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  • Author or Editor: Sheng Tang x
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Hydrogen sulfide (H2S) has been shown to be a gaseous molecule in the regulation of many processes in plants such as abiotic stress tolerance, root organogenesis, stomatal movement, and postharvest fruit senescence. We studied the role of H2S in the regulation of senescence and fungal decay in fresh-cut sweetpotato (Ipomoea batatas L., cv. Xushu 18) roots. H2S donor sodium hydrosulfide (NaHS) alleviated senescence in fresh-cut sweetpotato root tissue in a dose-dependent manner with the optimal concentration of 2.0 mmol·L−1 NaHS solution. At the optimal concentration of 2.0 mmol·L−1 NaHS, H2S fumigation maintained higher levels of reducing sugar in sweetpotato fresh-cut root. H2S treatment also significantly increased the activities of guaiacol peroxidase (POD) and decreased those of polyphenol oxidase (PPO) in sweetpotato during storage. Further investigation showed that H2S treatment maintained a lower level of lipoxygenase (LOX) activity compared with water control. Consistently, the accumulation of malondialdehyde (MDA) was reduced in H2S-treated groups. Three fungal pathogens, Rhizopus nigricans, Mucor rouxianus, and Geotrichum candidum, were isolated from sweetpotato tissue infected with black rot or soft rot. H2S fumigation at 1 to 2.5 mmol·L−1 NaHS resulted in effective inhibition of the three fungi when grown on medium. When the three fungi were inoculated on the surface of sweetpotato slices, H2S fumigation greatly reduced the percentage of fungal infection. In conclusion, these data suggest that H2S effectively alleviated the senescence and decay in sweetpotato slices and might be developed into a novel fungicide for reduction of black rot or soft rot in sweetpotato.

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Pear (Pyrus spp.) is the third-largest economic crop in China after apples (Malus pumila Mill.) and citrus (Citrus reticulata Blanco), and it is mainly cultivated by smallholders. Currently, the yield of Chinese pear ranks midlevel globally, with only 17.9 t⋅ha−1⋅year−1, which is lower than that of the United States (36.0 t⋅ha−1⋅year−1). However, the factors limiting pear production dominated by smallholders are unclear. We interviewed 75 smallholders about 18 yield-related indicators for pear-typical planting areas. The boundary line model was used to analyze the contribution of internal factors and dominant external factors affecting yield and to simulate strategies for increasing yield through the scenario analysis. The results showed that the average gap between the average and highest attainable yields for smallholders was 10.5 t⋅ha−1⋅year−1 in Luniao County. Among individual yield-limiting factors, chemical fertilizer nitrogen (N) input (13.3%) was the most significant, followed by the soil-available N content (12.0%) and leaf magnesium content (12.0%). Overall, the contribution of all soil factors (42.7%) was the largest compared with the other factor categories. However, the contribution of internal factors could not be ignored and accounted for 25.3% of the total. A scenario analysis showed that comprehensive strategies considering soil, management, and internal factors achieved the largest yield improvement (14%), as did reducing the fertilizer application rate (66%) compared with only using soil or leaf diagnosis methods. Therefore, integrated methods should be considered when developing pear orchard management measures and include soil, management, and internal factors.

Open Access