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This experiment researched the effects of supplementary light on cucumber [Cucumissativus(L.)] seedling growth and some physiological characteristics under the same temperature. The purpose was to afford basic light condition control of cucumber cultivation in a greenhouse during winter to spring. Two cucumber cultivars, No. 3 `Jinchun' (greenhouse cultivar) and No. 7 `Longzahuang' (open field cultivar), were transplanted with supplementary light at different intensities. The experimental results indicate that plant height, leaf area, and stem diameter of cucumber seedlings were significantly increased with increasing intensity of supplementary light. Supplementary light at the cucumber seedling stage led to the increase of chlorophyll content, soluble sugar content, protein content, and CAT activity. At the same time, reduction in POD activity and MDA content with increasing levels of supplementary light was found. In addition, cells of supplementary light treatments have more chloroplasts, grana, and starch grains. Chloroplast growth of supplementary light treatments was better than CK. The grana lamella was arranged in order and its structure was clear. These results show that supplementary light could improve the growth of seedling plants, alleviate the damage of membrane lipid peroxidation, and facilitate chloroplast growth. The effects of supplementary light on the two cultivars were the same, but their extent was different. Effects on No. 7 Longzahuang were more significant than those on No. 3 Jinchun.
Nanomaterials have recently been used as growth stimulants to promote the production of crops in saline-alkali through root application. However, if applied through leaves, little is known about the effect of Fe3O4 nanoparticles (NPs) on the root growth and yield, especially for medicinal crops. To fill this gap, a single factor experiment was conducted to explore the effects of Fe3O4 NPs on growth, yield, the dry matter distribution, chlorophyll content, photosynthetic characteristics, chlorophyll fluorescence parameters, and polysaccharide content of Pseudostellaria heterophylla by foliar spraying under field conditions. Fe3O4 NPs (20–50 mg·L–1) significantly promoted growth, the dry matter distribution of root and root tuber yield per unit area. Fe3O4 NPs enhanced net photosynthetic rate (P n) by increasing chlorophyll content. And Fe3O4 NPs increased the daily mean and peak value of P n, and alleviated the phenomenon of “midday depression” by improving nonstomatal limitation. Chlorophyll fluorescence parameters indicating that Fe3O4 NPs promoted the photochemical activity of PSII and alleviated photoinhibition by enhancing the photochemical use of excess excitation energy. Gray correlation analysis showed that Fe3O4 NPs enhanced the adaptability of P. heterophylla photosynthesis to high temperatures and strong light. Of note, Fe3O4 NPs enhanced the polysaccharide content of the root tuber. Phytotoxic effect was recorded at high NPs (100 mg·L–1) doses. Collectively, Fe3O4 NPs could promote performance of P. heterophylla by improving photosynthetic performance, enhancing its adaptability to the environment, and increasing the distribution ratio of photosynthates to the underground part.
In recent years, air circulation has been used in protected cultivation to improve the microenvironment around seedlings, which in turn enhances photosynthesis and seedling growth. However, a practical and precise air circulation device has not yet been reported, especially one for growing seedlings in a greenhouse. Considering the use of a seedbed in seedling cultivation, a blower that can move back and forth on the seedbed and accurately control the air velocity is designed. In this experiment, we take the nonblowing treatment as the control (CK); three air velocities (0.3, 0.6, and 0.9 m/s) were selected to investigate the effect of interval blowing on the microenvironment of the canopy, physiology of seedling growth, stomatal characteristics of leaves, and stem mechanics of tomato seedlings. The three air velocities were found to significantly reduce the canopy temperature by 0.44, 0.78, and 1.48 °C lower than the CK, respectively, and leaf temperature by 0.83, 1.57, and 2.27 °C lower than the CK, respectively, in cultivated seedlings during summer. The relative humidity of the tomato seedling canopy decreased by 2.7% to 7.0%. Compared with the CK, the plant height of tomato seedlings decreased by 13.54% and root dry mass, root-shoot ratio, and seedling quality index (SQI) increased by 34.63%, 21.43%, and 14.29%, respectively, at 0.6 m/s. In addition, mechanical indexes such as hardness and elasticity of the tomato seedling stem were higher under air disturbance than those of the CK. The best effect was seen in the treatment with the air velocity of 0.6 m/s, in which the hardness and elasticity of the stem base and the first node were significantly higher than that of the CK. In conclusion, air disturbance generated by the air blowing device we designed effectively improved the microenvironment around the plants, enhanced the physiological activity of the seedlings, and thereby promoted seedling growth.
