Abstract:In order to confirm the molecular basis underlying flower color variegation between Cymbidium hybrid ‘Yufeng’ and its mutant ‘Shuangyijinlong’, we used targeted metabolomics and transcriptomics to identify the differentially expressed metabolites (DEMs) and differentially expressed genes (DEGs) involved in flavonoid biosynthesis. The results showed that: (1) by using targeted metabolomics techniques, we identied 271 flavonoid metabolites, in which 30%-50% metabolites were flavonols and flavonoid metabolites. A total of 38 DEMs (15 up-regulated, 23 down-regulated) were identified. Among these, the content of dihydrokaempferol-7-O-glucoside (flavonol) in ‘Yufeng’ was 124 444 times of which was in ‘Shuangyijinlong’, while the content of uralenol (flavonol) in ‘Shuangyijinlong’ was 7 244 times of which was in ‘Yufeng’. (2) KEGG analysis showed that flavonoid biosynthesis, flavone and flavonol biosynthesis were significantly enriched. In flavonoid biosynthesis pathway, the contents of phlorizin, xanthohumol, dihydrokaempferol, dihydromyricetin and epigallocatechin all increased, the contents of naringin and dihydroquercetin decreased. In addition, the contents of trifolin and quercetin decreased in flavone and flavonol biosynthesis pathway. (3) By the transcriptome, a total of 563 DEGs were identified, 220 (39.1%) DEGs of which were up-regulated and 343 (60.9%) DEGs were down-regulated in the ‘Yufeng’ vs. ‘Shuangyijinlong’ comparison. KEGG analysis indicated that flavonoid biosynthesis-related DEGs (CCoAOMT, CHS, CHI, F3H and FLS) were found to be signiflcantly enriched. (4) QRT-PCR validation showed that the expression level of flavonoid biosynthesis-related DEGs (CHS2, CHS3, CHI, F3H and FLS) and transcription factor gene HD-ZIP were lower in ‘Shuangyijinlong’ than those in ‘Yufeng’. In general, the expression of genes showed a same trend to the accumulation of metabolites, suggesting that the color change of ‘Shuangyijinlong’ might be attributed to the down-regulation of CHS, CHI, F3H and FLS that led to block the downstream metabolites synthesis. It is speculated that the genes involved in the flavonoids biosynthesis may be the key genes for the flower color variegation in Cymbidium hybrid.

Abstract:In view of the key role of NCED gene family members in regulating plant response to drought stress, this study analyzed the distribution, structure and evolution of NCED gene family from zucchini (Cucurbita pepo L.) genome by bioinformatics technology, analyzed the expression specificity of NCED gene members in different tissues and their response to simulated drought (10% PEG 6000), hormone (0.1 mmol·L^-1 ABA) and natural drought (stop watering for 0, 1, 2, 3 and 4 d) stresses to understand the biological functions of NCED gene family. Experimental results show that: (1) a total of six NCED gene (i.e., CpNCED1-6) members were identified from the whole genome of zucchini; The six CpNCEDs were distributed on chromosome 1, 10, 12, 14, 19 and 20 of zucchini, and none of the NCED genes contained intron. (2) Physicochemical properties analysis showed that CpNCED1-6 proteins were 569-590 amino acids, and the theoretical molecular weight ranged from 62.64-65.54 kD. (3) Protein conserved motifs analysis showed that, the CpNCEDs containing 16 complete conserved protein motifs except for the CpNCED3 had three motifs (i.e., motif 12, motif 13 and motif 15) deletion, and CpNCED1-6 proteins conserved elements distributed within 600 amino acids, indicating most of NCED protein sequences were highly conserved. (4) The cis-acting elements analysis of NCED gene family upstream promoters (2 500 bp sequence before ATG) showed that the zucchini CpNCED1-6 genes contained potential drought stress response elements such as ABRE, W box, MBS, P-box, TCA-element, CGTCA-motif, TGA-element and TGA-box. (5) Real-time fluorescent quantitative PCR (qRT-PCR) revealed that the expression of CpNCEDs gene in different zucchini tissues was tissue specific, among which, the expression levels of CpNCED4 and CpNCED1 in stems were significantly higher than those of the other three genes, the expression levels of CpNCED2, CpNCED4 and CpNCED6 in flowers were significantly higher than those of the other three genes, and the expression level of CpNCED2 was the highest, while the expression levels of CpNCED1-6 in fruits and leaves were relatively low; The expression levels of six selected family members were induced by simulated drought, ABA hormone and natural drought stresses and increased in different degrees compared with the control group; With the emergence of drought stress, the abscisic acid (i.e., ABA) content gradually increased in leaves; This study found that six CpNCED1-6 genes played important roles in drought stress response and ABA biosynthesis of C. pepo, especially CpNCED2 and CpNCED4 genes.

