Generative
propagation of Jatropha curcas L. on
Kalahari Sand
Jacob Kahl Jepsen1, Reinhard K. Henning 2 and
Bongani Nyathi 3
1 Environment Africa, Victoria Falls Branch, P. O
Box CT., 502. Victoria Falls, Zimbabwe[1]
2 baganí, Rothkreuz 11, D –
88138 Weissensberg, Germany
3 Siphosami Project, P. O Box CT., 205. Victoria
Falls, Zimbabwe
Abstract
In southern Africa, larger areas are under semiarid and arid conditions
with a moderate-to-high risk of drought. The drought resistant plant, Jatropha
curcas L., Euphorbiaceae that can grow on lands not suited for agriculture
and both improve the environment and supply raw material for local communities
is attractive for resource-poor farmers. Although Jatropha is commonly planted in southern Africa, research on
cultivation and propagation of Jatropha
is limited. This study provides documentation of the germination of Jatropha seeds planted in nursery in
containers composed of Kalahari Sand. Sampling period was undertaken from late
raining season to the beginning of dry period (February to June 2003). The
study shows high viability of the seeds with a mean germination rate above 93
percent and a completed germination within 9 days. Manure during germination
phase appears to have a negative impact on the germination. However, the
results indicate that manure has a positive impact on the growth rate after
germination has been initiated. Likewise, the intensity of watering and
temperature seems to have a fundamental impact on the germination rate.
Pre-treatment of the seeds did not effect the germination positively.
Keywords: Jatropha curcas L.,
generative propagation, germination, Kalahari Sand, Zimbabwe.
Introduction
Since the oil crisis of the 1970s and recognition of the limitations of
world oil resources, vegetable oils have received special attention (Grimm
1996; Heller 1996; Henning 2000a; Pratt et
al. 2002). Special interest has been shown in the cultivation of the
tropical physic nut (Jatropha curcas L.,
Euphorbiaceae) for oil extraction, especially since it is drought resistant and
can be cultivated on marginal land, without competing with food production
(Heller 1996; Grimm 1996; RF 1998).
Jatropha was introduced into Zimbabwe in the 1940s. Jatropha curcas L. is a multipurpose
large shrub or small tree of Latin American origin. It is local adjusted
throughout arid and semiarid tropical regions of the world with an average
annual rainfall of between 300 and 1000 mm (Palgrave 1983; Heller 1996; CATIE
2000; Henning 2002). In Zimbabwe, it is now found in many parts of the country,
with known concentrations in the north-eastern districts of Mutoko, Wedza,
Chiweshe, Mudzi and Nyanga north. Jatropha
grows on well-drained soils with good aeration and is well adapted to marginal
soils with low nutrient content. It occurs mainly at lower altitudes (0-500 m)
in areas with average annual temperatures well above 20◦ C but
can grow at higher altitudes and tolerates slight frost. It is not sensitive to
day length (ICRAF 2003). Locally, it is grown as a boundary fence or live hedge
and can be used to reclaim eroded areas (Heller 1996; Jøker & Jepsen 2003).
Jatropha is not browsed. Its leaves and stems are toxic to animals,
but after treatment, the seeds or seed cake can be used as an animal feed
(Makkar et al. 2001). Being rich in
nitrogen, the seed cake is also an excellent source of plant nutrient (RF 1998;
Makkar et al. 2001). Traditionally
the seeds have been harvested by women and used for medical treatments and
local soap production (Duke 1983; Henning 2002). Jatropha is fast growing and produce seeds after approximately 1 –
3 years, depending on rainfall conditions and how the plant is propagated (from
cuttings or seeds, respectively). Jatropha
can reach a height up to 8 metre (Heller 1996). Jatropha seeds contain about 35 percent of non-edible oil. 6 kg of
dry seeds gives about 1.2 litre of oil. Research made by Henning 2002 indicates
that commercial exploitation of the plant is comparable with cotton farming.
Examples from Mali shows that villagers that plant 15 km of Jatropha hedges can harvest about 12
tons of seeds which may generate 1800 US$ of cash income when the oil is
extracted and the products sold (1998 figures). At least 2-3 tons of seeds per
hectare can be achieved in semi arid areas (Heller 1996). It is believed that
the total land area in Zimbabwe under Jatropha
is somewhat less than 2,000 hectares (Makkar et al. 2002).
