Proline content of sunflower cultivars in the Brazilian semiarid region

The objective of this work was to evaluate the proline content of sunflower (Helianthus annuus) cultivars, in the conditions of natural water deficit in the Brazilian semiarid region. Thirteen cultivars were sown in experiments set in three sites in the Brazilian Northeast. Proline content was determined on leaves from plants at the R4-R5 stage. Significant differences among cultivars occurred only where water availability was lower. Proline averages ranged from 3.47 to 17.41 μg g-1. The sunflower cultivars BRS387, BRS323, and BRS324 showed the greatest proline contents with 54.74, 46.27, and 35.16 μg g-1, respectively. These are the cultivars that accumulate more proline under conditions of a severe water deficit.