Search

Plant fossils, mainly leaf impressions, are described for the first time from the Tipam Group of rocks exposed at Subankhata Locality in Manas National Park in Baksa District of Assam. Two new fossil leaves showing affinities with Parashorea stellata Kurz and Shorea ovalis (Korth.) Bl. respectively of the family Dipterocarpaceae, along with a fern frond of Cyclosorus resembling C. proliferus (Retz.) Tard. and C. Chr. of the family Thelypteridaceae are described from the present assemblage. In addition, impressions of a monocot stem and a seed-like structure are also reported. These plant fossils indicate Middle-Late Miocene age and existence of rain forest in the region during the period of deposition of the rock successions.

Laboratory experiment on vermicomposting of distillation waste of java citronella (Cymbopogon winterianus Jowitt.) was carried out employing Eudrilus eugeniae, in two seasonal trials, covering summer and winter periods. Two vermicomposting treatments were conducted in earthen pots, one with citronella plant waste only (CW) and the other, a mixture of citronella waste and cowdung in the proportion 5:1 (CW+CD). Vermicomposting of citronella waste resulted reduction in C/N ratio (83.5-87.7%), enhancement of ash content and a number of macro and micronutrients. The FT-IR spectroscopy of the vermicompost revealed the reduction in aliphatic and aromatic compound as well as increase in amide group after the 105 days stabilization process. The vermicompost output was significantly enhanced in CW+CD treatment than CW treatment. Even, nutrient content of the vermicompost was also higher in CW+CD treatment than CW alone indicating the positive role of cowdung in improvement of quantity and quality.

Soil zone in the vicinity of plant roots is an area in which the chemistry and microbiology are influenced by their growth, respiration, and nutrient exchange known as rhizosphere. In the rhizosphere, bacteria are the most abundant microbes besides other microbes like fungi, protozoa, algae, etc. Plant roots release some nutrient rich substances. These substances could easily be utilized by some bacteria and developed colonies in the root zones of a plant. Such bacteria are known as rhizobacteria. These bacteria help to promote growth and development of the plants. Therefore, these bacteria are known as Plant Growth Promoting Rhizobacteria (PGPR). These bacteria have the ability to produce enzymes and hormones. They can fix nitrogen from the air and able to mineralize nutrients in the soil. Considering such multifunctional role of these bacteria, the application of such bacteria in the field of agriculture is increasing day by day and continuous research is going on to facilitate their application as a reliable component in the management of sustainable agricultural system. The applications of PGPR for improvement of medicinal plants along with their mechanism of action are discussed in this article.

Laboratory investigation on vermicomposting efficacy of Perionyx excavatus for recycling of distillation waste biomass of java citronella (Cymbopogon winterianus Jowitt) was carried out in two seasonal trials i.e. summer and winter periods. The experiment was conducted in earthen pots using a mixture of citronella waste material and cowdung in the proportion of 5:1. A control treatment without earthworms was setup for comparison of the results. The vermicompost had shown 5.8 folds reduction in C/N ratio and 5.6 folds enhancement in ash content. The nutrient contents (N, P, K, Ca and Mg) in the vermicompost had increase in the range of 1.2 – 4.1 fold than the initial level. The FT-IR spectra of the vermicompost confirmed increase in nitrogen rich compounds and decrease in aliphatic/aromatic compounds as compared to the initial level of the biowaste materials. The vermicomposting process is influenced by seasonal variation and summer was more productive than winter.