Subscribe Now Subscribe Today
Research Article
 

Dormancy Overcoming of Some Alfalfa Varieties



A.A. Kandil, A.E. Sharief and A.M.A. Odam
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail
ABSTRACT

The purpose of this study was to find out the impact of diverse temperature plus scarification actions and the same temperature without scarification on the lessening of percentage of hard seeds and enhancement other germination strictures in five alfalfa varieties i.e., Siriver, Sewa 1, Ismailia 1, Balady 1 and El-Wady El-Gaded 1. The experimental contained nineteen different treatments i.e., control treatment; 5 h+5°C; 5 h+0°C; 5 h+20°C; 5 h+40°C; 5 h+80°C; 5 h-5°C; 5 h-10°C; 5 h-20°C; 2 h-80°C and the same treatments plus sandpaper scarification(s) except control treatment. Alfalfa varieties significantly varied in means of hard seed percentage, percentage of abnormal seedling, percentage of dead seeds, germination percentage free of hard seeds, normal germs percentage, energy for germination percentage, coefficient velocity percentage, Mean Germination Time (MGT) by days and value of the vigour percentage. Balady 1 variety had only positive effects in all studied characters while; El-Wady El-Gaded 1 cultivar had only negative effects on all germination parameters under study. Break down dormancy managements significantly varied in all germination parameters under study. The two treatments, -80°C+(s) and -80°C were very effective since they reduced the percentage of hard seeds in judgment with the control by 70.455 and 63.636%, respectively, while their influence on dead seed percentage was completely different. The treatment of -5°C had only positive effects on other germination parameters that were reflected in the highest values for germination energy and germination percentage of free of hard seed.

Services
Related Articles in ASCI
Similar Articles in this Journal
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

A.A. Kandil, A.E. Sharief and A.M.A. Odam, 2012. Dormancy Overcoming of Some Alfalfa Varieties. Research Journal of Seed Science, 5: 19-31.

DOI: 10.3923/rjss.2012.19.31

URL: https://scialert.net/abstract/?doi=rjss.2012.19.31
 
Received: September 15, 2011; Accepted: December 10, 2011; Published: January 21, 2012



INTRODUCTION

Alfalfa (Medicago sativa L.) is one of the world's most valuable forage legumes such as, in Egypt, cultivated in newly reclaimed lands and grown for hay, pasture and silage and is appreciated as a livestock feed. Although, alfalfa seed production is widely disseminated, essentially all commercially varieties have high hard-seed content. For overcoming seed dormancy, hard seed instigated by a water-impermeable seed coat, is called physical dormancy and it develops during maturation drying of the seed (Van Staden et al., 1989). Lucerne is a crop characterized by presence of hard dormant seed that are viable but do not germinate in seed quality testing (Cupic et al., 2005). Hard alfalfa seed does not germinate due to seed plant impermeability having compacted cells with thickened outside cell walls usually coated by a wax layer and well developed cuticle (Kastori, 1984). Impermeable coat of alfalfa dormant seed can reduce germination to an extent unacceptable for commercial use (Acharya et al., 1999). There were differences among alfalfa cultivars in the proportion of viable seed that was hard (Hall et al., 1998). Acharya et al. (1999) reported significant effect of varieties on germination and hard seed content in freshly harvested seed.

Hard seed reduction is possible by seed thinning performed either mechanically, by temperature, by chemical agents or by other ways. Hard seed reduction in total seed by temperature was obtained by Rutar et al. (2001). Uzun and Aydin (2004) indicated that the most effective treatment in breaking hard seed dormancy of legumes seeds was mechanical scarification.

The objective of this study was to determine the influence of different temperature treatments plus sandpaper scarification and without scarification on seed dormancy breakdown of hard seed in some alfalfa cultivars under laboratory conditions.