Expansins are extracellular proteins that are involved in cell wall modifications such as cell wall disassembly, cell separation, and cell expansion. Little is known about expansin gene expression during flower development of wintersweet (Chimonanthus praecox). In the present study, an expansin gene, CpEXP1, was isolated from the wintersweet flower cDNA library through random sequencing; this gene encodes a putative protein of 257 amino acids with the essential features conserved, like in other alpha expansins. The CpEXP1 gene exhibited different transcription levels in different tissues and had a significantly higher expression in flowers than other tissues. It is strongly correlated with the development of the flower. The expression of CpEXP1 increased in the flower buds or whole flowers from Stage 1 to 4 and decreased from Stage 5 to 6 during natural opening. Ethephon (an ethylene releaser) treatment promoted cut flower senescence, whereas 1-methylcyclopropene (1-MCP) (an ethylene perception inhibitor) delayed the process of flower wilting. This result is associated with the concomitant lower transcript levels of CpEXP1 in the ethephon-treated samples as well as the steady expression in the 1-MCP-treated samples compared with that in control flowers. The studies show the interesting observation that the expression of an expansin gene CpEXP1 is correlated with the development of Chimonanthus praecox flowers, the upregulation during flower opening vs. the downregulation during senescence.
Sedum rubrotinctum is widely grown as an ornamental because of its attractive leaf shape and color. Increasing the morphological diversity and color will greatly add to its ornamental value. Environmental conditions such as light and temperature can change the leaf color of succulent plants, but the mechanism is uncertain. To examine this mechanism, we tested the effects of two commercial chemical products Sowing Goodliness (Sg) and Aromatic Garden (Ag) on the morphology, pigment content, and growth performance of Sedum rubrotinctum seedlings. The Sg treatment did not change foliage color, but can accelerate plant growth and increase lateral bud number. The Ag treatment had marked changes on the relative proportions of pigments and leaf color, and plant growth was severely reduced with mortality observed in some plants. After Ag stress was discontinued, the surviving plants began to regrow and had good ornamental value but had the fewest number of lateral buds and leaves, and the smallest leaf length and thickness, canopy diameter, and plant height. Foliage color changes are caused directly by shifts in the relative proportions of pigments, particularly chlorophyll b and anthocyanin. In Ag-treated plants, chlorophyll b declined much faster than chlorophyll a, indicating that the transformation of chlorophyll b into chlorophyll a is an important step in the chlorophyll degradation pathway. Ag provides a way to learn more about the mechanism of chlorophyll degradation and should be investigated further. Ag enhanced anthocyanin production rapidly and improved the ornamental value of Sedum rubrotinctum. Different concentrations of Ag and Sg were not studied in this trial and might be tested to determine the ideal balance between leaf color and plant growth.
The objective of this study was to investigate ascorbic acid (AsA) accumulation, mRNA expression of genes involved in AsA biosynthesis as well as recycling, activity of key enzymes, and the relationship of them to AsA levels during the development of apple fruit (Malus ×domestica cv. Gala). AsA concentration, which mainly depends on biosynthesis, was the highest in young fruit post-anthesis and then decreased steadily toward maturation. However, AsA continued to accumulate over time because of the increase in fruit mass. Transcript levels of guanosine diphosphate (GDP)-L-galactose phosphorylase, GDP-mannose pyrophosphorylase, D-galacturonate reductase, and the post-transcriptionally regulated L-galactono-1,4-lactone dehydrogenase were not correlated with AsA accumulation in apple. In contrast, patterns of expression for L-galactose dehydrogenase, L-galactose-1-phosphate phosphatase, and GDP-mannose-3′,5′-epimerase showed a pattern of change similar to that of AsA accumulation. Although activities and expression levels of monodehydroascorbate reductase and dehydroascorbate reductase in fruit, which had less capacity for AsA recycling, were much lower than in leaves, they were not clearly correlated with AsA level during fruit development.
