Physiological studies on breaking seed dormancy of some trees species and their effects on seedling growth




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Дата канвертавання22.04.2016
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Regarding the effect of chemical treatments on daily germination speed of K. pinnata , data in Table 1 show that treating seeds by ethyl alcohol for 30 min followed by soaking in tap water for 24h. gave the best results. In addition, using of different pregermination treatments on K. pinnata seeds resulted in a significant effect on increasing of daily germination speed compared to the untreated seeds (control) during the 2004 and 2005 seasons.

According to the present results, (Table 1), ethyl alcohol treatment of tested trees appeared to be the most prominent tool to destroy hardness of seed coat. It increased germination percentage and daily germination speed compared to the other treatments. It could be suggested that under these conditions other factors as microorganisms and PH effect are working on seed coat that may improved germination parameters . These results are in accordance with those of Singh and Ratnum (1983); Ho et al.(1995); Martins-Loucao et al.(1996) and Ebeid (2000).

c) Stem length (cm):

Data on stem length of the seedlings of two trees as affected by chemical treatments at the age of three months during the 2004 and 2005 seasons are shown in Table 2. Treating B. aegyptiaca seeds by sulphuric acid at 10 min with soaking in tap water for 24h. or by ethyl alcohol for 15 min. with the direct sowing resulted in the highest values (31.9 cm.)of stem length in the two seasons.



Concerning the chemical scarification treatments of stem length of k. pinnata , data in Table (2) revealed that the tallest stem (17.9 and 20.2 cm.) was due to the use of concentrated sulphuric acid for 10 min with soaking in tap water for 24h. during the two seasons. Meanwhile , the lowest values ( in the first season 10.7cm. and 12.1cm. in the second season) of K. pinnata stem length were obtained with soaking seeds in ethyl alcohol for 15 min then soaking seeds for 24h in tap water.
Table 2 : Effect of pregermination treatments on Stem Length ( S.L.), Stem Diameter ( S.D) and Root Length ( R.L) of Balanites aegyptiaca and Kigelia pinnata tree seedlings .

Trees

First season ( 2004 )

Second season ( 2005 )

Balanites

Kigelia

Balanites

Kigelia

Treatments

S.L

S.D

R.L

S.L

S.D

R.L

S.L

S.D

R.L

S.L

S.D

R.L

Control

19.4

0.18

11.3

9.4

0.33

15.5

20.2

0.20

14.0

10.0

0.40

17.9

Sulphuric (5m.0h)

22.3

0.24


17.8

12.2

0.45

17.3

22.1

0.23

17.1

13.8

0.52

20.6

Sulphuric (5m24h)

29.7

0.28

16.0

13.9

0.36

20.1

29.8

0.28

16.7

15.7

0.42

23.9

Sulphuric (10m.0h)

20.6

0.20

17.0

12.5

0.49

23.2

20.7

0.21

17.3

14.1

0.57

27.6

Sulphuric (10m.24h)

31.9

0.24

19.4

17.9

0.52

27.7

31.9

0.25

19.0

20.2

0.60

33.0

Ethyl (15m.0h)

31.9

0.22

20.4

13.7

0.48

26.7

31.1

0.23

18.2

15.4

0.56

31.8

Ethyl (15m.24h)

28.5

0.26

13.0

10.7

0.37

24.5

26.3

0.23

15.3

12.1

0.44

29.1

Ethyl (30m.0h)

28.0

0.23

16.1

13.5

0.43

17.3

26.6

0.26

19.6

15.3

0.50

20.4

Ethyl (30m.24h)

27.7

0.23

16.4

12.1

0.37

22.0

25.9

0.23

17.0

13.4

0.43

26.2

L.S.D 5%

2.4

0.03

3.2

1.1

0.04

3.3

2.2

0.03

2.5

2.8

0.04

3.0



d) Stem diameter :

Data of the effect of some treatments on stem diameter of Balanites aegyptiaca and Kigelia pinnata seedlings during 2004 and 2005 seasons are presented in Table 2. It is apparently noticed that immersing the B. aegyptiaca seeds in concentrated sulphuric acid for 5 min. then soaking in tap water for 24h resulted in the highest value (0.28 cm.) of stem diameter in the two seasons.

Whereas , the highest value of 0.52 cm. in the first season and 0.60 cm. in the second season of stem diameter for K. pinnata was obtained due to immersing seeds in concentrated sulphuric acid for 10 min. followed by soaking for 24h in tap water.

e) Root length (cm) :

Average of root length of seedling of Balanites aegyptiaca and Kigelia pinnata as affected by pregermination treatments during the 2004 & 2005 seasons are presented in Table 2. It is evident that soaking seeds of B. aegyptiaca in ethyl alcohol for 15 min. then direct sowing resulted in the tallest roots in the first season and ethyl alcohol for 30 min. then direct sowing in the second season , while the shortest roots were recorded with untreated seeds ( control ). Meanwhile , the tallest roots of k. pinnata was obtained due to immersing seeds in sulphuric acid ( 96% ) for 10 min followed by soaking in tap water for 24h.in the two seasons .



f) Stem fresh and dry weights ( gm/plant ) :

Mean stem fresh and dry weights of the aerial parts ( gm/plant ) as affected by different treatments on Balanites aegyptiaca and Kigelia pinnata are given in Table 3 It is clear that all treatments improved the weight of aerial parts compared with the control. Soaking seeds of B. aegyptiaca. in sulphuric acid for 5 min followed by immersing in tap water for 24h. pronouncedly increased fresh and dry weight of aerial parts. Meanwhile , soaking seeds of Kigelia pinnata in sulphuric acid for 10 min then soaking in tap water for 24h resulted in the highest value of weight of aerial parts compared to the treatments.



Table 3 : Effect of pregermination treatments on Stem Fresh Weight (S.F.W) and Stem Dry Weight (S.D.W) of Balanites aegyptiaca and Kigelia pinnata tree seedlings .


Trees

First season

( 2004 )

Second season

( 2005 )

Balanites aegyptiaca

Kigelia pinnata

Balanites aegyptiaca

Kigelia pinnata

Treatments

.F.W

S.D.W

S.F.W

S.D.W

S.F.W

S.D.W

S.F.W

S.D.W

Control

o.72

0.61

6.00

1.49

1.06

0.64

8.24

2.40

Sulphuric (5m.0h)

1.83

1.05

10.21

3.39

1.70

0.99

11.64

3.87

Sulphuric (5m.24h)

2.13

1.16

11.03

2.66

2.34

1.17

11.15

3.04

Sulphuric (10m.0h)

1.15

0.82

12.35

4.10

1.35

0.73

14.08

4.68

Sulphuric (10m.24h)

2.04

1.02

14.40

4.79

2.38

1.16

16.42

5.45

Ethyl (15m. 0h)

1.91

0.93

11.45

3.81

2.12

1.12

13.06

4.34

Ethyl (15m.24h)

1.62

0.78

9.70

3.22

2.06

1.15

10.73

3.68

Ethyl (30m.0h)

1.82

0.99

11.62

3.87

2.34

1.41

13.24

4.40

Ethyl (30m.24h)

1.74

1.14

11.10

3.69

2.15

1.35

13.24

4.34

L. S.D 5%

0.57

0.16

1.35

0.43

0.42

0.25

0.89

0.49
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