Fresh strawberry fruit is highly susceptible to damage during mechanical handlings. To prevent fruit macro-damage from external forces and predict damage evolution in internal tissues, the textural failure mechanics of strawberry fruit and its tissues were characterized by loading-unloading tests at different compression speeds. Strawberry fruit showed expected three stages of deformation during the loading phase, namely elastic, local plastic and structural failure deformation. Their cutoff points depended on the compression speed and loading direction, which was validated further by the corresponding visible browning processes in tissues from fruit longitudinal equatorial section. The peak force and absorbed energy depended on the loading direction and compression speed while the percentage of damaged mass only depended on the loading direction. The fruit was most susceptible to mechanical damage when it was compressed along its stem-blossom axis at low percentage deformation and along its radial axis at high percentage deformation. The absorbed energy and percentage of damaged mass of the strawberry fruit was correlated, which suggested that the absorbed energy could be an appropriate and easily measurable mechanical parameter for quantitatively assessing the degree of fruit damage. The failure stress, failure energy and elastic modulus of fruit tissues increased with the compression speed, while this factor did not affect the failure strain. The average failure stress, failure strain, failure energy and elastic modulus of fruit inner tissue were 0.093
Trace amounts of selenium (Se) are essential for several organisms, and deficiencies therein have adverse effects on growth, development, and reproduction; this is particularly significant in animals raised for milk and livestock production. To study the effect of Se on Guanzhong dairy goats, their diets were supplemented with different sources (inorganic or organic) and Se concentrations (0.2 or 0.4 mg Se/kg). A non-Se-fortified basal diet served as a negative control, and a sixth treatment group received both inorganic and organic Se sources (0.2 mg Se/kg diet each). Dietary Se supplementation increased milk production, with organic Se being more effective than inorganic Se. Selenium supplementation also increased Se concentration and glutathione peroxidase activity in whole blood, with organic Se more effective than inorganic Se at the same Se concentration. With increasing Se in diets, the Se content in milk increased markedly, reaching a plateau value at day 30 in all groups, and organic Se (0.4 mg/kg diet) had the best effect. In addition, dietary Se sources and concentrations markedly affected Se concentrations in different tissues and organs. Thus, organic Se supplementation of a basal diet at 0.4 mg/kg is practically applicable for Se-enriched milk and meat production in Guanzhong dairy goats.
One of the hallmarks of plant senescence is the global transcriptional reprogramming coordinated by a plethora of transcription factors (TFs). However, mechanisms underlying the interactions between different TFs in modulating senescence remain obscure. Previously, we discovered that plant ABS3 subfamily MATE transporter genes regulate senescence and senescence-associated transcriptional changes. In a genetic screen for mutants suppressing the accelerated senescence phenotype of the gain-of-function mutant abs3-1D, AUXIN RESPONSE FACTOR 2 (ARF2) and PHYTOCHROME-INTERACTING FACTOR 5 (PIF5) were identified as key TFs responsible for transcriptional regulation in the ABS3mediated senescence pathway. ARF2 and PIF5 (as well as PIF4) interact directly and function interdependently to promote senescence, and they share common target genes such as key senescence promoting genes ORESARA 1 (ORE1) and STAY-GREEN 1 (SGR1) in the ABS3-mediated senescence pathway. In addition, we discovered reciprocal regulation between ABS3-subfamily MATEs and the ARF2 and PIF5/4 TFs. Taken together, our findings reveal a regulatory paradigm in which the ARF2-PIF5/4 functional module facilitates the transcriptional reprogramming in the ABS3-mediated senescence pathway.
In this study, the textural thermo‐mechanical properties of three sweet cherry varieties were systematically investigated by the puncture test of whole fruit, uniaxial tension of the exocarp, and uniaxial compression test of mesocarp. It was found that the puncture test can not only reflect the shear mechanics of the exocarp in vivo at the tissue level, but it can also characterize the resistance level of fruit to puncture damage at the macroscopic level, particularly when the puncture failure stress is used. The environmental temperature had negative and positive significant effects on the puncture failure stress and the puncture failure deformation of the sweet cherry (p < .05), respectively. The environmental temperature showed a negative significant effect on the failure stress and elastic modulus of the sweet cherry exocarp under tension and mesocarp under compression (p < .05). As the environmental temperature increased from 5 to 40°C, the elastic modulus of the Black pearl, Summit, and Tieton sweet cherry exocarp ranged from 2.28 to 1.72, 2.57 to 1.47, and 1.98 to 1.24 MPa, respectively; and that of mesocarp ranged from 0.33 to 0.21, 0.27 to 0.19, and 0.43 to 0.23 MPa, respectively. The obtained exponential function relationships between environmental temperature and each mechanical parameter are useful for predicting the thermo‐mechanical properties of sweet cherry across a 5–40°C continuous temperature range. This study provided systematical thermo‐mechanical data for predicting the mechanical damage of sweet cherry in postharvest handling using the thermo‐mechanical coupling numerical simulation.
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