The relationship between seed dormancy, seed size and weediness, in Crepis tectorum (Asteraceae)

Oecologia ◽  
1990 ◽  
Vol 83 (2) ◽  
pp. 277-280 ◽  
Author(s):  
Stefan Anderson
1996 ◽  
Vol 74 (4) ◽  
pp. 568-572 ◽  
Author(s):  
Stefan Andersson

The present study of the winter annual Crepis tectorum examines the relationship between seed (achene) size and the extent to which seeds resist germination during the year of their production. I carried out two seed burial experiments, one at an outcrop site occupied by a small-seeded population, and another in an experimental garden with soil from the same field site, with seeds representing the local population and a segregating generation of a cross between two other populations. Using logistic regression with data corrected for seed viability, I found an association between small seed size and failure to germinate in the first autumn. The small seed size characterizing many outcrop populations may have evolved as a response to selection for delaying germination in a habitat subject to unpredictable droughts during the growth season. Keywords: Crepis tectorum, germination, seed bank, seed size.


2001 ◽  
Vol 44 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Mario Marega Filho ◽  
Deonisio Destro ◽  
Lilian Azevedo Miranda ◽  
Wilma Aparecida Spinosa ◽  
Mercedes Concórdia Carrão-Panizzi ◽  
...  

During 1995/96 and 1996/97, experiments were carried out at Londrina State University, aiming at quantifying the oil and protein contents in two groups of soybean genotypes; estimating the phenotypic, genotypic and environmental correlations existent among oil, protein content and seed size, and identifying genotypes for direct human consumption with high protein content. The evaluated characters were Weight of a Hundred Seeds (WHS), expressed in grams/100 seeds, Oil Content (OC) and Protein Content (PC), expressed in %. In the experiment carried out in the field, OC ranged from 12 to 20.37 % and PC from 35.66 to 41.75% while in the experiment carried out in the greenhouse OC ranged from 12.26 to 21.79 % and PC from 32.95 to 41.56 % . The correlations between oil and protein were negative and significant. The relationship among WHS with OC and PC was low and higly affected by the time effect. Due to their high protein content and stability to oil and protein contents, there were distinction among the treatments carried out in the field (GA23 and GA20), and those carried out in the greenhouse (PI408251, Waseda, B6F4 (L-3 less), PI423909 and Tambagura).


2003 ◽  
Vol 13 (1) ◽  
pp. 75-85 ◽  
Author(s):  
Bruno Cerabolini ◽  
Roberta M. Ceriani ◽  
Marco Caccianiga ◽  
Rossella De Andreis ◽  
Barbara Raimondi

AbstractSeed size is a good predictor of seed persistence in soil for British, Argentinean, Iranian and – to some extent – New Zealand species. It has been suggested that seed shape should also be linked to the ease of burial and, thus, to seed persistence, even if some studies failed to show this. The relationship between seed size and shape and persistence in soil was analysed for 259 species of the Italian flora, belonging to a wide range of habitats, from alpine pasture to limestone prairies and meadows of the Prealps, and from woodlands to Mediterranean maquis and garigues. Seed size was related to persistence in soil in the same way as in most other floras examined. Furthermore, seed shape was highly related to persistence in soil among the species analysed, when considered both altogether and divided among the different habitats. Our results suggest that not only seed size, but also seed shape, are key factors in determining seed fate and seed persistence in soil.


2017 ◽  
Vol 214 (4) ◽  
pp. 1527-1536 ◽  
Author(s):  
Rafael Rubio de Casas ◽  
Charles G. Willis ◽  
William D. Pearse ◽  
Carol C. Baskin ◽  
Jerry M. Baskin ◽  
...  
Keyword(s):  

1983 ◽  
Vol 61 (3) ◽  
pp. 667-670 ◽  
Author(s):  
E. P. Fuerst ◽  
M. K. Upadhyaya ◽  
G. M. Simpson ◽  
J. M. Naylor ◽  
S. W. Adkins

The hypothesis that loss of seed dormancy is associated with an increased activity of the pentose phosphate pathway (PPP) relative to glycolysis and the Krebs cycle was tested. The PPP activity was monitored by measuring the C6/C1 ratio in embryos excised from incubated caryopses of two genetically pure nondormant (ND) lines and in three dormant (D) lines of Avena fatua L., the wild oat. The C6/C1 ratios of all lines were similar at the commencement of incubation. In the two ND lines the ratio increased steadily prior to and during emergence of the radicle. In the three D lines the ratio increased during the first 24 h and then remained almost constant; there was no germination. When gibberellin treatment was used to overcome dormancy in the D lines, the C6/C1 ratio increased during the first 24 h in two of the lines and continued to increase parallel to germination in a manner similar to normal germination in ND lines. In the third D line, despite loss of dormancy from gibberellin treatment, the ratio did not increase after 24 h. Loss of dormancy during dry storage of seeds of a D-type pure line was accompanied by an increase in the C6/C1 ratio, as measured in freshly imbibed seeds. This indicates a decreased activity of the PPP relative to glycolysis and the Krebs cycle. These findings are contrary to Roberts's hypothesis that loss of dormancy in wild oats is associated with a relative decrease in the C6/C1 ratio.


