西藏农牧学院

Aims By investigating aboveground and belowground nutrient allocation strategies of dominant tree species(i.e.,Juniperus saltuaria and Rhododendron nivale)under different interaction intensities at the alpine treeline of Sygera Mountains,we aim to provide theoretical basis and support for ecological protection and restoration for alpine zone. Methods This study focuses on the J.saltuaria community(Canopy coverage of the arbor layer:60％),the J.saltuaria dominated community(Canopy coverage of the arbor layer:20％),the R.nivale dominated community(Coverage of the shrub layer:56％),and the R.nivale community(Coverage of the shrub layer:75％)at the alpine treeline of Sygera Mountains.In August 2022,leaves,roots,and soil within the canopy range of dominant species in these four plant communities were collected.The nutrient element content of the samples was measured,and the aboveground and belowground nutrient and other stoichiometric characteristics of J.saltuaria and R.nivale under different interaction intensities were analyzed using ecological stoichiometry and Partial Least Squares Path Model(PLS-PM).We aimed to clarify the differences in nutrient strategies of the two dominant tree and shrub species under varying interaction intensities at the alpine treeline of Sygera Mountains. Important findings The results showed that(1)leaf carbon(C)content in the J.saltuaria community was higher than that in the J.saltuaria dominated community,while nitrogen(N),phosphorus(P),and potassium(K)contents were opposite;root C content in the J.saltuaria community was lower than that in the J.saltuaria dominated community,while N,P,and K contents were higher.In the R.nivale dominated community,leaf C and K contents were higher than those in the R.nivale community,whereas N and P contents were lower;root C and N contents were higher in the R.nivale dominated community,while P and K contents were lower.In all four plant communities,leaf C,N,P,and K contents were significantly higher than in roots.(2)Compared to the J.saltuaria community,the J.saltuaria dominated community preferred to allocate more nutrients to leaves,representing an aggressive nutrient strategy.In contrast,the R.nivale dominated community transported more nutrients to roots compared to the R.nivale community,reflecting a more conservative nutrient strategy.Additionally,a positive feedback mechanism exists between plant communities and soil nutrients in the study area.

Soil microorganisms play a crucial role in the carbon and nitrogen cycles,contributing significantly to the maintenance of soil ecosystem health.This study investigated the effects of drip fertigation combined with dense planting on summer maize yield and soil bacterial communities in Southwest China.Two treatments were established:traditional water and fertilizer man-agement(F)and drip fertigation with dense planting(H).High-throughput sequencing of the 16S rRNA gene was employed to analyze the impact of these treatments on soil bacterial communities.The results revealed that the H treatment significantly in-creased maize yield and biomass by 30.92%and 56.03%,respectively,compared to the F treatment.Additionally,the H treatment markedly enhanced soil bacterial community diversity at different growth stages and altered bacterial community structure in 2022.At the taxonomic level,the H treatment increased the relative abundance of certain phyla,including Patescibacteria,Bacter-oidota,and Actinobacteriota,as well as specific genera such as Chujaibacter,Sphingomonas,Jatrophihabitans,and Flavisoli-bacter.In contrast,the relative abundance of Acidobacteriota in the F treatment was associated with yield,while the relative abundance of Sphingomonas in the H treatment was linked to biomass.Furthermore,at the maturity stage,the relative abun-dance of bacterial communities from three phyla(Myxococcota,Acidobacteriota,and Gemmatimonadota)and two genera(Ellin6067 and Gemmatimonas)in the H treatment was correlated with both biomass and yield.Notably,no such correlations were observed in the F treatment.Functional predictions using PICRUSt2 demonstrated that the H treatment enhanced the metabolic capacity of soil bacteria,particularly in pathways related to amino acid metabolism,xenobiotics biodegradation,glycan biosynthesis,and other metabolic processes.In conclusion,compared to traditional water and fertilizer management,drip fertigation with dense planting not only improved soil bacterial community diversity and metabolic capacity but also in-creased the relative abundance of beneficial bacterial phyla(Patescibacteria,Bacteroidota,and Actinobacteriota)and genera(Chujaibacter,Sphingomonas,Jatrophihabitans,and Flavisolibacter).This treatment influenced yield directly or indirectly by reducing the relative abundance of potentially harmful bacteria(Gemmatimonadota)and increasing the abundance of benefi-cial bacteria(Sphingomonas).

