Genomic selection (GS) is a promising approach exploiting molecular genetic markers to design novel breeding programs and to develop new markers-based models for genetic evaluation. In plant breeding, it provides opportunities to increase genetic gain of complex traits per unit time and cost. The cost-benefit balance was an important consideration for GS to work in crop plants. Availability of genome-wide high-throughput, cost-effective and flexible markers, having low ascertainment bias, suitable for large population size as well for both model and non-model crop species with or without the reference genome sequence was the most important factor for its successful and effective implementation in crop species. These factors were the major limitations to earlier marker systems viz., SSR and array-based, and was unimaginable before the availability of next-generation sequencing (NGS) technologies which have provided novel SNP genotyping platforms especially the genotyping by sequencing. These marker technologies have changed the entire scenario of marker applications and made the use of GS a routine work for crop improvement in both model and non-model crop species. The NGS-based genotyping have increased genomic-estimated breeding value prediction accuracies over other established marker platform in cereals and other crop species, and made the dream of GS true in crop breeding. But to harness the true benefits from GS, these marker technologies will be combined with high-throughput phenotyping for achieving the valuable genetic gain from complex traits. Moreover, the continuous decline in sequencing cost will make the WGS feasible and cost effective for GS in near future. Till that time matures the targeted sequencing seems to be more cost-effective option for large scale marker discovery and GS, particularly in case of large and un-decoded genomes.

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Temperature stress is one of the major limitations to crop productivity worldwide. Identifying suitable screening indices and quantifiable traits would facilitate the crop improvement process for high temperature tolerance. The objective of the present study was to screen and to identify temperature tolerant Brassica genotypes on the basis of physiological parameters viz. relative water content (RWC), total chlorophyll content, membrane stability index (MSI), total carotenoid content and yield. Fifteen Brassica juncea genotypes subjected to temperature stress by growing the crops at three dates of sowing i.e. 15th October (D 1 ), 1st November (D 2 ) and 15th November (D 3 ); showed decrease in RWC, MSI and chlorophyll content at D 2 and D 3 sowings compared to the D 1 . Genotypes like Proagro, NDR 8801 and CS-52 showed lower decline in MSI, RWC, chlorophyll and carotenoid content in leaves and seed yield/plant, while Pusa Agrani, EJ-15 and Pusa Tarak showed comparatively greater decline in the above parameters. The results suggest that physiological parameters like MSI, RWC and chlorophyll and carotenoid contents can be used as simple indices for screening and identifying temperature stress tolerant genotypes.