Present study was aimed to increase latex yield in Euphorbia antisyphilitica. It was observed that GA₃ supported maximum above ground plant height and fresh weight and biomass yield of the plant while the auxins (NAA and IAA) promoted growth and biomass yield over control and the hexane extractables and concluded that the application of growth regulators on Euphorbia antisyphilitica is beneficial to obtain raw material.

1.   Introduction

1.1 To meet the challenge of the increasing demand of energy, alternative sources of energy and new technologies for exploiting the available biomass sources was developed. Certain potential plants were selected and agro technology for their large scale cultivation was developed.

1.2 Energy plantation demonstration project centre has been established in the campus of the University of Rajasthan to conduct experiments on large scale cultivation of selected plants with the objective of developing optimal conditions for their growth and
productivity besides conserving the biodiversity. A three tier model consisting of (i) Laticiferous plants belonging to families Euphorbiaceae, Asclepiadaceae, Apocynaceae, Urticaceae, Convolvulaceae and Sapotaceae rich in hydrocarbons were taken as first colonizers. These plants are – Euphorbia antisyphilitica, E.






lathyris, E. tirucalli, and Pedilanthus tithymaloides. Agro technology for selected plants – was developed improving their growth 3-4 fold. (ii) Non-edible oil yielding plants – Atrophy curcas and Simmondsia chinensis. The seeds of J. curcas contain semidrying oil which can be used as diesel substitute. (iii) Bio-energy plantations of indigenous plants selecting leguminous and non leguminous plants not easily browsed by animals and giving yields up to 7-40 dry tones per annum per ha. at close plantations following short rotation.

1.3 Almost 90 per cent of the energy has origin in petroleum, coal and natural gas. A very small per cent age is derived from nuclear, geothermal and hydroelectric power. Even by liberal estimates the fossil fuel resources are not going to last long. This is indicated by continuous decline in per foot of well drilled and the oil and gas obtained (Calvin, 1984). Some of the options available for producing liquid fuels from biomass are the direct extraction of low molecular, non-polar constituents from plants (Calvin, 1979; Garg and Kumar 1986).

1.4 Growth regulators are commonly employed for rooting in the plants, vegetative propagation and for increasing the overall yield of the plant. Increased biomass and hexane extractables were noted in Euphorbia lathyris with the application of IAA and NAA, respectively (Garg and Kumar, 1987). The object of the present investigation was the study of different fertilizers and growth regulator on Euphorbia antisyphilitica Zucc. 

1.5 E. antisyphilitica is a rich source of hydrocarbons which is used for candellia wax (Johari et al 1990) multiplication of this plant is very poor because it can be multiplied through vegetative cuttings only and the number of such cuttings from selected plants is always a limiting factor.

1.6 The hydrocarbons from Euphorbia are primarily a blend of C₁₅, C₂₀ or C ₃₀ compounds, when subjected to catalytic cracking biocrude yields various products virtually identical to those obtained by cracking naphtha a high quality petroleum fraction i.e. one of the principal raw material used in chemical industries (Nielson et al 1977, 1979). Latex remains in special cells and/ or vessels called laticifers and are a byproduct of photosynthetic conversion of solar energy into biochemical energy.

2.   Methodology

2.1 Four kilogram humus less loamy soil was filled in the earthen pots after mixing with the proper amount of FYM and compost at a rate of 46 to 184 g/pot separately corresponding to the pots was watered to the 60 to 80% of the field capacity. The soil pH was 7.4 and electrical conductivity was 0.58mm hos/cm.

2.2 Growth regulators taken for present study included – IAA, IBA, NAA, and GA₃. Aqueous solution of all these growth regulators was prepared separately. A drop of Triton was added to each solution before spraying it on the plant to improve its retention on plant surface.

2.3 A 25 ppm, 50 ppm and 100 ppm concentration of each growth regulators were sprayed on each plant, of uniform size and age, in such a way that the entire plant became wet. Control plants were sprayed with equal amount of distilled water. Ten replicates were taken for each set of experiment. Plants were sprayed at fortnightly intervals up to a period of six months, i.e. total twelve sprays were given. Plants were harvested after fifteen days of last spray. They were cut into above ground parts and their length, fresh and dry weights were determined.

2.4 Hexane extractables were estimated by following method - Plants were cut from the above ground and their fresh weight and dry weight were determined. The plants were dried in shade for three days or more separately according to their height and fresh weight, till their dry weight became constant. The dried plant material was finally powdered. 10 g of the powdered plant material was packed in thimbles made from what man filter paper no. 1.

2.5 The extraction was done using hexane solvent systems in soxhlet apparatus. Initial extraction was done in hexane for 18h. in a soxhlet apparatus at 40-45 °C. The hexane extractables were collected after 18h and excess of solvent was removed by distillation at 45 °C. The fractions were transferred to the previously weighted vials and were finally dried at 40 °C for 24 h. or till the weights became constant for determination of biocrude.

