RESPONSES OF IN VITRO CULTURED KIWIFRUIT SHOOTS TO TREATMENTS WITH GREEN AMARANTH AQUEOUS EXTRACTS.

Because of environmental hazards related to the use of synthetic Fe-chelates in Fe-chlorosis control of plants, and with the purpose of using plant extract treatments as an alternative strategy, the effect of Amaranthus retroflexus L extracts on Actinidia deliciosa Liang et Ferguson shoot cultures was investigated, and the possibility of using in vitro cultures for fast evaluation of the effect of such extracts on growth and Fe-chlorosis control in fruit plants is discussed. The extract was obtained by macerating for a week 100 g plant fresh weigth in 1 liter distilled water, filter-sterilizing and adjusting the pH to 5.65; the extract was added at 0 (control), 20, 2, 0.2 and 0.02 ml to 100 ml of previously autoclave-sterilized modified Murashige and Skoog, MS, medium (PM), and salt-deficient PM/3 (third MS salt strenght) and rooting RM (lacking growth regulators, half MS salt strenght) media. The addition of 20 ml water extract to 100 ml PM/3 strongly reduced shoot and basal callus development, while 0.02 ml/100 ml increased both with respect to the control. Rooting was hastened with 0.02 ml extract/100 ml RM with respect to other concentrations. Moreover, roots produced with 0.02 and 0.2 ml extract/100 ml RM were longer than with other treatments and in control. The addition of 0.02 ml extract/100 ml PM/3 medium and of 0.02 to 2 ml extract/100 ml RM improved photosynthetic activity of cultures after five and four weeks in the proliferation and rooting phase, respectively.