Detection Model of Tea Disease Severity under Low Light Intensity Based on YOLOv8 and EnlightenGAN

In response to the challenge of low recognition rates for similar phenotypic symptoms of tea diseases in low-light environments and the difficulty in detecting small lesions, a novel adaptive method for tea disease severity detection is proposed. This method integrates an image enhancement algorithm based on an improved EnlightenGAN network and an enhanced version of YOLO v8. The approach involves first enhancing the EnlightenGAN network through non-paired training on low-light-intensity images of various tea diseases, guiding the generation of high-quality disease images. This step aims to expand the dataset and improve lesion characteristics and texture details in low-light conditions. Subsequently, the YOLO v8 network incorporates ResNet50 as its backbone, integrating channel and spatial attention modules to extract key features from disease feature maps effectively. The introduction of adaptive spatial feature fusion in the Neck part of the YOLOv8 module further enhances detection accuracy, particularly for small disease targets in complex backgrounds. Additionally, the model architecture is optimized by replacing traditional Conv blocks with ODConv blocks and introducing a new ODC2f block to reduce parameters, improve performance, and switch the loss function from CIOU to EIOU for a faster and more accurate recognition of small targets. Experimental results demonstrate that YOLOv8-ASFF achieves a tea disease detection accuracy of 87.47% and a mean average precision (mAP) of 95.26%. These results show a 2.47 percentage point improvement over YOLOv8, and a significant lead of 9.11, 9.55, and 7.08 percentage points over CornerNet, SSD, YOLOv5, and other models, respectively. The ability to swiftly and accurately detect tea diseases can offer robust theoretical support for assessing tea disease severity and managing tea growth. Moreover, its compatibility with edge computing devices and practical application in agriculture further enhance its value.

Plant Growth in LED-Sourced Biophilic Environments Is Improved by the Biochar Amendment of Low-Fertility Soil, the Reflection of Low-Intensity Light, and a Continuous Photoperiod

Introducing plants in the design of biophilic indoor environments is fundamental for improving human health, well-being, and performance. Previous studies showed that the phenotype of the model plant Arabidopsis thaliana grown under LED-sourced CoeLux® lighting systems was characterized by low biomass production rates, a small leaf area, and a low lamina-to-petiole length ratio, suggesting the onset of a strong shade avoidance syndrome. Therefore, it is essential to identify new strategies to improve plant growth under these peculiar light conditions. In the present work, we investigated the effects of two growing media (i.e., low-fertility soil and soil-less substrate), solid and liquid fertilizers, manure, biochar, perlite, mirror reflection of light, and a 24 h photoperiod on A. thaliana plants growing under CoeLux® lighting systems at a light intensity of 30 μmol m-2s-1. We found that the biochar soil amendment to low-fertility soil increases both the above-ground plant biomass and leaf area. Furthermore, the application of a mirror behind the plants and a continuous photoperiod improves not only the biomass and the leaf area but also the lamina-to-petiole length ratio. The combination of different beneficial treatments can further boost plant growth in the low-intensity light environment characterizing the CoeLux® biophilic lighting systems.

Effect of Low Light on Photosynthetic Performance of Tomato Plants-Ailsa Craig and Carotenoid Mutant Tangerine

The effects of a five-day treatment with low light intensity on tomato plants-Ailsa Craig and tangerine mutant-at normal and low temperatures and after recovery for three days under control conditions were investigated. The tangerine tomato, which has orange fruits, yellowish young leaves, and pale blossoms, accumulates prolycopene rather than all-trans lycopene. We investigated the impact of low light at normal and low temperatures on the functioning and effectiveness of photosynthetic apparatuses of both plants. The photochemical activities of Photosystem I (PSI) and Photosystem II (PSII) were assessed, and the alterations in PSII antenna size were characterized by evaluating the abundance of PSII-associated proteins Lhcb1, Lhcb2, CP43, and CP47. Alterations in energy distribution and interaction of both photosystems were analyzed using 77K fluorescence. In Aisla Craig plants, an increase in thylakoid membrane fluidity was detected during treatment with low light at a low temperature, while for the tangerine mutant, no significant change was observed. The PSII activity of thylakoids from mutant tangerine was more strongly inhibited by treatment with low light at a low temperature while low light barely affected PSII in Aisla Craig. The obtained data indicated that the observed differences in the responses of photosynthetic apparatuses of Ailsa Craig and tangerine when exposed to low light intensity and suboptimal temperature were mainly related to the differences in sensitivity and antenna complexes of PSII.

