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  • Author or Editor: Feng Liu x
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Walnut, a woody plant, is regarded as having difficulty rooting when propagated by vegetative methods, such as cutting and layering. A layering experiment was conducted in 2018 and 2022. In 2018, some Juglans species, including J. regia L. seedling (JR), J. regia cv. Liaoning 1 (JR LN1), J. hopeinesis Hu seedling (JH), J. mandshurica Maxim seedling (JM), and J. nigra L. seedling (JN), were the mother plants. The specific research hypotheses were that own-rooted walnut propagule could be obtained through layering. the rooting capacity of different Juglans species would be different, and the rooting ability of JN would be the highest among the samplings. The results indicated that all of these species in the experiment could be rooted by etiolation and indole-3-butyric acid (IBA) treatment and that root occurrence was found 6 to 7 weeks after IBA treatment. The layers (shoots from the mother plant) on the seedlings of JR, JH, and JM obtained rooting percentages (RP) of 75.55%, 84.45%, and 86.67%, respectively, and root numbers (RNs) of 21.8, 42.8, and 38.8, respectively, after 20 days of etiolation and 1% IBA treatment. JR LN1 had difficulty rooting in equal conditions and had a RP of 31.11%. In 2022, JR LN1 was the only mother plant and the IBA concentration was increased to obtain satisfactory RP and RN. With the 4% and 8% IBA treatments, RPs of 88.9% and 93.3% and RNs of 40.3 and 27.7, respectively, were achieved. During the experiment, the RP, RN, root length (RL), and root diameter (RD), as well as the layer height (LH) and layer diameter (LD), were investigated and evaluated. Layers with low vigor were more likely to root, as shown by a nonparametric test conducted for the height and diameter of the layers of the rooting and nonrooting groups. A significantly negative correlation (r = −0.548) was observed between RN and LH. Moreover, the quality of the best results of JR LN1 layering propagule and that with ‘liaoning 1’ 1-year-old seedling were compared. Our results provide more support for the possibility of vegetative propagation of walnut by layering and more information regarding the clonal cultivation of walnut trees and the own-rooted seedling establishment of walnut cultivars.

Open Access

To explore differences in sucrose metabolism between peach fruit subjected to chilling stress (5 °C) and nonchilling stress (10 °C), sucrose concentration as well as the activities and gene expression levels for enzymes associated with sucrose metabolism were compared. Fruits stored at 5 °C accumulated higher concentrations of H2O2 and developed severe chilling injury (CI) compared with fruit kept at 10 °C. Activities and gene expression levels for enzymes related to sucrose metabolism, such as acid invertase (AI), neutral invertase (NI), sucrose synthase (SS), and sucrose phosphate synthase (SPS) were higher in fruit stored at 5 °C than at 10 °C throughout or late in storage. A sharp increase in net sucrose cleavage activity dramatically decreased sucrose concentration and increased reducing sugars at 5 °C. The sucrose concentration at 10 °C increased over the first 21 days and then declined slightly, and was higher than in fruit at 5 °C throughout storage. The increase in net sucrose cleavage activity at 5 °C is contrary to the expectation that biochemical reactions ordinarily proceed more rapidly with increasing temperature. We conclude that chilling stress stimulates the activities and transcription levels of enzymes involved in sucrose metabolism, resulting in increased sucrose cleavage.

Free access

To investigate the characteristics of photosynthetic physiological changes in leaves of Mangifera indica L. cv. Guifei under enhanced ultraviolet (UV)-B radiation, natural light-exposed trees were used as controls and 96 kJ·m−2·d−1 enhanced UV-B radiation was artificially simulated in the field. The changes in fruit maturity and quality, the leaf net photosynthetic rate (Pn), photosynthetic pigment contents, photochemical reactions, the activities of photosynthetic enzymes and related gene expression levels were determined. Compared with the control, the percentage of mature fruits under the treatment significantly increased, and fruit quality improved. The net photosynthetic rate (Pn), photosynthetic pigment content, Hill reaction activity, and photochemical quenching coefficient (qP) of the treated leaves showed significantly higher values than those of the control leaves. The activities of Rubisco and Rubisco activating enzyme (RCA) and the expression levels of the Rubisco large subunit and Rubisco small subunit were significantly increased. Treatment with 96 kJ·m−2·d−1 enhanced ultraviolet-B radiation improved Rubisco activity by increasing the expression of the Rubisco large and small subunit genes, thereby enhancing the CO2-fixing capacity and dark reaction capacity of leaves. Thus, the net photosynthetic rate of leaves increased, which promoted the early maturity of ‘Guifei’ mango by the rapid accumulation of photosynthetic products.

