Published in Agron. J. 96:786-791 (2004).
© American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
CANOLA
Germination Characteristics of Polymer-Coated Canola (Brassica napus L.) Seeds Subjected to Moisture Stress at Different Temperatures
Christian J. Willenborga,
Robert H. Guldena,
Eric N. Johnsonb and
Steven J. Shirtliffe*,a
a Dep. of Plant Sci., Univ. of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada S7N 5A8
b Agric. and Agri-Food Canada, Scott Res. Farm, Box 10, Scott, SK, Canada S0K 4A0
* Corresponding author (shirtliffe{at}usask.ca).
Received for publication July 16, 2003.
 |
ABSTRACT
|
|---|
Polymer coatings have recently been developed to prevent germination and thereby reduce undesirable emergence of fall-seeded canola (Brassica napus L.) in western Canada. However, recent observations suggest that if seeds are not exposed to moist soil conditions in the fall, these polymer coats may prevent imbibition and subsequent germination during the following spring. Our objective was to determine the effects of moisture stress and polymer coat on canola seed germination characteristics in the laboratory. Polymer-coated and non-polymer-coated canola seeds were germinated in polyethylene glycol (PEG 8000) solutions with initial osmotic potentials ranging from 0 to –1.25 MPa at 5 and 15°C. Polymer coat treatments caused higher median germination times and lower final germination percentages compared with film-coated and uncoated control seeds. Germination characteristics of polymer-coated seeds were negatively influenced by decreasing initial osmotic potential, particularly at 5°C. Although not always significantly different from the uncoated control, film-coated control seeds behaved similarly to those coated with polymers. Among the three polymer coat treatments examined, one polymer coat treatment consistently exhibited higher germination compared with the other two. The results of this study help explain the occurrence of low spring seedling populations of fall-seeded, polymer-coated canola following a dry fall, particularly under low spring soil temperatures.
|
INTRODUCTION
|
|---|
CANOLA (Brassica napus L.) yield potential on the Canadian prairies is frequently limited by adverse environmental conditions, including low temperatures, frequent droughts, and a short growing season (Acharya et al., 1983; King et al., 1986; Rao and Dao, 1987; Blackshaw, 1991; Kirkland and Johnson, 2000). The mean soil temperature in the main canola-producing areas of western Canada can range from 5 to 13°C from 5 to 25 May (Environ. Canada, 1984); however, optimal soil temperatures for B. napus germination are between 15 and 20°C (Kondra et al., 1983). Low temperatures reduce both the final percentage as well as the rate of germination, which leads to delayed and reduced seedling emergence of canola (Zheng et al., 1994). In addition, low soil water potentials are a significant constraint on crop production in western Canada (Hao and De Jong, 1988). Decreasing soil water potentials also delay and reduce germination and plant establishment (Sharma, 1976; Hegarty, 1977; Schneider and Gupta, 1985).
To avoid some of these problems in canola production, alternative seeding dates such as seeding canola in the fall have been investigated (Kirkland and Johnson, 2000). The purpose of fall seeding is to plant canola seeds as close to freeze-up as possible when the soil is cold enough to prevent germination (Gan et al., 2001). Therefore, seeds lie dormant through the winter until spring soil temperatures are adequate for germination. Fall seeding allows canola seeds to utilize early spring moisture and limit exposure to dry soil conditions during germination. Early flowering resulting from early emergence allows fall-seeded canola to flower before midsummer heat stress, which frequently causes decreased seed set in spring-seeded canola (Kirkland and Johnson, 2000). Furthermore, canola yield can increase by as much as 38% with fall seeding compared with mid-May seeding (Kirkland and Johnson, 2000; Johnston et al., 2002). Thus, fall seeding of canola may be an attractive option with the further benefit of reducing the spring workload.