The aim of the experiment was to study the effects of adding three kinds of Tibetan herbs on the growth performance,blood physiology,serum biochemical indexes,and fecal microbiota composition of Tibetan pigs.Forty healthy nursery Tibetan pigs with an initial body weight of(9.30±0.72)kg were selected and randomly divided into four groups,with 10 replicates in each group and one pig in each replicate.The control group(Group A)was fed with basic feed.Groups B,C and D of the experiment were respectively fed with the experimental diets supplemented with 0.5%Lepisorous,Lagotidis Herba,and Terminalia bellirica.The pre-test period was seven days and the formal test period was 28 days.The results showed that Tibetan pigs in Group B had the highest final weight,average daily weight gain,average daily feed intake,and the lowest ratio of feed to gain(P<0.05).The average platelet volume in blood was significantly higher in Groups B and D than in group A(P<0.05),the albumin content in blood was significantly higher in Group D than in Groups A and C(P<0.05).The Ace index was significantly higher in Groups A and B than in Group D(P<0.05).There were certain differences in the composition of bacterial communities in the feces of Tibetan pigs among the four groups.The results show that the addition of Lepisorous to Tibetan pig diets can improve the growth performance and have a certain improvement effect on the diversity of bacterial flora in feces.

This study aimed to investigate the effects of different dietary digestible energy and crude protein levels on growth performance,biochemical indices,meat quality,and fecal microbiota in Tibetan pigs during the fattening period,to determine the optimal dietary digestible energy and crude protein levels.Ninety healthy Tibetan pigs(initial body weight:30.81±2.20 kg)were randomly divided into six groups(15 pigs per group,one pig per replicate)using a 2×3 two-factor experimental design.The dietary digestible energy levels were 12.22 MJ/kg and 13.47 MJ/kg,and crude protein levels were 12.0%,13.5%,and 15.0%.The pre-test lasted for seven days and the formal test lasted for 42 days.The results showed that the 12.22 MJ/kg digestible energy group exhibited significantly higher serum alanine aminotransferase(ALT)activity and lower alkaline phosphatase(ALP)activity compared to the 13.47 MJ/kg digestible energy group(P<0.05).At 0 h post-slaughter,the 12.22 MJ/kg digestible energy group showed significantly lower redness value(a*)and longissimus dorsi pH(P<0.05).The 13.5%crude protein group had a significantly lower lightness value(L*)at 0 h post-slaughter compared to other groups(P<0.05).The 12.22 MJ/kg digestible energy group had a significantly lower relative abundance of Oscillospira and a higher relative abundance of Parabacteroides compared to the 13.47 MJ/kg digestible energy group(P<0.05).The study suggests that the optimal dietary digestible energy and crude protein levels for Tibetan pigs during the fattening period are 12.22 MJ/kg and 12.0%,respectively.