Research on cultivation and propagation of Jatropha curcas L. is limited, especially in southern Africa (RF
1998). For the quick establishment of hedges and plantations for erosion
control, directly planted cuttings are recommended and for long –lived
plantations for vegetable oil production, plants propagated by seeds are better
(Heller 1996). Research shows that plants propagated by cuttings show a lower
longevity and possesses a lower drought and disease resistance than plants
propagated by seeds (Heller 1996). Likewise, pre-cultivation of Jatropha seedlings in poly-ethylene bags
has been shown to accelerate the installation of a plantation by at least 3
months (Henning 2000c).
The main aim of the present study was to document the generative
propagation of Jatropha curcas L.
planted on Kalahari Sand during germination phase and contribute to the
knowledge of cultivation of Jatropha
curcas L. The following three hypotheses have been tested:
Hypothesis 1: Manure has a positive impact on
germination of Jatropha. Seeds from Jatropha curcas L. germinate and grow
faster in soil with manure than in soil without manure.
Hypothesis 2: The intensity of watering has a
significant impact on the germination and growth of Jatropha curcas L.
Hypothesis 3: Temperature has a significant impact
on the germination and growth of Jatropha
curcas L.
Study area
The study was undertaken in Mkhosana, Victoria Falls situated in
northern-western Zimbabwe. The area is on Kalahari Sand (deep, well-drained,
nutrient-poor sands). The area receives a low and erratic mean rainfall of
about 650 mm, falling from November to April. Mean summer and winter
temperatures are 30 o C and 10 o C respectively. Ground
frost is sometimes experienced between May and August. The altitude is 980
metres above sea level.
Methods
The field methodology involved two stages: (i) a general assessment of
the viability of the seeds and the germination rate for generative propagation
of Jatropha curcas L.; (ii) a more
detailed assessment of the germination and growth rate of Jatropha curcas L. during the first eight weeks from seed planting.
Both assessments were undertaken in nursery with approximately 50 percent
density shade. Seeds used in both assessments were locally collected in June
2002. Seeds were stored in Hessian bags and kept under uncontrolled room
conditions until required for planting. The seed provenance is unknown. The
average temperature for each month is based on own data. Cow manure has been
used for trials in the detailed assessment.
General assessment
Pre-cultivation of Jatropha curcas
L. seeds in containers (milk packets, tin and poly-ethylene bags) composed of
Kalahari Sand. The seeds were sown in the soil at a depth of 3 cm in each
container (method after Henning 2000b). The assessment was undertaken in the
period February to April 2003. Watering in February was made four times per
week and two times per week in March and April. Numbers of days to first and
last germination for each trial were observed. Moreover, measurements of the
percentage of germinated seeds were made.
Assessment of the mean days of germination for seeds planted in May and
June 2003 were made afterwards. The total number of germinated seeds during
this period was not measured. Watering was made 2 times per week.
Detailed assessment
Six experimental trials were made. Each trial consisted of ten seeds
planted with one seed in each plant container. The seeds were planted in a dept
of 3 cm. In two trials (C and D), pre-treatment of the seeds were carried out
in order to enhance rapid and uniform germination by removing the testa by
cracking each seed in the hand, carefully.
The assessment was undertaken in eight weeks during the period May to
June 2003. The heights of the plant were measured once per week. The trails had
the following design:
A: Seeds planted in Kalahari Sand without added manure
B: Seeds planted in a mixture (50-50) of Kalahari Sand and manure
C: Pre-treated seeds planted in Kalahari Sand without added manure
D: Pre-treated seeds planted in a mixture (50-50) of Kalahari Sand and manure
E: Seeds planted in Kalahari Sand without added manure
F: Seeds planted in a mixture (50-50) of Kalahari Sand and manure.
Trails A, B, C, and D describe the impact of using manure and
pre-treatment of seeds. Trails A to D were watered three times per week.
Design of trails E and F were similar to trail A, B. Trails E and F
describes the impact of lower watering intensity on the germination rate in
soil with and without manure. Trials E, F were watered once a week.
Results
General assessment
In the period from February to April, out of 4771 planted seeds a total
number of 4616 seeds germinated (96.8 percent survival). The mean germination
rate for each month varied from 93.2 percent to 97.6 percent. The highest
germination rate among the trials was achieved in April (table 1).
The mean days of germination of Jatropha
curcas L. seeds were 6.2 days in February, 7.6 days in March, 7.8 days in
April (table 1). The mean day of germination for the seeds during all three
months was 7.2 days. Shortest germination period occurred in February after
four days and latest germination occurred in April after 10 days.
