Planting of more trees in forest reserves for reducing global warming has been universally accepted, the idea being that carbondi-oxide absorption would continue until the trees mature say for 40 to 100 years. Although it is recognized that this is not a permanent solution this “carbon sequestration” strategy buy time to develop alternative energy sources.
Tropical deforestation is currently a significant
environment and development issue. At the global level,
according to recent estimates by FAO the annual tropical
deforestation rate for the decade 1981 to 1990 was about
15.4 million h (Mha) . According to the latest data
published in 1994, for the assessment period 1989-1991,
the total area under forests is 64.01 Mha accounting for
19.5 percent of India’s geographic area .
At present there is hardly 0.4 percent forest below 25cm
rainfall zone and 1.3 percent above 30 cm rainfall zone.
There is rapid depletion of forest products and in order to
provide alternative energy sources a change is needed in
conventional forestry management.
Four broad categories of biomass use can be
distinguished – a) basic, e.g. food, fiber, etc.; b) energy,
e.g. domestic and industrial; c) materials, e.g.
construction and d) environmental and cultural, e.g. the
use of the fire. Biomass use through the course of history
has varied considerably, greatly influenced by two main
factors population size and resource availability.
Since the annual photosynthetic production of biomass is
about eight times the world’s total energy use and this
energy can be produced and used in an environmentally
sustainable manner, while emitting net CO2, there can be
little doubt that this potential source of stored energy
must be carefully considered in any discussion of present
and future energy supplies. The fact that nearly 90
percent of the worlds population will reside in
developing countries by a bout 2050 probably implies
that biomass energy will be with us forever unless there
are drastic changes in the world energy trading pattern.
Thus biomass is a scarce resource which should be used
sparingly from an ecological point of view. If biomass
should play a major role for CO2 reduction, the efficacy
of biomass use has to be increased. This can be achieved
by focusing on a “cascade utilization of biomass” the use
of biomass as raw material and as energy carrier should
be optimized in an integrated manner. The rationale
behind this is that if biomass is used for energy
generation which had been previously used for some
other, this will not contribute to an increase of NPP
appropriation. The development of optimal biomass
utilization cascades requires that conflicts of interest
have to be solved.
According to the widely held view of many
environmental experts, its utilization should be
encouraged for several purposes. Biomass should be used
instead of fossil energy carriers in order to reduce i) CO2
emissions ii) the anticipated resource scarcity of fossil
fuels and iii) need to import fuels from abroad.
2 MATERIALS AND METHODS
A 50 ha bioenergy plantation demonstration project
centre has been established in the campus of the
University of Rajasthan to conduct the experiments on
large scale cultivation of selected plants with the
objective of developing optimal conditions for their
growth and productivity, besides conserving the
biodiversity. Considerable work has been carried out on
Certain potential plants were selected and attempts were
made to develop agrotechnology for their large scale
cultivation [2,3,4,5,6,7,8,9,10]. The potential plants could
be characterized under the following categories i)
hydrocarbon yielding plants ii) high molecular weight
hydrocarbon yielding plants, iii) non edible oil yielding
plants, iv) short rotation fast growing energy plants, vi)
hill plants growing on Aravallis.
(I) Hydrocarbon yielding plants included :
♦ Euphorbia lathyris Linn.
♦ Euphorbia tirucalli. Linn.
♦ Euphorbia caducifolia Haines.
♦ Euphorbia nerifolia Linn.
♦ Pedilanthus tithymalides Linn.
♦ Pedilanthus tithymalides Linn.
♦ Calotropis procera (Ait.). R. Br.
♦ Calotropis gigantea (Linn) R. Br.
(II) High molecular weight hydrocarbon yielding plant
♦ Parthenium argentatum Linn
2nd World Conference on Biomass for Energy, Industry and Climate Protection, 10-14 May 2004, Rome, Italy
(III) Non edible oil yielding plants
♦ Jatropha curcas
♦ Simmondsia chinenesis
(IV) Short rotation energy plants
♦ Tecomella undulata
♦ Prosopis juliflora
♦ Pithocellobium dulce
♦ Azadirachta indica
♦ Dalbergia sisso
♦ Acacia tortilis
♦ Holoptelia integrifolia
♦ Parkinsonia aculeata
♦ Cassia siamea
♦ Albizzia lebbek
♦ Acacia nilotica
3 RESULTS AND DISCUSSION
In general these plants are easily propagated through
cuttings. The optimum period for raising cuttings in June-
July and March-April. Cuttings from apical and middle
portions of E. antisyphilitica exhibit 100 percent survival
rate, while non of the cuttings from the basal portions
survived. Spacing among the planted cuttings is also a
crucial factor for survival of cuttings. It was noted that
initially up to a period of two months the survival
percentage was maximum in closest planting density.
