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Data on scarification and stratification treatments on germination and seedling growth of Ziziphus Jujuba seeds.

Introduction

The Ziziphus genus with 135-170 species systematically was placed in Rhamnaceae family [3]. Five species of Ziziphus namely Z. nummularia (Burm. f.), Z. spina-christi, Z. jujuba, Z. oxyphylla, Z. aucheri grew in Iran. Z. jujuba is commercially important because of cosmetic and pharmaceutical uses. The trees are deciduous and tolerant to drought and it is able to grow in many types of soils with high salinity or alkalinity [2]. Drupe fruits are formed of red exocarp, edible fleshy mesocarp, and stony endocarp with 1-2 seeds.

Poor germination of Ziziphus seeds seems causes by dormancy, hard woody endocarp and even seed coat that covering around the seeds. The existence of these Barriers is useful for its survival, but on the other hand it is an undesirable characteristic for growers. Hard woody endocarp and also seed coat increase the time of achievement to final germination percentage. Maraghni et al. [6] achieved 100% germination in Z. lotus seeds when endocarps of fruits artificially were broken. According Baskin and Baskin [7,8] comprehensive classification System, Finch-Savage and Leubner-Metzger [10] were reported physiological, physical, physiological-physical and non-dormancy in Seeds of Rhamnaceae family. Non-dormancy was seen in a few species of Ziziphus [7]. Pareek [9] proposed applying of mechanical scarification and non-mechanical methods for seed broken dormancy of Ziziphus species to be effective.

Cold stratification are used for physiological and embryo dormancy while mechanical and chemical scarification are useful methods for physical ones. Olmez et al. [4] found the durations of cold stratification are insufficient to overcome seed dormancy of Z. jujuba. They also stated the greenhouse condition were more effective on seed germination over open field conditions. In addition to hard woody endocarp, it seems the seed coat delays or decreases seed germination in this species. So, this study was conducted to investigate the effect of stratification and scarification on seed germination and seedling growth of Z. jujuba seed in in vitro and in vivo conditions.

Materials and Methods

Z. jujuba seeds were collected in May 2012 from trees growing in in vivo condition of Khaf county (34[degrees]30' N, 60[degrees]00' E, 970 m altitude) of Razavi Khorasan Province, Iran. We used seeds in fully ripe stage when the exocarp has turned red. In both experiments exocarp, mesocarp and hard woody exocarp were removed and seed with brown seed coat were used.

First experiment: in vitro germination:

Seeds after disinfestant with 1% sodium hypochlorite (NaOCl) supplemented with Tween-20 (0.2%) for 10 minutes were cleaned with sterile distilled water. Then, seeds were treated with Sulfuric acid 98% ([H.sub.2]S[O.sub.4]) for 0 (as control), 5, 10 and 15 minute. Seeds were washed with sterile distilled water 3 times and were cultured in vials (100 ml) containing 20 ml medium (8 [gL.sup.-1] agar-agar, Merck[R]). The cultures were grown at 24[+ or -]1 [degrees]C in a 16-h photoperiod at light intensity of 40 Limol [m.sup.-2][s.sup.-1] provided by white fluorescent tubes.

Second experiment: in vivo germination:

In this experiment we used two groups of seeds: stratificated (30 days at 4 [degrees]C in wet sand) and unstratified seeds. Seeds were surface sterilized using 1% sodium hypochlorite (NaOCl) for 10 minutes, and washed three times with distilled water. Consequently, Seeds of both groups treated by acid scarification, Sulfuric acid 98% ([H.sub.2]S[O.sub.4]), for 0 (as control), 5, 10 and 15 minute and mechanical scarification and they were cleaned with distilled water for 3 times. In mechanical scarification, two incisions on either side of the seed coat were created by a sharp scalpel blade. Seeds were cultured in pots with sterile peat moss medium. Pots were maintained in laboratory conditions. Germination percentage (%), vigor index, seedling length (mm), radicle length (mm), the number of rootlets, rootlet length (mm) after 5 and 7 days were recorded for first and second experiment, respectively. Vigor index was calculated according to germination percentage x seedling total length [1].

