Biostimulatory activities of Ascophyllum nodosum extract in tomato and sweet pepper crops in a tropical environment

This study evaluated the effectiveness of a commercially available Ascophyllum nodosum alkaline extract as a plant growth stimulant and defense elicitor against foliar diseases of tomato and sweet pepper caused by Xanthomonas campestris pv. vesicatoria and Alternaria solani in a tropical environment. Foliar applications of 0.5% A. nodosum extract (AN) at 10-day intervals resulted in significant (P Ascophyllum extract significantly (P PR1-a, PinII and ETR-1, for the above pathways respectively. Both crop plants treated with A. nodosum extract had significantly higher expression levels of the PinII and ETR-1 marker genes than controls. This was coupled with a marked increase in gene transcripts involved in auxin (IAA), gibberellin (Ga2Ox) and cytokinin (IPT) biosynthesis, which provides possible evidence for induced growth in plants treated with AN extract. Cross-talks between growth and defense responses as a result of seaweed extract application could evidently implicate the benefits of seaweed extract usage in sustainable crop production.