Integrated Nutrient Management Boosts Inflorescence Biomass and Antioxidant Profile of Carlina diae (Asteraceae)—An Endangered Local Endemic Plant of Crete with Medicinal and Ornamental Value

Abstract

Due to the combined climate and biodiversity crisis, the sustainable utilization of phytogenetic resources stands as a one-way alternative, while nutrient management strategies are gaining an increasing role in agriculture. Building on previous studies regarding the Endangered local endemic of Crete (Greece) Carlina diae (Asteraceae), with medicinal and ornamental value, this investigation focused on its pilot cultivation and fertilization (foliar or soil application). Foliar application comprised inorganic fertilization (conventional) or integrated nutrient management (INM). Soil application consisted of conventional inorganic fertilizers, biostimulants, or INM with biostimulants. Above-ground biomass content of nutrients, leaf chlorophyll fluorescence, and color parameters (SPAD meter, DA meter, Chroma Meter) were estimated. The leaf chlorophyll content, three key antioxidant compounds, and nutrient titers were also determined. The fertilization scheme did not influence plant growth and visually perceived quality (leaf color and shape). Notably, foliar INM fertilization increased biomass partitioning to inflorescences (harvestable organs for either medicinal or ornamental purposes) and decreased tissue water content (facilitating processing). Considering all three antioxidants together, INM with biostimulant appeared the optimum scheme, being associated with the highest (carotenoids, phenolics) or the second highest (flavonoid) content. In C. diae, therefore, INM fertilization was optimal for upgrading yield (foliar) and herbal quality in terms of antioxidant profile (INM with biostimulant), which might be embraced as an eco-friendly approach for high-quality yields.

A Polysaccharide-Based Integrated Nutrient Management System Enhances the Antioxidant Properties in Origanum dictamnus (Lamiaceae), a Valuable Local Endemic Plant of Crete

“…Under this background, polysaccharidebased INM fertilizers were also tested owing not only to the reduced environmental footprint, but also to a powerful fertilization scheme leading to improved quality and yield [61]. Our previous research line employing other local endemic plants of Crete such as V. arcturus [26], O. microphyllum [27], S. syriaca [28] and C. diae [29] offer a first report regarding the evaluation of the total phenolic and flavonoid contents which may further inspire the usage of fertilization in stimulating herbal antioxidant content without compromised optical quality or yield in MAPs. Such investigations are supplementary to the current study dealing with O. dictamnus as they offer insight into several cases of exemplary neglected and underutilized local endemic species of Crete responding in similar ways to fertilization.…”

“…These rows had east-west direction and included as "guard plants" were other local Cretan endemics, i.e., individuals of Sideritis syriaca subsp. syriaca (Malotira or Cretan Mountain tea [28]), Origanum microphyllum (Cretan marjoram, [27]), Carlina diae (Carline of Dia [29]), and Verbascum arcturus (Cretan mullein, [26]), all investigated in the frame of the research project PRECISE-M. Each of the above plant species primarily aimed to identify species-specific responses to the fertilization schemes applied, thus testing the same fertilization treatments in terms of yield and quality characteristics in different biological species ("biological replicates at species level").…”

“…Carotenoids, flavonoids, and phenolics are common as well as major antioxidant compounds that exhibit a strong antioxidant ability [17,18]. Notably, organic fertilizers and INM strategies have been associated with increased antioxidant compound accumulation [19,[21][22][23][24][25][26][27][28][29]. Organic fertilizers and INM strategies have also been suggested to act as a tool in promoting leaf chlorophyll concentration [30] that is tightly related to green coloration intensity, which in an alternative and widely used quality index of herbal material [15].…”

“…syriaca [28] and Carlina diae (Rech.f.) Meusel and A.Kástner [29] and they inspire the usage of fertilization in stimulating the herbal antioxidant outline devoid of compromised optical quality or yield. These studies represent the first-ever cultivations of exemplary neglected and underutilized local endemic species of Crete, outlining their potential economic value.…”

“…Due to limited relevant data on range-restricted and threatened plant species cultivated for the first time or only locally, the data generated from the experiments of O. dictamnus may enable more accurate comparisons to previously published data on other local endemic plants of Crete, such as V. arcturus [26], O. microphyllum [27], S. syriaca subsp. syriaca [28] or C. diae [29], thus facilitating better results' interpretation. Context wise, the present study comparatively investigated the effects of different fertilization treatments and application techniques in a pilot field cultivation of O. dictamnus in Crete, contrasting a polysaccharidebased INM fertilization protocol with other schemes.…”