The effects of different types of mulch on soil properties and tea production and quality

T-YOLO: a lightweight and efficient detection model for nutrient buds in complex tea-plantation environments

BACKGROUND

Quick and accurate detection of nutrient buds is essential for yield prediction and field management in tea plantations. However, the complexity of tea plantation environments and the similarity in color between nutrient buds and older leaves make the location of tea nutrient buds challenging.

RESULTS

This research presents a lightweight and efficient detection model, T-YOLO, for the accurate detection of tea nutrient buds in unstructured environments. First, a lightweight module, C2fG2, and an efficient feature extraction module, DBS, are introduced into the backbone and neck of the YOLOv5 baseline model. Second, the head network of the model is pruned to achieve further lightweighting. Finally, the dynamic detection head is integrated to mitigate the feature loss caused by lightweighting. The experimental data show that T-YOLO achieves a mean average precision (mAP) of 84.1%, the total number of parameters for model training (Params) is 11.26 million (M), and the number of floating-point operations (FLOPs) is 17.2 Giga (G). Compared with the baseline YOLOv5 model, T-YOLO reduces Params by 47% and lowers FLOPs by 65%. T-YOLO also outperforms the existing optimal detection YOLOv8 model by 7.5% in terms of mAP.

CONCLUSION

The T-YOLO model proposed in this study performs well in detecting small tea nutrient buds. It provides a decision-making basis for tea farmers to manage smart tea gardens. The T-YOLO model outperforms mainstream detection models on the public dataset, Global Wheat Head Detection (GWHD), which offers a reference for the construction of lightweight and efficient detection models for other small target crops. © 2024 Society of Chemical Industry.

Capability of phytoremediation of glyphosate in environment by Vulpia myuros

Glyphosate is an herbicide extensively used worldwide that can remain in the soil. Phytoremediation to decontaminate polluted water or soil requires a plant that can accumulate the target compound. Vulpia myuros is an annual fescue that can be used as a heavy mental phytoremediation strategy. Recently, it has been used to intercrop with tea plant to prohibit the germination and growth of other weeds in tea garden. In order to know whether it can be used an decontaminating glyphosate' plant in water or soil, in this study, glyphosate degradation behavior was investigated in Vulpia myuros cultivated in a hydroponic system. The results showed that the concentration of glyphosate in the nutrient solution decreased from 43.09 μg mL-1 to 0.45 μg mL-1 in 30 days and that 99% of the glyphosate molecules were absorbed by V. myuros. The contents of glyphosate in the roots reached the maximum (224.33 mg kg-1) on day 1 and then decreased. After 3 days, the content of glyphosate in the leaves reached the highest value (215.64 mg kg-1), while it decreased to 156.26 mg kg-1 in the roots. The dissipation dynamics of glyphosate in the whole hydroponic system fits the first-order kinetic model C = 455.76e-0.21 t, with a half-life of 5.08 days. Over 30 days, 80% of the glyphosate was degraded. The contents of the glyphosate metabolite amino methyl phosphoric acid (AMPA), ranged from 0.103 mg kg-1 on day 1-0.098 mg kg-1 on day 30, not changing significantly over time. The Croot/solution, Cleaf/solution and Cleaf/root were used to express the absorption, transfer, and distribution of glyphosate in V. myuros. These results indicated that glyphosate entered into the root system through free diffusion, which was influenced by both the log Kow and the concentration of glyphosate in the nutrient solution, and that glyphosate was either easily transferred to the leaves through the transpiration stream, accumulated, or degraded. The degradation of glyphosate in V. myuros indicated that it has potential as a remediating plant for environmental restoration.