Abstract:This study employed conventional chromosome preparation techniques to observe and analyze the karyotypes of five natural geographic populations of Chionanthus retusus in Shandong Province, in order to reveal the karyotypic features, differences, and phylogenetic relationships among different populations, and to lay the cytological foundation for further investigation of the systematics and evolutionary relationships of C. retusus. The results showed that: (1) the chromosome number of the five populations of C. retusus was stable, with 2n=2x=46; small chromosomes were dominant, and the karyotypes were mainly composed of median centromeres (m) and submedian centromeres (sm), with the former being more abundant, and there were two types of chromosomes, 1B and 2B. (2) The karyotype formulae of the five populations of C. retusus were as follows: population B had 2n=2x=43m+3sm, population T had 2n=2x=46m, population S had 2n=2x=45m+sm, population WS had 2n=2x=44m+2sm, and population Z had 2n=2x=45m+sm. This may be related to their respective environments. (3) The asymmetry coefficients of the karyotypes of the five populations were between 54.29% and 58.00%, and the relative evolutionary levels of the populations were B > S > WS > Z > T. (4) The results of cluster analysis showed that when the genetic distance was 1, the populations T and WS and the populations B and S were first clustered together, indicating that their genetic relationships were relatively close. The study suggests that the B and S populations are more advanced in their evolutionary process, while the T population is relatively primitive, indicating that the T population (located at Mount Tais Luohan Cliff) is relatively well protected.

Abstract:The process of the tapetal apoptosis is a key event in microsporogenesis. Previous studies have mainly focused on angiosperms, but ferns have not reported this aspect. The cytological features of the tapetal cells during apoptosis of Osmunda japonica was studied using transmission electron microscopy (TEM) and immunofluorescence technology. The main aim of this paper is to clarify the development type and apoptosis characteristics of tapetal cells of O. japonica. It provides a basis for the further study of tapetum cell apoptosis and spore development of ferns. The results showed that: (1) the structure of tapetum in Osmunda was of the mixed type. The outer layer of the tapetum was of the secretion type, and the inner layer of the tapetum was of plasmodium type. (2) The plasmodium tapetum underwent apoptosis during development. The cell wall and plasmalemma degenerated and the cytoplasm became dense and gradually vacuolated. The nuclei were collapsed and deformed. The chromatin condenses and small nucleoli were formed. The DAPI fluorescence staining became weak gradually. Organelles of mitochondria, plastids, endoplasmic reticulum, Golgi bodies gradually degenerated. The vacuoles contained fibrous, flocculent, dark osmiophilic granules and some small vesicles. Multi-vesicle bodies and multi-membrane bodies and apoptosis bodies occurred in the tapetal cells. (3) In contrast to seed plant, apoptosis of Osmunda started earlier than in seed plants; no nucleus apoptosis bodies occured during apoptosis. Besides sporopollenin, the tapetal cells also produced the fibrous, flocculent, dark osmiophilic granules during apoptosis. The materials were considered to form perispore of ferns.

Abstract:In order to explore the effect of light quality on the growth and development of yellow-leaf pepper plants, we used pepper leaf yellowing mutant yl1 and its wild type 6421 as test materials and treated with different light qualities (white light, blue light, red light, green light, purple light, yellow light and far red light). The changes of phenotypic, physiological and photosynthetic characteristics were studied. The results showed that: (1) blue light and red light promoted the growth of pepper seedlings, while yellow light and far red light significantly inhibited the growth of seedlings. Compared with yl1, 6421 was more affected by different light qualities. (2) The photosynthetic pigment content of the two pepper materials decreased to varying degrees under different light qualities; the total chlorophyll content and carotenoid content of 6421 were higher than those of yl1 under different light qualities. The photosynthetic pigment content of yl1 and 6421 leaves was the lowest under purple light and yellow light, respectively. (3) Blue and green light could significantly increase the net photosynthetic rate (P_n) of yl1, while different light quality treatments significantly reduced the P_n of 6421. (4) Purple light treatment significantly reduced the PSII potential activity (F_v/F_o) and maximum photochemical efficiency (F_v/F_m) of yl1 and significantly lower than that of 6421, but increased the photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (NPQ) to resist photoinhibition damage. (5) Blue, red and green light can improve the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in pepper, while yellow light is the opposite. In summary, blue light and red light can promote the growth and development of pepper, while yellow light and far red light have a significant inhibitory effect. yl1 has a stronger ability to resist light stress, especially under purple light than 6421.

