Browsing by Author "Onkar Nath Singh"

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Marker-Assisted Improvement for Durable Bacterial Blight Resistance in Aromatic Rice Cultivar HUR 917 Popular in Eastern Parts of India
(MDPI, 2023) Manish Kumar; Ravi Pratap Singh; Debarchana Jena; Vineeta Singh; Diptibala Rout; Panduranga Bhagwan Arsode; Madhu Choudhary; Prakash Singh; Suman Chahar; Sanghamitra Samantaray; Arup Kumar Mukherjee; Chander Mohan; Abhishek Bohra; Goutam Das; Sumana Balo; Onkar Nath Singh; Ramlakhan Verma
Bacterial blight (BB) is a devastating disease of rice in the tropics of Indian sub-continent, where the presence of Xoo races with varying levels of genetic diversity and virulence renders disease management extremely challenging. In this context, marker-assisted improvement of plant resistance has been proven as one of the most promising approaches for the development of sustainable rice cultivars. The present study demonstrates the marker-assisted introgression of the three BB resistant genes (Xa21 + xa13 + xa5) into the background of HUR 917, a popular aromatic short grain (ASG) rice cultivar in India. The performance of the resulting improved products (near isogenic lines (NILs), HR 23-5-37-83-5, HR 23-5-37-121-10, HR 23-5-37-121-14, HR 23-65-6-191-13, HR 23-65-6-237-2, HR 23-65-6-258-10 and HR 23-65-6-258-21) establishes the utility of marker-assisted selection (MAS) approach for accelerated trait introgression in rice. The MAS-bred lines carrying three introgressed genes showed broad spectrum BB resistance (lesion length, LL of 1.06 ± 1.35 cm to 4.61 ± 0.87 cm). Besides, these improved lines showed the complete product profile of recurrent parent HUR 917 along with the enhanced level of durable BB resistance. The improved introgression lines with durable BB resistance would contribute to sustainable rice production in India, particularly in the Indo-Gangetic plane that has substantial acreage under HUR 917. © 2023 by the authors.
Operating characteristics of an optical filter with a linearly periodic refractive index pattern in the filter material
(1992) Sant Prasad Ojha; Pankaj Kumar Choudhury; Prasad Khastgir; Onkar Nath Singh
A design for the fabrication of an IR filter by using a linearly periodic refractive index pattern on the macroscopic scale in a suitable material has been proposed. To predict allowed and forbidden bands of wavelengths for the lower modes, a mathematical analysis is presented. Numerical estimates of allowed and forbidden bands are also made. Several parameters controlling the range of operation and region of allowed wavelength bands have been identified. It is being suggested that the technical knowhow used in the manufacturing of optical fibres and integrated optical devices can successfully be employed for the fabrication of these filters. © 1992 The Japan Society of Applied Physics.