The fine structure of the embryo of Lactuca sativa. II. Changes during germination

1968 ◽  
Vol 46 (11) ◽  
pp. 1447-1453 ◽  
Author(s):  
Lalit M. Srivastava ◽  
Ronald E. Paulson
Keyword(s):  
Fine Structure ◽  
Seed Germination ◽  
Lactuca Sativa ◽  
Root Tip ◽  
Membrane Systems ◽  
Lactuca Sativa L ◽  
Progressive Loss ◽  
Grand Rapids ◽  
Developmental Continuity ◽  
Embryo Cells

Changes in fine structure and reserve materials of the dormant embryos of Lactuca sativa L. var. Grand Rapids were studied during the first 4 days of germination. Activation of cells begins soon after the embryos are soaked and involves a progressive loss of reserve materials, an increased clarity of organelles and membrane systems, and development of structures either absent or present in a highly modified state in the dormant embryo. Cells of the hypocotyl just behind the root tip are first activated. Activation then progresses through the hypocotyl and acropetally in the cotyledons. These results are discussed in relation to physiology of seed germination. Plastids show several patterns of development, depending on the tissues in which they are localized. There is developmental continuity between the dissolution of protein bodies and formation of vacuoles.

The fine structure of the embryo of Lactuca sativa. I. Dry embryo

1968 ◽  
Vol 46 (11) ◽  
pp. 1437-1445 ◽  
Author(s):  
Ronald E. Paulson ◽  
Lalit M. Srivastava
Keyword(s):  
Lactuca Sativa ◽  
Osmium Tetroxide ◽  
Light And Electron Microscopy ◽  
Membrane Systems ◽  
Cortical Cells ◽  
Mesophyll Cells ◽  
Lactuca Sativa L ◽  
Processed Material ◽  
Grand Rapids ◽  
Definition Of

Dry embryos of Lactuca sativa L. var. Grand Rapids were studied by improved techniques of light and electron microscopy. Cells of the dry embryo are filled with reserve proteins and lipids; the latter are preserved in the processed material only if the material is fixed in osmium tetroxide at some stage before dehydration and embedment. Nuclei, mitochondria, ribosomes, and some membranes show the least modifications in the dry state; other organelles are poorly defined and some may be absent. The best definition of organelles and membrane systems is found in the root apical cells, least in the cortical cells of the hypocotyl and mesophyll cells of the cotyledons.

scholarly journals Preventing thermoinhibition in a thermosensitive lettuce genotype by seed imbibition at low temperature

2003 ◽  
Vol 60 (3) ◽  
pp. 477-480 ◽  
Author(s):  
Warley Marcos Nascimento
Keyword(s):  
Seed Germination ◽  
Low Temperature ◽  
High Temperatures ◽  
Lactuca Sativa ◽  
Lettuce Seed ◽  
Temperature Dependent ◽  
Lettuce Seeds ◽  
Lactuca Sativa L ◽  
Lettuce Seed Germination ◽  
Dark Green

Lettuce (Lactuca sativa L.) seed germination is strongly temperature dependent and under high temperatures, germination of most of genotypes can be erratic or completely inhibited. Lettuce seeds of 'Dark Green Boston' (DGB) were incubated at temperatures ranging from 15° to 35°C at light and dark conditions. Other seeds were imbibed in dark at 20°; 25°; 30°; and 35°C for 8 and 16 hours and then transferred to 20 or 35°C, in dark. Seeds were also incubated at constant temperature of 20° and 35 °C, in the dark, as control. In another treatment, seeds were primed for 3 days at 15°C with constant light. DGB lettuce seeds required light to germinate adequately at temperatures above 25°C. Seeds incubated at 20°C had 97% germination, whereas seeds incubated at 35°C did not germinate. Seeds imbibed at 20°C for 8 and 16 hours had germination. At 35°C, seeds imbibed initially at 20°C for 8 and 16 hours, had 89 and 97% germination, respectively. Seeds imbibed at 25°C for 16 hours, germinated satisfactory at 35°C. High temperatures of imbibition led to no germination. Primed and non-primed seeds had 100% germination at 20°C. Primed seeds had 100% germination at 35°C, whereas non-primed seeds germinate only 4%. The first hours of imbibition are very critical for lettuce seed germination at high temperatures.

Sign in / Sign up

Export Citation Format

Share Document