[Objective]The primary aim of this study was to elucidate the impact of fruit bagging on the quality of Chuxialü pear fruits,thereby providing a scientific basis for achieving high-quality produc-tion of this pear variety.[Methods]In this experiment,Chuxialü pears were used as the test material.The potential effects of five different types of fruit bags(Single-layer white bag,Double-layer fruit bag with yellow outer and white inner liner,Double-layer fruit bag with yellow outer and yellow inner liner,Double-layer fruit bag with yellow outer and red inner liner,and Double-layer fruit bag with yellow out-er and black inner liner)on the fruit quality and cultivation outcomes of pears in Linzhi City were inves-tigated.[Results]The research findings indicated that all five bagging treatments significantly altered the fruit peel color,enhanced the smoothness of the fruit surface of Chuxialü pears and effectively re-duced the size of the lenticels(fruit dots).Additionally,the bagging treatments had positive influences on several key fruit quality parameters,including fruit firmness,titratable acidity content,vitamin C content,and stone cell content.Specifically,the treatments led to an increase in the content of soluble solids and an improvement in the solid/acid ratio.To further evaluate the fruit quality under different bagging treatments,principal component analysis(PCA)and factor analysis were conducted.The re-sults of these analyses,ranking from the highest to lowest based on the composite scores,were as fol-lows:Double-layer fruit bag with yellow outer and red inner liner＞Single-layer white bag＞Double-layer fruit bag with yellow outer and black inner liner＞Double-layer fruit bag with yellow outer and yellow inner liner＞Control(unbagged)＞Double-layer fruit bag with yellow outer and white inner liner.(1)Effect on Fruit Peel Color and Surface Smoothness:The application of fruit bags significantly modified the coloration of the pear fruit peel across all five treatments.The Double-layer fruit bag with yellow outer and red inner liner,in particular,imparted a more vibrant and appealing color to the fruits,enhancing their marketability.Moreover,all bagging treatments contributed to a smoother fruit surface,which was a desirable trait for consumers.The reduction in lenticel size not only improved the aesthetic appeal of the fruits,but also potentially reduced the risk of pathogen entry and water loss during storage and transportation.(2)Impact on Fruit Firmness and Texture:Fruit firmness is a critical quality parame-ter that affects both the storage life and consumer acceptance for pears.The bagging treatments,espe-cially the Double-layer fruit bag with yellow outer and red inner liner,led to an increase in fruit firm-ness compared to the unbagged control.This enhancement in firmness could be attributed to the re-duced exposure to environmental stressors,such as sunlight,wind,and pests,which can otherwise cause softening of the fruit tissue.Additionally,the bagging treatments may have influenced the cell wall metabolism and texture-related biochemical processes in the fruits,contributing to their improved firmness.(3)Changes in Soluble Solids and Titratable Acidity:The content of soluble solids,primarily sugars,is a key indicator of fruit sweetness and overall palatability.The bagging treatments,particularly the Double-layer fruit bag with yellow outer and red inner liner,significantly increased the soluble sol-ids content in Chuxialü pears.This increase could be due to the altered microenvironment within the bag,which may have promoted photosynthesis and sugar accumulation in the fruits.Concurrently,the ti-tratable acidity content,which reflects the tartness of the fruits,was also influenced by the bagging treat-ments.While some treatments led to a slight decrease in acidity,the overall solid/acid ratio was im-proved,indicating a better balance between sweetness and tartness.(4)Vitamin C Content and Nutri-tional Value:Vitamin C is an essential nutrient with antioxidant properties that contribute to the nutri-tional value of fruits.The bagging treatments had a variable effect on the vitamin C content of Chuxialü pears.While some treatments,such as the Single-layer white bag,led to a slight increase in vitamin C levels,others,like the Double-layer fruit bag with yellow outer and white inner liner,showed a margin-al decrease.However,the overall nutritional value of the bagged fruits remained high,and the differenc-es in vitamin C content among treatments were not statistically and significantly enough to detract from the overall positive impact of bagging on fruit quality.(5)Stone Cell Content and Fruit Texture:Stone cells,which are sclerenchyma cells with thick and lignified cell walls,can contribute to a gritty texture in pears.The bagging treatments,especially the Double-layer fruit bag with yellow outer and red inner liner,effectively reduced the stone cell content in Chuxialü pears.This reduction in stone cells likely contributed to the improved texture and mouthfeel of the bagged fruits,making them more appealing to consumers.(6)Principal Component Analysis and Factor Analysis:To comprehensively evaluate the fruit quality under different bagging treatments,PCA and factor analysis were employed.These multi-variate statistical techniques allowed for the reduction of multiple quality parameters into a smaller number of principal components or factors,facilitating a more straightforward comparison of the treat-ments.The results of these analyses clearly indicated that the Double-layer fruit bag with yellow outer and red inner liner outperformed the other treatments in terms of overall fruit quality.This type of bag not only enhanced the visual appeal of the fruits,but also improved their taste,texture,and nutritional value.[Conclusion]In conclusion,the application of fruit bags significantly improved the quality of Chuxialü pear fruits.Among the five bagging treatments evaluated,the Double-layer fruit bag with yel-low outer and red inner liner emerged as the most effective in enhancing fruit color,surface smooth-ness,firmness,soluble solids content,solid/acid ratio,and reducing stone cell content.Therefore,it is recommended that this type of bag be widely promoted and adopted in the cultivation of Chuxialü pears to achieve high-quality production and meet the demands of both domestic and international markets.Further research could explore the optimal timing and duration of bagging,as well as the economic fea-sibility of different bagging materials,to optimize the bagging practice for Chuxialü pear production.