Fall seeding of canola does present some challenges. Fall seeding frequently entails seeding into hard, cold soil, which ultimately results in poor soil-to-seed contact (Kirkland and Johnson, 2000). As a result, plant population densities and yields may be severely reduced. Early spring frosts are more problematic with fall-seeded canola, which emerges earlier than canola seeded in early spring. Furthermore, warm temperatures in the fall often produce undesirable germination of fall-seeded canola. To minimize fall germination as well as seed death via desiccation, canola must be planted just before freeze-up (E.N. Johnson, unpublished data, 2003). Several types of polymer seed coats have recently been developed with the intent to extend the fall planting period (Zaychuk and Enders, 2001). The polymers are specifically designed to prevent germination of canola seeds until spring by absorbing water into the polymer coat matrix but preventing the passage of sufficient amounts of water to the seed coat to begin germination. After water entry into the polymer coat matrix, freezing is required to create microfractures in the polymer coat that act as water channels for imbibition.
Polymer seed coats have been shown to decrease imbibition (Chachalis and Smith, 2001) and final germination percentages (Valdes and Bradford, 1987). This may also be a problem with the polymer coats developed specifically for fall seeding canola as Gan et al. (2001) observed reduced canola emergence during a dry spring following a dry fall. Lower yields were also observed in polymer coat treatments. Similar observations have been made in other western Canadian studies (E.N. Johnson, unpublished data, 2003).
Little is currently known about the effects of low water potentials on the germination of polymer-coated canola seed at different temperatures. Although freezing is required to prevent rapid imbibition of the canola seed (Zaychuk and Enders, 2001), this requirement may not be met under dry fall and spring soil conditions. In this situation, polymer coat matrices may not absorb sufficient amounts of water to create the microfractures necessary for water imbibition into the seed coat during the spring. Therefore, the objective of this study was to determine the effects of moisture stress and polymer coats on unfrozen canola seed germination at two different temperatures in the laboratory.
|
MATERIALS AND METHODS
|
|---|
The seeds used throughout the study were from the same seedlot of ‘LG 3455’, a commercially available canola genotype. The experiment employed a completely randomized design with a factorial treatment arrangement consisting of seed coat (five), moisture stress (six), and temperature (two), with four replications per treatment. Seed coat treatments were comprised of the following polymer coats: G01-0906-3, Extender (commercially available polymer from GrowTec, Edmonton, AB, Canada); G01-0906-7, Ex 01-1 (experimental polymer); and G01-0906-4, Ex 01-2 (experimental polymer). The pesticides thiram [bis(dimethylthiocarbamoyl)disulfide], metalaxyl [methyl N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-DL-alaninate], carbathiin (5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide), and lindane [(1
,2,3ß,4,5,6ß)-1,2,3,4,5,6-hexachlorocyclohexane] were enclosed within the polymer coats. Two non-polymer-coat control treatments were also included: one without any seed coating applied (uncoated control) and one coated with the above pesticides enclosed in a water-soluble film (film-coated control). The film is a commercial coating commonly applied to spring-seeded canola in western Canada. The film reduced user exposure to seed-applied pesticides and has not been demonstrated to be an impediment to germination. Moisture stress treatments consisted of imbibed seeds in solutions of the following initial osmotic potentials: 0, –0.25, –0.50, –0.75, –1.00, and –1.25 MPa. Seeds were incubated at either 5 or 15°C.
One hundred seeds of each seed treatment were placed on two layers of filter paper (grade 413, VWR, Edmonton, AB, Canada) in each 9-cm Petri dish (Phoenix Biomedical, Mississauga, ON, Canada), which was irrigated with 8 mL of the appropriate osmotic solution. Osmotic potentials were created using polyethylene glycol (PEG 8000) and were adjusted for temperature according to Michel (1983). The Petri dishes were placed into trays and covered with a light-excluding plastic bag to prevent light penetration and moisture loss before placement into the respective germination cabinet.
Seeds displaying radicle emergence greater than 1 mm were considered germinated and were removed at set intervals of equal thermal time ranging between 24 and 216 h at 5°C and 8 and 72 h at 15°C. The intervals were extended as germination rates declined. The dishes were re-covered immediately after each counting. At the end of the study, a subsample of seeds that failed to germinate was subjected to a viability test at 15°C using tetrazolium (1% w/v; 2, 3, 5-triphenyl-tetrazolium chloride; Sigma Chemical Co., St. Louis, MO).
