Biostimulant Application Enhances Fruit Setting in Eggplant—An Insight into the Biology of Flowering

Abstract

Eggplant (Solanum melongena L.) is a warm climate crop. Its cultivation extends to temperate regions where low temperatures can affect the course of the generative phase, which is primarily sensitive to abiotic stress. The novelty of the present investigation consisted of characterising the heterostyly, pollination, and fertilisation biology of eggplants in field cultivations, which provided a basis for explaining the effect of a protective biostimulant on these processes. We aimed to investigate the flowering biology of three eggplant hybrids treated with Göemar BM-86®, containing Ascophylum nodosum extract, to determine the crucial mechanisms behind the increased flowering and fruit set efficiency and the final effect of increased yield. The flower phenotype (long, medium or short styled), fruit setting, and the number of seeds per fruit were recorded during the two vegetation periods. The numbers of pollen tubes and fertilised ovules in ovaries were evaluated during the generative stage of development to characterise the course of pollination and fertilisation for all types of flowers depending on the cultivar and biostimulant treatment. The expression of heterostyly depended on the eggplant genotype, age of the plant, fruit load, and biostimulant treatment. Domination by long-styled flowers was observed, amounting to 41%, 42%, and 55% of all flowers of “Epic” F1, “Flavine” F1, and “Gascona” F1, respectively. This flower phenotype contained the highest number of pollen tubes in the style and the highest number of fertilised ovules. The biostimulant had a positive effect on the flower and fruit set numbers, as well as on the pollination efficiency in all genotypes. Ascophylum nodosum extract could be used as an efficient stimulator of flowering and fruit setting for eggplant hybrids in field conditions in a temperate climatic zone.

Ascophyllum nodosum Extract Biostimulant Processing and Its Impact on Enhancing Heat Stress Tolerance During Tomato Fruit Set

“…This stimulatory response would explain the increase in flowers in the heat stressed plants. Although promoted flowering has previously attributed to other commercial ANE biostimulants (Abubakar et al, 2012;Pohl et al, 2019), there was only a significant increase in flower number in tomato plants treated with PSI-494. These results highlight that despite the ANE biostimulants being manufactured from the same raw material their processing conditions can affect their ability to provide phenotypic and physiological benefits.…”

“…Plants treated with C129 and PSI-494 had higher pollen viability percentages than the untreated group after heat stress exposure, without significant differences in the efficacy of both ANE biostimulants. Although previous studies have highlighted the positive impact of seaweed extracts on different pollination parameters of high value crops such as grape or eggplant (Sabir, 2015;Pohl et al, 2019), no research to date has demonstrated the protective effect of ANEs on pollen under heat stress conditions. Furthermore, it has been previously described in different plant species that different stress types can stimulate precocious flowering and further seed production as an emergency response to highly unfavorable environmental conditions (Takeno, 2016).…”

Physiological, Ecological, and Biochemical Implications in Tomato Plants of Two Plant Biostimulants: Arbuscular Mycorrhizal Fungi and Seaweed Extract

“…Poulton et al (2002) demonstrated that AMF colonization can enhance host plant fitness by positively affecting its reproductive functions. In addition, SEs may improve flower yield and fruit production by behaving as chelators (Battacharyya et al, 2015;Yuvaraj and Gayathri, 2017;Pohl et al, 2019). Also, hormonal responses are mainly attributed to the cytokinins present in the SE or to their production, transport, and mobilization into developing tissues, either vegetative or floral (Ganesan et al, 2015).…”

Recent Advances in the Molecular Effects of Biostimulants in Plants: An Overview

“…Interestingly, the application of A. nodosum-based biostimulants has been observed to lead to changes in the expression of cherry cell-wall and cuticular wax genes (PaEXP1, Pa -Gal and PaWS), which can be correlated to a reduction in fruit cracking [145]. New research regarding effects on flowering and fruit setting in eggplant also opened up a possible new function for these biostimulants, as these characteristics were positively influenced with the application of this SWE [146].…”