Abstract:In this study, using the inner petals of Chimonanthus praecox (L.) Link ‘Meirenzui’ in five flowering stages (budding, germination, initial flowering, full blooming and final flowering) as materials, we investigated the change of the chromaticity value, the contents of anthocyanidin, soluble proteins, soluble sugar and the activities of superoxide dismutase (SOD), phenylalanine lyase (PAL) during flowering, and analyzed the correlation between the indicators, so as to reveal the characteristics of physiological and biochemical indexes during the floral color change of C. praecox (L.) Link. The results showed that: (1) from budding stage to final flowering stage, the hue a^* of ‘Meirenzui’ petals decreased sharply, while the value of brightness L^*, hue b^*, chroma C^* and hue angle h° increased gradually. (2) During the flowering process of ‘Meirenzui’, the contents of flavonoids, anthocyanins and chlorophyll in petals gradually decreased, while the contents of carotenoids increased first and then decreased. (3) The soluble protein content of ‘Meirenzui’ petals decreased significantly in the germination stage and full blooming stage, while the soluble sugar content decreased to the lowest value in the initial flowering stage. (4) The PAL activity of ‘Meirenzui’ petals decreased first and then increased with the flowering process, while the SOD activity increased significantly first and then remained stable. (5) There was a significant correlation between the chromaticity value of ‘Meirenzui’ petals and the contents of flavonoids, chlorophyll, anthocyanin, soluble protein and PAL activity. The results showed that C. praecox (L.) Link ‘Meirenzui’ floral color change is the result of the joint action of anthocyanins, flavonoids and chlorophyll, but the change of anthocyanin content plays the most direct role, soluble protein, SOD and PAL play an indirect role in the change of floral color through physiological metabolic pathways.

Abstract:Taking Populus euphratica in Ejina as the research object, we analyzed the characteristics of leaf color parameters, pigment contents of P. euphratica and meteorological conditions in different periods. The main influencing factors of leaf discoloration of P. euphratica were explored, which laid a research basis for leaf senescence of P. euphratica and meteorological service of yellow leaf phenology landscape in Ejina in autumn. The results showed that: (1) the leaf color parameters L^*, a^* and C^* of P. euphratica showed a gradually rising tendency, the b^* and h values increased first and then decreased. The changes of leaf color showed green, light yellow, golden and orange in leaf color changing process. (2) During the discoloration period of P. euphratica, the content of leaf chlorophyll in leaves decreased significantly, while the lutein and carotenoids contents increased slowly first and then decreased slightly, the content of anthocyanin had little change, and the content of soluble sugar also increased first and then decreased. The ratio of total chlorophyll to carotenoids decreased by 97.5% at the end of discoloration compared with the initial stage. (3) In the same period of leaf discoloration of P. euphratica, the temperature gradually decreased, and the daily temperature range kept relatively stable at about 14 ℃, the direct radiation gradually decreased, and the average relative humidity first increased and then decreased, but the overall performance was an increasing trend. The evaporation decreased gradually as a whole. (4) During the color changing period, leaf color parameters L^*, a^*, b^*, C^* were significantly negatively correlated with chlorophyll a, chlorophyll b, total chlorophyll contents and the ratio of chlorophyll to carotenoids (P<0.01). The maximum temperature, minimum temperature and average temperature showed significant negative correlation with leaf color parameters L^*, a^*, b^*, C^* (P<0.05), while they showed significant or extremely significant positive correlation with chlorophyll a, chlorophyll b, total chlorophyll contents and the ratio of chlorophyll to carotenoid. Air relative humidity showed a significant or extremely significant positive correlation with lutein and carotenoid. The study revealed that the leaves landscape of P. euphratica in Ejina gradually showed light to dark yellow in the process of senescence, which was the result of large and rapid decomposition of chlorophyll and relative increase of carotenoid content. Temperature was the main limiting meteorological factor affected the senescence and etiolation of P. euphratica leaves. Chlorophyll decomposition was accelerated at low temperature, and higher air humidity was conducive to keeping carotenoid content remain stable and maintaining a longer viewer period of yellow leaf landscape.