Statistical Analysis
Seed germination analysis was conducted as described by Lafond and Baker (1986). Germination curves for each experimental unit were fitted to the logistic equation:
where Pt is the cumulative percentage germination, a is the y intercept, b is the slope, and t is the thermal time in degree hours (base temperature = 0°C) from the initiation of the experiment. The cumulative percentage germination was calculated at each measurement interval using:
where nt is the number of seeds germinated at time t and N is the final number of seeds germinated. These values were then transformed using:
To account for skewness in the germination curves, the logarithm (base 10) of thermal time was taken. The transformed logits where then regressed against thermal time using weighted linear regression in the REG procedure in SAS (SAS Inst., 1989) with weights (Wt)
to estimate the logistic function parameters –a and –b. Logit transformation provides a means to linearize the logistic germination curve. Weighting accounts for variability in the amount of information contained in the observations (Steele et al., 1997) or, in this case, adjusts for differences in the shapes of the germination curves. Employing this weighted linear regression places more emphasis on the slopes of the curves and less emphasis on the asymptotes. These parameters were then used to determine median germination time, 10(–a/b), and maximum germination rate, b/[4 x 10(–a/b)]. Median germination time is the time, in degree hours, to 50% germination of the total number of seeds that germinated while maximum germination rate is the maximum number of seeds germinating per degree hour. For each experimental unit, final germination percentage was also determined by dividing the total number of germinated seeds by the total number of viable seeds in each plate at the beginning of the experiment.
Median germination time, maximum germination rate, and final germination percentage were then subjected to three-way (seed coat * osmotic potential * temperature) factorial analysis of variance using the GLM procedure in SAS. To meet the assumptions of ANOVA, final germination percentage values were square root transformed. An arcsine transformation was also conducted on this data but was less effective in improving the assumptions of ANOVA than square root transformation. Before the transformations, 0.01 was added to all means to allow transformation of zero values. Observations for which the absolute values of the Studentized residuals exceeded 1.96 were deemed outliers and were omitted from the analysis (Norvell et al., 2000). The data were analyzed within temperature and within osmotic potential as significant interactions demanded. In this analysis, means were separated using Fisher's protected least significant difference, with treatment effects declared significant at P < 0.05. In addition, single degree-of-freedom contrasts were conducted comparing polymer-coated seed (Extender, Ex 01-1, and Ex 01-2) with non-polymer-coated seed (coated and uncoated controls). Due to substantially higher median germination time, maximum germination rate, and final germination percentage in the uncoated and film-coated control treatments, analyses of variance were also conducted on data of the polymer seed coat treatments only. Since the values for maximum germination rate were highly correlated with those for median germination time, maximum germination rate will not be discussed further in this paper.
|
RESULTS
|
|---|
Median Germination Time
Both seed coat and osmotic potential affected median germination time (Table 1 and Fig. 1)
. Differences in median germination time among the seed coat treatments were analyzed within temperature and osmotic potentials. In all cases, contrasts indicated significantly higher median germination time among the polymer coat treatments than in non-polymer-coat treatments at both temperatures. Where sufficient germination occurred for statistical analysis, significant differences were also observed among the polymer coat treatments at both temperatures.
