The 2012 ASHS Annual Conference

Biostimulant based on alga extracts have been reported to accelerate in-nursery growth of citrus, avocado, and other fruit crop species grown for transplants. There are no reports of the effect of biostimulants based on marine alga extracts on breadfruit (Artocarpus altilis) seedlings. The objective of this research was to determine the effects of rates of an extract of the marine alga Ascophyllum nodosum on breadfruit seedlings grown for rootstock. The experiments were conducted in Mayaguez, Puerto Rico, in 2011 and 2012. The biostimulant used was a formulation of an Ascophyllum nodosum extract approved for organic systems (Stimplex^TM). Seedlings 12-cm tall, growing in 2-L polyethylene bags in a substrate of alluvial soil and compost, were sprayed to run-off every 2 weeks with aqueous solutions of the biostimulant at rates 0 (check), 1.0, 2.5, 5.0, and 10.0 ml/L. A completely randomized design with 10 replications was used. The plants were managed organically. During three months, seedling height and stem diameter at 10 cm above the ground were measured every 15 days. Chlorophyll concentration in the most recent fully-expanded leaves was measured monthly using a SPAD meter. Results were submitted to regression analysis. Plant growth and chlorophyll concentration in expanded leaves were affected by biostimulant rate. The highest values for seedling height and stem diameter were found when using the biostimulant rates of 2.5 to 5.0 ml/L, whereas chlorophyll concentration in expanded leaves was highest at the biostimulant rates of 5.0 to 10.0 ml/L. The results of this research indicate that growth of breadfruit plants for rootstock may be accelerated using Ascophyllum nodosum extracts.