Open Access

2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) is one of the most toxic polybrominated diphenyl ethers (PBDEs). The toxic effects of BDE-47 on Chinese cabbage seedlings were analyzed in this study. After a 30-day hydroponic exposure to BDE-47 at different concentrations (25, 50, 75, and 100 µg·L−1), the fresh weight of Chinese cabbage seedlings was significantly decreased, whereas their root:shoot ratio was increased, indicating that BDE-47 inhibited the growth of the plant, especially the overground parts. The water content, chlorophyll content, and protein content of Chinese cabbage leaves also markedly decreased with the increase of the BDE-47 concentration. In addition, BDE-47 weakened the photosynthetic capacity of the leaves, which was supported by the decreased photosynthetic parameters [net photosynthetic rate (P n) and stomatal conductance (g S)]. Although the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in the leaves were enhanced after exposure to BDE-47, the increased malondialdehyde (MDA) content attested to the existence of membrane lipid peroxidation. The increased plasma membrane permeability and the decreased chlorophyll fluorescence parameters [the maximum quantum yield of PSII photochemistry at t = 0 (F v/F m), photosystem II (PSII) reaction centers (RCs) per cross section (CS) (RC/CS), absorption energy flux per CS (ABS/CS), trapped energy flux per CS (TR o/CS), electron transport flux per CS (ET o/CS), performance index on the absorption basis (PI abs), and driving force for photosynthesis (DF)] further proved that the plasma membrane and photosynthetic membrane were damaged by BDE-47. Our study demonstrated the phytotoxicities of BDE-47 to Chinese cabbage, which can provide valuable information for understanding the toxicity of BDE-47 on vegetables.

Free access

Jinyan (Actinidia eriantha × A. chinensis) is one of the gold-fleshed kiwifruit cultivars currently being promoted in south China. However, its fruit dry matter is usually less than 16%, which seriously affects fruit quality including taste and flavor. This causes a financial loss to growers: not only are the prices paid for the fruit low because of their bad reputation for quality, but some orchards have been removed. Improvement of fruit quality is essential. In this study, a method is described for squeezing and twisting flowering shoots before flowering and removing the distal vegetative parts of flowering shoots after fruit set. The effects on fruit quality were determined. The dry matter of fruit was increased by 6.6%. Fruit size also increased as did the chlorophyll a content and the chlorophyll:carotenoid ratio. The significantly increased fruit dry matter, resulting in significant increases in fruit soluble solids concentrations (P < 0.01), thereby possibly improving fruit taste. Fruit weight, fruit length, and carotenoid and ascorbic acid concentrations were significantly enhanced in comparison with controls (P < 0.01), increasing by 20%, 7%, 12%, and 19%, respectively. However, there was no significant difference in soluble sugar concentrations, titratable acid concentrations, and the reduced chlorophyll b concentrations. This research provides a practical method to increase fruit dry matter, and hence a way to allow fruit quality to reach commercial requirements for cultivars such as Jinyan, which under previous management systems had significant shortcomings in fruit flavor and taste.

Open Access

Hydrogen sulfide (H2S) has been proven to be a multifunctional signaling molecule in plants. In this study, we attempted to explore the effects of H2S on the climacteric fruit tomato during postharvest storage. H2S fumigation for 1 d was found to delay the peel color transition from green to red and decreased fruit firmness induced by ethylene. Further investigation showed that H2S fumigation downregulated the activities and gene expressions of cell wall–degrading enzymes pectin lyase (PL), polygalacturonase (PG), and cellulase. Furthermore, H2S fumigation downregulated the expression of ethylene biosynthesis genes SlACS2 and SlACS3. Ethylene treatment for 1 d was found to induce the expression of SlACO1, SlACO3, and SlACO4 genes, whereas the increase was significantly inhibited by H2S combined with ethylene. Furthermore, H2S decreased the transcript accumulation of ethylene receptor genes SlETR5 and SlETR6 and ethylene transcription factors SlCRF2 and SlERF2. The correlation analysis suggested that the fruit firmness was negatively correlated with ethylene biosynthesis and signaling pathway. The current study showed that exogenous H2S could inhibit the synthesis of endogenous ethylene and regulate ethylene signal transduction, thereby delaying fruit softening and the ripening process of tomato fruit during postharvest storage.

Free access