Seed Micromorphology, In Vitro Germination, and Early-Stage Seedling Morphological Traits of Cattleya purpurata (Lindl. & Paxton) Van den Berg

In the context of a symbiotic plant-fungus interaction study concerning Cattleya purpurata, we focused on some aspects of seed morphology and biology, and the early stages of seedling development. Seed morphology was characterized using light and scanning electron microscopy. In vitro seed germination capability was evaluated, comparing symbiotic and asymbiotic methods. The morphology of the seeds was overall comparable to that of other congeneric species, showing classical adaptations related to the aerodynamic properties and to the wettability of seeds, but calcium oxalate druses were identified inside the suspensor cells. Asymbiotic seed germination was successful in all tested media (17.1–46.5%) but was higher on 1/2 Murashige & Skoog. During symbiotic interaction with the fungal strain MUT4178 (Tulasnella calospora), germination rate was significantly lower than that obtained with the best three asymbiotic media, suggesting a low fungal compatibility. Seedling morphology was in line with other taxa from the same genus, showing typical characteristics of epiphytic species. Our observations, in particular, highlighted the presence of stomata with C-shaped guard cells in the leaves, rarely found in Cattleyas (where usually they are reniform), and confirm the presence of tilosomes in the roots. Idioblasts containing raphides were observed in both roots and leaves.

The Scientific Basis of the Target Plant Concept: An Overview

Reforestation and restoration using nursery-produced seedlings is often the most reliable way to ensure successful establishment and rapid growth of native plants. Plant establishment success—that is, the ability for the plant to develop within a set period of time with minimal further interventions needed—depends greatly on decisions made prior to planting, and yet nursery-grown plants are often produced independently of considering the range of stressors encountered after nursery production. The optimal plant or seedling will vary greatly with species and site (depending on edaphic and environmental conditions), and in having the biological capacity to withstand human and wildlife pressures placed upon vegetative communities. However, when nursery production strategies incorporate knowledge of genetic variability, address limiting factors, and include potential mitigating measures, meeting the objectives of the planting project—be it reforestation or restoration—becomes more likely. The Target Plant Concept (TPC) is an effective framework for defining, producing, and handling seedlings and other types of plant material based on specific characteristics suited to a given site. These characteristics are often scientifically derived from testing factors that are linked to outplanting success, such as seedling morphology and physiology, genetic source, and capacity to overcome limiting factors on outplanting sites. This article briefly summarizes the current knowledge drawn from existing literature for each component of the TPC framework, thereby helping land managers and scientists to meet objectives and accelerate reforestation and restoration trajectories.

Germination, Morphological and Physiological Evaluation of Seedlings Pretreated with Colchicine in Soybean (Glycine max L)

Wider genetic diversity has the potential to improve crop productivity of soybean, especially under environmental stress conditions. The pre-treatment of soybean seeds with antimitotic agents to establish improved genetic pool may also contribute to the enhancement of germination, seedling development, morpho-physiological growth and yield. In this study, 2 soybean genotypes viz. TGx1835-10E and Dundee were imbibed in solutions containing different amounts of colchicine (0.0, 0.1, 0.5 and 1 %) to evaluate the variations in germination, morphometric and physiological parameters. The seeds were imbibed for the period of 12 and 24 h before sowing for germination in plastic pots containing moistened sterile vermiculite. The variance components expressed as means, and mean percentage of total variations showed that colchicine concentration and imbibitional duration were the most important sources of variation for all traits, followed by the genotypes. Significant responses were detected for various germination parameters, seedling morphology and physiological contents such as; chlorophyll content, total phenolics, flavonoids as well as total protein and DNA content in the 2 genotypes used. HIGHLIGHTS Mutagenic pre-treatment of seeds via imbibition Germination and seedling growths of colchicine preconditioned seeds Chloroplastidic pigment analysis of pre-treated seedlings Physiological valuation of primary and secondary metabolites in grown seedlings Role of colchicine on germination, seedling development and growth of soybean plantlets GRAPHICAL ABSTRACT

Growth and morphological responses of gerbera seedlings to narrow-band lights with different light spectral combinations as sole-source lighting in a controlled environment

To optimize light-emitting diode (LED) spectral recipes for gerbera (Gerbera jamesonii) seedling propagation, seed germination and seedling morphology, biomass, flowering, and storage quality were observed in four cultivars, ‘Midi Dark Purple’, ‘Majorette Red Dark Eye’, ‘Maxi Pink’, and ‘Maxi White’, under six spectrum treatments: (1) FL, cool white fluorescent light; (2) RB, a photon flux ratio of 85% red and 15% blue (RB-LED); (3) RB + UVB, RB-LED combined with 0.5 µmol m-2 s-1 of ultraviolet-B; (4) RB + UVA, RB-LED combined with 9.6 µmol m-2 s-1 of ultraviolet-A; (5) RB + G, a photon flux ratio of 60% red, 15% blue, and 25% green; (6) RB + FR, RB-LED combined with 17.3 µmol m-2 s-1 of far-red. For all treatments, the photosynthetic photon flux density was 165 µmol m-2 s-1 under a 16-h photoperiod. Seedling growth and morphology were similar under FL and RB for all cultivars, except for a wider canopy of ‘Majorette Red Dark Eye’ under RB. Each of the tri-chromatic light treatments (i.e., RB + UVB, RB + UVA, RB + G or RB + FR) showed similar effects as RB, except for thicker ‘Maxi Pink’ stems under RB + FR. Furthermore, the quality index, an integrated evaluation of seedling quality, was similar under all the treatments for each cultivar. Given similar seedling quality and the advantages of LEDs, RB-LED can potentially replace FL for controlled-environment gerbera seedling production, but the tri-chromatic lights tested in this study appear to be unnecessary.

