Effect of Periods and Conditions of Preservation in Gene Banks

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Effect of Periods and Conditions of Preservation in Gene Banks on Seed Viability of Balanites aegyptiaca (L.) Del El-Azazi, El-Sayed M. A1, Ali, M. A. M2. Nour- EL-Din, Nahed M3. and El-mekawy, M. A2. ELAZAZI_GENEBANK@YAHOO.COM SMAALAZAZI80@GMAILCOM +20102684667

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Abstract The present study was carried out in Egyptian Deserts Gene Bank (EDGB), North Sinai Research Station, Desert Research Center, Egypt, during the period from 2005 to 2007. The aim of this study was to investigate the seed viability response of storage conditions under (room temperature, +4oc and -22 oC) and storage periods (fresh seeds, 6 months, 12 months and 5 years) and using different breaking dormancy treatments, on germination parameters of Balanites aegyptiaca (L.) Del. The results showed significant effects for conservation conditions, storage periods and dormancy treatments on seed viability parameters. Germination percentage were highest when seeds were stored under +4oC for six months and when treated by dry heat at 60oC for 15 minutes. The fresh seeds gave the highest viability percentage. The seeds, which stored at -22 oC gave the highest significant value and those were stored for 12 months showed the highest value for all germination parameters. The increase in germination parameters were greater for seeds that were treated with dry heat (60oC) for 15 min. This significantly denotes appeared that the seeds requirements for high temperature for achieving greater viability after storage. Key words: Balanites aegyptiaca.; storage conditions; storage periods; Gene Bank; seeds preservation; seeds dormancy; viability; conservation

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Introduction Many of Economic wild plants, which are growing in deserts, are facing the danger of the collapse and extinction because it's growing under unsuitable environmental condition. This beside to an error used from Bedouins this plant used as over grazing. And other of facts, which caused the collapse and extinction. So that concept, seed preservation in genebanks may be decrease the effect of previous reasons. Balanites aegyptica also known as desert date in English. (Hall & Walker, 1991), Desert date, myrobolan, heglig in Egypt . (Bolous 2000). is an important tree crop of the savannah zone and semi arid tropical region of Africa. The nut is obtained after the removal of the flesh and pulp of the fruit and it contains a kernel with oil content and protein contents ranging from 30% to 60% and from 20% to 30%, respectively. (Hall & Walker, 1991), It has been found to have potential for industrial applications as raw material in the manufacture of soap, candle, chemicals and cosmetics as well as pharmaceutical products. Many perennial species present a combination of endogenous (morphological and/or physiological) and exogenous (physical and/or mechanical) dormancy (Morpeth and Hall, 2000).

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MATERIAL AND METHODS

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Materials and methods Seed collection: Seeds of Balanites aegyptiaca (L.) Del' were collected from Paris village, New valley, Egypt. Latitude 24o 40' 82 N, Longitude 30o 36' 86 03 E and Altitude 51 M. fruit collected in maturity stage. Seed were spread on filter paper and dried in dry room +22 oC & 10 %RH. Seed storage conditions: Storage at room temperature, Mean temperature ranged from +20 ºC to+ 25 ºC in cloth bags. Storage at refrigerator temperature (+4ºC, 40% Relative humidity - Active Room – Short term), in vacuum-sealed aluminum polyethylene bags. Storage at (–22 ºC, no frost – Base Room – Long term) in vacuum-sealed aluminum polyethylene bags. Storage periods: Seeds are stored in conservation room up to( 6 months, 12 months and 5 years, comparing by fresh seeds ). Viability Parameters: T.Z viability % Germination Percentage (G %). Standard Germination Percentage (SG %) Viability Percentage (V %) Dormancy Percentage (D %) Germination rate (GR)

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Seed Conservation Drying unit ( +22 oC & 10% RH) Room temperature, from 20 ºC to 25 ºC Short term, active unit ( +4 oC& 40% RH) Long term ,base unit ( -22 oC) no frost

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Dormancy breaking treatments: Seeds of Balanites aegyptiaca (L.) Del. were subjected to the following pre- treatments before sowing:

Tetrazolium test for seed viability : 

Tetrazolium test for seed viability T.Z test preparing

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( TTC )TZ Test

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Seedling incubator

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Some Results

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Table (1) Effect of storage conditions on viability parameters of Balanites aegyptiaca (L.) Del it could be concluded that decreasing storing temperature -22oC caused an increase in G%, SG%,V% and GR in Balanites aegyptiaca these results are in agreement with those obtained by Genebank Standards, (1994) and Lewis et al (1998).