Statistical analysis:

First experiment was performed in completely randomized design with 5 replication containing 10 seeds. Second experiment was carried out in factorial (stratification and scarification) in a completely randomized design with 3 replication containing 20 seeds. Germination percentage was transformed to arcsine before analysis. Data were analyzed by SAS PROC GLM [14] and mean values were compared according to Least Significant Difference (LSD) test at 5% probability.

Results:

First experiment: In vitro germination:

ANOVA indicated that germination percentage, seedling length (p [less than or equal to] 0.05), vigor index, the rootlet number (p [less than or equal to] 0.01) were affected by acid exposure time while radicle and rootlet length was not affected (Table 1).

The highest of germination percentage was obtained in 15 and 10 minute acid exposure with 72% and 66% and the lowest was showed in 0 and 5 with 39% and 42%, respectively (Fig. 1 - a). With increasing of acid exposure time, seed coat dissolves more and becomes thinner that make germination easier. It was observed the highest vigor index in 15 minute acid exposure. The high vigor index in this treatment is because of high germination percentage (Fig. 1 - b).

In 5 minute acid exposure the highest of seedling length (81.23 mm) was showed and in 10 and 15 minute were decreased. Do not use acid induced lowest of seedling length (52.06 mm) (Fig. 1 - c). With increasing acid exposure time the rootlet numbers increased. The highest of the rootlet number (7.734 - 5.860) and the lowest (0.668) were observed in 15 and 10 minute acid exposure and non- acid exposure, respectively (Fig. 1 - d).

Second experiment: In vivo germination:

ANOVA indicated that all characteristics were affected by scarification and stratification x scarification interaction (p [less than or equal to] 0.01), seedling and radicle length were affected by stratification (p [less than or equal to] 0.05), too. Rootlet length only was affected by scarification and stratification x scarification interaction (p [less than or equal to] 0.05) (Table 2).

The highest of germination percentage (57.50%) was observed in mechanical scarification and with increasing acid exposure time decreased that the lowest of germination percentage (00.00%) was showed in acid scarification at 15 minute exposure time (Fig. 3 - a). Mechanical scarification without stratification induced the highest germination percentage (70.00%) in stratification x scarification interaction treatments (Table 3). Mechanical scarification induced the highest vigor index, it was indicated a decreasing process with increasing acid exposure time similar to germination percentage (Fig. 3 - b). Mechanical scarified seeds with unstratification had the higher vigor index (Table 3).

Unstratified seeds produced higher seedlings (90.60 mm) rather seeds were treated with stratification (61.24 mm) (Fig. 2). Stratification is a standard way to enhance the germination rate in some dormant seeds. Mechanical scarification led to the highest seedling length (210.72 mm) and we were a decreasing in seedling length when the time of exposure increased so that 74.39 mm to 0.00 mm in 0 reached in 15 minute acid exposure (Fig. 3 - c). Mechanical scarification without stratification led to more seedling growth (264.00 mm, Table 3).

Similar to seedling length, radicle length was affected by stratification and the stratification had a lowering effect on it that inhibited radicle growth. Radicle in seeds treated with mechanical scarification had higher growth (106.500 mm) and a decreasing trend was recorded from 0 up to 15 minute acid exposure from 21.388 mm to 0.000 mm (Fig. 3 - d). Radicle growth had higher amount (148.33) in mechanical scarified seeds that did not treated with stratification (Table 3).

Mechanical scarified seeds produced the highest rootlet number (2.712) and rootlet length (4.810 mm) (Fig. 3 - e and f). In contrast of above characteristics the rootlet number and rootlet length have the highest amount in seeds treated with stratification and mechanical scarification with 3.443 and 8.620 mm, respectively (Table 3).

Disscusion:

In in vitro condition it was observed an increase in germination percentage with acid exposure time enhancing result of more seed coat breakup, while in in vivo we showed decreasing in it. Because of the existence more suitable growth and sterile conditions in in vitro, more elimination of seed coat, as protective vegetative points, led to more germination, whereas the protective seed coat is needful for better germination in unsterile in vivo condition. Therefore, germination ranges were 39 - 72% and 0 - 25% in in vitro and in vivo, respectively. Despite the low germination percentage in in vivo condition, mechanical scarification on unstratified seeds had the highest of germination (70%).

