Observations and Experiments on the Multiplication, Cultivation, and Management of Vetiver Grass Conducted in China in the l950's
Xia Hanping (South China Institute of Botany, The Chinese
Academy of Sciences, Guangzhou, China)
Abstract This paper systematically summarizes observations and experiments on
methods to rapidly multiply vetiver conducted in China in the 1950's. Besides the general
practice of propagation by division of roots, other successful propagation methods
developed from experiments included: 1) multiplication by stem-culm cuttings, 2)
multiplication by pedicel-culm cuttings, 3) multiplication by longitudinal-slit stems, and
4) multiplication through pruning tops. New cultivation techniques were developed that
promoted rapid field establishment included: 1) water-cultivation for accelerating roots,
2) heeling-in for improved root establishment , 3) dipping roots, 4) retaining mother
tillers left in soil, and 5) oblique planting. Management measures that enhanced tillering
rates had: 1) intensive cultivation and strengthening management, 2) proper pruning, 3)
and rational close planting. Obviously, these successful multiplication, cultivation, and
management methods can play an instructive and reference role for the similar work in the
future.
Vetiver grass (Vetiveria zizanioides) was introduced to China in the middle 1950's. At
that time, some multiplication, cultivation and management experiments on this plant were
conducted in China. The purpose for introducing vetiver was for the production of
Essential Oil from vetiver roots. Seedlings for propagation were scarce; so experiments
were undertaken concentrating on two aspects: first, on the rapid multiplication of
seedlings , and secondly on breeding roots that yielded oil of high quality and content.
This paper summarizes the research and the results
1 INTRODUCTION OF VETIVER
The first introductory paper Oil vetiver was published in the magazine of Tropical Crops
(in Chinese) in 1957, whose title was just "Vetiveria zizanioides". This paper
covered in detail five different aspects of vetiver: 1) production; 2) the plant; 3)
multiplication and cultivation; 4) harvest and processing; and 5) characteristic of
vetiver oil. There are several points worth mentioning in this article. They are: China's
vetiver was introduced from Indonesia in 1956. (It has been widely believed that China's
vetiver was from India).
The undomesticated vetiver had been found in Hainan Island of China. (As a matter of fact,
there was a much larger area, approximately 6,000-7,000 ha, of wild vetiver communities,
maybe Vetiveria nigritana, found in Guangdong by South China Institute of Botany in
1957.)
Vetiver roots are 3-4 mm in diameter, and 1-1.5 m deep. It can produce dry roots 100-150
kg per mu (one-fifteenth hectare) 1 year after planting, from which can be refined 2-3 kg
vetiver oil.
Vetiver grass is rarely seeds, and is mainly replicated by vegetative propagation. Prior
to planting their tops should be pruned to about 20 cm, and the number of tillers per slip
should be 2-3.
The plant generally performs better in free and well drained soils, and best in young
soils developed from volcanic ash. The oil content will decrease if it is planted in
clayed soils. The grass grows best under full sunshine, and is not a shade-tolerant. The
oil content of roots is generally some 2-2.5%. 18-month-old roots contain the most oil
with the best fragrance. The older the root the greater the density of oil.
In addition, there was another introductory paper on vetiver oil. This paper, entitled
"Vetiver Oil", introduced the production and processing of vetiver oil in some
major oil producing countries and regions including Java, Reunion, Haiti, India, and some
countries from South America. It also made reference to chemical ingredients, physical and
chemical characteristics, functions and uses of vetiver.
2 SOME SUCCESSFUL METHODS FOR PROPAGATING VETIVER
Since vetiver has difficulty in producing viable seeds, the general propagation approach
is through division of roots. The availability of vetiver seedlings was very deficient in
the late 1950s, so priority was given to experimenting on the multiplication of materials.
The successful propagation methods obtained from these experiments and surveys are as
follows.