The pathogenic fungus Colletotrichum musae infects developing green bananas (Musa spp. AAA group), but remains latent until the fruit ripens. The aim of this research was to determine whether the appearance of disease symptoms is regulated by chitinase gene expression following treatment of fruit with benzothiadiazole (BTH) and methyl jasmonate (MeJA), and with physical (heat) and chemical (H2O2 and Ca2+-related) treatments. In bananas inoculated with C. musae, BTH and MeJA lowered disease severity and stimulated higher gene expression compared with the untreated controls during ripening. However, in naturally infected bananas, BTH and MeJA treatments slightly reduced transcription of the chitinase gene in green bananas, but they prolonged gene expression in ripe bananas and significantly reduced disease severity. The combination of H2O2 and the NADPH oxidase inhibitor, diphenylene iodonium, down-regulated chitinase gene expression and compromised disease resistance compared with H2O2 alone. Heat treatment (HT) or the combination of HT followed by CaCl2 reduced disease, but only the latter significantly upregulated chitinase gene expression. The combination of HT and a calcium ionophore (A23187) resulted in different disease indicies and different levels of gene expression depending upon the order of application: HT followed by A23187 induced higher gene expression and lower disease. The results suggest that disease resistance of green bananas could be related to high and prolonged levels of chitinase gene expression, and chitinase could be involved in harvested banana's anthracnose resistance activated by different defense pathway signals, such as BTH, MeJA, H2O2, and Ca2+.
Acer truncatum seeds are an excellent source of beneficial natural compounds, including high levels of unsaturated fatty acids (UFAs), that promote health. Recently, A. truncatum has emerged as an oil crop. Therefore, the transcriptomes of A. truncatum seeds at 70, 85, 100, 115, 145, 180 days after flowering (DAF) were analyzed to gain a better understanding of the transcriptional and translational regulation of seed development and oil biosynthesis. A total of 28,438 genes were identified, and 3069/2636, 3288/3438, 1319/2750, and 5724/5815 upregulated/downregulated genes were identified when comparing different samples with 85 DAF seeds. Sixteen lipid metabolism pathways with 754 differentially expressed genes (DEGs) were identified, including 34 DEGs associated with UFA biosynthesis. A phylogenetic analysis revealed that six putative fatty acid desaturase (FAD) genes clustered into five FAD groups. A quantitative real-time polymerase chain reaction analysis indicated that the temporal expression patterns of oil biosynthesis genes and transcription factors were largely similar to the RNA sequencing results. The results of this study will enhance the current understanding of oil metabolism in A. truncatum seeds and allow new methods of improving oil quality and seed yield in the future.
A protocol to achieve in vitro shoot apex grafting of Morus alba is described. Decoated seeds were incubated at 26C on Murashige and Skoog (MS) medium in 0.2% Gelrite for 10 days in darkness and 2 weeks with a 16-hour daily photoperiod. The shoots were excised from seedlings, and the shoot bases were soaked in 500 μm IBA for 30 min. The shoots were transferred to a vermiculite support medium moistened with half-strength MS salts and were incubated at 26C in darkness for 10 to 12 days. Seedling stems, now ≈8 mm in circumference, were used as rootstocks. Shoot apex scions 1 to 2 mm long were taken from adult plants of several major commercial cultivars of M. alba. The average successful frequency of in vitro shoot-apex grafts was 75% to 80%, indicating that thickening the circumference of rootstock stems was a critical factor. Chemical name used: indole-3-butyric acid (IBA).
Anoectochilus formosanus, a medicinal plant used to treat hypertension, lung disease, and liver disease, was grown to maximize biomass and secondary metabolite production in a controlled environment under four levels of photosynthetic photon flux (PPF), namely, 10, 30, 60, or 90 μmol·m−2·s−1, that is L10, L30, L60, and L90 treatments, respectively. On Day 45, all growth values were greatest for the L30 plants. Dry weight was lowest for the L10 plants. Leaf area, stem length, and fresh weight were lowest for the L90 plants. The chlorophyll concentration was highest in the L10 treatment and decreased with increasing PPF. Electron transport ratios of leaves were highest in the L30 treatment and lowest in the L90 for the second leaf (counted down from the apex) and in the L10 for the third leaf. An increase in light intensity from 10 to 60 μmol·m−2·s−1 increased the superoxide dismutase activity and was associated with an increase in the total flavonoid concentration. The total flavonoid concentration (mg·g−1 DW) was greatest in the L60 and lowest in the L90. However, the total flavonoid content (mg/plant) was highest in the L30 plants as a result of great biomass. The results indicated that A. formosanus is a typical shade plant suitable to grow under low light intensity at PPF of 30 to 50 μmol·m−2·s−1 for both growth and production of total flavonoid. A light intensity of 90 μmol·m−2·s−1 induced stress on plant growth and reduced photosynthetic capability and the flavonoid accumulation.