Wavelength and Light Intensity Affect Macro- and Micronutrient Uptake, Stomata Number, and Plant Morphology of Common Bean (Phaseolus vulgaris L.).

It is already known that light quality and intensity have major influences on the growth, etiolation, germination, and morphology of many plant species, but there is limited information about the effect of wavelength and light intensity on nutrient absorption by plants. Therefore, this study was established to evaluate the plant growth, stomata formation, chlorophyll index, and absorption of macro- and micronutrients by common bean plants under six light treatments. The experimental design was completely randomized and consisted of six treatments: strong blue (blue LED at high light intensity); weak blue (blue LED at low light intensity); strong red (red LED at high light intensity); weak red (red LED at low light intensity; pink (combined red + blue LED), and white (combined red + white led). The stomatal density (stomata mm-2); the SPAD index; plant height (cm); root length (cm); plant dry weight (g); root dry weight (g); and the concentrations of N, S, K, Mg, Ca, B, Zn, Mn, and Fe on leaf analysis were influenced by all treatments. We found that plant photomorphogenesis is controlled not only by the wavelength, but also by the light intensity. Etiolation was observed in bean plants under blue light at low intensity, but when the same wavelength had more intensity, the etiolation did not happen, and the plant height was the same as plants under multichromatic lights (pink and white light). The smallest plants showed the largest roots, some of the highest chlorophyll contents, and some of the highest stomatal densities, and consequently, the highest dry weight, under white LED, showing that the multichromatic light at high intensity resulted in better conditions for the plants in carbon fixation. The effect of blue light on plant morphology is intensity-dependent. Plants under multichromatic light tend to have lower concentrations of N, K, Mg, and Cu in their leaves, but the final amount of these nutrients absorbed is higher because of the higher dry weight of these plants. Plants under blue light at high intensity tended to have lower concentrations of N, Cu, B, and Zn when compared to the same wavelength at low intensity, and their dry weight was not different from plants grown under pink light. New studies are needed to understand how and on what occasions intense blue light can replace red light in plant physiology.

Orchid Micropropagation Using Conventional Semi-Solid and Temporary Immersion Systems: A Review.

Orchids, with their astonishingly stunning flowers, dominate the international floricultural market. They are considered prized assets for commercial applications in pharmaceutical and floricultural industries as they possess high therapeutic properties and superior ornamental values. The alarming depletion of orchid resources due to excessive unregulated commercial collection and mass habitat destruction makes orchid conservation measures an extreme priority. Conventional propagation methods cannot produce adequate number of orchids, which would meet the requirement of these ornamental plants for commercial and conservational purposes. In vitro orchid propagation using semi-solid media offers an outstanding prospect of rapidly producing quality plants on a large scale. However, the semi-solid (SS) system has shortcomings with low multiplication rates and high production costs. Orchid micropropagation using a temporary immersion system (TIS) overcomes the limitations of the SS system by reducing production costs and making scaleup and full automation possible for mass plant production. The current review highlights different aspects of in vitro orchid propagation using SS and TIS and their benefits and drawbacks on rapid plant generation.

Effectiveness of a micronutrient delivery system fertilizer in jatropha plants is related to enhanced photosynthesis, gas exchange and biomass allocation / Eficácia de um sistema de fornecimento de micronutrientes em plantas de jatropha está relacionado com incrementos na fotossíntese, troca gasosa e alocação de biomassa

This study aimed at comparing the growth and physiological changes in Jatropha curcas L. (jatropha or physic nut) young plants fertilized or not with a commercial product based on a micronutrient delivery system (MDS), under different doses of NPK. Measurements of growth, chlorophyll content, and leaf gas exchange were performed in the greenhouse, where plants were arranged in a split-split plot design. Plants were grown for 120 days in 3.9 L pots containing local soil, with or without MDS (main plot), combined with NPK doses (0; 1.8; 4.7 and 7.4 g L-1) in subplots. Dose-response curves showed that most variables were positively responsive to NPK doses in plants growing without MDS, whereas slight responses or even opposite behavior was observed in MDS-fertilized plants. MDS application under low NPK doses resulted in higher biomass allocation in leaves and roots, increases in number of leaves and chlorophyll content, plant height, stem diameter, shoot and root dry weight, stomatal conductance, photosynthesis, leaf transpiration, and water use efficiency, as well as decreases in intercellular CO2 in the leaf and vapor-pressure deficit. The enhanced biomass allocation, photosynthesis and gas exchange in MDS-supplemented plants indicates the relevant role played by this fertilizer in jatropha metabolism, resulting in more vigorous plants.

