DEVELOPMENT OF THE EMBRYO OF MEDICAGO SATIVA L. AFTER NORMAL FERTILIZATION AND AFTER POLLINATION BY OTHER SPECIES OF MEDICAGO

Abstract

The embryonic development of diploid and tetraploid Medicago sativa from the formation of the zygote to mature seed is described and illustrated. The embryo reaches the global stage at 7 to 8 days; the heart stage at 11 to 13 days; and the torpedo stage at 14 to 16 days after pollination. Full size is attained at about 25 days but food reserves apparently continue to be stored and maturity may not be reached until about the 35th day.Pollination of M. sativa stigmas with pollen from highly incompatible species failed to produce mature embryos. Crosses involving M. lupulina produced no sign of embryo development. However, when M. arborea, M. blancheana, M. marina, M. platycarpos, M. rigidula, M. ruthenica, or M. scutellata was used as a pollen parent the early stages of embryonic growth were initiated.