MATERIALS AND METHODS

This investigation was directed in Agronomy Department laboratory of the Faculty of Agriculture Faculty, Mansoura University, Egypt during May 2011. Five alfalfa cultivars were particular i.e., Balady 1, Ismailia 1, Sewa 1, El-Wady El-Gaded 1 and Siriver, to study the encouragement of different physical seed treatments and mechanical seed scarification on seed dormancy breakdown of hard seed above mentioned alfalfa varieties. Alfalfa seeds were gotten from Forage Research Department, Agriculture Research Center, except Siriver variety was obtained from private company which were hand harvested. About 10.000 intact seeds were carefully selected by hand for the study. Seeds were stored at laboratory conditions in cloth bags inside paper bags under laboratory conditions. Germination tests of alfalfa were determined. Nineteen seed treatments for physical dormancy breakdown were applied as following:

Control: Seed was not subjected to any seed treatment, 2-Seed exposed to 5°C for 5 h (Seed exp. to 5°C for 5 h), 3-Seed exposed to 5°C for 5 h plus sandpaper scarification (Seed exp. to 5°C for 5 h+S), 4-Seed exposed to 10°C for 5 h (Seed exp. to 10°C for 5 h), 5-Seed exposed to 10°C for 5 h plus sandpaper scarification (Seed exp. to 10°C for 5 h+S), 6-Seed exposed to 20°C for 5 h (Seed exp. to 20°C for 5 h), 7-Seed exposed to 20°C for 5 h plus sandpaper scarification (Seed exp. to 20°C for 5 h+S), 8-Seed exposed to 40°C for 5 h (Seed exp. to 40°C for 5 h), 9-Seed exposed to 40°C for 5 h plus sandpaper scarification (Seed exp. to 40°C for 5 h+S), 10-Seed exposed to 80°C for 5 h (Seed exp. to 80°C for 5 h), 11-Seed exposed to 80°C for 5 h plus sandpaper scarification (Seed exp. to 80°C for 5 h+S), 12-Pre-cooling at (-5°C) for 5 h (Seed exp. to -5°C for 5 hr), 13-Pre-cooling at (-5°C) for 5 h plus sandpaper scarification (Seed exp. to -5°C for 5 h+S), 14-Pre-cooling at (-10°C) for 5 h (Seed exp. to -10°C for 5 h), 15 Pre-cooling at (-10°C) for 5 h plus sandpaper scarification (Seed exp. to -10°C for 5 h+S), 16-Pre-cooling at (-20°C) for 5 h (Seed exp. to -20°C for 5 h), 17-Pre-cooling at (-20°C) for 5 h plus sandpaper scarification (Seed exp. to -20°C for 5 h+S), 18-Pre-cooling at (-80°C) for 2 h (Seed exp. to -80°C for 2 h), 19-Pre-cooling at (-80°C) for 2 h plus sandpaper scarification (Seed exp. to -80°C for 2 h+S).

After pre-treatments of alfalfa, seed was germinated for 7 days, incubating in a growth chamber adjusted to 20±1°C in dark. For each treatment, 50 seeds were counted at random and placed on a moist germination paper in a Petri dish. There were four replicates at each treatment, dishes were inspected daily and sterilized water was added as required. The number of normal seedlings, abnormal seedlings, dead seeds and hard seed in each replicate were recorded. Every 24 h the number of germinated seeds was counted. Seeds were categorized as germinated (radical 2 mm), hard (no imbibition or swelling) or nonviable (abnormal, dead or infected seeds) as described by ISTA (1993). It could distinguish hard or (dormant) seeds from dead seeds by pushing down on each un-germinated seed with the flat part of a pencil eraser. If the seed does not flatten with gentle pressure, it is considered as hard seed. All seeds which had taken up no water in six days were considered as hard seed. Dead seeds which at the end of test period neither were hard or did not produced any part of a seedling were estimated.

Studied characteristics: Seedlings were evaluated for:

Percentage of normal seedling = Number of normal seedling/Total number of seeds
Percentage of abnormal seedling = Number of abnormal seedling/Total number of seeds
Percentage of hard seed = Number of hard seed/Total number of seeds
Percentage of dead seed = Number of dead seed/Total number of seeds
Germination percentage = Number of germinating seeds 7 days after sowing/Total number of seeds
Energy of germination was recorded the 4th. Energy of germination was the percentage of germinating seeds 4 days after sowing relative to the number of seeds tested (Ruan et al., 2002)
Mean Germination Time (MGT) was determined according to the equation of Ellis and Roberts (1981):

Image for - Dormancy Overcoming of Some Alfalfa Varieties

where, (n) is the number of seeds which were germinated on day (d) and (d) is the number of days counted from the beginning of germination.

Coefficient of velocity (CV), a unit less parameter determined by a mathematical manipulation that incorporates the number of seeds germinated and the velocity of germination was calculated using the following formula:

Image for - Dormancy Overcoming of Some Alfalfa Varieties

where, N is the number of seeds germinated on day I and T is the number of days from sowing (Scott et al., 1984). In general, a higher CV value reflects increased germination and shorter germination time.