View this table:
[in this window]
[in a new window]
|
Table 1. Significance of single degree-of-freedom contrasts between polymer and non-polymer-coat treatment groups and means separation within osmotic potentials for median germination time at 15 and 5°C.
|
|
View larger version (22K):
[in this window]
[in a new window]
|
Fig. 1. The effects of polymer seed coat and osmotic potential on median germination time of canola at (A) 15°C and (B) 5°C. The bars indicate ± 1 SEM.
|
|
At 15°C and no osmotic stress (0 MPa), polymer-coated seed took between 3.5 and 10 times longer to reach 50% germination than non-polymer-coated seed (Fig. 1A). With decreasing osmotic potential, these differences became greater. In many cases, median germination time of seed coated with Ex. 01-1 was significantly lower than that of seed coated with other polymers (Table 1). For example, even when no osmotic stress was applied, median germination time of the Ex. 01-1 coat was 2.9 and 2.2 times lower at 15 and 5°C, respectively, than that of the polymer coat with the highest median germination time (Extender) (Fig. 1). Differences in median germination time between the uncoated control and the film-coated control treatments were only observed at the lowest osmotic potential at 15°C where median germination time was higher in the film-coated control treatment (Table 1 and Fig. 1A). This difference, however, was slight relative to those observed among the polymer coat treatments. In all polymer coat treatments, germination was too low to accurately determine median germination time at an osmotic potential of –1.25 MPa at 15°C (Table 1 and Fig. 1A).
At 5°C, similar trends were observed between and within seed coat treatments where median germination time could be determined (Fig. 1B). Median germination time increased more rapidly in polymer coat treatments at 5°C compared with 15°C as initial osmotic solution potential decreased. Although not statistically significant, similar trends were observed among the non-polymer-coat treatments with respect to decreasing osmotic potentials at 5°C than at 15°C (Fig. 1). Furthermore, a more substantial increase in median germination time in the uncoated control treatment was observed at osmotic potentials lower than –1.0 MPa at 5°C while a similar response was not observed in this treatment at the 15°C (Fig. 1). Due to low final germination, median germination times could not be determined in seed coated with Ex. 01-2 at osmotic potentials lower than –0.5 MPA and in the other two polymer treatments at osmotic potentials below –0.75 MPa at this temperature (Table 1 and Fig. 1B).
Final Germination Percentage
Contrasts indicated that polymer-coated canola seeds had significantly lower final germination at all osmotic potentials than the non-polymer-coat treatments at both temperatures (Table 2). Because polymer coat, osmotic potential, and temperature strongly influenced final germination, the influence of seed coats on final germination was analyzed within osmotic potential at each temperature. For ease of interpretation, means presented in the following two paragraphs were back-transformed, or converted back to original means by squaring the transformed means.
View this table:
[in this window]
[in a new window]
|
Table 2. Significance of single degree-of-freedom contrasts between polymer and non-polymer-coat treatment groups and means separation within osmotic potentials for final germination percentage at 15 and 5°C.
|
|
At 15°C, seed coated with Extender and Ex. 01-2 exhibited approximately 50% of the final germination compared with the nonpolymer control treatments when no osmotic stress was applied (Fig. 2A)
. This difference increased with increasing osmotic stress as final germination was greater than 80% in the non-polymer-coated treatments while final germination was less than 10% in all polymer-coated treatments at an osmotic potential of –1.0 MPa and lower at 15°C. Within polymer coat treatments, Ex. 01-1–coated seeds displayed up to 20% higher final germination than seeds coated with the other two polymers at high osmotic potentials at 15°C (Fig. 2A). At this temperature, differences in final germination among polymer coats were no longer observed at osmotic potentials lower than –0.5 MPa (Table 2). Substantial differences between the uncoated and film-coated control treatments were only observed at osmotic potentials lower than –0.75 MPa at 15°C.
View larger version (23K):
[in this window]
[in a new window]
|
Fig. 2. The effects of seed coat, temperature, and osmotic potential on the final germination percentages of canola at (A) 15°C and (B) 5°C. The bars indicate ±1 SEM.