2006 ◽  
Vol 86 (2) ◽  
pp. 525-537 ◽  
Author(s):  
Edith Fallon, Nicolas Tremblay ◽  
Yves Desjardins

In Quebec, grower income from processing peas is a function of yield and tenderometer reading. If peas are harvested early, the yield is poor, but the overall quality is superior, as indicated by lower tenderometer readings. Later harvests result in g reater yields but reduced quality (higher tenderometer readings). A better understanding of the relationship between harvest time, yield and quality is needed. In this study, the relationships between yield, tenderometer readings, size distribution and grain moisture content were examined as a function of growing degree-days (GDD) and production year for pea cultivars of different seed size categories. Yield and harvest attributes (tenderometer readings, seed size distribution and moisture content) were highly season dependent and their rates of change over the course of the harvest period also varied with the cultivar and year. Quality declined rapidly once the crop reached optimal maturity, while yield increased in a less predictable manner. Consequently, it was difficult to identify a harvest time that would consistently maximize grower returns. The highest income was generally not obtained at the optimal tenderometer readings presently used by the industry. Key words: Maturity, harvest date, climate, fresh matter yield, tenderometer, pea size


HortScience ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 99-101 ◽  
Author(s):  
Noël Pallais ◽  
José Santos-Rojas ◽  
Rosario Falcón

Sexual potato (Solanum tuberosum L.) seeds require many months of afterripening in dry storage to completely lose dormancy and germinate readily at >25C. We examined the relationship between storage temperature and seed dormancy, as assessed by the percentage of germination after 4 days. Two F1 hybrid lots of `Desiree' × 7XY.1 were used; one seed lot was produced by carefully removing half of the developing tubers from the mother plant during seed development, and the control remained undisturbed. Seeds were stored with 3.4% moisture (dry-weight basis) at 10, 20, 30, 40, and 50C and were tested eight times during 29 months for daily germination at 27/40C (21/3 h) for the first 8 days, followed by 6 days at 17C. After 29 months of storage, final germination was <97% only when control seeds were stored at 50C, in which germination was 72%. Germination after 4 days increased curvilinearly with increasing storage temperature, and both seed lots similarly lost dormancy (germination >90%) after 10 months at 40C. Optimum germination levels were maintained after 29 months at 40C. Seeds stored at 50C never completely lost dormancy, and after 7 months of storage, germination at 4 days gradually decreased to zero. Dormancy was eventually lost after 29 months in most seeds stored at <40C, and differences between seed lots suggest that removing tubers from the mother plant increased dormancy. We conclude that dry potato seeds can be safely afterripened at temperatures up to 40C; lower temperatures slow the rate of dormancy loss, and higher ones are detrimental to seed quality.


2014 ◽  
Vol 24 (1) ◽  
pp. 71-77 ◽  
Author(s):  
María Sosa Pivatto ◽  
Guillermo Funes ◽  
Ana E. Ferreras ◽  
Diego E. Gurvich

AbstractSeed size is one of the most important traits in the regenerative phase of a plant's life cycle; however, for cactus species the relationship of seed size and germination characteristics and seedling traits is still unclear. We studied the relationship between seed mass and germination and seedling characteristics in 17 cactus species from central Argentina, belonging to different genera and life forms. We measured seed mass, total seed germination, light requirements for germination and mean time to germination for these 17 cacti species; in addition, we recorded seedling size and shape in 15 species. To test light requirements we performed germination experiments under laboratory conditions at 25/15°C (day/night temperatures) and under light or dark conditions. We also calculated seedling volume by measuring seedling height and width. A shape index was obtained by dividing height by width (a value of 1 indicates ‘globose’ seedlings, whereas, as this value increases, seedlings become ‘columnar’). We found no significant relationship between seed mass and any of the germination characteristics considered. However, species with heavier seeds produced bigger seedlings, which were more cylindrical. Adult growth was not totally determined by seedling ‘growth form’, because some species that had globose seedlings were columnar at the adult stage.


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