Assessment of genetic diversity in a crop species is prerequisite to its improvement. The use of germplasm with distinct DNA profiles will help to generate genetically diversified breeding populations. The aims of the present experiment were to study molecular diversity among selected groundnut accessions and identify those with distinct DNA profiles for mapping and genetic enhancement. Twenty‐six accessions and eight primers of a 10‐mer were selected for random amplified polymorphic DNA assay. The genetic similarity (Sij) ranged from 59.0% to 98.8%, with an average of 86.2%. Both multidimensional scaling and unweighted pair‐group method with arithmetic averages (UPGMA) dendrograms revealed the existence of five distinct clusters. However, this classification could not be related to known biological information about the accessions falling into different clusters. Some accessions with diverse DNA profiles (ICG 1448, 7101, and 1471, and ICGV 99006 and 99014) were identified for mapping and genetic enhancement in groundnut.

This chapter discusses the target growing environments and sensitivity of pearl millet, sorghum, maize, groundnut, chickpea and pigeon pea to drought; phenotypic screens and natural genetic variations for response to drought; empirical and trait-based breeding methods to enhance drought tolerance; and deployment of emerging biotechnological tools (DNA markers and transgene) to enhance crop adaptation and productivity under drought stress conditions.

Photoperiod insensitivity plays a significant role in ensuring wide adaptability of genotypes across environments. The effect of photoperiod in groundnut (Arachis hypogaea L.) is manifested in post-flowering development including partitioning. The partitioning of assimilates, as measured by harvest index (HI), has the greatest effect on pod yield. The F1 progenies (excluding reciprocals) and their parents from a six-parent diallel cross were studied to estimate combining ability for biomass and HI under short (SD)-and long (LD)-day conditions, and to identify good combiners with high biomass and HI for use in breeding programmes. The experiment was conducted for three seasons in a split plot design with two photoperiods as main plots and 21 genotypes as subplots. The two photoperiod treatments were SD defined as normal-day light period and LD defined as normal-day light period extended by 4 h using incandescent lamps. The multi-environment analogue of Griffing's Method 2 -Model 1 was modified to analyse data for combining ability. While biomass was controlled by both GCA and SCA effects, HI was predominantly controlled by GCA effects. GCA and SCA effects for biomass and HI interacted with environments (six factorial combinations of photoperiods and seasons). SCA effects remained insensitive to variation in photoperiod both for biomass and HI. However, GCA effects for HI were sensitive to photoperiod. V6 (ICG 2405) was a good general combiner for both biomass and HI across environments. None of the crosses showed positive and significant SCA effects for both biomass and HI. Photoperiod influenced the sensitivity of GCA effects of V2 (ICGV 86694) and V6 for HI. However, the difference between SCA effects of V2 x V6 was not significant. The results of this study emphasise the need for future experiments with random genotypes over a range of photoperiods.

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The occlJ!fence of peanut bud necrosis (PBN) disease in Ind�a was flrst reported in 1968. The high incidence ofPBN disease durin' g the 19605 coincided with large scale imports of the peanut cultivars Asiria MWitunda ' e of which are highly susceptible to PEN. Since then, a number of reports have been