Investigation the effect of two red seaweed species on growth, physiological indices and fruit yield of Ecballium elaterium under the influence of extraction method

Today, there is a growing interest in using cultivation methods such as natural biostimulants, which improve yield without any negative effects on plant quality. Such a strategy allows for increasing biomass production, but also induces the natural resistance of plants, as well as improves nutraceutical quality of plant food. Products of natural origin, such as seaweed extract are used as a stimulator of the growth and development of agricultural and horticultural plants. Seaweed extracts contain a wide variety of plant growth-promoting substances such as auxins, cytokinins, betaines, gibberellins, and organic substances, including amino acids, macronutrients, and trace elements that improve crop yield and quality. The aim of this study was to investigate the effect of different extraction methods of two red seaweed species: Gracilaria corticata and Acanthophora spiciferais on growth, physiological indices and fruit yield of Ecballium elaterium.

This experiment was carried out as a completely randomized design with four replications in the research greenhouse of University of Zanjan during 2020 on growth and yield of Ecballium elaterium. Experimental treatments include 5 extraction methods (ME: microwave extract with aqueous solvent, OE: autoclave extract with aqueous solvent, BE: extract extracted by boiling with distilled water, NE: extract extracted with liquid nitrogen, EE: soaked extract in ethanol) and a control sample (C: (foliar application with distilled water)). During the growth cycle, the number of leaves, the number of male and female flowers and the number of fruits were measured. At the end of the growing season, number of lateral branches, plant height and lateral branch length, leaf area index, fresh and dry weight of shoots, fresh and dry weight of fruit and fruit yield, root length and diameter and root sub-branches, root volume and area, Total chlorophyll, carotenoids, total phenol and total flavonoids contents were measured.

The results showed that foliar application of seaweed extracts had significant effects (P < 0.01) on all traits. The plants treated with extract extracted by aqueous solvent in autoclave method was increased 43.6% plant height, 59.4% lateral branch length, 58.3% shoot fresh weight, 71.7% shoot dry weight, 65.7% number of male flowers, 39.5% number of female flowers, 41.6% fruit number, 20.2% fruit fresh weight, 32.8% fruit dry weight, 55.6% fruit yield, 70.5% root length, 80.7% root volume and 66.9% flavonoids content compared to control plants. Also, the highest leaf area index with increasing 42.9 and 41.5%, root diameter (57 and 53.4%), root area (78.3 and 73.9%), total chlorophyll (45.8 and 45.2%), carotenoids (69.3 and 71%) and total phenol contents (42.6 and 43.2) was observed in plants treated with the extract resulted of autoclave and microwave method, respectively compared to control plants.

According to the results, all methods of extracting red seaweed extract had positive effect on the growth, physiological traits and fruit yield of watercress. But in general, newer methods (autoclave, microwave) had better effect than traditional methods (boiling, liquid nitrogen, and ethanol), and extracts of these methods had more growth hormones, organic compounds and nutrients. Therefore, autoclave and microwave methods are proposed to extract seaweed extract. These results showed that the red seaweed Gracilaria (Gracilaria corticata) and Acanthophora (Acanthophora spicifera) of the Persian Gulf region, if extracted properly, can be a suitable biofertilizer for plant production.