Biomass currently supplies about a third of the developing countries’ energy varying from about 90% in countries like Uganda, Rawanda and Tanzania, to 45 percent in India, 30 percent in China and Brazil and 10-15 percent in Mexico and South Africa. The crucial questions are whether the two billion or more people who are now dependent on biomass for energy will increase. The fact that 90 percent of the worlds population will reside in developing countries by about 2050 probably implies that biomass energy will e with us forever. Planting of more trees in forest reserves for reducing global warming has been universally accepted, the idea being that carbon-dioxide 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.
1.1 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) (Anonymous 1995). 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 (Anonymous, 1995).
1.2 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.
1.3 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.
1.4 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.
1.5 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
1.6 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.
· 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 these plants
· Certain potential plants were selected and attempts were made to develop agrotechnology for their large scale cultivation (Kumar 1984b, c, 1994a, b, 1998; Kumar et al., 1995, 1998; Roy, 1998). 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.
Hydrocarbon yielding plants included :
i. Euphorbia lathyris Linn.
ii. Euphorbia tirucalli. Linn.
iii. Euphorbia caducifolia Haines.
iv. Euphorbia nerifolia Linn.
v. Pedilanthus tithymalides Linn.
vi. Pedilanthus tithymalides Linn.
vii. Calotropis procera (Ait.). R. Br.
viii. Calotropis gigantea (Linn) R. Br.
High molecular weight hydrocarbon yielding plants
Parthenium argentatum Linn
1. Non edible for yielding plants
Jatropha curcas
Simmondsia chinenesis
2. Short rotation energy plants
Tecomella undulata
Prosopis juliflora
Pithocellobium dulce
Azadirachta indica
Dalbergia sisso
3. Acacia tortilis
Holoptelia integrifolia
Parkinsonia aculeata
Cassia siamea
Albizzia lebbek
Acacia nilotica
3.1 Propagation
Ø 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 upto 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 (Kumar 1990). 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 (Johari and Kumar, 1992).
3.2 Edaphic Factors
Ø Among different soil types, sand was best for the growth of E. lathyris (Garg and Kumar, 1990) and P. tithymaloides (Rani et al, 1991) 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 (Johari et al., 1990), while red+sand combination in equal amounts was best for P. tithymaloides (Rani and Kumar, 1992, 1994a). A mixture of gravel + sand favoured maximum increase in plant height, fresh weight and dry weight in E. lathyris (Garg and Kumar, 1990; Kumar and Garg, 1995). Environmental factors influenced the growth and yield of Calotropis procera (Rani et al, 1990).
3.3 Growth Curve
Ø 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 hexane extractable.
3.4 Fertilizer application
Ø Application of NPK singly of in 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 (Kumar and Kumar, 1983, 1986). 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 (Garg and Kumar, 1990) and P. tithymalides (Rani and Kumar, 1994a). 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 (Johari et al., a, 1990; Johari and Kumar, 1994a). Addition of FYM alone and with combination of urea improved FMY+Urea applications improved the productivity in comparison with FMY increased the plant height, fresh weight and dry weight to varying degrees. Hexane and methanol extractable also increased (Garg and Kumar ,1986, 1987b).
3.5 Influence of Salinity
Salinity stress studies were also made of on Euphoriba tirucalli (Kumar and Kumar 1986). Salinity was applied in the form of irrigation water. Lower concentrations of salinity improved plant growth of E. antisyphilitica (Johari et al, 1990, 1994b). 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 (Garg and Kumar, 1989a, 1990).
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 (Rani et al., 1991).
3.6 Effect of growth regulators
Spray of growth regulators resulted in enhanced fresh and dry weight production (Johari et al, 1991). 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.
Ø Whereas on E. lathyris they induced favourable results, regarding chlorphyll (Garg and Kumar, 1987a).
Ø In E. lathyris IBA caused maximum fresh weight productivity followed by IAA, GA3 and NAA. NAA sprayed plants exhibited more production of hexane extractable. Favourable influence of growth regulators was also observed in sugar yield, maximum being in NAA followed by IBA, GA3 and IAA (Garg and Kumar 1987b)
3.7 Disease affecting hydrocarbon yielding plants
The cultivation of these plants suffers from plant pathogenic diseases affecting at root level. Investigations of pathogenicity and control aspects of charcoal root of E. lathyris (Garg and Kumar, 1987c); E. antisyphilitica (Johari and Kumar 1993) were carried out.
3.8 Tissue culture techniques
Plant tissue culture has been successfully employed to achieve rapid clonal propagation of E. lathyris (Kumar and Joshi, 1982), Pedilanthus tithymaloides (Rani and Kumar, 1994b), Eucalyfotus camaldulendis (Bhargava and Kumar, 1984) and E. antisyphilitica (Johari and Kumar 1994c). Likewise propagation of jojoba has also been carried out (Roy, 1992a).
Jatropha curcas Linn is potential diesel fuel oil yielding plant and details about this are given in Roy and umar (1988) and Roy (2000 this volume)
3.9 Bio-diesel production
First efforts to cultivate hydrocarbon producing plants for fuel production were made by Italians in Ethiopia and French in Morocco. Later on Calvin and his collaborators have revived the idea again and have advocated the study of petro-crops as a possible feedstock for petroleum like materials. Presently the largest fuel programme is in Brazil where government currently spends a considerable amount on subsidizing the production of alcohol, mostly from biomass of sugarcane. Production was estimated to increase so muich that around 11 to 14 million cars will use alcohol (with gasoline) by the year 2000 (Korbitz, 1996).
Recently about 30 thousand tones of rape biofuel yearly is produced at the industrial chemical factories in Poland (Grazybek et al., 1996). The important source investigated during last years from 1993 to 1996 included.
of water, produce sufficient biomass and are unpalatable to the cattlefolk due to their sticky latex. Degraded and denuded soils are no hindrance to their growth.
Jatropha curcas Linn is potential diesel fuel oil yielding plant and details about this are given in Roy and Kumar (1988) and Roy (2000 this volume)4.3
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