Intercropping Cover Crops for a Vital Ecosystem Service: A Review of the Biocontrol of Insect Pests in Tea Agroecosystems

The intercropping of cover crops has been adopted in several agroecosystems, including tea agroecosystems, which promotes ecological intensification. Prior studies have shown that growing cover crops in tea plantations provided different ecological services, including the biocontrol of pests. Cover crops enrich soil nutrients, reduce soil erosion, suppress weeds and insect pests, and increase the abundance of natural enemies (predators and parasitoids). We have reviewed the potential cover crops that can be incorporated into the tea agroecosystem, particularly emphasizing the ecological services of cover crops in pest control. Cover crops were categorized into cereals (buckwheat, sorghum), legumes (guar, cowpea, tephrosia, hairy indigo, and sunn hemp), aromatic plants (lavender, marigold, basil, and semen cassiae), and others (maize, mountain pepper, white clover, round-leaf cassia, and creeping indigo). Legumes and aromatic plants are the most potent cover crop species that can be intercropped in monoculture tea plantations due to their exceptional benefits. These cover crop species improve crop diversity and help with atmospheric nitrogen fixation, including with the emission of functional plant volatiles, which enhances the diversity and abundance of natural enemies, thereby assisting in the biocontrol of tea insect pests. The vital ecological services rendered by cover crops to monoculture tea plantations, including regarding the prevalent natural enemies and their pivotal role in the biocontrol of insect pests in the tea plantation, have also been reviewed. Climate-resilient crops (sorghum, cowpea) and volatile blends emitting aromatic plants (semen cassiae, marigold, flemingia) are recommended as cover crops that can be intercropped in tea plantations. These recommended cover crop species attract diverse natural enemies and suppress major tea pests (tea green leaf hopper, white flies, tea aphids, and mirid bugs). It is presumed that the incorporation of cover crops within the rows of tea plantations will be a promising strategy for mitigating pest attacks via the conservation biological control, thereby increasing tea yield and conserving agrobiodiversity. Furthermore, a cropping system with intercropped cover crop species would be environmentally benign and offer the opportunity to increase natural enemy abundance, delaying pest colonization and/or preventing pest outbreaks for pest management sustainability.

A Novel LED Light Radiation Approach Enhances Growth in Green and Albino Tea Varieties

Light, as an energy source, has been proven to strongly affect photosynthesis and, thus, can regulate the yield and quality of tea leaves (Camellia sinensis L.). However, few comprehensive studies have investigated the synergistic effects of light wavelengths on tea growth and development in green and albino varieties. Thus, the objective of this study was to investigate different ratios of red, blue and yellow light and their effects on tea plants' growth and quality. In this study, Zhongcha108 (green variety) and Zhongbai4 (albino variety) were exposed to lights of different wavelengths for a photoperiod of 5 months under the following seven treatments: white light simulated from the solar spectrum, which served as the control, and L1 (red 75%, blue 15% and yellow 10%), L2 (red 60%, blue 30% and yellow 10%), L3 (red 45%, far-red light 15%, blue 30% and yellow 10%), L4 (red 55%, blue 25% and yellow 20%), L5 (red 45%, blue 45% and yellow 10%) and L6 (red 30%, blue 60% and yellow 10%), respectively. We examined how different ratios of red light, blue light and yellow light affected tea growth by investigating the photosynthesis response curve, chlorophyll content, leaf structure, growth parameters and quality. Our results showed that far-red light interacted with red, blue and yellow light (L3 treatments) and significantly promoted leaf photosynthesis by 48.51% in the green variety, Zhongcha108, compared with the control treatments, and the length of the new shoots, number of new leaves, internode length, new leaf area, new shoots biomass and leaf thickness increased by 70.43%, 32.64%, 25.97%, 15.61%, 76.39% and 13.30%, respectively. Additionally, the polyphenol in the green variety, Zhongcha108, was significantly increased by 15.6% compared to that of the plants subjected to the control treatment. In addition, for the albino variety Zhongbai4, the highest ratio of red light (L1 treatment) remarkably enhanced leaf photosynthesis by 50.48% compared with the plants under the control treatment, resulting in the greatest new shoot length, number of new leaves, internode length, new leaf area, new shoot biomass, leaf thickness and polyphenol in the albino variety, Zhongbai4, compared to those of the control treatments, which increased by 50.48%, 26.11%, 69.29%, 31.61%, 42.86% and 10.09%, respectively. Our study provided these new light modes to serve as a new agricultural method for the production of green and albino varieties.