Abstract:In this study, Nagina22 (a heat-resistant rice variety) and YR343 (a heat-sensitive rice variety) were selected as test varieties. Six treatments were set: spray water + normal temperature treatment (NT0), spray water + high temperature stress at panicle initiation stage (HT0), and spray exogenous trehalose + high temperature stress (HT1, HT2, HT3, HT4) at 5, 10, 15, 20 mmol·L^-1, respectively. The effects of exogenous trehalose on chlorophyll content, photosynthetic gas-exchange parameters, antioxidant enzyme activities, osmotic regulatory substance content, active oxygen content and yield of rice during panicle initiation stage under high temperature stress, were analyzed to provide theoretical basis for developing heat-resistant rice cultivation and breeding heat-resistant varieties. The results show that: (1) under high temperature stress at panicle initiation stage, the contents of chlorophyll, photosynthetic gas exchange parameters and osmotic regulatory substances in the leaves of the two rice varieties decreased, while the contents of MDA and H₂O₂ in the leaves, as well as the production rate of O₂^-· increased, and the activities of antioxidant enzymes in the leaves increased first and then decreased; which resulted in a significant decline in the kernels yield and its constituent factors. (2) Application of exogenous trehalose could significantly increase the number of grains per panicles, 1000-grain weight and seed setting rate of rice at panicle initiation stage under high temperature stress, thus improving yield. The 1000-grain weight and seed setting rate of the inferior spikelets were higher than that of the superior spikelets. The optimal concentration of exogenous trehalose was 15 mmol·L^-1. (3) Exogenous trehalose spray with appropriate concentration can improve the chlorophyll content of rice leaves, promote the photosynthetic rate, enhance the activities of antioxidant enzymes SOD, POD and CAT, increase the contents of soluble sugar and soluble protein, and reduce the contents of MDA, H₂O₂ and the production rate of O₂^-·, so as to alleviate the damage to rice caused by high temperature stress at panicle initiation stage and improve the yield. It was found that exogenous application of 15 mmol·L^-1 trehalose could improve the photosynthetic physiological characteristics of rice leaves, enhance osmotic regulation ability, enhance the activity of antioxidant enzyme system, and thus improve the heat resistance and grain yield of rice under high temperature stress at the panicle initiation stage. The results can provide a theoretical basis for developing heat-resistant cultivation and breeding of heat-resistant rice varieties.

Abstract:Using pot experiment for 4 water-controlled treatments: control (80% soil water content), mild drought (65% soil water content), moderate drought (50% soil water content) and severe drought (35% soil water content), we explored the response of drought stress on photosynthetic characteristics of Polygonatum cyrtonema Hua. with 3-year-old seedlings. The results showed as following: (1) with the deepening of drought stress, the contents of chlorophyll (a+b) and chlorophyll b in the leaves showed a trend of increase first and then decrease, while the content of chlorophyll a decreased gradually. However, the chlorophyll a/b and carotenoids content showed an trend of “up-down-up”. (2) The diurnal variation of net photosynthetic rate (P_n) showed a “single-peak” curve under control and mild drought stress conditions, while under moderate and severe drought stress conditions, the diurnal variation of P_n showed a “double-peak” curve, and the main influencing factor of the “photosynthetic midday depression” phenomenon was non-stomatal limitation.(3) With the deepening of drought stress, the average daily net photosynthetic rate, average daily transpiration rate, average daily stomatal conductance and average daily light use efficiency were decreased, while the average water use efficiency was increased. (4) With the deepening of drought stress, the light compensation point decreased first and then increased sharply, while the light saturation point increased first and then decreased, and its apparent quantum efficiency was gradually decreased. Meanwhile, the CO₂compensation point and CO₂ saturation point both showed an trend of “increase-decrease-increase”, while their carboxylation rates gradually decreased, and they all were significantly different from the rest of the treatments under severe drought stress. (5) Under severe drought stress, the initial fluorescence (F_o), maximum fluorescence (F_m), potential activity of PSⅡ (F_v/F_o) and maximum photosynthetic efficiency of PSⅡ (F_v/F_m) were significantly lower than those of other treatments. It was found that P. cyrtonema has certain adaptability to mild drought stress, while the moderate drought stress may be the turning point of drought damage. However, the severe drought stress would seriously inhibit the photosynthetic capacity.

