Litter dynamics of six multipurpose trees in a homegarden in Southern Kerala, India     

Sheeba Rebecca Isaac  M. Achuthan Nair 《Agroforestry Systems》2006,67(3):203-213

Multipurpose trees, the integral components of homegardens, contribute significantly to the closed nutrient cycling processes and sustainability of the ecosystem. Although, the litter production and probable nutrient returns via litter in homegardens have been documented, quantification and characterization of the decomposition and bioelement release from the litter have received relatively little scientific attention. The objective of the present study is to explore the litter dynamics of six locally important multipurpose trees (Mangifera indica L., Artocarpus heterophyllus Lamk., Anacardium occidentale L., Ailanthus triphysa Dennst., Artocarpus hirsutus L. and Swietenia macrophylla L.), in an agroforestry homegarden in Southern Kerala, India. Litterfall and nutrient additions in the six species ranged from 383 to 868 g m⁻² yr⁻¹, nitrogen, 6.4 to 8.8, phosphorus, 0.17 to 0.42 and potassium, 1.1 to 2.8 g m⁻² yr⁻¹. The annual litter output in the homegarden was 425 kg with A. hirsutus, M. indica, A. heterophyllus and A. occidentale recording significantly higher litter and nutrient additions. Leaf litter decay studies revealed A. heterophyllus and A. occidentale to be the most labile litter species and S. macrophylla the most recalcitrant. The decay rate coefficients varied significantly among the species. Foliage decomposition rates related to the initial chemical composition of the litter revealed best correlation with lignin. NPK release was almost complete by the end of decay in all species inspite of the initial phases of accumulation observed for nitrogen and phosphorus. Two-way analysis of variance test revealed significant differences in the contents of the three elements as a function of species and time elapsed. Macronutrients were released in the order K>N/P. The higher rates of decay and nutrient turnover in M. indica, A. heterophyllus and A. occidentale foliage indicated the potential of using these species’ litter as nutrient inputs in agriculture while A. triphysa, A. hirsutus and S. macrophylla perform better as organic mulches taking a longer time for decay and hence nutrient release.  相似文献   

Multipurpose tree prunings as a source of nitrogen to maize under semiarid conditions in Zimbabwe     

P. L. Mafongoya  P. K. R. Nair  B. H. Dzowela 《Agroforestry Systems》1996,35(1):31-46

When multipurpose-tree (MPT) prunings are used as a source of nitrogen to annual corps in agroforestry systems, it is important that high levels of N recovery are attained. In order to test the effect of pruning quality and method of pruning application on N-recovery rates, a field experiment was conducted using prunings of five MPT species and two methods of application (surface versus incorporation). There was an interaction of pruning quality and method of pruning application on N recovery and maize grain yield. For most MPT species used, incorporated prunings gave high nitrogen recovery compared to surface applied prunings. In order to achieve synchrony between N supply from prunings and N demand by a maize crop, relatively large amounts of N should be released into the soil before peak N demand by the maize crop. This could be achieved by incorporating adequate quantities of high quality prunings such as those ofCajanus cajan andLeucaena leucocephala. Florida Agricultural Experiment Station Journal Series Number R-05489.  相似文献   

Lipoperoxidation and cyclooxygenases 1 and 2 inhibitory compounds from Iryanthera juruensis     

Silva DH  Zhang Y  Santos LA  Bolzani VS  Nair MG 《Journal of agricultural and food chemistry》2007,55(7):2569-2574

Plants from Iryanthera genus have been traditionally used as food supplements by South American Indians. The MeOH extract of leaves of Iryanthera juruensis, one of the plants endemic to the Amazon region and consumed in Brazil, and the hexane extract from its seeds inhibited lipid peroxidation (LPO) and cyclooxygenase (COX-1 and -2)) enzymes in in vitro assays. Further analyses of these extracts yielded 5-deoxyflavones (1-5) from the leaf extract and sargachromenol (6), sargaquinoic acid (7), a novel juruenolic acid (8), omega-arylalkanoic acids (9a-c), and the lignan guaiacin (10) from the seed extract. Compounds 3-5 inhibited LPO by 86%, 77%, and 88% at 10 ppm, respectively, and compounds 6 and 9a-c showed inhibition at 76% and 78% at 100 ppm, respectively. However, compounds 7 and 8 were inactive and lignan 10 exhibited LPO inhibitory activity by 99% at 100 ppm compared to commercial antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and vitamin E. The flavones 1-5 also inhibited COX-1 and -2 enzymes by 50-65% at 100 ppm. Compound 6 showed high but nonselective inhibition of COX-1 and COX-2 enzymes, when compared to aspirin and Celebrex, a nonsteroidal anti-inflammatory drug (NSAID). Compounds 7 and 10 inhibited COX-1 by 60% and 65% and COX-2 by 37% and 18%, respectively, whereas compounds 8 and 9a-c showed little or no activity against these enzymes.  相似文献   

