II.1.5 Phenotyping pearl millet for adaptation to drought

Abstract

Pearl millet is highly resilient to some of the driest areas of the world, like the Sahel area or fringes of the Thar desert in India. Despite this, there is a wealth of variation in pearl millet genotypes for their adaptation to drought and the object of this paper was to review some related work in the past 25 years to harness these capacities toward the breeding of better adapted cultivars. Work on short duration cultivars has been a major effort. Pearl millet has also some development plasticity thanks to a high tillering ability, which allows compensating for possible drought-related failure of the main culm under intermittent drought. The development of molecular tools for breeding has made great progress in the last 10–15 years and markers, maps, EST libraries, BACs are now available and a number of quantitative trait loci (QTLs) for different traits, including drought, have been identified. Most of the work on drought has focused on the drought tolerance index (DTI), an index that reflect the genetic differences in drought adaptation that are independent of flowering time and yield potential. The DTI is closely associated to the panicle harvest index (PNHI), a trait that relates to a better grain setting and grain filling capacity. Initial work on the DTI involved empirical breeding and selection based on PNHI. A QTL for PNHI has then been identified and introgressed by marker-assisted backcrossing. More recently, a thorough dissection of that QTL has been carried out and shows that high PNHI is related to the constitutive ability of tolerant lines to save water (lower leaf conductance and sensitivity of transpiration to high vapor pressure deficit) at a vegetative stage and use it for the grain filling period. However, there is no contribution of root traits in this QTL. Current work is taking place to map these water saving traits, understand their genetic interactions, and design ideotypes having specific genetic make-up toward adaptation to specific rainfall environments.

Analysis of Genotype by Environment Interaction of Improved Pearl Millet for Grain Yield and Rust Resistance

“…However, on-farm productivity is low partly due to the effect of rust disease. The economical approach to control rust is through resistance breeding (Singh, 1990) and selecting genotypes adapted to low input and drought-prone environments (Vadez et al, 2012). Unfortunately, the potential performance of improved genotypes under marginal conditions is always obscured by the effect of genotype by environment interaction (GEI) (Yan & Racjan, 2002); leading to selection of genotypes not suitable for particular environments (Cooper & Delacy, 1994) and subsequently leading to low yield.…”

Evaluation of Genotype x Environment Interaction and Stability of Grain Yield and Related Yield Components in Pearl Millet (Pennisetum glaucum (L.) R.Br.)

“…The economical approach to control this constraints is through resistance breeding [9] and selecting genotypes adapted to low input and droughtprone environments [10,11]. Unfortunately, the potential performance of improved genotypes under marginal conditions is always affected by the effect of genotype by environment interaction (GE) [12].…”

Genomic Tools in Pearl Millet Breeding for Drought Tolerance: Status and Prospects

“…Discovery of high throughput markers enabled genotyping of larger mapping population and construction of high and ultrahigh density maps in crops with no reference genome sequence available (Poland et al, 2012). As compared to other orphan crops, a sizable progress has been made for pearl millet in the development of molecular tools that are proven efficient in expediting the breeding of improved cultivars in the last two decades (Vadez et al, 2012). Development of molecular markers, EST libraries, BACs, and genome mapping were some of the areas in which progress has been observed.…”

“…Development of molecular markers, EST libraries, BACs, and genome mapping were some of the areas in which progress has been observed. Nevertheless, to harness the wealth of genetic variability in the germplasm for improvement in yield, drought tolerance, and other desired traits much is remaining to be done (Vadez et al, 2012). …”