Stratification was used for elimination of embryo requirements in order to improve germination [11,12,13] in our study; it was found stratification had no effect on germination percentage, vigor index, the rootlet number and length. Mechanical scarification improved germination and seedling growth characteristics, so it can be state that Z. jujuba has physical dormancy that avoided water absorption not physiological dormancy. Since the absorption of water by seed coat was occurred in stratification, the seed coat was more susceptible to acid exposure time, that it is enhanced seed survival risks. Consequently, by increasing acid exposure time we showed a decrease in seedling and radicle length in stratified seeds. Stratified seeds in compared with control enhanced germination percentage from 0% up to 50%.

Superiority of mechanical scarification treatment over the other treatments was quite evident in both stratification and unstratification. Stratification is useful when acid stratification was not used and the higher acid exposure time of 5 minute was not suggested. As noted above, we can observe stratification effect on improving of seed coat water absorption. 14.1% germination was reported for Z. jujuba seeds that were 20 days stratified and greenhouse condition cultured [4] while Lyrene [5] recommended H2SO4 scarification (120 - 360 minute) and stratification (5 [degrees]C) for 60 to 90 days.

References

[1.] Abdul-Baki, A. and J.D. Anderson, 1973. Vigor determination in Soybean seed by multiple criteria. Crop Sci., 13: 630-633.

[2.] Azam-Ali, S., E. Bonkoungou, C. Bowe, C. DeKock, A. Godara and J.T. Williams, 2001. Fruits for the Future 2, Ber and other jujubes. Southampton, UK, University of Southampton, International Centre for Underutilised Crops.

[3.] Rechinger, K.H., 1977. Plants of the Touran Protected Area, Iran. Iran J Bot., I: 155-180.

[4.] Olmez, Z., F. Temel, A. Gokturk and Z. Yahyaoglu, 2007. Effect of cold stratification treatments on germination of drought tolerant shrubs seeds. Journal of Environmental Biology, 28(2): 447-453.

[5.] Lyrene, P.M., 1979. The jujube tree (Ziziphus jujuba Lam.). Fruit Varieties Journal, 33(3): 100-104.

[6.] Maraghni, M., M. Gorai, M. Neffati, 2010. Seed germination at different temperatures and water stress levels, and seedling emergence from different depths of Ziziphus lotus. South African Journal of Botany, 76: 453-459.

[7.] Baskin, C.C. and J.M. Baskin, 1998. Seeds, ecology, biogeography, and evolution of dormancy and germination. San Diego, Academic Press.

[8.] Baskin, J.M. and C.C. Baskin, 2004. A classification for seed dormancy. Seed Science Research, 14: 1-16.

[9.] Pareek, O.P., 2001. Fruits for the Future 2: Ber. International Centre for Underutilised Crops, University of Southampton, Southampton, UK.

[10.] Finch-Savage, W.E. and G. Leubner-Metzger, 2006. Seed dormancy and the control of germination. New Phytologist, 171: 501-523.

[11.] Falleri, E., 2004. Dormancy breaking in Cornus sanguine seeds. Seed Sci Technol., 32: 1-4.

[12.] Pipinis, E., E. Milios, P. Smiris and C. Gioumnosidisc, 2011. Effect of acid scarification and cold moist stratification on the germination of Cercis siliquastrum L. seeds. Turk J Agric For., 35: 259-264.

[13.] Abu-Qaoud, H., 2007. Effect of scarification, gibberellic acid and stratification on seed germination of three Pistacia species. An - Najah Univ J Res (N. Sc.), 21: 1-10.

[14.] SAS Institute Inc, 1989. SAS/STAT User's Guide. Version 6. 4th ed. Volume 2. SAS Institute, Inc., Cary.

S. Karimpour, G.H. Davarynejad, H. Rouhbakhsh, E. Ardakani

Department of Horticultural Science, Ferdowsi University of Mashhad, Mashhad, Iran.

