Theobroma cacao L. cultivar CCN 51: a comprehensive review on origin, genetics, sensory properties, production dynamics, and physiological aspects

Many decades of improvement in cacao have aided to obtain cultivars with characteristics of tolerance to diseases, adaptability to different edaphoclimatic conditions, and higher yields. In Ecuador, as a result of several breeding programs, the clone CCN 51 was obtained, which gradually expanded through the cacao-production regions of Ecuador, Colombia, Brazil and Peru. Recognized for its high yield and adaptability to different regions and environments, it has become one of the most popular clones for breeding programs and cultivation around the world. This review aims to summarize the current evidence on the origin, genetics, morphological, volatile compounds, and organoleptic characteristics of this clone. Physiological evidence, production dynamics, and floral biology are also included to explain the high yield of CCN 51. Thus, characteristics such as osmotic adjustment, long pollen longevity, and fruit formation are further discussed and associated with high production at the end of the dry period. Finally, the impact of this popular clone on the current and future cacao industry will be discussed highlighting the major challenges for flavor enhancement and its relevance as a platform for the identification of novel genetic markers for cultivar improvement in breeding programs.

Viability of pollen grains and stigma receptivity in Desert Rose

Adenium obesum (Forssk.) Roem. & Schult., popularly known as desert rose, has become a valuable ornamental plant. In floriculture, the production of hybrids is prioritized. Hence, knowledge on floral biology and sexual reproduction of the target species is fundamental. The objectives of this study were: (1) to test sucrose concentrations and temperatures for in vitro germination of A. obesum pollen grains; (2) to identify the effect of temperature on the viability of A. obesum pollen grains; and (3) to evaluate the viability of pollen grains and stigma receptivity in pre-anthesis, at flower opening, and 72 h post-flower opening in three accessions of A. obesum. A significant relationship between temperatures and sucrose concentrations was observed in the in vitro germination test. The highest percentage of in vitro germination of pollen grains, 39.81%, was observed at an estimated temperature of 26.05 °C. Desert rose accessions maintained in biochemical oxygen demand (BOD) chambers at 30 °C during a 16-h light photoperiod showed faster flowering, and temperatures ≥ 25 °C induced pollen grain viability percentages above 69%. Temperature is one of the most important abiotic factors, influencing mainly in pollen germination, pollen tube growing and in efficiency fertilization. The ICA-wd accession stood out and can be considered a pollen donor in artificial pollination. The stigmas of flowers were receptive from a day before flower opening until three days after. The two parameters presented above, stigma receptivity and pollen viability, allow inferences about the appropriate time for successful pollination and subsequent fertilization in desert roses.

Genetic diversity and structure in natural populations of Cajui from Brazilian Cerrado

Cajui (Anacardium spp.) is a native fruit tree (small cashew) of the Brazilian Cerrado and possesses the potential for commercialization. However, cajui exploitation occurs exclusively through extractivism in the absence of conservation strategies. The lack of conservation strategies may lead to a decrease in genetic diversity of Anacardium. In this work, the genetic diversity and population structure of three natural populations in Sete Cidades National Park (PNSC; PI, Brazil) were assessed using ISSR analysis of 56 cajui accessions and two A. occidentale accessions (outgroup) from Pacajus (CE, Brazil). A total of 112 markers were obtained, 93 (83.04%) of which were polymorphic. The diversity indices of these populations indicated moderate levels of genetic diversity. According to AMOVA, 96.17% of the genetic variability lay within populations, with low genetic differentiation among populations (ΦST = 0.03828). Furthermore, STRUCTURE analysis indicated the existence of four connected genetic groups. The findings show that the individuals from the three collection sites did not represent different subpopulations, likely due to the high gene flow (Nm = 6.7) favored by the floral biology of Anacardium, pollinators and small-animal seed dispersers. This research identifies genetically divergent individuals (C-03, C-05, C-22, C-26, C-34 and C-39), which should be considered priority individuals for conservation and can inform conservation programs for Anacardium spp.

A Comprehensive Review on Biology, Genetic Improvement, Agro and Process Technology of German Chamomile (Matricaria chamomilla L.)