The value of the vigour (V) of each seed lot was calculated as a measure of the germination rate, because the values of this index reflect the germinate capability of the seeds per unit time, as recommended (Bradbeer 1988). The formula used was:

V= (a/1+b/2+c/3+d/4+...+ x/n)x100/S

where, a, b, c..., respectively represent the number of seeds which germinated after 1, 2, 3... days of imbibition, x is the number of seed for day n and S the total number of seeds sown.

Statistical analysis: All data of this study were statistically analyzed according to the technique of variance (ANOVA) for the factorial Randomized Complete Block Design, by using means of "MSTAT-C" computer software package as published by Gomez and Gomez (1984). Least Significant Difference (LSD) method was used to test the differences between treatment means at 5% level of probability as described by Snedecor and Cochran (1980).

RESULTS AND DISCUSSION

Performance of varieties: The five tested varieties of alfalfa significantly varied for averages of hard seed percentage, percentage of abnormal seedlings, percentage of dead seeds, germination percentage free of hard seed, normal germs percentage, energy for germination percentage, coefficient velocity percentage, Mean Germination Time (MGT) by days and value of the vigour percentage as showed in Table 1-3. Balady 1 variety significantly exceeded other studied varieties in percentage of normal germs percentage while; El-Wady El-Gaded 1 variety produced the lowest averages.

Table 1: Averages percentage of hard seed, abnormal germs and dead seed as affected by alfalfa cultivars and break down dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5%, **: Significant at 1%

Table 2: Averages of germination percentage free of hard seed, normal germs and energy for germination as affected by alfalfa cultivars and break down dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5%, **: Significant at 1%

However, Siriver, Sewa 1 and Ismailia 1 varieties produced intermediate values of these characters, respectively. Balady 1 and Siriver varieties significantly exceeded other studied cultivars in germination percentage free of hard seed, energy for germination percentage, coefficient velocity percentage and value of the vigour percentage, followed by Sewa 1 and Ismailia 1 varieties in the second and third ranks, respectively, Vice versa, El-Wady El-Gaded 1 variety produced the lowest values of these characters. El-WadyEl-Gaded1 variety had significantly exceeded other studied varieties in hard seed percentage, percentage of abnormal seedlings and Mean Germination Time (MGT) by days. Balady 1 and Siriver varieties did not show significant differences in all characters except normal germs percentage and percentage of abnormal seedlings characters, Balady 1 variety surpassed Sewa 1, Ismailia 1 and El-Wady El-Gaded 1 varieties in germination percentage free of hard seed by 7.684, 10.447, 32.632, respectively, in normal germs percentage by 14.947, 15.158 and 42.974, respectively, in energy for germination percentage by 8.000, 11.815 and 36.631%, respectively, in coefficient velocity percentage by 2.201, 3.606, 8.600%, respectively and in value of the vigour percentage by 5.110, 7.095, 19.704%.

Table 3: Averages coefficient velocity (C.V%), mean germination time (MGT by days) and values of the vigour as affected by alfalfa cultivars, break down dormancy treatments and their interaction
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5%, **: Significant at 1%

Vice versa, El-Wady El-Gaded 1 variety surpassed Balady 1, Siriver, Sewa 1 and Ismailia 1 varieties in hard seed percentage by 3.00, 3.394, 2.631 and 1.684%, respectively, in abnormal germs percentage by 9.369, 6.487, 0.921 and 4.684%, respectively, in dead seed percentage by 29.698, 29.540, 22.356 and 20.685%, respectively and in mean germination time (by days) by 19.290, 19.097, 14.969 and 12.153%, respectively. Similar conclusions were reported by Acharya et al. (1999), Rutar et al. (2001) and Balouchi and Sanavy (2006).

