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March 2019 – Vol. 102 No. 1

The legume tree Pongamia pinnata (also called Millettia pinnata) is a non-food crop that can grow on marginal land not destined for the cultivation of food crops. It is an important candidate for the production of biofuels (such as biodiesel and aviation fuel) from its oil-rich seeds. Pongamia is resilient against abiotic stresses such as drought, salinity and acidity. An important trait that establishes Pongamia as a superior biofuel feedstock is its ability to grow in marginal, nitrogen-limited soils. This growth ability is attributed to the nitrogen-fixation activity of root nodules developed by symbiosis with bacterial microsymbionts broadly known as rhizobia.

Pongamia-Rhizobia symbiosis was improved by the inoculation of Rhizobium-related strain PR-UQ-05 to pongamia, which naturally occurs in soils across Queensland. Pongamia pinnata produced active and efficient nodules using this strain when cultivated with low levels of nitrate and even under saline conditions. Nodules started to form within three weeks of inoculation and became mature (nitrogen fixing) between 8-12 weeks. Pongamia may also utilize ureides such as allantoin, aside from amides, to transport fixed nitrogen in the plant, as determined by ureide analysis. Lastly, the assessment of the process of nitrogen fixation through – (i) acetylene reduction assay, (ii) N-difference method and (iii) isotope dilution, proved that Pongamia fixed sufficient amounts of nitrogen for growth and reproduction. Therefore, Pongamia can now be commercially grown without the addition of potentially environmentally harmful and expensive chemical fertilizers, since its symbiotic nitrogen fixation has been established and improved with the use of an efficient rhizobia strain and grown under favourable nodulation conditions.

(Photographs courtesy of Phoebe Nemenzo-Calica, former PhD student at the University of Queensland, Australia and currently a faculty member of Ateneo de Davao University, Roxas Avenue, Davao City, Philippines 8000)

List of Articles

Optimization of Process Parameters for the Extraction of Anthocyanins from Black Rice Bran Using Response Surface Methodology
Rodel M. Bulatao, John Paulo A. Samin, Reniel P. Tubera, Mac Michael M. Rubio, Dina C. Romano and Rosalie R. Rafael

Comparative Assessment of Biological Nitrogen Fixation in Pongamia pinnata, a Biofuel Legume Tree
Phoebe N. Calica and Peter M. Gresshoff

Cytotoxicity of Peperomia pellucida (L.) HBK Extracts on Cancer Cell Lines and Their Effects on cfos and cjun Genes
Sarah Patricia C. Buhian, Glenn G. Oyong and Esperanza C. Cabrera 

Allelopathic Influence of Sorghum Aqueous Extract on Growth, Physiology and Photosynthetic Activity of Maize (Zea mays L.) Seedling
Muhammad Kamran, Zahid Ata Cheema, Muhammad Farooq, Qasim Ali, Muhammad Zohaib Anjum and Ali Raza

Evaluation of Carcass Characteristics and Meat Quality Traits in Lechon-Size Black Tiaong and Kalinga Native Pigs (Organic Farm) and Landrace, Large White, and Their F1 Crosses (Conventional Farm)
Orville L. Bondoc, Jorge Michael D. Dominguez, Cristy M. Bueno and Rene C. Santiago

Detection of Multidrug-Resistant Salmonella sp. in Philippine Native Swine (Sus scrofa L.) from Selected Municipalities of Quezon Province, Philippines
Czarina Anne E. de Mesa, Vachel Gay V. Paller and Rina B. Opulencia

Radio Frequency Dielectric Heating Combined with Ultraviolet Irradiation Induces Changes in Structural, Oxidative and Antioxidant Properties of β-Lactoglobulin
Yuwei Wu, Yuanrong Zheng, Danfeng Wang, Zhenmin Liu and Yun Deng

Role of Morphological Traits and Biochemical Contents in Imparting Resistance Against Cucumber Mosaic Virus and Zucchini Yellow Mosaic Virus in Cucumber Genotypes
Muhammad Mozamil, Muhammad Azam Khan, Muhammad Ashfaq and Maila Al Saba Shah

Native Entomopathogenic Fungi Isolated from Duzce, Turkey and Their Virulence on the Mealworm Beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae)
Salih Karabörklü, Nedim Altin and Yeşim Keskin

Research Note

Elimination of the Asian Subterranean Termite [Coptotermes gestroi (Blattodea: Rhinotermitidae)] Using Above Ground Chlorfluazuron Baits
Mark Jun A. Rojo and Menandro N. Acda


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