Distribution characteristics of soil AM fungi community in soft sandstone area

To explore the diversity and distribution characteristics of soil arbuscular mycorrhizae fungi (AMF) communities in the soft sandstone area, thirteen arsenic sandstone rock samples were collected from three planting plots (SI, SII and SIII) and one bare control plot (CK), separately. The sampling locations are as follows: the top of the slope (denoted by the number 1), sunny slope (2), shady slope (3) and gully bottom (4). These samples were then tested with an Illumina HiSeq PE250 high-throughput sequencing platform. Experimental results show that the SIII4 sample (from the gully bottom of the SIII plot) has the highest moisture content of 9.1%, while the CK sample in the control plot has lowest moisture content. SI2 has the highest pH of 9.58 and CK has the lowest pH of 8.73. SII1 has the highest available phosphorus (AP) content of 9.61 mg/kg, while SII3 has the lowest AP content of 2.29 mg/kg. Furthermore, SI2 has the highest NH₄-N content of 11.24 mg/kg, while SII1 has the lowest NH₄-N of 4.09 mg/kg. SII1 has the highest available potassium (AK) content of 48.92 mg/kg and CK has the lowest AK content of 1.82 mg/kg. In the observed-species index reflecting AMF genetic diversity, SI1 differences significantly from SII4 and SIII3 (P < 0.05). In the Shannon index, SI1 is significantly different from SI2, SI3, SI4; SII2 is significantly different from SII3; SI2, SI4, SII1 and SII3 are quite different from CK (P < 0.05). The dominant genera of AMF in these plots include Glomus (17.24%-65.53%), Scutellospora (0.04%-67.38%), Septoglomus (2.83%-43.03%) and Kamienskia (0.64%-46.38%). The dominant genera of AMF vary significantly between sunny slope and shady slope. Positive correlation exists between soil NH₄-N and the AM fungal community structure. There are prominent positive correlations exist among genetic diversity index chao1, observed-species, pH and AP (P < 0.05), and obviously negative correlation between observed species and AK (P < 0.05). The research findings on the distribution characteristics of AM fungus community in the arsenic sandstone plot and their relationship with environmental factors can help with arsenic sandstone management in other similar areas.

K-solubilizing bacteria (Bacillus) promote theanine synthesis in tea roots (Camellia sinensis) by activating CsTSI activity

Theanine is an important quality parameter referring to tea quality. Applying nitrogen fertilizers is one strategy to improve the level of theanine; however, the effect of plant growth-promoting rhizobacteria on theanine synthesis in tea roots has been less studied. In this study, the bacteria isolated from Qimen County with the maximum potassium (K) solubilization were identified as Bacillus by biochemical and molecular analyses. We show that tartaric and pyruvic acids produced by Bacillus were important components related to K solubilization in vitro. Pot experiments and enzymatic assays in vitro showed that inoculation with Bacillus-secreted organic acids increased the level of available potassium in the soil. The increased K level activated recombinant CsTSI activity (theanine biosynthesis enzyme) and increased ethylamine content (the synthesis precursor of theanine), resulting in promoted theanine synthesis in tea roots. Therefore, our study indicates that Bacillus can be a potential bioinoculant for biofortification of tea.

Theanine metabolism and transport in tea plants (Camellia sinensis L.): advances and perspectives

