Ultracooling (to - 196 C) Effects on Barnyard Grass (Echinochloa crusgalli [L.] Beauv.) Secretory Epithelium Ultrastructure and Caryopsis Germination

Barnyard grass (Echinochloa crusgalli [L.] Beauv) florets were ultracooled 0-10 times for 5 min each time to -196 C in liquid nitrogen, thawed for 1 h in air at 24 C, and germinated Germination of caryopsis not ultracooled was 60%, while germination of caryopsis ultracooled 10 times was 99%. Changes occurred in the structure of lipid bodies of the secretory epithelium of unimbibed florets ultracooled either four or 10 times Following water imbibition, lipid bodies regained a similar form as existed prior to ultracooling Protein bodies were digested faster in the secretory epithelium of embryos ultracooled 10 times than in embryos not ultracooled