First report of Calonectria cerciana causing leaf blight of Eucalyptus in northern India     

Ratnaboli Bose  Shailesh Pandey  Pooja Joshi  Sabyasachi Banerjee  Amit Pandey  Maneesh S. Bhandari 《Forest Pathology》2021,51(1):e12658

Eucalyptus spp. and their hybrids are frequently cloned and mass planted across farmland tracts and commercial plantations in northern India. It is a viable feeder species to the paper and pulp industries in this region. In 2018 and 2019, during field surveys conducted in northern India, a serious leaf blight disease was frequently observed in E. tereticornis plantations. Isolation from the blighted leaf samples consistently yielded fungal isolates having Calonectria‐like morphology. Morphological features coupled with sequence analysis of partial β‐tubulin (TUB2) and partial translation elongation factor‐alpha (TEF1) gene regions of two fungal isolates confirmed the species as Ca. cerciana. In detached leaf assays and glasshouse inoculation experiments, both isolates produced symptoms similar to those observed on the naturally infected leaves. Koch's postulates were fulfilled by re‐isolating Ca. cerciana from the inoculated leaves. This work is the first to confirm that Ca. cerciana is associated with a serious leaf blight disease of Eucalyptus in northern India and is an important addition to the taxonomy of Calonectria fungi in India.  相似文献   

A B-cell targeting virus disrupts potentially protective genomic methylation patterns in lymphoid tissue by increasing global 5-hydroxymethylcytosine levels     

Nick A Ciccone  William Mwangi  Alexey Ruzov  Lorraine P Smith  Colin Butter  Venugopal Nair 《Veterinary research》2014,45(1)

The mechanisms by which viruses modulate the immune system include changes in host genomic methylation. 5-hydroxymethylcytosine (5hmC) is the catalytic product of the Tet (Ten-11 translocation) family of enzymes and may serve as an intermediate of DNA demethylation. Recent reports suggest that 5hmC may confer consequences on cellular events including the pathogenesis of disease; in order to explore this possibility further we investigated both 5-methylcytosine (5mC) and 5hmC levels in healthy and diseased chicken bursas of Fabricius. We discovered that embryonic B-cells have high 5mC content while 5hmC decreases during bursa development. We propose that a high 5mC level protects from the mutagenic activity of the B-cell antibody diversifying enzyme activation induced deaminase (AID). In support of this view, AID mRNA increases significantly within the developing bursa from embryonic to post hatch stages while mRNAs that encode Tet family members 1 and 2 reduce over the same period. Moreover, our data revealed that infectious bursal disease virus (IBDV) disrupts this genomic methylation pattern causing a global increase in 5hmC levels in a mechanism that may involve increased Tet 1 and 2 mRNAs. To our knowledge this is the first time that a viral infection has been observed to cause global increases in genomic 5hmC within infected host tissues, underlining a mechanism that may involve the induction of B-cell genomic instability and cell death to facilitate viral egress.  相似文献   

Molecular diversity in Indian sugarcane cultivars as revealed by randomly amplified DNA polymorphisms   总被引：5，自引：0，他引：5  

N.V. Nair  A. Selvi  T.V. Sreenivasan  K.N. Pushpalatha 《Euphytica》2002,126(2):219-225

Genetic diversity in 28 prominent Indian sugarcane varieties cultivated under a wide range of agroclimatic conditions, was studied using 25 RAPD markers. The mean genetic distance among the 28 varieties was only 29.31%, implying that a large part of the genome is similar among the varieties. This probably arises from the lack of parental diversity, with few clones which are themselves related, contributing to the parentage of these varieties. The parentage of the varieties did not contribute significantly to the clustering pattern. Varieties belonging to the same parentage were grouped under different clusters while varieties from different parentages were grouped under the same cluster. The tropical and subtropical identities of the varieties also did not contribute to the clustering pattern as individual clusters included varieties from both tropics and subtropics. This shows that genetically similar varieties are present in both the regions. Among the varieties, Co 7717 was found to be totally distinct and divergent from rest of the varieties. The study reveals the limited genetic base of the current Indian commercial varieties and the need to diversify the genetic base by using new sources from the germplasm. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Identification of soybean strains resistant to Xanthomonas campestris pv. glycines     