|
|
At 5°C, trends in all treatments were similar to those observed at 15°C. In the polymer coat treatments, however, final germination at 0 MPa was approximately 20% lower than that observed at 15°C at the same osmotic potential (Fig. 2). Final germination among the polymer-coated treatments below 20% was reached at an osmotic potential as high as –0.5 MPa at 5°C, whereas the same response was not observed until an osmotic potential of –1.0 MPa at 15°C. Similarly, differences between the nonpolymer control treatments occurred at higher osmotic potentials at 5°C than at 15°C. Reductions in final germination in the uncoated control were observed at –0.75 MPa at 5°C, with a severe reduction (<20%) at –1.25 MPa (Fig. 2B). This reduction in final germination was not observed at 15°C. Final germination of seeds coated with Ex. 01-1 was approximately double that of Extender at both temperatures when no osmotic stress was applied (Fig. 2). As osmotic stress increased, however, the differences among polymer seed coats tended to become less. At the end of the experiment, all ungerminated seeds were viable as determined by tetrazolium staining, and therefore all final germination percentages were based on 100 viable seeds.
|
DISCUSSION
|
|---|
Polymer-coated canola seed required both a longer time to reach 50% germination and had lower final germination percentages (Fig. 1 and 2). This occurred in all polymer-coated canola seed at all temperatures and initial solution osmotic potentials. These differences between polymer-coated and non-polymer-coated seed were not unexpected as delayed germination has also been observed in lettuce (Lactuca sativa L.) seeds coated with a clay-based seed coating (Valdes and Bradford, 1987). Nevertheless, the differences we observed between polymer-coated and non-polymer-coated seed were surprisingly high when no osmotic stress was applied (0 MPa) and only became greater as initial solution osmotic potentials decreased (Fig. 1 and 2). In fact, germination was reduced so dramatically that statistical analysis could not be performed for median germination time at osmotic potentials above –1.00 MPa. It is important to note that the permanent wilting point of soils occurs at –1.50 MPa, a value typically reached in western Canada. Nonetheless, not all polymer coats affect germination characteristics negatively, as the application of a hydrophobic polymer in soybean [Glycine max (L.) Merr.] exhibited reduced imbibition but only had a limited effect on time to 50% germination (Chachalis and Smith, 2001).
Interestingly, seed germination characteristics were influenced negatively by the non-polymer-coated control. Although not noticeable at high osmotic potentials, the differences between the film-coated and uncoated control seeds became more apparent as osmotic potentials and temperatures decreased (Fig. 1 and 2). The germination characteristics of uncoated canola seeds as influenced by temperature and decreasing osmotic potential were similar to those previously reported (Acharya et al., 1983; Kondra et al., 1983; Schopfer and Plachy, 1984; King et al., 1986).
In the polymer coat treatments, the reduction in final germination among successive decreases in osmotic potentials without a concomitant decrease in median germination time indicates the failure of germination in a portion of the seedlot without a marked decrease in germination rate and median germination time in the germinated portion of that seedlot (Fig. 1 and 2). These observations agree well with Bradford's (1990) germination model that relies on differential base water potentials that must be exceeded for successful germination among different seed fractions within a seedlot. Given that this response was observed primarily at high osmotic potentials and among the polymer coat treatments only, our results suggest differential water permeability among seeds treated within polymer coats. We presume that this may have been the result of uneven polymer seed coat applications to seeds within a seedlot. The degree of this inherent variation in the application method and its significance in the field, however, remain to be investigated.
In this study, the first coated germinated seeds were removed at approximately 65 h at 15°C and 96 h at 5°C compared with 24 h or fewer in uncoated seeds when no osmotic stress was applied (data not shown). These results suggest that the polymer seed coats can prolong the opportunity to successfully fall-seed canola by 3 d or more at cool soil temperatures immediately before freeze-up. At similar osmotic potentials, however, imbibition and germination of canola is slower in soil than in Petri dishes (Shaykewich and Williams, 1971), and therefore the opportunity for successfully fall-seeding canola would be greater than our results indicate. Nevertheless, imbibed seeds that have not completed germination have decreased desiccation tolerance (Senaratna and McKersie, 1983; Reisdorph and Koster, 1999), which may lead to a loss in viability over winter in the northern Great Plains. The importance of this to spring seed viability has not yet been investigated and may significantly shorten the period for successful fall seeding provided by these polymer seed coats under wet soil conditions.
