Regeneration of Acacia albida with Direct Seeding...
Regeneration of Acacia albida with Direct Seeding ’
S.A.N. Samba’
Abstract
conducted at Thiénaba, Senegal by Cazet (1987) compared direct seeding and outplanting of
potted seedlings. Re&ts showed that direct seeding cari give better survival rates than outplanted
potted seedlings. As a regeneration technique, direct seeding is
cost efficient and labor e.tensive.
Introduction
seeds were then sown in pots on 28 Apr 1986. Seeds
used for direct seeding were also pretreated with sul-
Throughout the northwestern part of the Groundnut
furie acid.
Basin, Senegal, Acacia albida parks consist predomi-
In preparation for planting and seeding, 50 x 50 x
nantly of mature trees. However,
natural regeneration
60 cm holes were dug on the site, treated with di-
beneath them is virtually non-existent. In 1986, the
eldren, then backfilled. Outplanting was done on 11
DRPF/ISRA, Senegal, etiablished a direct seeding
Jul 1986 following a rain of 22 mm. At the time of
study to determine if this inexpensive method
could
planting, the bottoms of pots were tut to remove the
be used to regenerate this regionally important spe-
coiled roots of the Il-week old plants. A Il-day
cies (Cazet 1987).
drought period followed the planting date, requiring
resowing of direct seeding plots on 5 Aug because of
high mortality.
Site Description
The design was a randomized complete block de-
sign. Each of the 4 blocks of 2 treatments (direct
Thiénaba, the site chosen for the regeneration tria1
seeding or potted seedlings) formed plots of 24 (6 x
was located in the Sahelian zone of Senegal charac-
4) plants. Potted seedlings were planted at 4 x 4 m
terized by a 9-month dry season and a 3-month rainy
whereas seed pockets (each seeded with 3 pregermi-
season. Annual precipitation ranges between 400 and
nated seeds) were spaced at 2 x 4 m. Plots were
500 mm. The soils were sandy (90-94%) and domi-
weeded in August, September, and October.
nated by fine sands (54-62%). The clay plus silt frac-
Survival rate, plant height, diameter at the mot
tion was less than 5%. Organic matter content of the
collar, dry shoot mass, taproot length, maximum di-
soi1 was estimated at 0.2% and available soi1 water
ameter of the taproot, total length of roots, and dry
was approximately 4%.
root mass were recorded. Samples for weighing were
dried at 105°C to constant weight.
Materials and Methods
Results
Seeds used in the triai were collected in a region with
similar ecological conditions as those of Thiénaba.
On 29 Nov, 49% of the hills had 3 seedlings, 33% had
Seeds used in the nursery were pretreated with con-
2 seedlings, and 15% had 1 seedling. Only 3% of the
centrated sulfuric acid for 30 minutes. Following
hills had no emergence. T~US, the survival rate of the
pregermination in an incubator (95% germination),
total number of seeds planted was 76% at 3.8 months.
1. Direction des recherches sur les productions forestières (DRPFMnstitut
sénégalais de recherches agricoles (ISRA), B.P. 2312. Dakar.
Sent&
Samba, S.A.N. 1992. Regenention of
Awciu ~I/~~&I with direct seeding. Pages 139-140
irr Fuidkrhkc ul/)idr in the West Africün semi-wid
tropics: proceedings of a workshop. 22-26 Apr 1991, Niamey. Niger (Vündenbeldt. R.J.. ed.). Patancheru, A.P. 502 324.
India: International
Crops Research lostitute for the Semi-Arid Tmpics; 2nd Nairobi. Kenya: International Centre for Resexch in Agroforestry.
139
.
No mortality was observed afterwards. Survival of
Recommendations
seedlings grown in pots decreased from 79% at 3
months to 66% at 6.5 months. Comparison of juvenile
For a11 the parameters studied, direct seeding gave the
growth parameters between the two techniques are
best results. Favorable conditions at the time of seed-
shown in Table 1.
ing, however, were critical for the success of this
technique. Besides the clear superiority of direct
seeding over potted seedlings in terms of growth (Ta-
Table 1. Comparison of juvenile growth differences
ble 1), survival rates of direct-seeded plants were
in
as a function of planting
much higher. At month 6, direct seeding of three
method, Thiénaba, Senegal, 1986. (Source: Cazet
pregerminated seeds per hill had a 48% higher sur-
1987.)
vival rate than potted seedlings raised 2.5 months in
Ratio
the nursery.
Direct
Based on these results, direct seeding cari be rec-
Direct
seeding:
ommended provided that seeding is done when the
Growth parameter
seeding Pots
p o t s
soil is moist to a depth of over 50 cm. Weeds must be
suppressed and the site must be adequately preparated
Height (cm)
42.31
21.7
1.9
to encourage rapid taproot development.
Diameter (mm)
6.4
2.6
:!S
Dry shoot mass (g)
8.7
0.5
17.7
Taproot length (cm)
273
149
1..8
References
Taproot diameter (mm)
8.5
1.3
6.5
Cumulative root
Cazet, M. 1987. La régkntration artificielle de
length (cm)
520
173
3.0
Fuidherhia albida en zone sahélienne. Plantation ou
Dry root mass (g)
34.5
1.4
24.5
semis direct? Premiers résultats de l’expérimentation
conduite à Thiénaba (Sénégal) en 1986. Dakar,
Sene-
1. AU mean pairs comparing direct seeding versus pots are
gal: Direction des recherches sur les productions for-
significantly different at P ~0.05.
estières. 49 pp. (Limited distribution.)
