Water uptake dynamics under progressive drought stress in diverse accessions of the OryzaSNP panel of rice (Oryza sativa)

In addition to characterising root architecture, evaluating root water uptake ability is important for understanding drought response. A series of three lysimeter studies were conducted using the OryzaSNP panel, which consists of 20 diverse rice (Oryza sativa L.) genotypes. Large genotypic differences in drought response were observed in this genotype panel in terms of plant growth and water uptake. Total water uptake and daily water uptake rates in the drought-stress treatment were correlated with root length density, especially at depths below 30 cm. Patterns of water uptake among genotypes remained consistent throughout the stress treatments: genotypes that initially extracted more water were the same genotypes that extracted more water at the end of the study. These results suggest that response to drought by deep root growth, rather than a conservative soil water pattern, seems to be important for lowland rice. Genotypes in the O. sativa type aus group showed some of the greatest water uptake and root growth values. Since the OryzaSNP panel has been genotyped in detail with SNP markers, we expect that these results will be useful for understanding the genetics of rice root growth and function for water uptake in response to drought

Characterization of AhMITE1 transposition and its association with the mutational and evolutionary origin of botanical types in peanut (Arachis spp.)

AhMITE1 is an active miniature inverted repeat transposable element (MITE) in peanut (Arachis hypogaea L). Its transpositional activity from a particular (FST1-linked) site within the peanut genome was checked using AhMITE1-specifc PCR, which used a forward primer annealing to the 50-flanking sequence and a reverse primer binding to AhMITE1. It was found that transposition activation was induced by stresses such as ethyl methane sulfonate (EMS), gamma irradiation, environmental conditions, and tissue culture. Excision and insertion of AhMITE1 at this particular site among the mutants led to gross morphological changes resembling alternate subspecies or botanical types. Analysis of South American landraces revealed the presence of AhMITE1 at the site among most of the spp. fastigiata types, whereas the element was predominantly missing from spp. hypogaea types, indicating its strong association. Four accessions of the primitive allotetraploid, A. monticola were devoid of AhMITE1 at the site, indicating only recent activation of the element, possibly because of the ‘‘genomic shock’’ resulting from hybridization followed by allopolyploidization

Farmers' perception on plant protection in India and Nepal: a case study

Participatory rural appraisal was undertaken in 70 villages in India and Nepal, covering 1185 farmers to generate baseline information on the current plant protection practices. The study revealed that 93% of the farmers in India and 90% in Nepal had adopted chemical control for the management of various insect pests in different crops; however, less than 20% of the farmers expressed confidence on their efficacy. In India, 52% of farmers get their plant protection advice from pesticide dealers, while in Nepal, the majority of the farmers (69%) make their plant protection decisions through agricultural officers. A majority of the farmers (73% in India and 86% in Nepal) initiate the plant protection based on the first appearance of the pest, irrespective of their population, crop stage and their damage relationships. About 50% of the farmers in India and 20% in Nepal were not using any protective clothing while spraying. Health problems associated with the application of plant protection chemicals were reported by farmers. The cost of plant protection on various crops ranged from 7 to 40% of the total crop production cost. Though integrated pest management (IPM) has been advocated for the past two decades, only 32% in India and 20% in Nepal were aware of IPM practices. IPM implementation in selected villages brought a 20-65% reduction in pesticide use in different crops. The vegetable samples analysed for pesticide residues revealed the presence of residues

Construction of a genetic linkage map and QTL analysis for late leaf spot and rust in groundnut (Arachis hypogaea L.)

Late Leaf Spot (Phaeoisariopsis personata [(Berk. and Curt.) Deighton] and rust (Puccinia arachidis Speg.) are the major foliar diseases of groundnut that often occur together leading to 50-70% yield loss in the crop. Two hundred and sixty eight RILs (TAG 24 × GPBD 4) segregating for late leaf spot (LLS) and rust were used to undertake QTL analysis. Phenotyping of the population was carried out under artificial disease epiphytotics for three seasons. Positive correlations between different stages, high to very high heritability and independent nature of inheritance between both the diseases was observed. Parental genotypes (TAG 24 and GPBD 4) were screened with 1089 SSR markers, of which 67 (6.15%) were found polymorphic. The study yielded partial linkage map with 14 linkage groups integrating 56 SSR markers with 364.40 cM genome coverage and average marker distance of 8.7cM. Composite interval mapping (CIM) showed 12 QTLs for LLS (1.2 to 5.6%) in three different environments. In case of rust, 13 QTLs were detected in three different environments with phenotypic variance ranged upto 54.4%. Furthermore, a major QTL associated with rust was identified by both CIM and single marker analysis (SMA) that contribute 18.4 to 54.4% phenotypic variance. Markers linked with this QTL are being validated using a wide range of resistant / susceptible breeding lines as well as progeny lines of another mapping population (TG 26 × GPBD 4). SSR marker(s) linked with major QTL for rust, once validated, will be the potential marker(s) for undertaking molecular breeding for rust resistance

