Review of the biotechnological applications of rice allelopathy in agricultural production

An improvement in the allelopathic potential of rice will have a great impact on both low‐input and high‐input management systems. Allelopathy alone is not likely to replace other weed control practices, but it surely functions as a component of integrated weed management technology. Allеlораthу is thе рrосе?? whеrеbу аn organic сhеm?саl (аllеlосhеm?саl) that is rеlеа?еd from one рlаnt influences the growth and dеvеlорmеnt of other plants. Allelochemical biosynthesis, release, environmental fate and action on other plant species can depend on genetic factors or on the environment and their interaction. As a result of these interactions, allelopathy is a complex phenomenon with limited repeatability. The term “allelopathy” has undergone several changes and it has been defined as any direct or indirect harmful or beneficial effect of a plant on another through the production of chemical compounds that it releases into the environment. Rice allelopathy is one of the modes of interaction between receptor and donor plants and could exert either positive effects or negative effects. The development of genetic modification by enhancing crops with allelopathic traits should be done cautiously, given the ecological risk (untoxic and safe for humans and the ecosystem, crop productivity, the ratio of benefit and cost etc.). Finally, this article reviews the agricultural production system allelopathy of novel applications, including the role of allelochemical consortia and their potential use in no‐tillage cropping systems, cover crops or mulches.     

Development and evaluation of water-in-oil formulation of Pseudomonas fluorescens (FP7) against Colletotrichum musae incitant of anthracnose disease in banana

Banana anthracnose incited by Colletotrichum musae (Berk & Curt.) Arx. is a serious disease both in the field and after harvest. Nineteen isolates of antagonistic bacteria and twelve isolates of yeast were screened for the biocontrol activity against this disease. Pseudomonas fluorescens (FP7) had the highest inhibition rate of mycelial growth of C. musae. Water-in-oil formulation of P. fluorescens (FP7) was developed by adding various oils such as coconut (28.50 %), rice bran (28.50 %) and castor (28.50 %) individually to the bacterial culture. Addition of these oils allowed bacterial populations to survive at various levels up to 210 days of storage, the duration of experiment; whereas in the control treatment (NA broth) it survived at high levels only up to 45 days. Biochemical and antibiotic characterization of P. fluorescens (FP7) in water in oil formulation showed more intensity up to 180 days. Two field trials were conducted to standardize the water in oil formulation. The application of water-in-oil formulation significantly increased the yield (63.56 t/ha), and nutritional factors.     

Ovicidal and oviposition deterrent activities of the flavonoid pectolinaringenin from Clerodendrum phlomidis against Earias vittella

Fractions derived from Clerodendrum phlomidis Linn. F. and isolated compounds from chloroform extract were evaluated against Earias vittella Fab. for their ovicidal and oviposition deterrent activities. There were 12 fractions obtained with silica gel column chromatographic techniques using different solvent systems. Among the fractions, fraction 5 recorded maximum ovicidal activity of 68.49% and oviposition deterrent activity of 100% at 1000 ppm concentration followed by 500 ppm concentration. The active fraction was further purified using HPLC. The purified fraction was subjected to UV, ¹HNMR, ¹³CNMR, IR and EI-Mass spectroscopy and their spectral data confirmed the compound pectolinaringenin which belongs to the flavonoids. The compound pectolinaringenin was screened for its ovicidal and oviposition deterrent activities. It showed maximum ovicidal activity of 64.29% and oviposition deterrent activity of 100% at 100 ppm concentration against E. vittella. To the best of our knowledge, this is the first report of fractions and isolated compounds from C. phlomidis evaluated against E. vittella for their ovicidal and oviposition deterrent activities. The results from the present investigation clearly suggest that the active fraction or the isolated compound could be used to develop a novel pesticidal formulation to control economically important agricultural pests.     