Break down dormancy treatments effect: The results in Table 1-3 indicated that break down dormancy treatments had significant effects on averages of hard seed percentage, abnormal seedlings, dead seeds, germination, normal germs, energy for germination, coefficient velocity, Mean Germination Time (MGT) by days and value of the vigour in percentage. Exposed alfalfa seed to cold stratification treatment at (-80°C) for 2 h plus sandpaper scarification treatment and exposed alfalfa seed to cold stratification treatment at (-80°C) for 2 h treatment significantly reduced hard seed% by 70.455 and 63.636% compared with control treatment, respectively. Exposure seed to a temperature of cold stratification treatment at (-5°C) for 5 h treatment had significant positive effects that were reflected in the highest value for germination percentage free of hard seed and energy for germination (%) without significant negative effects for other traits when compared to control treatment. While, cold stratification treatment at (-80°C) for 2 h resulted in the lowest value and significantly reduced hard seed (%) with significantly increase of germination (%) free of hard seed and energy for germination (%) but with significant negative effects for dead seed (%) and coefficient velocity (%) when compared to control treatment, Vice versa, exposed seed to a temperature of (80°C) for 5 h plus sandpaper scarification and exposed seed to a temperature of (80°C) for 5 h treatments had a negative effects for all traits. Similar finding were recorded by Egley (1989), Rutar et al. (2001), Uzun and Aydin (2004) and Narem and Xu (2009).

Interactions effect: The results in Table 4 to 11 indicate percentage of abnormal seedlings, of dead seeds, germination free of hard seed, normal germs, energy for germination, coefficient velocity, Mean Germination Time (MGT) by days and vigour which were significantly affected by the interaction between varieties and break down dormancy treatments.

Table 4: Abnormal germs percentage as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5%, **: Significant at 1%

Table 5: Percentages of dead seed as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: significant at 5% **: Significant at 1%

Vice versa, hard seed% were not affected by the interaction. Exposed Balady cultivar seed to a temperature of 10°C for 5 h surpassed other treatments which recorded the highest averages of normal germs and energy for germination percentage, while the lowest %averages were of abnormal seedlings and of dead seeds. In addition, exposed Balady 1 cultivar seed to cold stratification at -10°C for 5 h plus scarification treatment surpassed other treatments which recorded the highest averages of germination percentage free of hard seeds and energy for germination percentage, Exposed Balady 1 cultivar seed to cold stratification at -20°C for 5 h had the lowest averages of abnormal seedlings%. Exposed Balady 1 cultivar to control treatment had the lowest averages of dead seeds%. Balady 1 cultivar exposed seed to cold stratification at (-20°C) for 5 h plus scarification treatment surpassed other treatments which documented the lowest %averages of abnormal seedlings. The highest averages of coefficient velocity% were obtained with exposed Balady 1 cultivar seed to cold stratification at (-5°C) for 5 h treatment or exposed seed to a temperature of (10°C) for 5 plus scarification treatment. Exposed Siriver cultivar seeds to cold stratification at -5°C for 5 treatment recorded the highest %averages of energy for germination, value of the vigour and the lowest %averages of Mean Germination Time (MGT) by days. In addition, exposed Siriver cultivar seed to cold stratification at -80°C for 2 treatment surpassed other treatments where recorded the highest %averages of energy for germination.

Table 6: Percentages of germination free of hard seed as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant *: Significant at 5% **: Significant at 1%

Table 7: Percentages of normal germs as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant *: Significant at 5% **: Significant at 1%

Table 8: Percentages of energy for germination as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5% **: Significant at 1%

Table 9: Percentages of coefficient of velocity as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: scarification, NS: Not significant, *: Significant at 5%, **: Significant at 1%

Table 10: Mean germination time by days as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5%, **: Significant at 1%

Table 11: Value of the vigour as affected by the interaction between cultivars and break gown dormancy treatments
Image for - Dormancy Overcoming of Some Alfalfa Varieties
h: Hours, S: Scarification, NS: Not significant, *: Significant at 5% **: Significant at 1%

It could be noticed that exposed Siriver cultivar seed to a temperature of (10°C) for 5 treatment surpassed other treatments where recorded the lowest %averages of dead seed, exposed El-Wady El-Gaded 1 cultivar seed to a temperature of (80°C) for 5 plus sandpaper scarification treatment recorded the lowest percentage (%) value of germination of free of hard seed, normal germs, energy for germination, coefficient velocity and value of the vigour and the highest percentage (%) value of were dead seed and Mean Germination Time (MGT) by days. In addition, exposed Ismailia 1 variety seed to a temperature of (80°C) for 5 treatment had the highest value percentage of abnormal seedlings.

CONCLUSIONS

For maximizing breakdown dormancy of hard seed and improving germination characters by cultivation of Balady 1 and Siriver varieties which surpassed other studied varieties under laboratory testing conditions, El-Wady El-Gaded 1 variety was more affected by break down dormancy treatments when compared to other studied cultivars.

