Artocarpus altilis as Affected By Foliar Applications of a Phytostimulant

The breadfruit (Artocarpus altilis) is an emerging crop in Puerto Rico. The plant does not produce viable seeds, and selected trees may be propagated by root cuttings or by grafting onto rootstocks of the same or related species. Producing transplants from root cuttings is generally slow, and there is little information regading the effects of practices that may help hasten their growth, such as fertilizers and phytostimulants. The objective of this research was to assess the effects of a commercially available extract of the sea alga Ascophyllum nodosum on the growth of breafruit plants from cuttings while still in the nursery. Root cuttings from a selected tree ('Corozal 6') 15 cm-long and 2.5 cm in diameter were planted on a peat moss susbstrate in plastic containers 20-cm in diameter and 30-cm tall and watered daily. When breadfruit shoots were 20 cm tall, the phytostimulant was applied as a foliar spray to run-off, at the rates of 0, 2, 4, 6, and 8 ml/L of water. Applications were conducted every 14 days, for a total of 10 applications. A completely randomized design with 7 replicates was used, and results were submitted to regression analysis. Phytostimulant rates did not affect stem diameter, but a quadratic response was found for root dry weight, leaf number, leaf area, leaf biomass, and shoot height, with the highest values between 2 and 4 ml of phytostimulant/L. Leaf SPAD values (related to chlorophyll) were greater than in control plants when the phytostimulant was applied at rates of up to 4 ml/L, with no change at higher rates. These results show that phytostimulants based on Ascophyllum nodosum may be used to accelerate the growth of breafruit in the nursery.