2.1 Multiplication by Stem-culm Cuttings
No matter how many nodes, mono-, bi-, or poly-node, are contained in a culm, old culms
from the first four nodes in the base part of a stem have the highest survival rate, which
goes up to about. 50-60%; whereas the culms from the 5-6th nodes only have 20-30% survival
rate. The further the culms are from the base part, the lower their survival rates
eventually to zero. In the same nodes, those which are deprived of sheaths and have
revealed "bud-eyes" and "root points" sprout more rapidly, and produce
more roots, than those which are not deprived of their sheaths. This is because the bud
~eyes~ and root points in culms whose sheaths are peeled off are capable of contacting
directly with moisture in soil, which promotes root points to stretch and bud-eyes to
sprout. If older cuttings are put in sand with saturated water, they will show "white
dots" next day, and produce new roots in the third day; if younger cuttings are used
it will takes more than 20 days, but they do not become dry or dead.
2.2 Multiplication by Pedicel-culm Cuttings
During the period of flowering, pull open leaves lying next to the 5 - 8th nodes, and cut
off the pedicel from the top 3-4 nodes. Over 5-6 days after the top is cut, prune the
pedicel culm at 1-2 cm from the ground. Divide each node of the pedicel into one section,
then dip the sections into 0.01 % KMnO4 solution for 5 -10 minutes. After that plant them
in a nursery. The nursery should well drained and fertile, water sufficient, and be in the
shade. Irrigation is given 2-4 times per day, new roots will grow out some 10 days after
planting.
2.3 Multiplication by Longitudinal-slit Stems
This method is interesting. Vetiver stems have opposite axillary buds and radicles. If a
strong stem is longitudinally slit into two halves, then both can produce new tillers and
roots. Longitudinal-slit seedlings should be cultivated in shade and the management must
be meticulous. It is necessary to usually irrigate the bed in order to keep it wet. New
roots will appear after stems have been transplanted for 6 days, and their establishment
rate may be up to 100%. Furthermore, the propagation with longitudinal-slit stems has a
pretty rapid tiller-formation; and can enhance multiplication speed by 2-5 times as
compared to non-longitudinal-slit approach.
2.4 Multiplication through Pruning Tops
This is a quite novel approach. The main operation is as follows. Cut the top from the
growth point when the plant grows up to 5-6 nodes; the purpose is to control top growth.
Then peel off sheaths node by node to accelerate axillary buds aging. After top pruning
and sheath removing, nutrients in plant will concentrate chiefly on the buds, thus new
seedlings are beginning to sprout from the buds in 1-2 weeks. When the seedlings grow up
to round 20 cm, pick them up with the mother buds and culms together. Then heel in them
under shade to produce roots as soon as possible. After new roots come out in about one
week, they can be outplanted. This propagation way usually has a establishment rate of
over 95%, and its speed of forming seedlings is far faster than propagation by
pedicel-culm cuttings.
3 CULTIVATION TECHNIQUES FOR PROMOTION ESTABLISHMENT
3.1 Water-cultivation for Accelerating Root Growth
The method of water cultivation for speeding root growth is quite simple and is
accomplished by laying the cuttings or root divisions vertically in 5-centimeter-deep
water (e.g. shallow pool) for 7-10 days.
This advantages of this method are as follows:
_ Has quicker growth and tillering Through water cultivation, seedlings no longer
undergo the green-turning process, but grow directly. Thus they can produce tillers in
advance.
_ Roots rapidly. Water cultivation makes seedlings strike new roots only in 2-3
days, whereas the ordinary transplanting way takes at least one week. (In spring 1997, we
did the same experiment, the result was that fastest new roots were produced in 3 days,
and the slowest in a week or so.)
_ Increased the survival rates, and better promotion of growth and development.
While cuttings are used as multiplication materials, they will not take roots and from
tillers until transplanting after 10 days or a longer, respectively, even if cuttings are
from the older culms. If cuttings are the younger culms, the majority do not survive after
transplanting. Through water cultivation, however, old stems grow new roots and leaves
only in 2-3 days; young stems also take roots only in 10-15 days, and only a few become
dry and dead.