Germinations trials made in February had a faster germination rate of
1.4-1.6 days compared to the trials established in March and April. However,
the mean germination for trials made in February was 2.2 - 4.4 percent lower,
compared to the trials made the two following months. The average monthly
temperature during the three months varied 1.7 ◦C from 22.8 ◦C
in February and March to 21.1 ◦C in April.
Table 1 Analysis of mean
days of germination and mean germination rate across month and water intervals.
|
Month |
Mean
days of germination (µ) |
S.D*) |
Mean
germination rate (%) |
No. of planted seeds |
No. of seeds germinated |
Treatment Water interval |
Average temperature (◦C) |
|
February |
6.2 |
1.8 |
93.2 |
441 |
411 |
4 times a week |
22.8 |
|
March |
7.6 |
1.5 |
95.4 |
930 |
887 |
2 times a week |
22.8 |
|
April |
7.8 |
1.6 |
97.6 |
3400 |
3318 |
2 times a week |
21.1 |
|
Total |
|
|
|
4771 |
4616 |
|
|
*) S.D Standard
Deviation
The mean days of germination for seeds planted in May and June were 7.9
days and 11.8 days, respectively. The mean day of germination for the seeds
during all five months was 8.3 days. The average monthly temperature during the
whole sampling period varied 7.8 ◦C from 22.8 ◦C
in February and March to 15 ◦C in June. Most significant
difference in temperature was observed from April to May (3.3 ◦C)
(fig. 1). The most significant difference in mean day of germination was seen
from May to June (3.9 days).
Fig. 1 Mean monthly
germination rate for Jatropha curcas L.
(ٱ) and
monthly average temperature (о).
Detailed assessment
A significant difference in germination rate was identified (fig. 2).
Out of six experimental trails, germination occurred in five trials. Highest
percentage germination was obtained in trail A on sand without added manure and
watered three times a week (70 percent). Lowest percentage germination was
measured in trail D for pre-treated seeds planted in a mixture of sand and
manure and watered three times per week (20 percent). No germination was
identified in trail E on sand without added manure and watered once a
week.
Fig. 2 The germination of Jatropha curcas L. in different trails
Figure 3 illustrate the mean shoot length of seedling during the first
eight weeks. During the first three weeks seeds in trial B and C had a
significant faster mean growth rate compared to the three other trials. Seeds
in trial B and C had after three weeks achieved a high of app. 8 cm compared to
1.8 cm for trial A, D and F. Seeds in trail A, D and F had started shooting
after two weeks compared to one week for seeds in trial B and C.
Between week three and four, the highest increase in growth was obtained
by seeds in trail A, D and F. During one week the seeds grew from 1.8 cm to
7-9.5 cm. The growth rate for seeds in trial B and C were decreasing during
this week.
From week four to eight, seeds in all the trials had a decreasing growth
rate. During the period from week four to five seeds from trial F changed its
position from being the trial with the second lowest length of seedling to be
the trial with the longest length of seedling. After eight weeks highest mean
length of seedling was above 14 cm (trail F) and lowest length of seedling was
about 8 cm (trial D).
Fig.3. Mean shooting length of seedlings. Seeds in trials A to D have been watered three times per week, while seeds in trials E and F have been watered once per week. A): Seeds planted in Kalahari Sand without added manure B): Seeds planted in a mixture (50-50) of Kalahari Sand and manure C): Pre-treated seeds planted in Kalahari Sand without added manure D): Pre-treated seeds planted in a mixture (50-50) of Kalahari Sand and manure E): Seeds planted in Kalahari Sand without added manure F): Seeds planted in a mixture (50-50) of Kalahari Sand and manure.
Discussion
Comparative research on the influence of different propagation methods
on viability and vegetative development was conducted by Kobilke (1989) in Cape
Verde and by Heller (1992) in Senegal. The results achieved in Cape Verde and
Senegal show that both vegetative cultivation methods and methods of generative
precultivation were more successful than direct seeding.
Factors responsible for the survival of direct seeding (seeding time,
seeding depth) have been studied by Heller (1992). The result shows low
viability for direct seeding (19.8 %) whereas the same provenance seeded in
plastic bags showed a higher germination (68 %). The viability depended not
only on sowing time and depth of sowing, but also on the trial year.
In our general assessment, Short-term storage under uncontrolled room
conditions did not appear to affect the germination of Jatropha curcas L. as this showed high viability (> 93 percent).