Abstract:In this study, we treated four-year-old Toona sinensis with stubble height 20 cm (T₁), 50 cm (T₂), 80 cm (T₃) and no stubble (CK) to investigate the growth of sprouting branches and leaves, as well as the changes of leaf gas exchange parameters, photosynthetic pigment content and non-structural carbohydrate (NSC) content. We analyzed the differences in growth physiological response to different stubble heights and preliminarily explored the physiological mechanism of renewing and rejuvenating regeneration of T. sinensis plants under different stubble treatments. The results showed that: (1) different stubble heights could significantly improve the sprouting ability and promote the growth of lateral branches and leaves of T. sinensis. The sprouting number and lateral branch length of T. sinensis were the highest under T₃ treatment, while the sprouting number,leaf length, leaf width, leaf area and side branch diameter reached the maximum under T₂ treatment. (2) With the increase of stubble height, the net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s) and water use efficiency (WUE) of leaves increased first and then decreased, and reached the maximum in T₂ treatment, which significantly increased by 17.33%, 10.00%, 13.51% and 6.98% compared with CK, respectively. Different stubble heights also increased the photosynthetic pigment content of leaves, chlorophyll a, chlorophyll b, total chlorophyll contents and carotenoid content in T₂ treatment significantly increased by 18.34%, 27.07%, 21.11% and 23.05%, respectively, compared with CK. (3) The contents of soluble sugar, starch and NSC in leaves, branches and roots of T. sinensis under different stubble heights were higher than those of CK, and the increases in T₂ and T₃ treatments reached a significant level. The distribution rules of soluble sugar, starch and NSC contents in different organs of leaves, branches and roots of T. sinensis were consistent between stubble treatment and no stubble treatment, and NSC contents showed the order of leaves > roots > branches. The results indicate that different stubble heights could improve the photosynthetic capacity of T. sinensis by increasing photosynthetic pigment content and photosynthetic gas exchange parameters of leaves, and promote the accumulation and distribution of non-structural carbohydrates in different organs through priority storage strategy to adapt to the effects of stubble treatment and regulate the occurrence and growth of sprouts. The comprehensive results of this experiment showed that the regeneration of T. sinensis with stubble height 50 cm was the best for growth recovery and photosynthetic capacity.

Abstract:Taking the fruits of Hass avocado in 9 different cultivation areas in Yunnan as test materials, we observed the main internal and external quality of avocado fruits after ripening under the same conditions, in order to analyze the main quality differences of avocado fruits in different cultivation areas in Yunnan and explore the suitable ecological region for avocado cultivation in Yunnan. The results showed that: (1) in terms of appearance indexes, the coefficient of variation of avocado single fruit weight, seed weight and edible rate in different production areas was large, which were 31.31%, 38.09% and 8.08%, respectively. The single fruit weight and edible rate of avocado in LJ production area were the largest. The coefficient of variation of fat, soluble protein and Vc contents in the internal quality of pulp was large, which were 37.57%, 22.42% and 17.89%, respectively. The production area with the highest fat content was BS, and the production area with the highest soluble protein and Vc contents was BN. (2) Correlation analysis showed that Vc, total flavonoids, fat contents, pulp weight per fruit and fruit longitudinal stem quality of avocado fruit were significantly affected by tree age and climate factors. Among them, tree age was positively correlated with fat, soluble solids, Vc and total flavonoids, and significantly negatively correlated with pulp weight per fruit. Longitude was positively correlated with fat, soluble solids, dry matter and soluble protein. Latitude was positively correlated with soluble solids, pulp density and seed length, and significantly negatively correlated with Vc and total flavonoids. Altitude was positively correlated with fat, soluble solids, Vc and total flavonoids. The annual average temperature was positively correlated with pulp density, single fruit weight, single fruit pulp weight and fruit longitudinal stem. The annual average rainfall was positively correlated with fat and soluble solids. The annual average sunshine hours were positively correlated with fat, Vc and total flavonoids. (3) Principal component analysis showed that the quality index was an important factor to evaluate the fruit quality of avocado in Yunnan, and the cumulative variance contribution rate of the four principal components was 68.955%. The result of factor analysis showed that the top three places of origin were LJ, LL and BS, which were 0.833, 0.611 and 0.551, respectively. (4) Cluster analysis showed that avocado from nine producing areas in Yunnan could be divided into three categories. The first category was GM, YD, YM and ZF. This kind of avocado fruit had the characteristics of medium fruit size, small seeds, high edible rate, high dry matter, Vc and soluble protein contents. The second category was BN and XG. This kind of avocado fruit were the points of small fruit, small seed, high edible rate, relatively high contents of Vc, soluble protein and total flavonoids, and relatively low content of dry matter fat. The third category was LJ, LL and BS, which were characterized by large fruit, many pulp, thick meat, large seeds and high contents of fat, dry matter, Vc, soluble protein and total flavonoids. It could be seen that tree age and ecological factors had a significant impact on avocado fruit quality. There were significant differences in avocado fruit quality from different places in Yunnan. LJ, LL, BS producing areas were the best ecological areas for avocado fruit comprehensive quality in Yunnan.