Genetic enhancement of resistance to foliar diseases

Rust and Late leaf spot are among the most destructive and widespread diseases of groundnut. Cultivation of resistant varieties is economically most viable and environmentally sound strategy. Germplasm with high level of resistance is available in cultivated and/or related wild species. In spite of innumerable attempts, breeding has met with limited success in combining resistance with yield, crop quality and adaptation. The modern tool of Marker Assisted Selection (MAS) is expected to improve the speed and precision of resistance breeding. The progress and challenges in the application of molecular markers in breeding for resistance to foliar diseases will be discussed

A tuberculosis prevalence survey based on symptoms questioning and sputum examination

A sample survey was undertaken in Raichur district of Karnataka State to estimate the prevalence of bacteriologically positive pulmonary tuberculosis among symptomatics aged 15 years and above. A population of 72,448 persons was registered in a representative sample of 57 villages and 21 enumeration blocks. Of the 42,580 persons aged 15 years and above eligible for symptoms questioning, 40,657 (95.5%) were examined and 3,846 (9.5%) were found to be symptomatics and eligible for sputum examination. Sputum was collected from 3,685 (95.8%) of the 3,846 symptomatics, and subjected to bacteriological examination i.e., smear, culture and drug susceptibility. Certain important findings were as follows: (i) the number of symptomatics increased with increase in age, more often among males (11.9%) than among females (7.1%), (ii) the prevalence of tuberculosis, as assessed by smear and/or culture was 10.9 per 1,000 in population aged 15 years and above, (iii) the prevalence increased with age and was 3 times higher among males as compared to females, (iv) cough was found to be the predominant symptom among the symptomatics (87%) as well as among the cases detected (92%), (v) the prevalence rate based on smear examination of the sputum specimens, using the two microscopy methods (Ziehl-Neelsen and Fluorescence) was 7.6 per 1,000, (vi) culture examination of these specimens yielded 3.3 per 1,100 additional cases, (vii) both the microscopy methods were equally efficient in detecting smear positives, (vii) of the 355 culture positive cases, 17.7% were resistant to Streptomycin, 29.6% to Isoniazid and 7.6% to Rifampicin either alone or in combination with other drugs

Ramsauer approach to Mie scattering of light on spherical particles

The scattering of an electromagnetic plane wave by a spherical particle was solved analytically by Gustav Mie in 1908. The Mie solution is expressed as a series with very many terms thus obscuring the physical interpretations of the results. The purpose of the paper is to try to illustrate this phenomenon within the Ramsauer framework used in atomic and nuclear physics. We show that although the approximations are numerous, the Ramsauer analytical formulae describe fairly well the differential and the total cross sections. This allows us to propose an explanation for the origin of the different structures in the total cross section

Promoting biopesticides for crop protection through partnerships-an on-going drive

Inappropriate and excessive use of synthetic (chemical) persticides is threatening the development of sustainable agriculture and environmental protection. This calls for an urgent need to look for different strategies to protect crops. Biopesticides (botanical and microbial) are an important alternative, with convincing track record on biosafety and efficacy, when used strategically. In addition, many of these can reacn farmers at an affordable cost Some biopesticides can be prepared by farmer themselves, thereby reducing the cost of production which is a major issue confronting fanners and policy makers alik

Multiple biotic stress resistant and productive genotypes identified under Spanish bunch background in groundnut (Arachis hypogaea L.)

The cultivated groundnut is an important oil seed crop of the world. Several pest and diseases damage the crop and reduce groundnut yields considerably. Cultivation of resistant varieties is an ecologically sound and economically viable approach to reduce the loss due to these stresses, but their occurrence and intensity vary in space and time necessitating the use of multiple stress resistant genotypes. Several diverse groundnut germplasm were assessed for different biotic stresses under epiphytotic conditions. Most of the cultivated varieties were susceptible to different stresses. Interspecific deri vati ves constituted the best source of resistance to late leaf spot (LLS), rust and Sclerotium; while mutants were superior for late leaf spot, Spodoptera and bud necrosis. Pedigree of multiple stress resistant genotypes revealed contribution of wild species for resistance to many biotic stresses. Trait association studies indicated late matUling nature of resistant germplasm. Induced mutagenesis and extensive hybridization with interspecific derivatives were sought to break these undesirable associations. Several foliar disease resistant mutants and second cycle interspecific-derivatives were isolated in Spanish bunch background. Mutant (28-2) and second cycle interspecific derivative (GPBD-4) were resistant to foliar diseases with high yield potential even under foliar disease epidemic. 28-2 was also resistant to Spodoptera, thrips and Aspergillus infection besides having bold kernels. GPBD-4 was iron absorption efficient and had OIL ratio of 1.68. They also possessed desirable agronomic features, early maturity, high partitioning and better quality. Mutant 28-2 and GPBD-4 have been registered with National Bureau of Plant Genetic Resources (NBPGR), New Delhi with INGR numbers 98003(IC296686) and 0 I 031 (IC2968LO), respectively. These cultures had stable and superior performance over popular cultivars (JL-24 and TMV-2) across years. GPBD-4 has been accepted by farmers and traders; under active seed chain and cultivation in the farmers' fields in India. GPBD-4 has been widely employed for MABC at ICRISAT and UASD as the source of resistance to LLS and rust