Dry Matter and Nitrogen Remobilization of Two Wheat Genotypes under Post - anthesis Water Stress Conditions

Current assimilation, as a source of carbon for grain filling in cereals, may be limited for normal grain filling under Mediterranean climate. In such conditions reserves accu-mulated before anthesis play an important role in grain growth, but the extent of their contribution depends on prevailing environmental conditions. The experiment described here was carried out to determine the effects of different levels of water stress on dry mat-ter and nitrogen accumulation and their remobilization from the shoot to the grain. The pot experiment was conducted in the glasshouse using two wheat cultivars (Sun 92A and Vasco) differing in yield and protein content. The plants were subjected to water stress at 10 days after anthesis (daa). The following treatments were established: not watered (se-vere stress), medium stress (-2 Mpa water potentional of the Flag leaf), mild stress (-1 Mpa water optional of the Flag leaf), divided root and control. Results indicated that the dry matter and N content of vegetative organs and its concentration were greater at 24 daa than at maturity under all conditions. Water stress during the post anthesis period was unfavorable to a high assimilation rate, so yield was determined to a great extent by the availability of water and the behavior of the cultivars related to shoot reserve remo-bilization during the grain filling period.