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Many cereals landraces are being tested by several institutions around the world
to identify new potential genes/alleles for drought and heat adaptation. The com-
parison between modern varieties and landraces under near-optimal and sub- optimal
conditions has led to the identification of candidates to provide traits of interest for
drought and heat adaptation in several countries. In most cases the landraces, as
compared to modern varieties, did not show higher grain yield under both near or
sub-optimal conditions nor higher yield stability but some candidates and specific
traits to improve adaptation to sub-optimal environments have been identified
(Denčić et al. 2000 ; Dodig et al. 2012 ).
Some important traits related to drought and heat tolerance are given in Table 1.
Similarly, canopy temperature, photosynthesis, stomatal conductance, transpiration
Table 1 Traits related to drought and heat
Drought and heat related traits Function
Leaf angle To reduce the water loss through transpiration
Leaf area
Leaf rolling
Leaf reflectance
Leaf pubescence
Root length To increase the water uptake from soil
Number of lateral roots
Root diameter
Root hair density
Rooting depth
Root vertical distribution
Total root size
Root- shoot ratio
Large seed and embryo
Seedling vigor
Coleoptile length
Early plant vigor To decrease evaporation from soil surface and to cover
Rapid ground cover the weeds that compete for limited water resources
Early flowering To escape terminal drought
Short life cycle
Balance phenological development
Stomatal density To decrease the rate of transpiration
Stomatal size
Stomatal conductance
Cuticle waxes
Canopy temperature depression
Osmotic adjustment Maintenance of tissue water status, and the grain
Stay green character developing rate even under less than optimum conditions.
Remobilization of assimilate from
stem for seed fillingQ. Sohail et al.