Este estudo teve como objetivo comparar o crescimento e as mudanças fisiológicas em plantas jovens de Jatropha curcas L. (pinhão manso), fertilizadas ou não, com um produto comercial baseado em um sistema de fornecimento de micronutrientes (MDS), sob diferentes doses de NPK. Medidas de crescimento, teor de clorofila e troca gasosa foliar foram realizados em casa de vegetação, onde as plantas foram arranjadas em um delineamento de blocos casualizados com parcela subdividida. As plantas foram cultivadas por 120 dias em potes de 3,9 L contendo solo local, com ou sem MDS (parcela principal), combinado com doses de NPK (0; 1,8; 4,7 e 7,4 g L-1) nas subparcelas. Curvas doseresposta mostraram que a maioria das variáveis responderam positivamente às doses de NPK em plantas crescendo sem MDS, enquanto respostas fracas ou mesmo comportamento oposto foi observado em plantas fertilizadas com MDS. A aplicação de MDS em doses baixas de NPK resultaram em maior alocação de biomassa nas folhas e raízes, aumento no número de folhas e teor de clorofila, altura da planta, diâmetro do caule, pesos secos da parte aérea e raiz, condutância estomatal, fotossíntese, transpiração foliar e eficiência no uso da água, bem como na redução do CO2 intercelular na folha e déficit de pressão de vapor. O aumento na alocação de biomassa, fotossíntese e troca gasosa em plantas suplementadas com MDS indica o papel relevante deste fertilizante no metabolismo de pinhão manso, resultando em plantas mais vigorosas.

Cryopreservation of banana's cv Grand Naine in vitro rhizomes

ABSTRACT The preservation of banana genetic material is usually performed through seedlings. However, most banana cultivars do not produce seed and are propagated vegetatively. Therefore, cryopreservation is a feasible technique that allows the preservation of banana genotypes indefinitely. For the success of cryopreservation protocols, the selection of cryoprotectants and pre-freezing techniques are important factor. Therefore, the objective of this study was to verify the effects of different cryoprotectants with and without 1% phloroglucinol and pre-cooling periods on the development of a protocol for cryopreservation of in vitro rhizomes ofMusa accuminata(AAA) cv Grand Naine banana. The addition of 1% phloroglucinol to the cryoprotective solutions, such as PVS2 enhanced recovery of cryopreserved banana rhizomes. In addition, pre-cooling of explants in ice for 3 hours in PVS2 + 1% of phloroglucinol allowed efficient cryopreservation of banana rhizomes, followed by successful recovery and regeneration of in vitro shoots of banana cv Grand Naine.

Cryopreservation of banana's cv Grand Naine in vitro rhizomes.

The preservation of banana genetic material is usually performed through seedlings. However, most banana cultivars do not produce seed and are propagated vegetatively. Therefore, cryopreservation is a feasible technique that allows the preservation of banana genotypes indefinitely. For the success of cryopreservation protocols, the selection of cryoprotectants and pre-freezing techniques are important factor. Therefore, the objective of this study was to verify the effects of different cryoprotectants with and without 1% phloroglucinol and pre-cooling periods on the development of a protocol for cryopreservation of in vitro rhizomes ofMusa accuminata(AAA) cv Grand Naine banana. The addition of 1% phloroglucinol to the cryoprotective solutions, such as PVS2 enhanced recovery of cryopreserved banana rhizomes. In addition, pre-cooling of explants in ice for 3 hours in PVS2 + 1% of phloroglucinol allowed efficient cryopreservation of banana rhizomes, followed by successful recovery and regeneration of in vitro shoots of banana cv Grand Naine.

Genetic structure from the oldest Jatropha germplasm bank of Brazil and contribution for the genetic improvement.

Jatropha is a potential oilseed crop, which requires mitigating factors such as the low genetic variability of the species. The solution runs through the research of Brazilian germplasm. Attention should be given to the germplasm of jatropha the north of Minas Gerais, because this is the oldest national collection and because this region may be a regions of jatropha diversity due to selection pressure arising from environmental adversities. Therefore, the objective of this study was to investigate the genetic diversity of 48 accessions of collection from Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG), using SSR and ISSR markers. The results showed low genetic diversity, but some individuals stood out as J. mollissima (48), J. podagrica (47), Mexican accessions (42, 43, 44 and 45) and some national accessions (28, 29, 41 and 46). Therefore, aiming to increase the genetic variability and improve the effectiveness of jatropha breeding programs, it is suggested to explore such as parental accessions to generate commercial hybrids. This fact implies the possibility to support future production of jatropha, since this culture may be an important source of income, especially for small farmers living in semiarid regions of Brazil.