German chamomile (M. chamomilla) is recognized as a star herb due to its medicinal and aromatic properties. This plant is found across a wide range of climatic and soil conditions. Both the flower heads and blue essential oils of German chamomile possess several pharmacological properties of an anti-inflammatory, antimicrobial, antiseptic, antispasmodic and sedative, etc., nature, which makes it a highly sought after herb for use in many pharma and aroma industries. Chamomile tea, prepared from its flower heads, is also a well-known herbal tea for mind and body relaxation. Though it is a high-demand herb, farmers have not adopted this plant for large scale cultivation as a crop, which could improve their livelihood, due to the high cost in flower heads harvesting, loss in over mature and immature flower heads picking during harvesting, unavailability of varieties and agrotechnologies for machine harvesting, a lack of efficient process development of oil extraction and in the lack of improved stable varieties. There are many studies that have reported on the phytochemistry and pharmacological uses of chamomile, which further explore its importance in the medicine industry. Several studies are also present in the literature on its cultivation practices and plant ecology. However, studies on breeding behavior, genetic improvement, varietal development and mechanical harvesting are scarce in German chamomile. Hence, keeping in mind various aspects of farmers’ and researchers’ interest, earlier reports on taxonomy, floral biology, processing of oil extraction, active constituents, uses, agronomy, breeding challenges and opportunities in German chamomile are summarized in this review.

Morpho-phenological Variability of Flowers Traits and Hybridization of Five Inbred Lines of Cowpea [Vigna unguiculata (L.) Walp.] in Côte d'Ivoire

Knowledge of the morphology and floral phenology and the mastery of a manual pollination technique in a plant species are essential for its genetic improvement. The objective of this work will be to determine the morpho-phenological characteristics of the flowers of five self-fertilization lines of cowpea and to identify an indicated manual pollination technique. The study was carried out in the Botanical Garden of University Peleforo GON COULIBALY, Côte d’Ivoire where 10 morpho-phenological characters of the flower were evaluated on five lines of cowpea self-fertilization. Thus, three manual pollination techniques (A, B and C) were tested by evaluating traits such as knotting rates, filling rates and maternal and paternal effects on fruit yields. The results revealed four stages of flower development in cowpea. These are successively stage of “floral button initiation”, “dark green floral button”, “pale green or pale-yellow floral button” and “blooming flower”. Of the three manual pollination techniques tested, technique C resulted in higher rates of knotting (45.38%) and pod filling (58.03%). Results also showed significant maternal and xenia effects on fruit yields in the cowpea. On the basis of the results generated on the floral biology of the cowpea, it appears that a hybridization program can now be conducted at the UPGC Botanical Garden for the creation of high-performance varieties adapted to climate change for the benefit of producers in Côte d’Ivoire.

FLORAL BIOLOGY AND BEEKEEPING POTENTIAL OF Croton heliotropiifolius KUNTH (EUPHORBIACEAE) AT SEMI ARID REGION, BRAZIL1

ABSTRACT The aim of the present study was to determine the beekeeping potential of Croton heliotropiifolius Kunth (Euphorbiaceae) based on flowering strategy, floral characteristics, available floral resources, and the individuals frequencies and foraging activities of Apis mellifera L. on its flowers in Fazenda Ingazeira, Brazil. Each C. heliotropiifolius plant possessed inconspicuous diclinous flowers clustered into 560 ± 60 dense terminal inflorescences containing 59 ± 12 pistillate and 160 ± 26 staminate flowers. Although both types of flowers produced nectar (pistillate: 2.8 ± 0.8 μL ; staminate: 0.3 ± 0.06 μL ), A. mellifera workers mostly visited staminate flowers (98%) during the peak visitation period (08:00-11:00 h). Moreover, during the foraging period, each plant produced approximately 5.376 × 10 8 pollen grains, ensuring approximately 33 visitation cycles from a colony of A mellifera workers that picked up an average of 405 pollen grains per visit per flower. Further, C. heliotropiifolius showed an annual cornucopia flowering strategy with high flower production for five months, which is an important characteristic that ensures floral resource availability in the environment. These findings suggest that C. heliotropiifolius has a great potential for apiculture in this region.