Effect of Probiotics on Growth Performance of Koi Carp (Cyprinus carpio)

A 45-day feeding experiment was conducted to measure the effects of enhancing the diet of koi carp (Cyprinus carpio) fingerlings with lactic acid bacteria, Lactobacillus acidophilus (LAD) and/or brewer's yeast, Saccharomyces cervisiae (SCD). Fish with an average initial weight of 0.26g were fed one of four diets prepared for this study as follows: Diet 1 = basal diet (control); Diet 2 = basal diet + 0.5% LAD; Diet 3 = basal diet + 0.5% SCD; and Diet 4 = basal diet + 0.25% LAD + 0.25% SCD. Significantly (P < 0.05) highest growth rate was achieved in diet 3 followed by diet 4, diet 2, and diet 1. The highest gut microbial load and total heterotrophic count were also higher in diet 3 followed by diet 4, diet 2, and diet 1. Incorporation of 0.5% of brewer's yeast in the basal diet significantly (P < 0.05) improves growth performances and gut microbial load in koi carp.     

A chromogenic column for determining phosphine in air

A 1% solution of mercuric chloride in 0.1% cresol red in ethanol, impregnated onto celite and filled into a glass tube [17.8 cm × 0.2 cm (i.d.)] could accurately determine even 0.06 μg phosphine in air. The samples were injected quickly through a rubber septum cap on the glass tubes under low suction. A red coloured band developed instantaneously, the length being proportional to the concentration of phosphine. A calibration curve was prepared with known concentrations of phosphine. The concentrations present in a fumigation chamber were determined and compared with concurrent chemical analysis. There was close agreement between the two methods. A 1:3 and 1:6 mixture of phosphine and ammonia produced two bands, a yellow ammonia band preceding the red phosphine band. However, ammonia interfered with the proper development of the phosphine band.     

Rapid evaluation of phosphine permeability through various flexible films and coated fabrics

Phosphine permeability through forty-one different flexible films and coated fabrics including polyethylene, cellophane, polyvinyl chloride, rubber and cellulose was tested using a sensitive indicator strip. It diffused through all of them; the rate of diffusion, however, varied among them. Four, namely 0.53 mm thick high molecular weight polyethylene, 0.07 mm thick wax paper laminated with polyethylene, 0.23 mm thick unsupported polyvinyl chloride and 0.44 mm thick polyvinyl chloride treated cloth coated with aluminium paint on the cloth side, were the least permeable. Proper screening of commercially available polymer films before their use for fumigation is emphasised. The discussion of the results attempts to rank the films or laminates on the basis of their relative permeability of phosphine. The physicochemical principles of permeability and rapid evaluation method for assessing the performance of flexible film barriers are also discussed.     

Assessment of tree species diversity and its distribution pattern in Pachamalai Reserve Forest,Tamil Nadu

An increased understanding of the importance of forest diversity for ecosystem services such as medicine, wood, climate control, etc., has lead to greater interest in the study of forests. This study aims to analyze the diversity, composition, and distribution pattern of tree species in Pachamalai Reserve Forest in the Eastern Ghats of Tamil Nadu State. Data were collected in the quadrant method, where 10 × 10 m² plots at different altitudes from 230 to 930 m with 50-m regular intervals were plotted. A total of 73 tree species belonging to 35 families with the density of 1,372 individuals were enumerated from 3 ha. Overall, the most dominant tree species family was Fabaceae (21 species). The highest number in terms of density of tree species was observed for Pongamia pinnata and the most dominant on the basis of basal area was Tamarindus indica. The species inventory was calculated by Shannon-Weiner index (3.916), Simpson index (0.0206), and Margalef index (9.9667). With the increasing altitudinal gradient, the maximum species richness was observed in the middle elevation zone from 580 to 780 m. The results from the study could be helpful for monitoring and sustaining the forest resources, and important in preventing the loss of biodiversity and mitigating climate change.     

First report of leaf blight of noni caused by <Emphasis Type="Italic">Alternaria alternata</Emphasis> (Fr.) Keissler

A severe outbreak of leaf blight was observed in noni crop for the first time in Tamil Nadu and Karnataka states of India during 2008–2009. Based on pathogenicity, morphology and ribosomal DNA spacer sequences, the pathogen was identified as Alternaria alternata (Fr.) Keissler. This report is the first of Alternaria leaf blight of noni.