The seed material used in both assessments was collected from the same
area in June 2002. The Jatropha seeds
are oily and do not store for long. Research on viability of Jatropha seeds shows a decrease due to
term of storage. Seeds older than 15 months show viability below 50 % (Kobilke
1989). In our general assessment the viability for seeds planted in May and
June was not measured. It can therefore not be excluded that more than ten
months storage under uncontrolled room condition could have had a negative
affect on the germination of the seeds.
In our assessment no statement can be made on depth of sowing or the
occurrence of water stress shortly after seeding, since soil moisture was not
determined. However, in the general assessment; it seems that watering
intensity and temperature have had an effect on the mean days of germination
and germination rate of the seeds planted in February. Compared to the two
other months (March and April) we achieved the fastest mean days of germination
in February under highest mean temperature and watering intensity. The higher
moisture conditions have had a positive effect on the mean days of germination
but have also resulted in a lower germination rate due to mouldy seeds.
Assessments made in February to April are comparable with trials made in
May and June. The watering intensity was two times per week and the seeds were
planted in Kalahari Sand only. However, the germination period was longer in
May and June, especially. It seems that the temperature and the fact that the
general assessment was made during the end of the raining season have had an
impact on the mean days of germination of the seeds. The watering intensity and
humidity have been higher during the raining season than in the dry period (May
and June).
In the literature the germination is said to take 10 days under good
moisture conditions (Heller 1996; Henning 2000a; ICRAF 2003). In our research
we have achieved germination after four days depending on which month the seeds
were planted. The best time for planting Jatropha
curcas L. on Kalahari Sand, in the period late raining season to start of
dry season, will be during the raining season. Experience in Zimbabwe has shown
that high rainfall in relatively cooler parts of the country does not encourage
the same vigorous growth. However, in the low-weld areas, Jatropha grows well. Jatropha
does not thrive in wetland conditions (RF 1998).
In the detailed assessment the general germination rate was low (0 - 70 %),
which is likely caused by lower temperature during the period of assessment and
dry season. From the trials, manure seems to have an impact on the germination
of Jatropha. Trials in figure 2 shows
highest germination (70 percent) for seeds planted in soil without added manure
when watered three times per week and no germination at all when watered once
per week. However, germination was identified in all trials which included
manure. Even in trial F which was watered once per week 40 percent germination
was achieved. In comparison no germination was achieved in trial E for seeds
planted on Kalahari sand and watered once per week. From our research adding of
manure seems to keep the soil moist and have a positive impact on the
germination rate of the specie. Henning 2000b recommends germination of Jatropha in small plastic bags filled
with soil with a high concentration of organic material (compost). However,
from our research the optimum germination condition for Jatropha planted on Kalahari sand was achieved in pure sand under
high temperature conditions > 20 ◦C in combination with
high watering intensity (three times weekly).
Our observation of the growth rate indicate that Jatropha curcas L. is a fast starter and do not need manure to
germinate. When germination is initiated the shooting of the seedling is fast
and will within two weeks grow app. 10 cm.
The impact of adding manure to the soil is not significant. From our
observation during the eight week assessment of the growth rate adding of
manure seems to have a positive impact on the growth rate. From our data the
two trials with the highest growth after eight weeks (app. 14 cm) has both been
planted in a mixed soil with manure. Highest growth rate for all trials was
achieve in trial F with manure and watered once a week.
From our research adding of manure after germination in order to
increase the growth rate seems to be a possibility.
Freshly harvested seeds show dormancy and after-ripening is necessary before
the seeds can germinate (Jøker and Jepsen 2003). Kobilke (1989) tried to break induced dormancy. Removal of the
testa proved more successful than presoaking alone. However, Pre-treatment of
the orthodox seeds did in our research not seem to make an improved impact on
the germination and growth rate. The trials with pre-treated seeds appear to
have the lowest growth rate.
Conclusion
This study has provided data on the germination of the specie Jatropha curcas L. planted on Kalahari
Sand. The study shows high viability of the seeds with a mean germination rate
above 93 % and a completed germination within 9 days.
Use of manure in generative propagation of Jatropha curcas L. on Kalahari Sand seems to reduce the need for
watering. Adding of manure has a negative impact on the germination but a
positive impact on the growth rate after germination has been initiated.
The intensity of watering and temperature seem to have a fundamental
impact on the germination rate. An increase in the mean days of germination is
observed due to temperatures below 15◦ C. Moderate watering
intensity increases the germination rate.
Pre-treatment of the seeds before planting did not effect the
germination positively.
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