The Distribution of Relative Light Intensity in a Peach Tree Canopy Affects Fruit Yield and Texture

Light is crucial to the uniform production of high-quality fruit since it is the driving force for leaf photosynthesis and hence overall plant nutrition.The objective of this study was to evaluate the relationship between the distribution of relative light intensity in the peach tree(Prunus persica)canopy and the yield and texture of peach fruits.The canopy of 7-year-old‘Qiuyan’was divided into cubical volumes and the relative light intensity distribution was measured for each cube,along with yield distribution and fruit textural properties at different growing times.The relative light intensity decreased gradually from outside to inside the canopy and from top to bottom.The yield distribution and the relative light intensity were clearly correlated.The percentage of the canopy receiving<30%relative light intensity was 49.07%in May,56.02%in June,and 58.95%in July,whereas the percentage receiving>80%relative light intensity was 32.72%,17.28%,and 10.96%,respectively.Consistent with this,peaches were found in the upper and middle portions of the canopy,within 1.5-3.0 m of the top.The regression equation showed that fruit texture index correlated significantly with relative light intensity.Relative light intensity is the main factor affecting peach yield and texture and must be above 41.83%for good peach quality.Orchardists should carefully plan summer pruning strategies to adjust the number and spatial distribution of branches accordingly.

Surface‑Enhanced Raman Scattering Fiber Probe Based on Silver Nanocubes

Surface-enhanced Raman scattering(SERS)provides a novel method for low concentration molecular detection.The performances were highly dependent on the sizes,geometries and distributions of metal nanostructures.Here,highly sensitive SERS fber probe based on silver nanocubes(Ag NCs)was fabricated,by assembled nanostructures on planar and tapered fber tips.Ag NCs were synthesized by polyol method,and controlled by reductant content,reaction temperatures and crystal growth durations.Tapered fbers with diferent cone angles were prepared by chemical etching.The electromagnetic distribution simulation indicated that nanocubes had stronger electric feld between two cubes and vertex corners than nanosphere,under 532 nm laser excitation.The intensity could reach 53.52 V/m,for cubes with 70 nm edge length.The SERS performance of probes was characterized using crystal violet analyte.The detectable lowest concentration could reach 10^(-9) and 10^(-10) M for planar and tapered fber probes,respectively.The corresponding enhancement factor could be 9.02×10^(7) and 6.22×10^(8).The relationship between SERS peak intensities and analyte concentrations showed well linear,which indicated both fber probes could be applied for both qualitative and quantitative analysis.Furthermore,optimal cone angle of tapered fber SERS probe was 8.3°.The tapered fber SERS probes have highly sensitive activity and great potential in substance detection.