The results of this study may have provided some insight into observations of low spring seedling populations of fall-seeded, polymer-coated canola (Gan et al., 2001). Low water potentials dramatically reduced final germination and also increased median germination time in all polymer seed coat treatments relative to uncoated seed (Fig. 1 and 2), particularly at low temperatures. It is important to note that the polymer-coated seeds used in this study were not frozen following hydration of the polymer coats. After water entry into the polymer coat matrix, freezing is a requirement for proper functioning of the polymer coat (Zaychuk and Enders, 2001) and freezing-imbibed polymer-coated seeds may have improved germination characteristics in our study. This requirement, however, may not be met under dry fall and spring soil conditions. Therefore, our laboratory results help explain why low spring seedling populations of fall-seeded, polymer-coated canola may occur when fall and spring soil conditions are dry.
|
CONCLUSIONS
|
|---|
Decreasing osmotic potential and temperature significantly reduced the germination of both coated and uncoated canola seeds. However, this decrease was much more pronounced in seeds treated with a polymer coating. Polymer-coated seeds exhibited delayed germination even in the absence of moisture stress, an effect that was magnified at more negative water potentials and at a lower temperature. Final germination percentages were significantly reduced for seeds coated with polymers compared with uncoated control seeds throughout most treatments. Median germination time of polymer-coated seed was significantly higher than for uncoated control seed throughout all temperature and osmotic potential treatments. Differences between the polymer coats resulted in the Ex. 01-1 polymer coat providing the highest germination of the three polymer coats examined.
|
ACKNOWLEDGMENTS
|
|---|
The authors express their sincere appreciation to Dr. R.J. Baker for his assistance in the statistical analysis. We also thank GrowTec for supplying the seed used in the study.
|
REFERENCES
|
|---|
- Acharya, S.N., J. Dueck, and R.K. Downey. 1983. Selection and heritability studies on canola/rapeseed for low temperature germination. Can. J. Plant Sci. 63:377–384.
- Blackshaw, R.E. 1991. Soil temperature and moisture effects on downey brome vs. winter canola, wheat, and rye emergence. Crop Sci. 21:1034–1040.
- Bradford, K.J. 1990. A water relations analysis of seed germination rates. Plant Physiol. 94:840–849.[Abstract/Free Full Text]
- Chachalis, D., and M.L. Smith. 2001. Hydrophobic-polymer application reduces imbibition rate and partially improves germination or emergence of soybean seedlings. Seed Sci. Technol. 29:91–98.
- Environment Canada. 1984. Canadian climate normals. Vol. 9. Soil temperature, lake evaporation, days with, 1951–1980. Environment Canada, Downsview, ON, Canada.
- Gan, Y., F. Selles, and S. Angadi. 2001. Fall seeded canola: To coat or not to coat, that is the question. Semiarid Prairie Agric. Res. Cent. Newsl. 17 Sept.
- Hao, X., and E. de Jong. 1988. Effect of matric and osmotic suction on the emergence of wheat and barley. Can. J. Plant Sci. 68:207–209.
- Hegarty, T.W. 1977. Seed activation and seed germination under moisture stress. New Phytol. 78:349–359.
- Johnston, A.M., E.N. Johnson, K.J. Kirkland, and F.C. Stevenson. 2002. Nitrogen fertilizer placement for fall and spring seeded Brassica napus canola. Can. J. Plant Sci. 82:15–20.
- King, J.R., Z.P. Kondra, and M.R. Thiagarjah. 1986. Selection for fast germination in rapeseed (Brassica napus L. and Brassica campestris L.). Euphytica 35:835–842.
- Kirkland, K.J., and E.N. Johnson. 2000. Alternative seeding dates (fall and April) affect Brassica napus canola yield and quality. Can. J. Plant Sci. 80:713–719.
- Kondra, Z.P., D.C. Campbell, and J.R. King. 1983. Temperature effects on germination of rapeseed (Brassica napus L. and Brassica campestris L.). Can. J. Plant Sci. 63:1063–1065.