Regarding environmental variations. March to October
period was best suitable for E. antisyphilitica because of
linear increase in growth was recorded in this period
. Overall growth and productivity was lowest in the
winter months from November to February. Higher
accumulation of hexane extractable corresponded with
higher temperatures of summer season .
3.2 Edaphic Factors
Among different soil types, sand was best for the growth
of E. lathyris  and P. tithymaloides  while red
loamy soil was best for E. antisyphilitica. When different
combinations of these soil types were made biomass of
E. antisyphilitica was maximum in red+sand+gravel ,
while red+sand combination in equal amounts was best
for P. tithymaloides [016,17]. A mixture of gravel + sand
favoured maximum increase in plant height, fresh weight
and dry weight in E. lathyris . Environmental factors
influenced the growth and yield of Calotropis procera
3.3 Growth Curve
Maximum growth was observed during June-July to
October-November and also from February-March to
May-June. Increase in hexane extractable was recorded
upto 6-7 months; thereafter percent hexane extractable
(HE) did not increase significantly in E. lathyris, E.
antisyphilitica and P. tithymaoildes. Higher levels of HE
were recorded in leaves as compared to the stem in E.
lathyris, E. antisyphilitica and P. tithymaoildes. Higher
levels of HE were recorded in leaves as compared to the
stem in E. lathyris and in fruits of Calotropis procera.
Active phase of growth exhibited gretaer amounts of
3.4 Fertilizer application
Application of NPK singly of or various combinations
improved growth of all the selected plants. In general NP
combination gave better growth which was only slightly
improved by the addition of K for E. tirucalli [19,20].
When best doses of NPK were applied in different
combinations like NP, NK, KP) and NPK, the last
combination gave best results in the form of biomass,
latex yield, sugars and chlorophyll in E. lathyris  and
P. tithymalides . In E. antisyphilitica however, NP
combination gave best results, followed by NPK, for
biomass production. Chlorophyll, sugars and latex yield
was best in KP combination . Addition of FYM alone
and with combination of urea improved FYM+Urea
applications improved the productivity in comparison
with FYM increased the plant height, fresh weight and
dry weight to varying degrees. Hexane and methanol
extractable also increased [21,22].
3.5 Influence of Salinity
Salinity stress studies were also made of on Euphoriba
tirucalli . Salinity was applied in the form of
irrigation water. Lower concentrations of salinity
improved plant growth of E. antisyphilitica . But
higher concentrations inhibited further increase in
growth. Sugars however did not increase in any saline
irrigation. A slightly higher level of salinity impaired
chlorophyll synthesis also. At higher level of salinity,
leaves of E. antisyphilitica became yellow and fell off
but stem did not show any visible adverse effects. E.
lathyris could also tolerate lower salinity levels, but its
tolerance was higher than E. antisyphilitica. In E. lathyris
salinity adversely affected the root growth [23,13].
P. tiothymaloides also exhibited increases in biomass and
yield at lower salinity levels and higher concentrations
adversely affected the plants. Its underground part could
tolerate slightly higher salinity concentration .
3.6 Effect of growth regulators
Spray of growth regulators resulted in enhanced fresh
and dry weight production . However biocrude
synthesis occurred more in auxins, NAA and IAA in E.
antisyphilitica. Out of all the growth regulators employed
on P. tithymaloides IAA supported maximum plant
growth in terms of fresh weight and dry weight of
aboveground and undergound plant parts. 2,4,5-T showed
minimum plant growth, besides, certaion nodular
structures were observed on the sterm of the plants
treated with 2,4,5-T. Biocrude yield was best in IAA
followed by 2,4,5-T, GA3, CCC, NAA and control.
Application of growth regulators on P. tithymaloides
resulted in slight decrease in chlorophyll over the control
plants. Whereas on E. lathyris they induced favourable
results, regarding chlorphyll .