Dioecious hemp (Cannabis sativa L.) plants do not express significant sexually dimorphic morphology in the seedling stage

Some economically important crop species are dioecious, producing pollen and ovules on distinct, unisexual, individuals. On-the-spot diagnosis of sex is important to breeders and farmers for crop improvement and maximizing yield, yet diagnostic tools at the seedling stage are understudied and lack a scientific basis. Understanding sexual dimorphism in juvenile plants may provide key ecological, evolutionary and economic insights into dioecious plant species in addition to improving the process of crop cultivation. To address this gap in the literature, we asked: can we reliably differentiate males, females, and co-sexual individuals based on seedling morphology in Cannabis sativa, and do the traits used to distinguish sex at this stage vary between genotypes? To answer these questions, we collected data on phenotypic traits of 112 C. sativa plants (50 female, 52 male, 10 co-sexuals) from two hemp cultivars (CFX-1, CFX-2) during the second week of vegetative growth and used ANOVAs to compare morphology among sexes. We found males grew significantly longer hypocotyls than females by week 2, but this difference depended on the cultivar investigated. Preliminary evidence suggests that co-sexual plants may be distinguished from male and female plants using short hypocotyl length and seedling height, although this relationship requires more study since sample sizes of co-sexual plants were small. In one of the cultivars, two-week old male plants tend to produce longer hypocotyls than other plants, which may help to identify these plants prior to anthesis. We call for increased research effort on co-sexual plants, given their heavy economic cost in industrial contexts and rare mention in the literature. Our preliminary data suggests that short hypocotyl length may be an indicator of co-sexuality. These results are the first steps towards developing diagnostic tools for predicting sex using vegetative morphology in dioecious species and understanding how sexual dimorphism influences phenotype preceding sexual maturity.

Seed and seedling morphology of Bauhinia scandens L.

Bauhinia scandens has potential importance as an ornamental and medicinal plant. Researchers have isolated and identified 1-O-alkylglycerol in the leaves of the B. scandens plant, and established antitumor properties using the Brine Shrimp toxicity test, an internationally accepted bioassay. Although this species has high potential, little is known about the viability of seedling production and the morphology of these plants, particularly in terms of seed characteristics and initial stages of germination. The objective of this study was to characterize the seed morphology, germination, and seedlings of B. scandens. Seed water content, weight, and coloration were evaluated. This study also included a description of seed biometrics, external and internal structures, germination, and seedling morphology. Internal seed morphology was evaluated by the anatomical sectioning and X-ray methods. The morphology data obtained were subjected to descriptive statistical analysis and germination data were determined using Cramér’s V. B. scandens seeds have a coloration ranging from very dark grayish-red to dark reddish-brown, flat oblong shapes, and rounded bases and apexes with full or slightly undulating margins. Healthy seedlings are produced mainly by seeds with well-formed internal structures. The reddish petiole of the seedling leaves is a taxonomic character for B. scandens identification. The non-domestication and genetic variability of this species reflect on the seed and seedling color and size variation.

Seedling morphology of different wheat genotypes at early stages under hydrocultural conditions

Consuming “sprouted seeds” is one of the most important factors of a healthy diet. An experiment was conducted in the University of Debrecen, Research Centre of Nyíregyháza (Hungary) in 2014 to analyse some morphological traits of four winter wheat genotypes (Triticum aestivum L.) and one spelt (T. spelta) variety. Our results showed that the spelt wheat variety “Franckenkorn” could maintain higher root length throughout the experimental period. On average, both “Perbetei” and “Franckenkorn” varieties could maintain higher root number compared to the other varieties. The extensive breeding line “1401 HK” had the highest shoot length throughout the whole experiment, being significantly higher than the landrace variety “Perbetei” and both of the varieties “KG Bendegúz” and “KG Kunhalom”. It could be concluded that “KG Bendegúz” cultivar and “Perbetei” landrace seem to be the most suitable for aquaculture techniques. In addition, “1401 HK” breeding line can be the most suitable for the production of juice since the minimal required shoot length (12 cm) was achieved within the shortest period of time after sowing (9 days). This breeding line and “Franckenkorn” can also be suitable for production of “wheatgrass”, because it is consumed without roots. Further research is needed to evaluate nutritional values of these genotypes.