Abstract:In order to explore the differences in the quality of hulless barley (Hordeum vulgare L. var. nudum Hook.f.) varieties in the Qinghai-Tibet Plateau, establish the quality evaluation index system of hulless barley, and regionalize the ecological adaptability of hulless barley quality, we used 15 main hulless barley varieties in the Qinghai-Tibet Plateau as experimental materials and measured thirteen quality indexes such as total starch, crude protein, ether extract and β-glucan. One-way analysis of variance, correlation analysis, principal component analysis and cluster analysis were used to analyze the measured indexes. The results showed that: (1) among the 13 quality indexes, 11 indexes had significant differences among the 15 tested varieties, and 12 indexes had significant differences in the 8 planting zones. There was a significant positive correlation between the total flavonoid content and the total polyphenol content, and the β-glucan content. Based on the performance of different varieties in different ecological regions, the contents of amylopectin, amylose, total flavonoids, β-glucan and total polyphenols were the greatest influence on the comprehensive quality of hulless barley. (2) The 15 tested varieties were divided into 4 categories by cluster analysis, and the 8 regions were divided into 3 ecological zones. The varieties with better quality in each ecological zone were Kunlun 18, Kunlun 19, Kunlun 15, Ganqing 8 and Ganqing 4. (3) These results showed that 13 indicators could be converted into 5 principal components, and the cumulative variance contribution rates were 85.16% and 94.40%, respectively. The variety with the highest comprehensive evaluation score was Kunlun 18, and the area with the best quality was Guinan, Qinghai province.

