Seed water content in relation to phytochrome-mediated germination of lettuce seeds (Lactuca sativa L. var. Grand Rapids)

1971 ◽  
Vol 49 (1) ◽  
pp. 111-115 ◽  
Author(s):  
A. I-Hsiung Hsiao ◽  
William Vidaver
Keyword(s):  
Water Content ◽  
Lactuca Sativa ◽  
Red Light ◽  
Second Stage ◽  
Lettuce Seeds ◽  
Lactuca Sativa L ◽  
Grand Rapids ◽  
Two Stages ◽  
Seed Water Content ◽  
Stimulation Of

It is possible to distinguish two stages in the influence of light on the germination of Lactuca sativa var. Grand Rapids (lettuce) seeds. The first stage, which is represented by the photoactivation or transformation of phytochrome, requires only a relatively low seed water content. Slightly higher seed water content is required for maximum far-red light repression, than for red light stimulation of germination. The second stage is indicated by the well-known situation in which previous red irradiations of the seeds can enhance germination but this takes place only with relatively high seed water content. Phototransformed phytochrome appears to persist and to be susceptible to photoreversal for at least 24 h after irradiation in the seeds with relatively low water content.

Some aspects of the function of the endosperm during the germination of lettuce seeds

1974 ◽  
Vol 52 (5) ◽  
pp. 1117-1121 ◽  
Author(s):  
Henry L. Speer
Keyword(s):  
Lactuca Sativa ◽  
Red Light ◽  
Intact Seed ◽  
Lettuce Seeds ◽  
Grand Rapids

The response to red and far-red light of intact and punched seeds of Lactuca sativa var. Grand Rapids is compared. Punched seeds are fully responsive to red light after only 1 min of hydration; intact seeds require 15 min. Punching has no effect on the usual red and far-red light mediation of germination of these seeds. It does, however, raise the level of dark germination, indicating that there are at least two mechanisms by which the seed can germinate, only one of which is controlled by phytochrome.Treatment of seeds with dichloromethane enhances germination in seeds imbibed 1 min but not the penetration of arsenate, which is normally excluded by the intact seed. The detergent Brij greatly enhances the penetration of arsenate into the seed.

Characterization of SAN 9789-Stimulated Lettuce (Lactuca sativa) Seed Germination

Weed Science ◽  
1985 ◽  
Vol 33 (2) ◽  
pp. 160-164 ◽  
Author(s):  
Karl-Olof Widell ◽  
Christer Sundqvist ◽  
Hemming I. Virgin
Keyword(s):  
Abscisic Acid ◽  
Seed Germination ◽  
Lactuca Sativa ◽  
Red Light ◽  
Inhibitory Effect ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Minor Degree ◽  
A Minor

Dark germination of light-requiring lettuce seeds (Lactuca sativaL. ‘Grand Rapids’) was stimulated by SAN 9789 [4-chloro-5-(methylamino-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] and to a minor degree by BASF 13761 [4-chloro-5-methoxy-2-phenyl-3(2H)-pyridazinone] and BASF 44521 [4-chloro-5-methoxy-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], but not by’ pyrazon [5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone], SAN 9785 [4-chloro-5-(dimethylamino)-2-phenyl-3 (2H)-pyridazinone], SAN 9774 [5-amino-4-chloro-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], or SAN 6706 [4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone]. SAN 9789 stimulation was inhibited by cis-4-cyclohexene-1,2-dicarboximide (CHDC), and abscisic acid (ABA) at 1 × 10-4M. Red light nullified the inhibitory effect of CHDC (1 × 10-4M) but not the inhibitory effect of ABA (1 × 10-4M) on SAN 9789 stimulated germination. Gibberellic acid (GA3) and kinetin (6-furfurylaminopurine) increased the germination stimulatory effect of SAN 9789 in darkness. Temperatures above 25 C decreased the effect of SAN 9789, with a temperature of 35 C completely inhibiting germination. The inhibitory effect of CHDC was strongly decreased at temperatures below 20 C. SAN 9789-induced germination in darkness was always the same (25 to 26% units increase in germination) even though the red light-stimulated germination differed with the seed batch.

