Science et changements planétaires / Sécheresse


La germination des semences en conditions sèches Volume 2, issue 4, Décembre 1991

Institut National de la Recherche Agronomique Station de Science du sol BP 91, Domaine St Paul 84143 Montfavet Cedex, France, Institut Agronomique et Vétérinaire Hassan II Département d’Agronomie BP 6202 Rabat, Maroc.
  • Page(s) : 239-49
  • Published in: 1991

This article provides an analysis of water transfer from soil to seed (maize and wheat) and its consequences on seed imbibition and germination under dry conditions. The main variables governing the imbibition process are the seed-soil water potential difference and the seed contact area as affected by gas or liquid transfer. Experiments have shown that the imbibition process occurs in both the liquid - and gas - phases. Wheat and maize seeds must reach a critical moisture content before germinating, and the rate of imbibition depends upon the seed surface area affected by liquid or gas transfer and on the water potential of the external medium governing the seed’s ability to reach its critical moisture content. Different applications of these results are presented. First, typical cases of imbibition and deshydratation of seeds located in a drying seed bed are presented. These results show the importance of seed depth in the soil on seed-soil water movements and germination. Second, predictions for the success of seed imbibition and germination according to conditions or greater or lesser dryness are put forward. Finally, simulated results compare the effects of climatic conditions and sowing techniques on wheat germination for three climatic sequences. Climate is the major limiting factor and illustrates the importance of selecting suitable sowing techniques to optimize the seed imbibition and germination process.