Genotypic Variation of Purple Rice in Response to Shading in Yield, Anthocyanin Content, and Gene Expression

Purple rice (Oryza sativa L.) contains anthocyanin, which acts as an antioxidant and functional food for humans. The levels of anthocyanin growth and production in rice are mainly controlled by the availability of light. However, shade can affect anthocyanin biosynthesis genes. Therefore, the objective of this study was to determine the yield and anthocyanin content among four purple rice varieties, which provide the difference in colors of purple and green leaves. This study also evaluated gene expression affected by shading treatment to understand the relation of grain anthocyanin and expression level. This research was conducted using a split plot design using four levels of shading (levels of shading from anthesis to maturity) with three replications, no shading, 30% shading, 50% shading, and 70% shading, as the main plots and purple rice varieties as subplots, KJ CMU-107, K2, K4, and KDK10, from anthesis to maturity. Shading significantly decreased yield and yield components, but increased grain anthocyanin content. Nonetheless, the response of yield and grain anthocyanin content to shading did not show a significant different between purple and green leaf varieties. In addition, the level of OsDFR gene expression was different depending on the shading level in four rice varieties. The OsDFR gene presented the highest expression at shading levels of 30% for K4 and 50% for KDK10, while the expression of the OsDFR gene was not detected in the purple rice varieties with green leaves (KJ CMU-107 and K2). The response of grain anthocyanin and gene expression of OsDFR to light treatment did not show significantly differences between the purple and green leaf varieties, suggesting that the appearance of anthocyanin in leaves might be not related to anthocyanin synthesis in the grain. Taken together, the results suggest that some purple rice varieties were more suitable for planting under low light intensity based on a lower level of grain yield loss, strong shade tolerance, and high anthocyanin content in leaf and grain pericarp. However, it is necessary to explore the effects of light intensity on genes and intermediates in the anthocyanin synthesis pathway for further study.

Glucose sensing by regulator of G protein signaling 1 (RGS1) plays a crucial role in coordinating defense in response to environmental variation in tomato

Low light intensities affect the outbreak of plant diseases. However, the underlying molecular mechanisms remain poorly understood. High-performance liquid chromatography analysis of tomato (Solanum lycopersicum) revealed that apoplastic glucose (Glc) levels decreased in response to low light. Conversely, low-light-induced susceptibility to Pseudomonas syringae pv tomato (Pst) DC3000 was significantly alleviated by exogenous Glc treatment. Using cell-based biolayer interferometry assays, we found that Glc specifically binds to the tomato regulator of G protein signaling 1 (RGS1). Laser scanning confocal microscopy imaging revealed that Glc triggers RGS1 endocytosis, which influences the uncoupling of the RGS1-Gα (GPA1) and GPA1-Gβ (SlGB1) proteins, in a dose- and duration-dependent manner. Analysis of G protein single and double mutants revealed that RGS1 negatively regulates disease resistance under low light and is required for Glc-enhanced defense. Downstream of RGS1-Glc binding, GPA1 negatively mediates the light-intensity-regulated defense, whereas SlGB1 positively regulates this process. These results reveal a novel light-intensity-responsive defense system that is mediated by a Glc-RGS1-G protein signaling pathway. This information will be critical for future investigations of how plant cells sense extracellular sugars and adjust defense under different environments, as well as for genetic engineering approaches to improve stress resilience.

Photo-Carrier-Guiding Behavior of Vertically Grown MoS2 and MoSe2 in Highly Efficient Low-Light Transparent Photovoltaic Devices on Large-Area Rough Substrates

Two-dimensional MoX₂ (X = S, Se) films were vertically grown on highly rough transparent conducting F-doped SnO₂ glass substrates for the first time and successfully used as photogenerated carrier-guiding layers (CGLs) in transparent hydrogenated amorphous silicon (a-Si:H) thin film solar cells (TFSCs). The MoSe₂ CGL layers could be grown at 530 °C using thermally cracked small Se-molecules on transparent FTO glass substrates and significantly improved cell performance. A transparent cell transmitting 26.0% of visible light with a 20 nm-thick vertically grown MoSe₂ CGL showed an outstanding power conversion efficiency of 27.1% at a light intensity of 0.16 mW cm^-2 (500 lx; corresponding to normal indoor irradiation). The shunt resistance (R_sh) of the TFSCs reached 32,000 Ω at a light intensity of 7 mW cm^-2. An R_sh value this large is essential for low-light photovoltaic (PV) devices to prevent the dissipation of photogenerated carriers. These results strongly demonstrate that transparent a-Si:H-TFSCs with vertically grown MoX₂ films should find wide use in building-integrated PV windows or indoor PV applications, as they can generate power even in very low-light environments.