Abstract:The pure bamboo forest with basically the same site conditions was selected, and the sample plots with a width of 6 m, 8 m, and 10 m and a vertical length of 30 m were set for strip cutting. The same width was set at the adjacent position of the cutting zone. In addition, three conventionally managed bamboo forests without cutting were randomly selected as controls. The nutrient status of rhizome, rhizome root, bamboo stump and root of Phyllostachys edulis with different cutting widths were measured, and the recovery potential of underground components of moso bamboo after different cutting widths was analyzed. We explored the reasonable cutting width to provide theoretical basis for the scientific management of moso bamboo forest. The results showed that: (1) the organic carbon content of rhizome, rhizome root and root of moso bamboo in the cutting belt increased first and then decreased with the increase of cutting bandwidth, while the organic carbon content of bamboo root continued to increase. The organic carbon content of bamboo root in three width cutting belts, 8 m cutting belt and 10 m cutting belt was significantly higher than that in the retaining belt (P < 0.05). The organic carbon content of rhizome root in 8 m cutting belt, bamboo root and root in three width cutting belts were different from that in the control. The proportion of organic carbon content of rhizome root in 6 m and 10 m cutting belts and rhizome root in 8 m cutting belt was significantly higher than that in the retaining belt. (2) The total nitrogen (TN) content of bamboo rhizome, rhizome root and bamboo root in the three cutting bandwidths showed a relationship of 8 m > 6 m > 10 m, and the TN content of bamboo root continued to increase with the increase of bandwidth. There was only a significant difference between the 8 m cutting band and the 10 m cutting band. The TN content of rhizome root, bamboo root and root of three kinds of bandwidth was different from that of the control. The proportion of TN content in each component was basically bamboo rhizome > bamboo root > rhizome root > basket root. The proportion of TN in rhizome root of 8 m cutting belt and rhizome, rhizome root and root of 10 m cutting belt increased significantly. (3) The total phosphorus (TP) content of bamboo rhizomes, bamboo stumps and bamboo stumps increased first and then decreased with the increase of bandwidth, while the TP content of rhizome roots continued to rise. The TP content of bamboo rhizomes in the 8 m cutting zone was significantly higher than that in the control, and the TP content of bamboo stumps was significantly higher than that in the corresponding retention zones and the control. The TP content of bamboo stumps accounted for the highest proportion of total phosphorus content in underground components in the 8 m and 10 m cutting zones, while the TP content of bamboo rhizomes accounted for the highest proportion in the 6 m cutting zone. (4) The total potassium (TK) content of the underground components of moso bamboo in the cutting belt was the highest in the 8 m bandwidth. The TK content of the bamboo root and the root in the 8 m cutting belt was significantly higher than that in the 6 m cutting belt by 17.69% and 106.90%, respectively, which was significantly higher than that in the 10 m cutting belt by 102.87% and 121.12%. The TK content of bamboo rhizome, rhizome root and root in the 8 m cutting belt was significantly higher than that in the retaining belt and the control. With the increase of bandwidth, the proportion of TK content showed a downward trend in bamboo rhizome and bamboo root in the cutting belt, an upward trend in rhizome root, and a first increase and then decrease in root. It can be seen that the strip cutting treatment can promote the development of the underground components of moso bamboo, and the nutrient absorption efficiency of the underground components of moso bamboo in the 8 m cutting zone is significantly increased, and the nutrient element content is relatively high, which can provide a lot of energy and growth potential for the recovery and growth of bamboo forest. 8 m cutting width is a reasonable cutting width, which is conducive to the rapid recovery of bamboo forest after cutting.

Abstract:Litter-derived metabolites play important ecological roles in plant-soil systems. In this study, the litters of 5 typical arboreal, shrubby and herbaceous species, including Robinia pseudoacacia, Pinus tabuliformis, Hippophae rhamnoides, Setaria viridis and Lespedeza daurica, in the hilly and gully region of the Loess Hilly Region were studied. Soil from a site that far from the litter sampling area was mixed with sterile water, fully shocked and precipitated, and the supernatant was used for inoculating litters. Then, based on an indoor-decomposition simulation under room temperature (25 ℃) and constant humidity (the water-holding rate of litters was approximately 100%), and the degradation or release characteristics of 7 types of metabolite in this process were studied, aiming to get more deeply understand the decomposition process of litters and its subsequent ecological effects, and to provide scientific basis for the management of forest and grass ecosystems. The results indicated that: (1) during the decomposition process of 150 d, the lignin of 5 types of litter showed little degradation (<30%) in the early stage (0-60 d) and tended to stagnate in later stage; most (>80%) of water soluble phenolics, condensed tannins and flavones released rapidly in the early stage (0-30 d) of decomposition, but slowed down significantly in later stage. The release of terpenoids was continuous and even accelerated at the later stage during the experiment. The release of soluble sugars and amino acids showed a trend of rapid release in a short time and then slow release. In general, except for lignin, which degraded significantly slower during litter decomposition, all other metabolites exhibited an overspeed release trend. (2) The annual degradation or release rates of 7 types of metabolite were significantly higher in the litters of H. rhamnoides and R. pseudoacacia than in the those of L. daurica, S. viridis and P. tabuliformis (P<0.05). (3) The annual degradation or release rates of lignin, condensed tannins, terpenoids and flavones were not significantly correlated with their initial contents (P>0.05), while the annual release rates of water soluble phenolics, soluble sugars and amino acids were positively correlated with their initial contents (P<0.05). In conclusion, except for lignin, which degraded significantly slower during litter decomposition, all other metabolites exhibited an overspeed release trend; the annual degradation or release rates of almost all these 7 types of metabolite were positively correlated with the initial nitrogen and phosphorus contents of litter.