Theanine, a tea plant-specific non-proteinogenic amino acid, is the most abundant free amino acid in tea leaves. It is also one of the most important quality components of tea because it endows the "umami" taste, relaxation-promoting, and many other health benefits of tea infusion. Its content in tea leaves is directly correlated with the quality and price of green tea. Theanine biosynthesis primarily occurs in roots and is transported to new shoots in tea plants. Recently, great advances have been made in theanine metabolism and transport in tea plants. Along with the deciphering of the genomic sequences of tea plants, new genes in theanine metabolic pathway were discovered and functionally characterized. Theanine transporters were identified and were characterized on the affinity for: theanine, substrate specificity, spatiotemporal expression, and the role in theanine root-to-shoot transport. The mechanisms underlying the regulation of theanine accumulation by: cultivars, seasons, nutrients, and environmental factors are also being rapidly uncovered. Transcription factors were identified to be critical regulators of theanine biosynthesis. In this review, we summarize the progresses in theanine: biosynthesis, catabolism, and transport processes. We also discuss the future studies on theanine in tea plants, and application of the knowledge to crops to synthesize theanine to improve the health-promoting quality of non-tea crops.

Contribution of K solubilising bacteria (Burkholderia sp.) promotes tea plant growth (Camellia sinesis) and leaf polyphenols content by improving soil available K level

K+ availability is important for growth and quality of tea (Camellia sine sis L.). K solubilising bacteria convert insoluble K to available K. This study was conducted to screen K solubilising bacteria isolated from tea rhizosphere soil in Qimen county, Anhui province, China. The maximum K solubilisation colony (the ratio of diameter halo/colony was 2.54) was identified as Burkholderia sp. (storage number: M2021105) by biochemistry and molecular analysis. Pot experiments (Laterite) showed that the inoculation of Burkholderia sp. significantly improved tea plant height (Zhongcha108, 1 year old) and total polyphenols content by 21.14% and 21.58% compared with the control, respectively. Higher polyphenol level promoted the formation of theaflavin in the fermentation experiments. Further experiments showed that tartaric acid and pryuvic acid produced by Burkholderia sp. are important components associated with K solubilisation in vitro . Burkholderia sp. significantly increased soil available K by 15.12%; however, there was no significant difference in available N and P, and Cu, Mg, Zn and Ca compared with the control. K content in inoculated tea roots and leaves was significantly higher (50% and 10%, respectively) than the control. Compared with the control, exogenous supply of 60mgkg-1 K significantly increased levels of polyphenol (53.97%), theaflavin (16.31%), theaflavin-3-gallate (20%), theaflavin 3'-gallic acid ester (32.24%) and theaflavin 3,3'-gallic acid ester (40.95%). Due to its ability to enable higher available soil K, ur study indicated that Burkholderia sp. have potential to increase total polyphenols content be a bio-inoculant for biofortification of tea.

Exogenously applied Spd and Spm enhance drought tolerance in tea plants by increasing fatty acid desaturation and plasma membrane H+-ATPase activity

Polyamines, due to their positive charges, bind to ROS Reactive oxygen species (ROS) thereby stabilizing the plasma membrane (PM). Drought is one of the main limiting factors affecting tea plant yield and quality. However, the effect of Spermidine (Spd) or Spermine (Spm) on membrane stability and fluidity in tea plants under drought stress is poorly understood. In this investigation, an exogenous supply of 1 mM Spd or Spm did not mitigate drought stress-induced damage, however, an exogenous supply of 0.2 mM Spd or Spm application significantly alleviated drought-induced damage in tea plants. To further illustrate the role of 0.2 mM Spd or Spm in maintaining membrane integrity and fluidity, the fatty acid percentage and PM H⁺-ATPase activity were analyzed. Spd and Spm application significantly increased PM H⁺-ATPase activity by 43.79% compared with that without the addition of polyamine under drought stress. In addition, exogenous application of Spd and Spm also significantly increased C18:3 by approximately 10%, hence alleviating drought-reduced fatty acid unsaturation. In contrast, Spd and Spm metabolic inhibitors dicyclohexylamine (DCHA) further impaired PM H⁺-ATPase activity and fatty acid desaturation under the drought + DCHA treatment compared with the drought treatment, respectively. Taken together, 0.2 mM Spd and Spm application significantly enhanced drought tolerance by increasing fatty acid unsaturation and maintaining PM H⁺-ATPase activity in tea plants. Therefore, foliar application of 0.2 mM Spd or Spm can be a potential foliar-spraying substances for improving tea drought tolerance.