- Lafond, G.P., and R.J. Baker. 1986. Effects of temperature, moisture stress, and seed size on germination of nine spring wheat cultivars. Crop Sci. 26:563–567.[Abstract/Free Full Text]
- Michel, B.E. 1983. Evaluation of the water potentials of solutions of polyethylene glycol 8000 both in the absence and presence of other solutes. Plant Physiol. 72:66–70.[Abstract/Free Full Text]
- Norvell, W.A., J. Wu, D.G. Hopkins, and R.M. Welch. 2000. Association of cadmium in durum wheat grain with soil chloride and chelate-extractable soil cadmium. Soil Sci. Soc. Am. J. 64:2162–2168.[Abstract/Free Full Text]
- Rao, S.C., and T.H. Dao. 1987. Soil water effects on low-temperature seedling emergence of Brassica cultivars. Agron. J. 79:517–519.[Abstract/Free Full Text]
- Reisdorph, N.A., and K.L. Koster. 1999. Progressive loss of desiccation tolerance in germinating pea (Pisum sativum) seeds. Physiol. Plant. 105:266–271.
- SAS Institute. 1989. SAS user's guide. Version 6. 4th ed. SAS Inst., Cary, NC.
- Schneider, E.C., and S.C. Gupta. 1985. Corn emergence as influenced by soil temperature, matric potential, and aggregate size distribution. Soil Sci. Soc. Am. J. 49:415–422.[Abstract/Free Full Text]
- Schopfer, P., and C. Plachy. 1984. Control of seed germination by abscisic acid: II. Effect on embryo water uptake in Brassica napus L. Plant Physiol. 76:155–160.[Abstract/Free Full Text]
- Senaratna, T., and B.D. McKersie. 1983. Dehydration injury in germinating soybean (Glycine max L. Merr.) seeds. Plant Physiol. 72:620–624.[Abstract/Free Full Text]
- Sharma, M.L. 1976. Interaction of water potential and temperature effects on germination of three semi-arid plant species. Agron. J. 68:390–394.[Abstract/Free Full Text]
- Shaykewich, C.F., and J. Williams. 1971. Influence of hydraulic properties in pre-germination water absorption by rapeseed (Brassica napus). Agron. J. 63:454–457.[Abstract/Free Full Text]
- Steele, R.G.D., J.H. Torrie, and D.A. Dickey. 1997. Linear regression. p. 253–285. In Principles and procedures of statistics: A biometrical approach. McGraw-Hill, New York.
- Valdes, V.M., and K.J. Bradford. 1987. Effects of seed coating and osmotic priming on the germination of lettuce seeds. J. Am. Soc. Hortic. Sci. 112:153–156.
- Zaychuk, K.S., and N.H. Enders. 2001. Water soluble, freeze sensitive seed coatings. U.S. Patent 6 230 438. Date issued: 15 May.
- Zheng, G.H., R.W. Wilen, A.E. Slinkard, and L.V. Gusta. 1994. Enhancement of canola seed germination and seedling emergence at low temperature by priming. Crop Sci. 34:1589–1593.[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
B. M. Upadhyay, E. G. Smith, G. W. Clayton, K. N. Harker, J. T. O'Donovan, and R. E. Blackshaw
Economic Value of Polymer Seed Coat for Fall-Seeded Canola
Agron. J.,
March 12, 2007;
99(2):
489 - 493.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
G. Q. Zhao, B. L. Ma, and C. Z. Ren
Growth, Gas Exchange, Chlorophyll Fluorescence, and Ion Content of Naked Oat in Response to Salinity
Crop Sci.,
January 22, 2007;
47(1):
123 - 131.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
C. J. Willenborg, J. C. Wildeman, A. K. Miller, B. G. Rossnagel, and S. J. Shirtliffe
Oat Germination Characteristics Differ among Genotypes, Seed Sizes, and Osmotic Potentials
Crop Sci.,
August 26, 2005;
45(5):
2023 - 2029.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
ABSTRACT
INTRODUCTION