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Table (2) Effect of storage periods on viability parameters of Balanites aegyptiaca (L.) Del Seeds stored up to 12 months gave the highest germination percentage (68.19) and standard germination percentage (65.27). While the least value of these parameters appeared with fresh seeds. This gave the highest value of viability percentage (99.99), dormancy percentage (55.31) and germination rate (1.17). These parameters gave the least value with seeds

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Effect of interaction between storage conditions and storage periods

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Data in table (3) indicted the effect of interaction between storage conditions and storage periods on viability parameters of Balanites aegyptiaca (L.) Del. Storing seeds under room temperature for one year gave the highest value for germination percentage followed by storing up to 6 months as well as seed conserved either under -22 oC or +4 oC for one year or 6 months gave the highest value. On the other hand, when seeds stored for five years or as freshed the germination percentage were decreased. Similar results were confirmed by Lewis et al (1998). The same trend were observed for standard germination percentage. Fresh seed under room temperature gave the highest value of viability percentage and germination rate, as well as seed stored under +4oC gave the same trend for conservation seeds under different conditions data. Gupta et al (2005) noticed similar trends. Although the fresh seeds gave the highest values for viability percentage when stored under different conditions but it gave the highest values for dormancy percentage, it will be concluded that Balanites aegyptiaca (L.) Del. seeds contain the hard seed coat with led to increase the dormancy percentage and storing seed for different periods led to minimizing the dormancy percentage especially under room temperature for five years. These results are in agreement with those obtained by Yogeesha et al (2005).

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Effect of pre-sowing treatments Variation in germination responses across different breaking dormancy treatments were elucidated in (table 4). Results are shown an increasing in germination percentage from 40.03% to 73.50 %, standard germination percentage from 39.03 % to 70.62% and germination rate from 0.99 to 1.30 when seeds treated with dry heat 60 oC for 15 min. while the highest dormancy percentage (58.97%) and with control treatment. Schelin et al (2003) confirmed similar results. As well, as when seed soaking in Normal water for 72 h and treated with GA310 -3M for 24 h gave the highest viability percentage. But the seed untreated (control treatment) achieved highest dormancy value. Table (4) Effect of seeds dormancy breaking treatments on viability parameters of Balanites aegyptiaca (L.) Del

Table (5) Effect of interaction between storage conditions and storage periods on seeds viability with tetrazolium test (fast test) : 

Table (5) Effect of interaction between storage conditions and storage periods on seeds viability with tetrazolium test (fast test) Data tabulated in table (5) revealed that there is different significantly between interaction storage conditions and storage periods on viability percentage, storing seeds for five years under -22oC enhanced the viability percentage but storing seed under room temperature for five years decreases the viability percentage. It could be conclude that when seed stored under room temperature it must be decrease the period over year and used dry heat 60oC for 15 min to obtained the high germination percentage. However, when the storing conditions available it must be conserve under -22oC or +4 oC for any time,as well as using fresh seed for germination directly.

Effect of interaction between storage conditions, storage periods and breaking dormancy treatments : 

Effect of interaction between storage conditions, storage periods and breaking dormancy treatments T1: Control T2: Hot water 70 oC for 24h T3: GA310 -3M for 24h T4: H2SO4 98% for 10 min T5: Dry heat 60 oC for15 min T6: KNO3 0.2% T7: Normal water for 72 h T8: H2O2 1% for 24 h T9: Mechanical scarification

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T1: Control T2: Hot water 70 oC for 24h T3: GA310 -3M for 24h T4: H2SO4 98% for 10 min T5: Dry heat 60 oC for15 min T6: KNO3 0.2% T7: Normal water for 72 h T8: H2O2 1% for 24 h T9: Mechanical scarification

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T1: Control T2: Hot water 70 oC for 24h T3: GA310 -3M for 24h T4: H2SO4 98% for 10 min T5: Dry heat 60 oC for15 min T6: KNO3 0.2% T7: Normal water for 72 h T8: H2O2 1% for 24 h T9: Mechanical scarification

Conclusions : 

Conclusions The results from the present study provide that storing seed under room temperature save seed viability up to one year. Storing seed under +4oC or -22 oC saved the viability of seeds up to any time, physical dormancy is a major hurdle for completed and rapid germination of Balanites aegyptiaca (L.) Del. seed that can treated with dry heat 60oC for 15 min before sowing enhancing the seed germination

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Thank You