Ascophyllum nodosum and Spirulina platensis affect plant growth, yield, concentration of hormones in the leaves and nematode communities in the rhizosphere of cucumber plants

Abstract

ABSTRACT Increased concerns about residues in vegetables and soil contamination necessitate the use of safer and eco-friendly fertilisers and pesticides. The present study investigated effects of applying Ascophyllum nodosum extract (SW) and Spirulina platensis (SP) on in vitro plant morphogenesis of Hybrid Beit Alpha F1 cucumbers, followed by an evaluation of their effects on plant growth, fruit yield and rhizosphere inhabiting nematodes under greenhouse conditions. Treatments in the greenhouse trial consisted of soil drenching with Spirulina platensis at: 1000 mg l−1 (SP2) and 2000 mg l−1 (SP4); with Ascophyllum nodosum (v:v%) at: 0.25% (SW0.25), 0.5% (SW0.5) and 0.75% (SW0.75); and a control where seedlings were treated with neither seaweed or Spirulina (Control: C). In the greenhouse trial, both biostimulants improved the growth of the cucumbers; plant height, biomass (SW only), leaf chlorophyll, fruit firmness (SW only), fruit length, fruit diameter and fruit total soluble solids, compared with the control. SW0.25 resulted in the highest overall positive effects on the cucumbers with enhancement of plant growth and yield parameters. Application of Ascophyllum nodosum and Spirulina platensis significantly influenced the endogenous IAA hormonal concentration in the cucumber leaves. In addition, the tested biostimulants influenced the relative abundance of major nematode taxa in the cucumber rhizosphere: percentages of free-living nematodes (FLN%) and bacterivores and fungivores (BF%). The results of the study indicated opportunities for developing strategies for sustainable organic production of cucumbers using safe biostimulants to replace the traditional use of chemical inputs.