 4.51 percent points and linolenic (18:3) by 2.11 percent points when the parental plants exposed to water stress at R3 stage up to harve stmaturity compared to non-stressed plants. These results indicated that to obtain high quality seeds from irrigated soybean in dry region such as Egypt, it is important to avoid exposing soybean crop to water stress before physiological maturity because the nutritional value of seed as well as its physiological traits with regard to viability and vigor parameters well be decrease.