Arun Sharma  P. M. Nair  S. E. Pawar 《Euphytica》1993,67(1-2):95-99

Summary Soybean germplasm was screened for resistance to bacterial pustule disease. The etiological agent, Xanthomonas campestris pv. glycines, was isolated from the leaves of field grown soybean in Maharashtra, India. The screening of soybean stocks was carried out by excised leaf inoculation method. A differential susceptibility to the pathogen was observed in the tested stocks. Two stocks P-4-2 and P-169-3 were found to be completely resistant to the pathogen and displayed an incompatible reaction. Four cultivars, EC-34160, Bragg, Kalitur and PK-472 displayed moderate resistance and the remaining stocks were susceptible to the attack of the pathogen. The stocks P-4-2 and P-169-3 remained resistant even to a high concentration of 10⁹ colony forming units (cfu)/ml of the pathogen.  相似文献   

Cloning of a gene encoding LRR protein and its validation as candidate gall midge resistance gene,Gm4, in rice     

Dhanasekar Divya  Kudapa Himabindu  Suresh Nair  Jagadish S. Bentur 《Euphytica》2015,203(1):185-195

  相似文献   

Seed set and seedling variation in greater yam (Dioscorea alata L.)     

K. Abraham  S. G. Nair  M. T. Sreekumari  M. Unnikrishnan 《Euphytica》1986,35(2):337-343

Summary A high degree of fruit and seed set was obtained in Dioscorea alata L. by hand pollination. The sexual progeny was studied in comparison with the clonal plants. In general, the seedlings were poor in growth vigour, flowering and tuber production but the variations observed in the different characters were unprecedented, indicating scope for efficacious genetic improvement in this vegetatively propagated crop.  相似文献   

Genetic analysis of a CSR10 (indica) × Taraori Basmati F3 population segregating for salt tolerance using ISSR markers     

Amit Kaushik  Navinder Saini  Sunita Jain  Poonam Rana  R.K. Singh  Rajinder K. Jain 《Euphytica》2003,134(2):231-238

Segregation for salinity tolerance and ISSR markers based molecular polymorphism were investigated in a F₃ plant population raised via single-seed descent method from a cross between salt-tolerant indica rice variety CSR10 and salt-susceptible premium traditional Basmati rice variety Taraori Basmati HBC19. A total of 130 F₃plants were evaluated individually for salinity tolerance on 1–9 scale on the basis of seedling growth parameters; the average score ranged between 1.7 to 8.3. Frequency distribution curve obtained using the salinity tolerance data of F₃ population and a chi-square analysis, showed a good fit to a normal distribution. Eleven plants each in the category of salt-tolerant and salt-susceptible were selected from the segregating F₃ population for ISSR marker analysis. A total of 149 bands (4–11 bands per primer) ranging from 200 to 3530 bp were scored for the two rice varieties and the selected CSR10 × HBC19 segregating F₃ plants using 26 ISSR primers. Of these, 89 were monomorphic and 60 were polymorphic. Of the 60 polymorphic bands,36 and 20 bands were specific to CSR10 andHBC19 respectively. The remaining four bands were amplified using UBC primers 810,848, 853 and 886 and present in only some of the CSR10 × HBC19 F₃ plants. Notably, ISSR primers with dinucleotide repeat motif and 5'-anchored end amplified more number of bands (7.0 bands/primer) compared to3'-anchored dinucleotide primers (5.4bands/primer), but 3'-anchored dinucleotide primers revealed higher level of polymorphism (2.6 polymorphic bands/primer) compared to 5'-anchoreddinucleotide primers (1.43 polymorphic bands/ primer). While distribution of majority of the polymorphic bands were more or less in the expected ratios in salt-tolerant and/or salt-sensitive F₃segregating plants, but some of the bands amplified using UBC ISSR primers 823, 825,826, 849, 853, 864, 866 and 884 showed highly skewed distribution. Such polymorphic bands stand greater chances of having a linkage with the genes/ QTLs for salinity tolerance and shall be the target for further studies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献