Foliar sprays with ABA promote growth of Ilex paraguariensis plants by alleviating diurnal water stress

SANSBERRO, P.; MROGINSKI, L.; BOTTINI, R.

PLANT GROWTH REGULATION

Kluwer Acad. Publ.

Lugar: Holanda; Año: 2004 vol. 42 p. 105 - 111

0167-6903

Stomatal closure, relative water content (RWC) and vegetative growth were monitored in Ilex paraguariensis plants grown under well-watered conditions with a photosynthetic photon flux density (PPFD) varying from 100% to 1.5%, and sprayed weekly with either distilled water (control) or 1.89 mM ABA. ABA treatments caused stomatal closure, ranging from 62 to 73%. These treatments also increased RWC in the early evening from 82 to 92% and 88 to 94% in mature and immature leaves, respectively. Such alleviation of the water stress was correlated with increases in leaf area, leaf DW, shoot length and shoot DW. On day 35 from the beginning of the experiment, the increases in DW of both leaves and shoots were 1.5-fold at the 1.5% PPFD and 3-fold (for leaves) and 4.5-fold (for shoots) under 100% PPFD. In water-sprayed control plants grown under 1.5% PPFD shoot length also increased significantly, although these shoots contained more ABA (assessed by GC-MS) than those of plants grown under 100% PPFD. These results show that ABA sprayed on to leaves promotes growth in I. paraguariensis plants by alleviating diurnal water stress.