Pollination and Floral Biology of a Rare Morning Glory Species Endemic to Thailand, Argyreia siamensis

Argyreia siamensis is extremely rare, and very little is known about its reproduction. The species has colorful flowers that seem likely to attract pollinators, but population sizes are typically small (<30 individuals). To determine whether poor reproduction contributes to its rarity, we investigated its mating system and potential pollinators in two populations. We also examined the staminal trichomes and floral nectary to investigate their role in pollinator attraction. The mating system was assessed with a bagging experiment and pollinator visits were recorded with action cameras. Additionally, we tested the staminal trichomes and floral nectary for terpenes and flavonoids and examined floral nectary micromorphology via scanning electron microscope and compound light microscope. Our results reveal that A. siamensis is self-incompatible and dependent on pollinators; the western population was pollinated by bees (Meliponini and Amegilla), while the eastern population was mainly pollinated by skipper butterflies (Hesperiidae). Both staminal trichomes and the floral nectary appear to contribute to pollinator attraction through the presence of terpenes and flavonoids (in both secretory structures) and nectariferous tissue and nectarostomata (in the nectary). Our results indicate that A. siamensis has reliable and effective pollinators and that insufficient pollination is likely not a primary cause of its rarity.

Comparative Floral and Pollen Micromorphology of Leonurus japonicus and L. macranthus (Lamiaceae)

Floral micromorphology and pollen morphology of two Leonurus (Lamiaceae) species were examined and compared using scanning electron microscopy to evaluate the diagnostic value of these features to facilitate future studies on floral biology and taxonomy. Floral epidermal patterns were similar in both species, with the conical to central-conical epidermal cells on the adaxial side of the lower lip (corolla). Capitate, peltate, scale-like glandular, and non-glandular trichomes were distributed on the surface of the floral organs. Notably, scale-like anther glands and floral stomata were found on the anthers and abaxial side of the calyx, respectively. Pollen grains had bi-reticulate exine with angular primary lumina and rounded secondary lumina. These characteristics provide indirect evidence of a close association between plant-pollinator interactions and effective pollination. In addition, quantitative traits of pollen grains and trichome types on the adaxial side of the lip differed between the two species. These characteristics may have diagnostic and taxonomic value for the genus Leonurus and family Lamiaceae.

Combining ability, floral biology, and seed producibility of promising cytoplasmic male-sterile (CMS) lines for hybrid rice development

Background A combining ability analysis is a useful tool of plant breeders in screening and identifying promising parental lines with high potential for developing competitive rice hybrids. Also, one important factor that strongly determines the suitability of commercial utilization of hybrid rice parental lines is their extent of seed producibility. Methods In this study, the combining ability, floral biology and seed producibility of cytoplasmic male sterile (CMS) lines were investigated to identify good combiners with good seed production potential. The Line × Tester analysis was used to determine the general combining abilities (GCA) of hybrid rice parental lines, and Specific Combining Abilities (SCA) of the different hybrid combinations. A correlation analysis was also done to determine floral traits that influence the outcrossing rate of the CMS lines. There were 4 CMS lines, 6 restorer lines, 24 hybrid combinations and 1 check variety in a randomized complete block Design (RCBD) with 3 replicates. Results Results indicated that CMS lines IR79128B and IR102758B were good combiners and the most promising restorer lines were D2031-7-1-2R, Hanareumbyeo 2, and XTR036-54-10R. Based on specific combining ability test, the most promising combination was entry 10 (IR58025A/D2013-7-1-2R). It has the highest yield of 7496 kg ha−1, a high positive SCA score of 570.54, and highest standard heterosis of 12.9%. Based on floral traits, IR79128B was the most promising with a high positive GCA score of 186.93, panicle exertion rate of 74.8%, and a high outcrossing rate of 51%. There was a significant positive association between outcrossing rate, duration of floral opening, panicle exertion rate, and general combining ability. Conclusion The floral traits found to be significantly associated with outcrossing rate are useful selection criteria not only for identifying economically usable CMS lines but also for developing new and promising parental lines and hybrids. These CMS lines do not only give heterotic combinations but are also commercially producible, the two most important factors to the success of any hybrid rice breeding program.