Corresponding Author

S. Karimpour, Department of Horticultural Science, Ferdowsi University of Mashhad, Mashhad, Iran.

E-mail: s.karimpour@yahoo.com Mobile: +98 915 654 6439 Fax: +98 511 8787430

Table 1: ANOVA of different acid exposure time on
germination and some seedling growth
characteristics of Z. jujuba seeds
in vitro condition.

Sources               df                    Mean
                                           Square

                            Germination    Vigor     Seedling
                            percentage     index      length

Acid scarification    3     1391.25 *     10.36 **   753.543 *
Error                 16     281.25         1.76      258.501
Corrected Total       19

Sources                                Mean
                                      Square

                       Radicle      The rootlet    Rootlet
                        length        number        length

Acid scarification   101.650 (ns)    51.579 **    3.117 (ns)
Error                   99.572         2.808        9.036
Corrected Total

** : significant at 0.01, * : significant at
0.05 and ns: not significant.

Table 2: ANOVA of different acid exposure time on
germination and some seedling growth
characteristics of Z. jujuba seeds
in vivo condition.

Sources            df                   Mean
                                       Square

                        Germination     Vigor       Seedling
                        percentage      index        length

Stratification     1    120.00 (ns)    24.76ns     6463.017 *
Scarification      4    3011.25 **    173.06 **   40519.791 **
Stratification x   4    1563.75 **    71.97 **    19786.662 **
Scarification
Error              20     307.50        13.39      1036.810
Corrected Total    29

Sources
                                     Mean
                                    Square

                     Radicle      The rootlet     Rootlet
                      length        number        length

Stratification      1820.056 *    0.449 (ns)    24.752 (ns)
Scarification      11581.578 **    7.540 **     23.036 (ns)
Stratification x   3167.094 **     6.919 **      33.888 *
Scarification
Error                272.369         1.526        11.538
Corrected Total

** : significant at 0.01, * : significant at
0.05 and ns: not significant.

Table 3: The stratification x scarification
interaction effect on germination percentage,
vigor index, seedling length, radicle length,
the rootlet number and rootlet length of
Z. jujuba in vivo condition.

      Treatments                  Germination
                                 percentage (%)
      Mechanical
     scarification               UST         ST
                              ([dagger])

                              70.00 a *   45.00 ab
Acid            0 (control)    00.00 d    50.00 ab
exposure             5        30.00 bc     00.00
time                10         15.00 d     00.00
(minute)            15         00.00 d     00.00

     Treatments                   Vigor             Seedling
                                  index            length (mm)
     Mechanical
    scarification              UST      ST       UST         ST

                              18.8 a   7.0 b   264.00 a   157.45 b
Acid            0 (control)   0.0 c    7.1 b    0.00 c    148.78 b
exposure             5        4.4 cb   0.0 c   148.00 b    0.00 c
time                10        0.0 c    0.0 c    41.00 c    0.00 c
(minute)            15        0.0 c    0.0 c    0.00 c     0.00 c

     Treatments                   Radicle             The rootlet
                                 length (mm)            number
     Mechanical
    scarification               UST         ST       UST       ST

                              148.33 a   64.67 b    2.0 ab   3.443 a
Acid            0 (control)    0.00 d    42.78 bc   0.0 b    1.7 ab
exposure             5        27.00 cd    0.00 d    3.7 a     0.0 b
time                10        10.00 cd    0.00 d    0.7 b     0.0 b
(minute)            15         0.00 d     0.00 d    0.0 b     0.0 b

     Treatments                     Rootlet
                                  length (mm)
     Mechanical
    scarification               UST        ST

                              1.00 bc    8.62 a
Acid            0 (control)    0.00 c    5.92 ab
exposure             5        3.62 abc   0.00 c
time                10        0.83 bc    0.00 c
(minute)            15         0.00 c    0.00 c

([dagger]) UST: unstratification and ST: stratification.
* Means followed by the same letter in columns
are not significantly different by LSD's test
at 0.05 probably level.
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Article Details
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Title Annotation:Original Article
Author:Karimpour, S.; Davarynejad, G.H.; Rouhbakhsh, H.; Ardakani, E.
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:Mar 1, 2013
Words:2558
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