3. Results and Discussion

3.1 Maximum plant height of above ground parts was observed in GA₃ followed by NAA, IBA and IAA. Spray of different growth regulators resulted in enhanced fresh and dry weight production in aboveground plant parts.

3.2 GA₃ favoured maximum production of aboveground biomass percent dry weight and NAA, IBA and IAA favored the increase in fresh weight over the control. GA₃ promoted maximum growth but did not induce maximum biocrude production which was at the highest level in the plants treated with NAA and IAA.

 

 

 

 

 

Table 4 : Effect of Different growth regulators on plant growth and hexane extractables of Euphorbia antisyphilitica Zucc.

 

 

3.3 Hexane extractables increased in E. antisyphilitica plants treated with IAA and NAA. The auxins, especially 2, 4-D were found to influence strongly the carbohydrate content in Hevea latex (Wort, 1964 and Kumar, 1984). A rise in sucrose level of latex was recorded in auxin treated plants.

3.4 Increase in invertase activity in the treated plants might be responsible for enhanced sucrose utilization in latex serum. And carbohydrates are presumed to be the main source of carbon for hydrocarbon and rubber formation. Thus, the influence of auxin on hydrocarbon formation may be indirect, through increasing invertase, to increase carbohydrate contents of latex, which in turn affect hydrocarbon and rubber formation (Garg and Kumar, 1990 and Johari and Kumar, 1994).

3.5 Gibberellins supported maximum aboveground plant height and fresh weight. Gibberellin treatment is reported to increase the fresh and dry weight of Physalis peruviana L. and P. angulata L. (Kumar, 1995 and Kumar et al., 1995). The effect of GA₃ might be due to its direct action on cell permeability, extension and cell division, or mediated through ethylene production. GA₃ and IAA oppose the inhibitory action of ethylene when they act as a promoter. Hence, the effect may be direct or mediated through enhancement of auxin level and regulation of ethylene action. It has been suggested that the higher concentrations of gibberellins counter-act the effect of abscisic acid which causes growth inhibition. One important feature of regulatory system of hormones is that during the development of many tissues and organs of the plant, the content of physiologically active, i.e. free form of these hormones changes. Probably an interaction between endogenous and exogenous levels of hormones might also play an important role in growth of the plant.

3.6 It was concluded that the application of growth regulators on E. antisyphilitica is beneficial to obtain raw material i.e., hydrocarbons from latex, and to utilise it at commercial scale.  

 

References

1.    Calvin, M. (1984). Renewable fuels for the future, J. Appl. Biochem., 6, 3-18.

2.    Garg J and Kumar A 1987, In: Prog. Photosynth. Res., Proc. Int. Congr. Photosynth. Vol. 4(Ed.) J. Eiggins. p. 403. Nijhoff: Dordrecht, Netherlands.

3.    Garg, J.&A. Kumar (1990). Improving the growth and hydrocarbon yield of Euphorbia lathyris L. in semi-arid regions of Rajasthan. In : Biomass for Energy and Industry Vol. I. (G. Grassi, G. Gosse&G. dos Santos. Eds.). pp. 1.527-1.531. Elsevier Applied Science, London.

4.    Johari, S.&A. Kumar (1994). Influence of growth regulators on biomas and hydrocarbon yield from Euphorbia antisyphilitica (Zucc), J. Phytol Res. 7 : 65-68.

5.    Kumar, A. (1995). Cultivation of hydrocarbon yielding plants in Rajasthan as an alternative energy source. J. Environment & Pollution 2, 67-70.

 

6.    Kumar, A.S. Johari & S. Roy (1995). Production and improvement of bioenergy sources. J. Indian. Bot. Soc. 74A: 233-234.

7.    Wort DJ 1964, In: The Physiology and Biochemistry of Herbicides (Ed.) L.J. Audus, p. 291, Academic Press, London.

8.    Calvin M 1979 Petroleum plantations for fuel and materials. Bioscience 29 533-537.

9.    Garg J & A Kumar 1986 Studies on biomass production and improvement in biocrude content Proc. Workshop on Petrocrops New Delhi p 69-81.

10.    Johri S, S Roy & A Kumar 1990 Influence of edaphic and nutritional factors on groeth and hydrocarbon yield of Euphorbia antisyphilitica Zucc. In Proc. Biomass for Energy and Industry Vol. I (Grassi G, G Gosse & G dos Santes eds) Elsevier Appl Sci, London p 1.522-1.526.

11.    Nielsen P E, H Nishimura, J W Otvos & M Calvin 1977 Plant crops as a source of fuel and hydrocarbon materials. Science 198 942-944.

12.    Nielsen P E, H Nishimura, Y Liang & M Calvin 1979 Steroids from Euphorbia and other latex bearing plants. Phytochemistry 18 103-104.

13.    Kumar A 1984 Hydrocarbons from plants in arid and semiarid regions In : Applications on Science and Technology for Afforestation Act Jaipur, p 81-86.

Table 4 : Effect of Different growth regulators on plant growth and hexane extractables of Euphorbia antisyphilitica Zucc.

 

 

14.