To incorporate durable resistance against bacterial blight, a major disease rice, three resistance genes, xa 5, xa13 and Xa21, from IRBB 60 were transferred through marker-assisted backcrossing using RG 556, RG 136 and pTA248 markers linked to the three genes to supplement the Xa4 gene present in Lalat, a popular rice cultivar. Effective selection enabled the transfer in three back-crosses and a generation of selfing and background selection employing morphological and grain quality traits and molecular markers, led to >90 % recovery of the recurrent parental genome. The gene pyramids exhibited high levels of resistance against the pathogen in multi-location evaluation trials conducted over several locations of bacterial blight in India. IL-2 (CRMAS2621-7-1), a gene pyramid, was identified as being promising for several endemic regions of bacterial blight and was released as Improved Lalat in one of the identified regions. The success of the study demonstrates the vast potential of marker-assisted selection for gene stacking and recovery of the parental genome with high precision.
An attempt to derive a relation between spectral data of rice canopies and their grain yield has been made in the Cuttack and Puri districts of Orissa for Kharifrice using Landsat MSS digital data of three years (1984)(1985)(1986). Necessary sensor-to-sensor transformations of Landsat MSS to IRS LISS-I and acquisition date normal::zation with respect to a typical rice growth profile were also carried out. Using srch an empirical relation, rice yield was estimated for Kharif in 1988 using IRS-IA LISS-I data at district level. Deviation of the estimated yields from the reported figures varied from 2 per cent to 14 per cent at the district-aggregated level.
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