An influence of water regime on the light response in germination of lettuce (Lactuca sativa var. Grand Rapids) seed

1971 ◽  
Vol 49 (8) ◽  
pp. 1359-1362 ◽  
Author(s):  
A. I-hsiung Hsiao ◽  
G. M. Simpson
Keyword(s):  
Lactuca Sativa ◽  
White Light ◽  
Water Regime ◽  
Red Light ◽  
Light Response ◽  
Lactuca Sativa L ◽  
Grand Rapids ◽  
Influence Of Water ◽  
Low Levels ◽  
Petri Plate

The germination response of Lactuca sativa L. var. Grand Rapids to different light qualities (red, blue, far-red, white) compared with darkness, is modified by the level of water in the petri plate used for germinating the seeds. Far-red light and blue light inhibit germination for 24 h in all levels of water studied whereas red inhibits in low levels and promotes in high levels. White light inhibits germination in low levels of water but not in high levels. At least part of the inhibiting effects of light on germination in low levels of water may be associated with induced lowering of water potential in the seeds.

Activity of glucose-6-phosphate dehydrogenase from lettuce seeds (Lactuca sativa)

1974 ◽  
Vol 52 (10) ◽  
pp. 2225-2227 ◽  
Author(s):  
Henry L. Speer
Keyword(s):  
Enzyme Activity ◽  
Lactuca Sativa ◽  
Red Light ◽  
Supernatant Fraction ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Lactuca Sativa L ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of phosphate, arsenate, arsenite, and sulfate on lettuce seed (Lactuca sativa L.) glucose-6-phosphate dehydrogenase were investigated. All four substances inhibited the enzyme and inhibition was substrate dependent. The reaction was specific for glucose-6-phosphate and NADP. No effect of red or far-red light could be observed on enzyme activity. All enzyme activity was confined to the supernatant fraction.

Acidification, growth promoter, and red light effects on germination of skotodormant lettuce seeds (Lactuca sativa)

1984 ◽  
Vol 62 (6) ◽  
pp. 1108-1115 ◽  
Author(s):  
Andrew I. Hsiao ◽  
William Vidaver ◽  
William A. Quick
Keyword(s):  
Lactuca Sativa ◽  
Red Light ◽  
Critical Factor ◽  
Growth Promoter ◽  
Growth Promoters ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Increased Sensitivity ◽  
Light Effects ◽  
Different Sources

Increasing the period of dark storage (DS) within a uniform seed lot of lettuce (Lactuca sativa L. cv. Grand Rapids) increased the degree of secondary dormancy (skotodormancy) induced, as evidenced by a loss of sensitivity to red light (R) and growth promoters such as gibberellin A3 (GA3), kinetin, thiourea, and ethylene. Differential degrees of skotodormancy were induced in lettuce seeds from three different sources (lot I < lot II < lot III). Either R or GA3 significantly increased the germination of skotodormant seeds if seeds were first immersed in strongly acidic solutions (pH ≤ 3.0) and then rinsed with water. The critical factor was found to be pH, not ionic strength. Promotion of germination by R or GA3 was positively related to increasing acidity, and also to the duration of DS. Sensitivity of the germination response to acid immersion varied with the seed lots, as little as 1 s being effective with some seeds. Acid treatment thus enables skotodormant seeds to recover much of their responsiveness to R and GA3. Extended DS (21 days) produced such pronounced skotodormancy (seed lot III) that acid immersion followed by usual R and GA3 produced only 10% germination. Continuous R or a seed-piercing treatment produced complete germination in otherwise skotodormant seeds. Responsiveness of germination to thiourea, kinetin, and ethylene, however, was not regained by treatment with acid. The action of these three chemicals on skotodormant seeds thus seems to be dependent on an active phytochrome and GA3-sensitive system. Acid-immersion treatments appear primarily to weaken membrane barriers of the endosperm cells, with resulting increased sensitivity of seeds to R treatment and GA3 penetration.

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.

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