S.A.N. Samba’
Abstract
conducted at Thiénaba, Senegal by Cazet (1987) compared direct seeding and outplanting of
potted seedlings. Re&ts showed that direct seeding cari give better survival rates than outplanted
potted seedlings. As a regeneration technique, direct seeding is
cost efficient and labor e.tensive.
Introduction
seeds were then sown in pots on 28 Apr 1986. Seeds
used for direct seeding were also pretreated with sul-
Throughout the northwestern part of the Groundnut
furie acid.
Basin, Senegal, Acacia albida parks consist predomi-
In preparation for planting and seeding, 50 x 50 x
nantly of mature trees. However,
natural regeneration
60 cm holes were dug on the site, treated with di-
beneath them is virtually non-existent. In 1986, the
eldren, then backfilled. Outplanting was done on 11
DRPF/ISRA, Senegal, etiablished a direct seeding
Jul 1986 following a rain of 22 mm. At the time of
study to determine if this inexpensive method
could
planting, the bottoms of pots were tut to remove the
be used to regenerate this regionally important spe-
coiled roots of the Il-week old plants. A Il-day
cies (Cazet 1987).
drought period followed the planting date, requiring
resowing of direct seeding plots on 5 Aug because of
high mortality.
Site Description
The design was a randomized complete block de-
sign. Each of the 4 blocks of 2 treatments (direct
Thiénaba, the site chosen for the regeneration tria1
seeding or potted seedlings) formed plots of 24 (6 x
was located in the Sahelian zone of Senegal charac-
4) plants. Potted seedlings were planted at 4 x 4 m
terized by a 9-month dry season and a 3-month rainy
whereas seed pockets (each seeded with 3 pregermi-
season. Annual precipitation ranges between 400 and
nated seeds) were spaced at 2 x 4 m. Plots were
500 mm. The soils were sandy (90-94%) and domi-
weeded in August, September, and October.
nated by fine sands (54-62%). The clay plus silt frac-
Survival rate, plant height, diameter at the mot
tion was less than 5%. Organic matter content of the
collar, dry shoot mass, taproot length, maximum di-
soi1 was estimated at 0.2% and available soi1 water
ameter of the taproot, total length of roots, and dry
was approximately 4%.
root mass were recorded. Samples for weighing were
dried at 105°C to constant weight.
Materials and Methods
Results
Seeds used in the triai were collected in a region with
similar ecological conditions as those of Thiénaba.
On 29 Nov, 49% of the hills had 3 seedlings, 33% had
Seeds used in the nursery were pretreated with con-
2 seedlings, and 15% had 1 seedling. Only 3% of the
centrated sulfuric acid for 30 minutes. Following
hills had no emergence. T~US, the survival rate of the
pregermination in an incubator (95% germination),
total number of seeds planted was 76% at 3.8 months.
1. Direction des recherches sur les productions forestières (DRPFMnstitut
sénégalais de recherches agricoles (ISRA), B.P. 2312. Dakar.
Sent&
Samba, S.A.N. 1992. Regenention of
Awciu ~I/~~&I with direct seeding. Pages 139-140
irr Fuidkrhkc ul/)idr in the West Africün semi-wid
tropics: proceedings of a workshop. 22-26 Apr 1991, Niamey. Niger (Vündenbeldt. R.J.. ed.). Patancheru, A.P. 502 324.
India: International
Crops Research lostitute for the Semi-Arid Tmpics; 2nd Nairobi. Kenya: International Centre for Resexch in Agroforestry.
139
.
No mortality was observed afterwards. Survival of
Recommendations
seedlings grown in pots decreased from 79% at 3
months to 66% at 6.5 months. Comparison of juvenile
For a11 the parameters studied, direct seeding gave the
growth parameters between the two techniques are
best results. Favorable conditions at the time of seed-
shown in Table 1.
ing, however, were critical for the success of this
technique. Besides the clear superiority of direct
seeding over potted seedlings in terms of growth (Ta-
Table 1. Comparison of juvenile growth differences
ble 1), survival rates of direct-seeded plants were
in
as a function of planting
much higher. At month 6, direct seeding of three
method, Thiénaba, Senegal, 1986. (Source: Cazet
pregerminated seeds per hill had a 48% higher sur-
1987.)
vival rate than potted seedlings raised 2.5 months in
Ratio
the nursery.
Direct
Based on these results, direct seeding cari be rec-
Direct
seeding:
ommended provided that seeding is done when the
Growth parameter
seeding Pots
p o t s
soil is moist to a depth of over 50 cm. Weeds must be
suppressed and the site must be adequately preparated
Height (cm)
42.31
21.7
1.9
to encourage rapid taproot development.
Diameter (mm)
6.4
2.6
:!S
Dry shoot mass (g)
8.7
0.5
17.7
Taproot length (cm)
273
149
1..8
References
Taproot diameter (mm)
8.5
1.3
6.5
Cumulative root
Cazet, M. 1987. La régkntration artificielle de
length (cm)
520
173
3.0
Fuidherhia albida en zone sahélienne. Plantation ou
Dry root mass (g)
34.5
1.4
24.5
semis direct? Premiers résultats de l’expérimentation
conduite à Thiénaba (Sénégal) en 1986. Dakar,
Sene-
1. AU mean pairs comparing direct seeding versus pots are
gal: Direction des recherches sur les productions for-
significantly different at P ~0.05.
estières. 49 pp. (Limited distribution.)