Abstract:The Himalaya is regarded as one of the most important biodiversity hotspots on earth. Based on the combination of species lists and distribution data on the southern and northern slopes of the Himalaya collected by previous studies, as well as supplement of online databases, this study summarized the distribution of Himalayan seed plants in China, India, Nepal and Bhutan, and analyzed the characteristics, species composition similarity, floristic composition and elevational distribution patterns, which would provide data support for Himalayan biodiversity studies and conservation. The results show that: (1) the Himalaya harbors 11 875 seed plants species (belonging to 2 086 genera and 223 families), of which 7 906 are herbaceous species (66.6%), 2 583 are shrub species (21.8%) and 1 386 are tree species (11.7%), respectively. (2) Families with a large number of species (including Asteraceae, Orchidaceae, Poaceae, Fabaceae, Ericaceae and other families) contain 7 456 species, accounting for 62.8% of the species in the Himalaya, and genera with a large number of species (including Rhododendron, Primula, Pedicularis, Saxifraga, Carex and other genera) contain 2 235 species, accounting for 18.8% of the Himalayan plants. (3) Floristic components of family and genus are mainly tropical element (accounting for 51.6% and 54.2%, respectively). (4) China, India, Nepal, Bhutan of the Himalaya have 8 571, 5 306, 5 304 and 5 613 plant species, respectively, and species similarity between Nepal and Bhutan is the highest (The similarity of family, genus and species are 92.7%, 75.0% and 54.9%, respectively), while China and India have the lowest species similarity (The similarity of family, genus and species are 83.7%, 61.9% and 31.1%, respectively). (5) With an increase of elevation, species richness first increased, then fluctuated horizontally, and finally decreased rapidly, and most species occurred at low-intermediate elevations (1 500-3 500 m), only a few herbaceous plants are found at elevation above 4 000 m.

Abstract:Qinghai-Tibet Plateau is rich in species, and belongs to the climate change sensitive area. Studying the impact of climate change on the potential distribution of species on Qinghai-Tibet Plateau is of great significance for the biodiversity conservation. In this study, we selected the endangered Tibetan medicinal plant Meconopsis integrifolia as the research object, and constructed an ensemble model of Random Forest (RF), Flexible Discriminant Analysis (FDA) and Artificial Neural Network (ANN) using the weighted average algorithm (WAA). At the same time, we also compared the prediction accuracy of the WAA model and different ecological niche models. Finally, we used the WAA model to predict the potential distributions of M. integrifolia under current (averaged 1970-2000) and future (averaged 2041-2060) climate scenarios. For the uncertainty of future climate, we chose two “Shared Socioeconomic Pathways” (SSP2-45 and SSP5-85). The results showed that: (1) the WAA model predictions showed that the AUC of the ensemble model based on RF, FDA and ANN was 0.926, which was 3% higher than that of the RF model with the highest AUC value, and 5% higher than the AUC value for both FDA and ANN models. (2) The WAA model determined that the potential distribution of M. integrifolia was most sensitive to annual precipitation and precipitation of warmest quarter, followed by max temperature of warmest month, and showed lower sensitivity to precipitation of wettest month and isothermality. (3) The current potential distribution areas of M. integrifolia were mainly distributed in southwestern Gansu, eastern and southern Qinghai, western and northwestern Sichuan, northwestern and northeastern Yunnan, and eastern Tibet. (4) The prediction of potential distribution of M. integrifolia on the Qinghai-Tibet Plateau under future climate change showed that under the SSP2-45 scenario in 2050, the size of potential distribution of M. integrifolia was basically the same as that of current, but the potential distribution would spread to the high altitudes and latitudes in the northwest. However, under the SSP5-85 scenario, the size of potential distribution of M. integrifolia would shrink significantly, and the trend of spreading to the northwest high-altitude and -altitude areas was more obvious.

Abstract:Lichens of the genus Cladonia consist of primary squamules and secondary cylindric podetia. More than 500 species have been reported in the world, which are the important components of lichen diversity and have significant ecological functions. With the in-depth investigation of Cladonia species in China, we identified C. camerunensis and C. imbricata as new to China based on morphological characteristics, chemistry and phylogenetic analysis of nrDNA ITS sequence data from Yunnan and Hebei, respectively. Detailed characteristics and pictures of two Cladonia species are presented with comparison with some similar species.