A comparative appraisal of three important oil yielding plants for their biodiesel potential.

In the present scenario, alternative energy sources are required to achieve the future economic prosperity where shortage of fossil fuels will be a limiting factor and hamper the global economic growth. Therefore, interest in biofuel is increasing continuously. The best way of sustainable development is fossil fuel supplementation with biodiesel to reduce the fossil fuel demand. Biodiesel is a clean burning, ester-based, oxygenated fuel derived from natural and renewable sources. Till now, majority of the people have worked on the biodiesel derived from edible oil. Instead of using edible oil, non-edible oil needs to be explored as feedstock for biofuel because half of the world's population is unable to afford the food oil as feedstock for fuel production. Looking at the significance of biodiesel and the resources of biofuel, in this paper, a comparative exhaustive study has been reported with for three important plants, namely Jatropha curcas, Pongemia pinnata and Balanites aegyptiaca. These plants were selected based on their biodiesel potential, availability, cultivation practices and general information available. The present study involves scientometric publications, comparison of fatty acid composition and biodiesel parameters. We have also compared climatic conditions for the growth of the plants, economic feasibility of biodiesel production and other ecological services. The study paves a way for sustainable solution to policy makers and foresters looking for selection of plant species as bioenergy resource.

Comparative study on growth, yield and carbon content in Pongamia pinnata under water stress and urea supplementation.

The growth, yield, and carbon content of eight-month old seedlings of Pongamia pinnata were compared under water and urea supplementation. One set of plants were subjected to water stress condition (WS), whereas the other supplied with 2 g of urea (WS+U) under WS. Both the experimental set ups were exposed to varying treatment levels which include full irrigation (100%, control) followed by 75% (T1), 50% (T2), 25% (T3) and 12.5% (T4). The growth, leaf area and relative water content were maximum under WS when compared to WS+U (p < 0.001). The maximum biomass was produced in the seedlings under WS in control (1.68 g) followed by T1 (1.38 g), T2 (1.53 g), T3 (0.93 g) and T4 (0.73 g). A significant (p < 0.001) reduction in biomass production was observed in WS+U in control (1.28 g), T1 (0.66 g), T2 (1.13 g) and T3 (0.44 g). T4 of WS+U showed similar biomass (0.73 g) as that of T4 of WS. Under WS, the highest biomass allocation was recorded in shoots followed by leaves and roots. Similar trend was observed in WS+U. However, the percentage of allocation was more in the roots of WS+U (27.2%) when compared to WS (22.24 %). The highest amount of carbon content was observed in control plants treated under WS (9.59 g) followed by control plants of WS+U (7.31 g) (p < 0.001). The results of the preliminary study clearly indicated that P. pinnata seedlings were able to cope-up with water stress conditions without urea application and can perform well in 50% water availability and is best suited for the plantation programs in the semi-arid ecosystems.

Tree legumes as feedstock for sustainable biofuel production: Opportunities and challenges.

Concerns about future fossil fuel supplies and the environmental effects of their consumption have prompted the search for alternative sources of liquid fuels, specifically biofuels. However, it is important that the sources of such biofuel have minimal impact on global food supplies, land use, and commodity prices. Many legume trees can be grown on so-called marginal land with beneficial effects to the environment through their symbiotic interaction with "Rhizobia" and the associated process of root nodule development and biological nitrogen fixation. Once established legume trees can live for many years and some produce an annual yield of oil-rich seeds. For example, the tropical and sub-tropical legume tree Pongamia pinnata produces large seeds (∼1.5-2g) that contain about 40% oil, the quality and composition of which is regarded as highly desirable for sustainable biofuel production. Here we consider the benefits of legume trees as future energy crops, particularly in relation to their impact on nitrogen inputs and the net energy balance for biofuel production, and also ways in which these as yet fully domesticated species may be further improved for optimal use as biofuel feedstock.

[Soil nitrogen mineralization under different land use patterns in Xishuangbanna].

Nitrogen (N) cycle is very important for forest ecosystem, and soil N mineralization rate is often used as the index of soil N availability and its losses. Using Close-Top incubation method, we measured the N mineralization rate in soils (0-15 cm) of monsoon evergreen broadleaf forest, seasonal rain forest, rubber plantation, heavily disturbed seasonal rain forest, Millettia laptobotrya secondary forest and upland rice field. The results showed that the net N mineralization rate and N nitrification rate were decreased in the sequence of heavily disturbed seasonal rain forest > Millettia laptobotrya secondary forest > seasonal rain forest > monsoon evergreen broadleaf forest > rubber plantation > upland rice field. Rubber plantation and upland rice field were the most seriously disturbed land use patterns. Their soil N storage and mineralization rate were very low and exhibited significant variations, compared with other land use patterns. Lower net N mineralization rate correlated with lower N storage, and also, with lower fungi numbers. The N mineralization rate in disturbed forest soil which had recovered for several years was similar to that in primary forest soil, but decreased significantly when the forests were converted to agricultural land.