Nitric Oxide Is Involved in the Regulation of the Ascorbate-Glutathione Cycle Induced by the Appropriate Ammonium: Nitrate to Mitigate Low Light Stress in Brassica pekinensis

Low light intensity is common in northern China due to fog or haze, and causes stress for crop plants. To solve the problem of low light intensity stress on the growth and development of vegetable crops in China, new cropping strategies must be developed. We previously showed that an appropriate ratio of ammonium and nitrate (NH₄⁺:NO₃⁻) can alleviate the effect of low light stress on plants, although it is not clear what mechanism is involved in this alleviation. We propose the hypothesis that an appropriate ammonium/nitrate ratio (10:90) can induce NO synthesis to regulate the AsA-GSH cycle in mini Chinese cabbage seedlings under low light intensity. To test the hypothesis, we conducted a series of hydroponic experiments. The results indicated that, under low light intensity conditions, appropriate NH₄⁺:NO₃⁻ (N, NH₄⁺:NO₃⁻ = 10:90) decreased the contents of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and superoxide anion (O₂⁻) in leaves compared with nitrate treatment. Exogenous nitric oxide (SNP) had the same effects on MDA, H₂O₂, and O₂⁻. However, with the addition of a NO scavenger (hemoglobin, Hb) and NO inhibitors (N-nitro-l-arginine methyl ester, L-NAME), NaN₃ (NR inhibitor) significantly increased the contents of MDA, H₂O₂, and O₂^-. The application of N solution enhanced the AsA-GSH cycle by increasing the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and ascorbate oxidase (AAO), compared with control (NH₄⁺:NO₃⁻ = 0:100). Meanwhile, exogenous SNP significantly increased the above indicators. All these effects of N on AsA-GSH cycle were inhibited by the addition of Hb, L-NAME and NaN₃ in N solution. The results also revealed that the N and SNP treatments upregulated the relative expression level of GR, MDHAR1, APXT, DHAR2, and AAO gene in mini Chinese cabbage leaves under low light stress. These results demonstrated that the appropriate NH₄⁺:NO₃⁻ (10:90) induced NO synthesis which regulates the AsA-GSH cycle in mini Chinese cabbage seedlings under low light stress.

Does Acacia dealbata express shade tolerance in Mediterranean forest ecosystems of South America?

The distribution of Acacia dealbata Link (Fabaceae) in its non-native range is associated with disturbed areas. However, the possibility that it can penetrate the native forest during the invasion process cannot be ruled out. This statement is supported by the fact that this species has been experimentally established successfully under the canopy of native forest. Nonetheless, it is unknown whether A. dealbata can express shade tolerance traits to help increase its invasive potential. We investigated the shade tolerance of A. dealbata under the canopy of two native forests and one non-native for three consecutive years, as well as its early growth and photosynthetic performance at low light intensities (9, 30, and 70 μmol m⁻²sec⁻¹) under controlled conditions. We found many A. dealbata plants surviving and growing under the canopy of native and non-native forests. The number of plants of this invasive species remained almost constant under the canopy of native forests during the years of study. However, the largest number of A. dealbata plants was found under the canopy of non-native forest. In every case, the distribution pattern varied with a highest density of plants in forest edges decreasing progressively toward the inside. Germination and early growth of A. dealbata were slow but successful at three low light intensities tested under controlled conditions. For all tested light regimes, we observed that in this species, most of the energy was dissipated by photochemical processes, in accordance with the high photosynthetic rates that this plant showed, despite the really low light intensities under which it was grown. Our study reveals that A. dealbata expressed shade tolerance traits under the canopy of native and non-native forests. This behavior is supported by the efficient photosynthetic performance that A. dealbata showed at low light intensities. Therefore, these results suggest that Mediterranean forest ecosystems of South America can become progressively invaded by A. dealbata and provide a basis for estimating the possible impacts that this invasive species can cause in these ecosystems in a timescale.