3.2 Heel-in for Taking Roots
An ad hoc survey showed that the survival rate of vetiver through heel-in was 97.5%,
whereas that with no heel-in was only 92.3%. Another experiment indicated no difference in
survival rates in the rainy season between vetiver transplanted on the same day of
uprooting and vetiver transplanted through heel-in. Therefore, it is best, in the rainy
season, to plant vetiver immediately after it is dug up. In the dry season, however,
heel-in for striking roots is an ideal measure to guarantee a high survival rate (Table
1). Heel-in can enhance the survival rate, but the time of heel-in is important, and it is
best at 6-10 days after transplanting when new roots reach 2-4 cm.
Table 1 Comparison of effects of heel-in and non heel-in on the survival rate of vetiver
Weather condition Treatment Survival rate(%) Note
High temperature Heel-in 98.0 1
Drought Non heel-in 76.8 2
Low temperature Heel-in 92.0 3
Drought Non heel-in 81.0 4
1 ) Both treatments are 500 clumps and
2) Planting oil July 6, checking Aug. 4
3 ) Both treatments are 200 clumps
4) Planting on Jan. 17, checking Feb.10
3.3 Dipping Roots
Before planting, dip vetiver roots in 5-25 ppm 2,4-D, dilute fecal sewage, or even slurry.
This method may increase survival rates, and promote tiller formation and growth. For
example, the numbers of tillers and new roots whose seedlings were dipped into dilute
ox-feces and water increased by 26.4% and 80.2%, respectively, compared with those
seedlings not during the first three months after transplanting.
3.4 Keeping Mother Tillers in the Soil
When lifting from a nursery, keep 2-3 tillers from per clump in the ground to gain a more
rapid multiplication rate for the next nursery. A special trial compares the tillering
rate of the following 2 treatments : 1) the plants from mother plants left in soil, and 2)
the plants replanted with the same mother plants. Both start with 10 tillers. After 35
days , treatment 1 goes up to 53 tillers , and treatment 2 becomes only 6 tillers. It is
clear that till ring rate with mother plants left in the soil is by far the quickest.
3.5 Oblique Planting
Plant vetiver obliquely into soil when transplanting. It is possibly better to plant at an
angle of about 45-600 rather than vertically.
4 MANAGEMENT MEASURES FOR ENHANCING TILLERING RATE
4.1 Intensive Cultivation and Improved Management
The nursery must have fertile soil, adequate moisture and sufficient sunshine. When clumps
of vetiver are divided into pieces for seedlings, it would be best to tear them where they
tare best, otherwise seedlings will be damaged. Basal manure and water should be applied
when seedlings are planted. Number of tillers may be enhanced by 2-3 times if good, enough
basal manure is applied. Top dressing, liquid fertilizer is best, should be applied twice
a month. Vetiver is drought-resistant, but the nursery should be supplied with sufficient
water; so irrigation should be given once per 2-3 days if there is no rain. There is a
trial that indicates the survival rate of vetiver planted in a wet field is 59.8%, and
tillers number per clump averages 13.4, but in a dry field both are only 57.5% and 2.7,
respectively, in the same period.
4.2 Proper Pruning
After transplanting seedlings to a nursery for 10 months (August -June), the nursery was
set up for 4 treatments: 1 ) unpruned and unfertilized, 2) pruned and unfertilized, 3)
unpruned and fertilized, and 4) pruned and fertilized. The plants were cut to 30 cm,
fertilization with night soil, and observation time was 1 month. The results were that
treatment 2 enhanced the number of tillers by 46.4%, but treatment 1 only by 17.7%;
treatment 4 increases the number of tillers by
52.6%, whereas treatment 3 only by 26.9%. However, if the plants are pruned in less
than 4 months after transplanting (February -June), they will suffer physical damages
owing to their young age, which retards the growth and tillering. In the experiment above,
the tillers number for treatment 2 increased only by 8.2%, but treatment 1 by 41.4%, after
transplanting for less than 4 months.