In vitro conservation of Dendrobium germplasm.

Dendrobium is a large genus in the family Orchidaceae that exhibits vast diversity in floral characteristics, which is of considerable importance to orchid breeders, biotechnologists and collectors. Native species have high value as a result of their medicinal properties, while their hybrids are important as ornamental commodities, either as cut flowers or potted plants and are thus veritable industrial crops. Thus, preservation of Dendrobium germplasm is valuable for species conservation, breeding programs and the floriculture industry. Cryopreservation represents the only safe, efficient and cost-effective long-term storage option to facilitate the conservation of genetic resources of plant species. This review highlights 16 years of literature related to the preservation of Dendrobium germplasm and comprises the most comprehensive assessment of thorough studies performed to date, which shows reliable and reproducible results. Air-drying, encapsulation-dehydration, encapsulation-vitrification, vitrification and droplet-vitrification are the current cryopreservation methodologies that have been used to cryopreserve Dendrobium germplasm. Mature seeds, pollen, protoplasts, shoot primordia, protocorms and somatic embryos or protocorm-like bodies (PLBs) have been cryopreserved with different levels of success. Encapsulation-vitrification and encapsulation-dehydration are the most used protocol, while PLBs represent the main explant explored.

Germination, carbohydrate composition and vigor of cryopreserved Caesalpinia echinata seeds

The present study investigated the germination and vigor of Caesalpinia echinata (Brazilwood) seeds stored at negative temperatures. Recently harvested seeds were cryopreserved at -18º or -196ºC and periodically evaluated for germination, seed vigor and carbohydrate composition. The temperatures did not influence the germination percentages or vigor. The germination percentage decreased from 88% in recently harvested seeds to 60% after 730 days of storage. The different temperature and storage times tested did not affect the vigor seed germination as indicated by the measures of plant growth and survival. The different temperatures used did not cause changes in the carbohydrate composition. The tegument cell walls were rich in lignin, arabinose and xylose. The cytoplasm of the cotyledons and embryos had high levels of glucose, fructose, and sucrose. The cryopreservation technique here presented was effective in the conservation of Brazilwood seeds for the medium term.

Asymbiotic germination response to photoperiod and nutritional media in six populations of Calopogon tuberosus var. tuberosus (Orchidaceae): evidence for ecotypic differentiation.

BACKGROUND AND AIMS: Ecotypic differentiation has been explored in numerous plant species, but has been largely ignored in the Orchidaceae. Applying a specific germination protocol for widespread seed sources may be unreliable due to inherent physiological or genetic differences in localized populations. It is crucial to determine whether ecotypic differentiation exists for restoration and conservation programmes. Calopogon tuberosus var. tuberosus, a widespread terrestrial orchid of eastern North America, is a model species to explore ecotypic differences in germination requirements, as this species occupies diverse habitats spanning a wide geographical range. METHODS: Mature seeds were collected from south Florida, north central Florida, three locations in South Carolina, and the upper Michigan peninsula. Effects of three photoperiods (8/16, 12/12, 16/8 h L/D) were examined on asymbiotic in vitro seed germination and seedling development of C. tuberosus. Germination and early development was monitored for 8 weeks, while advanced development was monitored for an additional 8 weeks. In an additional experiment, asymbiotic seed germination and development was monitored for 8 weeks on six culture media (BM-1 terrestrial orchid medium, Knudson C, Malmgrem, half-strength MS, P723, and Vacin and Went). A tetrazolium test for embryo viability was performed. KEY RESULTS: Short days promoted the highest germination among Florida populations, but few differences among photoperiods in other seed sources existed. Different media had little effect on the germination of Michigan and Florida populations, but germination of South Carolina seeds was higher on media with higher calcium and magnesium. Tetrazolium testing confirmed that South Carolina seeds exhibited low viability while viability was higher in Florida seeds. Seed germination and corm formation was rapid in Michigan seeds across all treatments. Michigan seedlings allocated more biomass to corms compared with other seed sources. CONCLUSIONS: Rapid germination and corm formation may be a survival mechanism in response to a compressed growing season in northern populations. Ecotypic differentiation may be occurring based on seed germination and corm formation data.