Exposing seed to a temperature of cold stratification treatment at (-80°C) for 2 plus sandpaper scarification. It had the lowest value and significantly reduced hard seed percentage and significantly increase %germination of free of hard seed and %energy for germination. Exposing seed to a temperature of cold stratification treatment at -5°C for 5 treatment resulted in significant positive effects that were reflected highest %germination of free of hard seed and energy for %germination.

REFERENCES
1:  Acharya, S.N., D.G. Stout, B. Brooke and D. Thompson, 1999. Cultivar and storage effects on germination and hard seed content of alfalfa. Can. J. Plant Sci., 79: 201-208.
CrossRef  |  Direct Link  |  

2:  Balouchi, H.R. and S.A.M.M. Sanavy, 2006. Effect of gibberellic acid, prechilling, sulfuric acid and potassium nitrate on seed germination and dormancy of annual Medics. Pak. J. Biol. Sci., 9: 2875-2880.
CrossRef  |  Direct Link  |  

3:  Bradbeer, J.W., 1988. Seed Dormancy and Germination. Chapman and Hall, New York, pp: 27-54.

4:  Cupic, T., S. Popovic, S. Grljusic, M. Tucak, L. Andric and B. Simic, 2005. Effect of storage time on alfalfa seed quality. J. Cent. Eur. Agric., 6: 65-68.
Direct Link  |  

5:  Egley G.H., 1989. Water-Impermeable Seed Coverings as Barriers to Germination. In: Recent Advances in the Development and Germination of Seeds, Taylorson, R.B. (Ed.). Plenum Press, New York, USA., pp: 207-223.

6:  Ellis, R.H. and E.H. Roberts, 1981. The quantification of ageing and survival in orthodox seeds. Seed Sci. Technol., 9: 373-409.
Direct Link  |  

7:  Gomez, K.A. and A.A. Gomez, 1984. Statistical Procedures for Agricultural Research. 2nd Edn., John Wiley and Sons Inc., New York, USA., Pages: 704.

8:  Hall, J.W., D.G. Stout and B.M. Brooke, 1998. Alfalfa seed germination tests and stand establishment: The role of hard (water impermeable) seed. Can. J. Plant Sci., 78: 295-300.
CrossRef  |  Direct Link  |  

9:  ISTA., 1993. International rules for seed testing. Seed Sci. Technol., 21: 1-288.

10:  Kastori, R., 1984. Fiziologija Sjemena. Matica Srpska Publisher, Novi Sad, Serbia, Pages: 234.

11:  Narem, D. and L. Xu, 2009. Effect of stratification, warm treatment and mechanical and acid scarification on the emergence of yellow-flowered alfalfa (Medicago sativa subsp. falcate) seeds. J. Undergraduate Res., 7: 99-105.
Direct Link  |  

12:  Ruan, S., Q. Xue and K. Tylkowska, 2002. The influence of priming on germination of rice (Oryza sativa L.) seeds and seedling emergence and performance in flooded soil. Seed Sci. Technol., 30: 61-67.
Direct Link  |  

13:  Rutar, R., M. Stjepanovic, S. Popovic, Z. Bukvic and D. Pacek, 2001. Effect of temperature on germination and hard alfalfa seed. CIHEAM, 2: 137-139.
Direct Link  |  

14:  Scott, S.J., R.A. Jones and W.A. William, 1984. Review of data analysis methods for seed germination. Crop Sci., 24: 1192-1199.
CrossRef  |  Direct Link  |  

15:  Snedecor, G.W. and W.G. Cochran, 1980. Statistical Methods. 7th Edn., Iowa State University Press, Iowa, USA., ISBN-10: 0813815606, Pages: 507.

16:  Uzun, F. and I. Aydin, 2004. Improving germination rate of Medicago and Trifolium species. Asian J. Plant Sci., 3: 714-717.
CrossRef  |  Direct Link  |  

17:  Van Staden, J., J.C. Manning and K.M. Kelly, 1989. Legume Seeds, the Structure: Function Equation. In: Advances in Legume Biology, Stirton, C.H. and J.L. Zarucchi (Eds.). Missouri Botanical Garden, St Louis, MO., USA., pp: 417-450.

©  2021 Science Alert. All Rights Reserved