Influence of crop combinations and soil factors on diversity and association of arbuscular mycorrhizal fungi in arecanut based cropping systems

Arbuscular mycorrhizal (AM) species diversity and extent of association were investigated in arecanut based cropping systemsdiffering in crop combinations. The study was carried out in farmers’ fields under acidic soil conditions at three locations representinglow land (Maneikkara), midland (Cheruvanjeri) and high land (Nedumpoyil) regions of Kannur district in Kerala. The croppingsystems in Maneikkara, Cheruvanjeri and Nedumpoyil had arecanut-banana, arecanut-banana-black pepper and arecanut-bananablackpepper-cardamom as component crops. AM spore load and root colonization differed significantly in arecanut in the threecropping systems. Highest spore load was recorded in Maneikkara followed by that in Nedumpoyil and Cheruvanjeri regions.Crops which formed components of the cropping system differed in root colonization levels, with banana recording the highestlevel, followed by arecanut, black pepper and cardamom. Colonization pattern was Paris type in all crops, but varied with respectto predominance of arbuscules in arecanut and vesicles in banana. Arecanut-black pepper-banana system at Cheruvanjeri inmidland was superior with respect to species diversity and species richness as evidenced by Shannon–Weiner index (Hs), Simpson’sindex of diversity (Ds) and species richness index. Arecanut-banana cropping system in Maneikkara in low land had low level ofspecies diversity and species richness, indicating the combined influence of crop combinations and soil factors such as N and P onAM diversity and distribution. Rhizophagus fasciculatus, Funneliformis geosporum, F. mosseae, Glomus macrocarpum,G. aggregatum, G. multicaule, G. glomerulatum and Acaulospora bireticulata were the AMF species identified from the arecanutcropping systems. F. geosporum was the most abundant (29-50%) species in the cropping system. The relative occurrence andabundance of AM species varied significantly with respect to the crops and locations

Antagonistic activity of coconut rhizospheric and endophytic Bacillus spp. against Ganoderma applanatum and Thielaviopsis paradoxa

A screening study was carried out to detect the antagonistic potential of Bacillus spp. against Ganoderma applanatum and Thielaviopsis paradoxa, fungal pathogens of coconut. A total of 327 heat resistant, endospore producing bacilli were isolated from the rhizospheric soil and roots of coconut growing in Kerala, Tamil Nadu, Karnataka, Andhra Pradesh and Maharashtra. All the isolates were tested for antifungal activity against G. applanatum and T. paradoxa by dual cultural technique on nutrient agar medium. The zone of inhibition was measured and percentage of inhibition was calculated. More than 90 % of the rhizospheric and root endophytic isolates were found to effectively inhibit the mycelial growth of G. applanatum, with a maximum inhibition zone of 12 mm and percentage inhibition ranging from 44 to 91. About 86 % of the isolates inhibited the mycelial growth of T. paradoxa, with a maximum inhibition zone of 14 mm and percentage inhibition ranging from 42 to 93. Further tests of potent antagonists revealed that more than one mode of mechanisms like production of chitinase, siderophores, HCN, antibiotics, ammonia, β-1,3- glucanase and salicylic acid may be involved in the antagonistic activities. The results of this study revealed 13 Bacillus spp. having potential for use as biocontrol agents against G. applanatum and T. paradoxa, fungal pathogens of coconut

Isolation and identification of spore associated bacteria (SAB) from Glomus and Gigaspora spp. in coconut and arecanut based cropping systems

Arbuscular mycorrhizal symbiosis is exhibited by 80% of the terrestrial plants. The spores of arbuscular mycorrhizal fungi (AMF) form a unique microhabitat for the colonization by many species of bacteria. The present study was undertaken to isolate and identify spore associated bacteria (SAB) and evaluate their functional role in AMF-host interactions with respect to germination of spores. Coconut and arecanut based cropping systems under organic management practices in farmer’s field in Kasaragod district, Kerala and high density multi species cropping system (HDMSCS), CPCRI farm were selected for the study. The results revealed that AMF spore load of a particular cropping system increase with the number of intercrops. Spore associated bacteria (SAB) were isolated from the cytoplasm of surface sterilized spores of Glomus and Gigaspora spp. Identification based on BIOLOG and 16S rRNA sequencing revealed the presence of bacteria - Citrobacter amalonaticus, Staphylococcus arlettae, Bacillus subtilis, Bacillus amyloliquefaciens, in association with spores of Glomus spp. Corynebacterium coyleae, Bacillus cereus and Bacillus subtilis were found to be associated with Gigaspora spp. In vitro studies to determine the germination potential in spores showed the maximum results with Bacillus cereus GiPHD1 and Citrobacter amalonaticus GLNCB1 with 40% increase over control

In vitro antagonism of rhizospheric fluorescent pseudomonads of coconut against Ganoderma applanatum and Thielaviopsis paradoxa, fungal pathogens of coconut

A total of 156 fluorescent pseudomonads were tested for antagonistic activity towards G. applanatum and T. paradoxa in a dual-plate assay on King’s B agar plates. Eight percent of the total fluorescent pseudomonads showed antagonism towards G. applanatum (inhibition ranging from 39% to 73%) and 16% of the isolates inhibited T. paradoxa in the range of 20% - 76%. Moreover, eight percent of the fluorescent pseudomonads significantly inhibited both pathogens tested. They were found to possess some important biocontrol traits such as HCN, siderophores, ammonia and antibiotics. Among them fluorescent Pseudomonas spp. KiSF 17 and KiSF 16 exhibited strong antagonistic activity. They were identified as P. aeruginosa by Biolog® GEN III microplate identification system and confirmed by 16S rDNA sequencing. The present studies revealed the survival of useful bacterial antagonists in the rhizosphere of coconut palm, which have the potential to be used as a biocontrol agent

Different solutions lead to similar life history traits across the great divides of the amniote tree of life

Amniote vertebrates share a suite of extra-embryonic membranes that distinguish them from anamniotes. Other than that, however, their reproductive characteristics could not be more different. They differ in basic ectothermic vs endothermic physiology, in that two clades evolved powered flight, and one clade evolved a protective shell. In terms of reproductive strategies, some produce eggs and others give birth to live young, at various degrees of development. Crucially, endotherms provide lengthy parental care, including thermal and food provisioning-whereas ectotherms seldom do. These differences could be expected to manifest themselves in major differences between clades in quantitative reproductive traits. We review the reproductive characteristics, and the distributions of brood sizes, breeding frequencies, offspring sizes and their derivatives (yearly fecundity and biomass production rates) of the four major amniote clades (mammals, birds, turtles and squamates), and several major subclades (birds: Palaeognathae, Galloanserae, Neoaves; mammals: Metatheria and Eutheria). While there are differences between these clades in some of these traits, they generally show similar ranges, distribution shapes and central tendencies across birds, placental mammals and squamates. Marsupials and turtles, however, differ in having smaller offspring, a strategy which subsequently influences other traits

Design and Synthesis of Metal Complexes of (2 E

The photocatalytic degradation has been considered to be an efficient process for the degradation of organic pollutants, which are present in the effluents released by industries. The photocatalytic bleaching of cationic dye methylene blue was carried out spectrometrically on irradiation of UV light using Cu(II), Ni(II), and Co(II) complexes of (2E)-2-[(2E)-3-phenylprop-2-en-1-ylidene]hydrazinecarbothioamide (HL). The effects of pH and metal ion were studied on the efficiency of the reaction. Cu(II) complex shows better catalytic activity and the highest percentage degradation (~88.8%) of methylene blue was observed at pH 12. A tentative mechanism has also been proposed for the photocatalytic degradation of methylene blue