Science et changements planétaires / Sécheresse


Impact of climatic risk on durum wheat (Triticum durum Desf.) yields in semiarid regions. An ecophysiological approach Volume 11, issue 1, Mars 2000


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  • Page(s) : 45-51
  • Published in: 2000

In southern semiarid Mediterranean regions, low rainfall levels and random distributions often leads to drought spells can occur at any durum wheat growth stage. An analysis of annual and monthly rainfall data highlighted the type of regime and confirmed its erratic character, but did not reveal the specific plant growth stages at which the constraint had an impact. Daily rainfall data would seem more suitable for this analysis, while taking into joint account constraint intensity and plant response at each growth and development stage. The risk of this water constraint was estimated in terms of dry spells (successive days without rain counted from the last rainy day), their length, incidence, and consequent water balance variability. The length of these dry spells and their distribution throughout the growing season indicated that there can be a risk of water stress at any given stage of the growth cycle, which can affect yield to different extents. Plant responses to water stress involve continuous adjustments according to water availability and water needs. These adjustments, which vary with respect to genotype, dry spell incidence and duration, can lead to poor crop establishment, a reduction in tillering and heads per unit area and in the number of kernels/head, a high proportion of small or shrivelled kernels, and a marked decline in final crop yield.