The reasons why pruning can promote growing and tillering are because: 1) Vetiver is
150-160 cm high, and the bed's coverage usually exceeds 90% when the plants are up to this
height, thereby results in closing between rows. Vetiver, the C4 plant, demands lots of
sunshine for its growth and development, however. Therefore, proper pruning may lessen the
closing density and heighten sunshine density in all parts of the plant, especially
improved photosynthesis of the new tillers . 2) prunings comprise mainly old stems and
leaves. There is no serious effect of pruning them on the plant; on the contrary, removal
of old parts can diminish the consumption of moisture and nutrients. 3) Pruning also cuts
off pedicels or inhibits the plants from moving into the stage of reproductive growth,
which would consume a great ideal of water and nutrients owing to flowering and seeding.
4) That old parts when cut off possibly produces stimulation to the plant itself, thus can
also improve its growth and tillering.
4.3 Rational Close Planting
Vetiver has a very strong ability to produce new tillers, and therefore planting density
has a significant influence on growth and tillering. An ad hoc trial indicates that
different planting densities, according to table 2, 1 tiller per clump, produce the
tangibly different numbers of tillers in 2 months. Certainly, it does not mean from table
2 that the sparser the planting density is, the better. Generally speaking, the planting
density of 20 cm to 30 cm for multiplication is pretty ideal.
Table 2 Effects of different planting densities on tiller formation
Spacing | Net Increment of Tillers per Clump |
15 x 20 cm | 3.8 |
20 x 20 cm | 4.4 |
20 x 25 cm | 5.6 |
20 x 30 cm | 6.6 |
30 x 35 cm | 7.0 |
5 OTHER ASPECTS NEEDING CONSIDERATION
5.1 Shallow Planting Is Probably Better Than Deep Planting
Table 3 indicates that vetiver planted 3-4 cm deep is best, 5-6 cm second, and 7-8 cm
worst, no matter which aspect, survival rate or tillers number of per clump. It is clear
from this survey that shallow planting is better than deep planting. The crown must be
buried in the ground, however. In addition, in the dry season the plants can not be
inserted too shallowly, otherwise they would suffer from drought and result in a decrease
of survival rate.
Table 3 Effects of different planting depths on establishment rate and tillering rate
Planting Depth (cm) | Estab. Rate (%) | # tillers/clump at 4 months |
3-4 | 96.6 | 24.7 |
5-6 | 92.3 | 15.4 |
7-8 | 91.3 | 9.5 |
5.2 Keeping Long Roots Is Possibly Better Than Keeping Short
Roots
An experiment tested 2 treatments: pruning roots to 15 cm, and to 4 cm. After
transplanting for 3 months, the result shows that the plants with 15 cm long roots had
more than more 8.2% of tiller numbers than those with 4 cm long roots. When heeling in,
the former had 19.8% increase in the rate of tiller than the latter, in the same period.
The difference, however, gradually dwindles as time goes on. Furthermore, effects of the
two treatments had no significant effect on the survival rates. In general, 10 cm long
roots are enough; too long roots are not recommended.
5.3 How Many Tillers Per Clump Should Be Planted
Three treatments in an experiment were set up : 1 tiller, 2 tillers, and 3 tillers per
clump. After 2 months, their survival rates and new tiller increments were significant
(table 4). Obviously, it is better to plant 2-3 tillers per clump in order to get the best
establishment rate. It is certainly feasible to plant 1 tiller for each clump when
seedlings are scarce. However, a rule, as mentioned above, is to tear off clumps at the
place most easily-torn.
Table 4 Effects of different numbers planting on survival and tillering rates Treatment
# Tillers per Clump | Survival rate (%) | Net increment of tillers per clump | Net increment of tillers per tiller |
1 | 70 | 1.19 | 1.19 |
2 | 81 | 1.30 | 0.65 |
3 | 98 | 2.03 | 0.68 |
Acknowledgment
The author are grateful to Professor He Daoquan for providing some precious reference
material.
(19 reference 5 are not used here because they are in Chinese. Any of you who are
interested in them please contact the author).