Table of Content

20 August 2024, Volume 33 Issue 8

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Changes in vegetation and soil characteristics and their correlations in grasslands at different stages of degradation on the desert steppe in an arid wind-sandy area of Ningxia

Ying CAO, Ming-he NIE, Yan SHEN, Yan HU, Deng-bao MA, Dong LI, Teng-si HOU, Peng FANG, Xue-qin WANG

2024, 33(8):  1-14.  DOI: 10.11686/cyxb2023342

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The aim of this research was to gain a deeper understanding of the variations in vegetation and soil of desert grasslands at different stages of degradation， and to investigate the correlations between soil properties and vegetation characteristics within these stages. A field study was conducted in desert grasslands in the arid wind-sandy region in Ningxia， with an aim to compare the vegetation and soil characteristics across grasslands at four stages of degradation： Non-degraded， lightly degraded， moderately degraded， and heavily degraded. The relationship between vegetation and soil during the process of grassland degradation was analyzed. The results revealed that， as the degree of grassland degradation increased， there was a transition in the dominant species from perennial legumes and graminoids to annual miscellaneous grasses. The plant functional groups exhibited diverse responses in terms of vegetation coverage， height， and above-ground biomass （P<0.05）. The Shannon-Wiener diversity index， Simpson’s dominance index， and Pielou’s evenness index showed consistent trends of decreasing as the degree of grassland degradation increased. Furthermore， with increasing severity of grassland degradation， there were significant decreases in soil organic matter content， total carbon and nitrogen levels， available nitrogen and phosphorus concentrations， and silt content， and a significant increase in bulk density. The results of a redundancy analysis revealed a strong correlation between the characteristics of desert grassland vegetation and soil factors in general. However， the specific soil properties influencing these vegetation characteristics varied among grasslands at different stages of degradation. In non-degraded grasslands， the total carbon content significantly affected vegetation characteristics， while bulk density played a significant role in moderately degraded grasslands. Heavily degraded grasslands were considerably impacted by the available nitrogen content （P<0.01）. Improvements in vegetation or the supplementation of soil nutrients can be considered as effective strategies for restoring grasslands.

Effects of Caragana intermedia stubble on soil water characteristics and water balance on the desert steppe

Teng-si HOU, Yan SHEN, Hong-bin MA, Peng FANG, Ying CAO

2024, 33(8):  15-24.  DOI: 10.11686/cyxb2023360

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Leaving stubble is an important method to optimize the management of Caragana intermedia on the desert steppe. The aim of this study was to determine the effects of Caragana stubble on the soil water characteristics and water balance， to provide a theoretical basis and practical guidance for rational cropping of Caragana on the desert steppe. A field study was conducted at a Caragana plantation in desert grassland of Ningxia， involving four cropping configurations： No stubble （WP）； one belt stubble and one belt no stubble （G₁P₁）， three belts stubble and three belts no stubble （G₃P₃）， and five belts stubble and five belts no stubble （G₅P₅）. The effects of these different cropping configurations on soil moisture and water balance were analyzed. It was found that： 1） The highest soil moisture content was in the G₃P₃ treatment， and the moisture content in the 0-200 cm soil layer increased with increasing soil depth； 2） Compared with natural grassland without Caragana， the WP， G₁P₁， G₃P₃， and G₅P₅ treatments all resulted in soil water deficit to varying degrees； the lowest water deficit index was in the G₃P₃ treatment， indicative of reduced soil water consumption. 3） Under the influence of environment and stubble treatments， the treatments were ranked， from highest transpiration of vegetation to lowest， as follows： G₃P₃<G₁P₁<G₅P₅<WP； and from highest evapotranspiration between trees to lowest， as follows： G₃P₃<G₁P₁<WP<G₅P₅. The ratio of evapotranspiration to rainfall was lowest in the G₃P₃ treatment. Based on the characteristics of soil water and water balance， the G₃P₃ treatment was more conducive to water retention and water balance in areas planted with Caragana on the desert steppe.

Effects of root separation on aboveground biomass， soil nutrient contents， and root characters of intercropped oat and pea

Wen-pan DU, Gui-qin ZHAO, Ji-kuan CHAI, Li YANG, Jian-gui ZHANG, Yi-chao SHI, Guan-lu ZHANG

2024, 33(8):  25-36.  DOI: 10.11686/cyxb2023370

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The aim of this research was to explore the effects of root separation on aboveground biomass and soil nutrient contents in an oat （Avena sativa）/pea （Pisum sativum） intercropping system. Five treatments were applied in a field experiment： Oat monoculture， pea monoculture， unseparated oat/pea intercropping， oat/pea intercropping with nylon mesh separation， and oat/pea intercropping with plastic film separation. The changes in plant height， aboveground biomass， soil nutrients and root traits after oat/pea intercropping were analyzed. The results showed that the plant height and the aboveground biomass of intercropped oat/pea were reduced by the plastic film separation treatment， with a land equivalent ratio lower than 1， whereas the land equivalent ratios in the nylon mesh separation and unseparated treatment were higher than 1， and intercropping had obvious advantages. The soil organic matter content and available phosphorus content were 14.75%-78.53% lower and 9.31%-29.73% lower in the plastic film separation treatment than in the nylon mesh separation treatment and unseparated treatment， respectively. In the root separation treatments， there was no significant difference in the soil total nitrogen content between the jointing and flowering stages （P>0.05）. Compared with the nylon mesh separation and upseparated treatments， the plastic film separation treatment showed 22.16% and 18.38% lower soil total nitrogen content， respectively， at the grain-filling stage. At the mature stage， the soil total nitrogen content was 10.83% higher in the non-separated treatment than in the plastic film separation treatment （P<0.05）. For pea， the soil organic matter content was significantly higher in the plastic film separation treatment than in the unseparated and nylon mesh separation treatments. In addition， the length of oat roots in the unseparated treatment was 43.03%， 59.02%， and 96.38% higher than that in the nylon mesh separation treatment， single cropping treatment， and plastic film separation treatment， respectively. The surface area of oat roots in the unseparated treatment was 14.84%， 30.20% and 45.55% higher than that in the nylon mesh separation treatment， single cropping treatment， and plastic film separation treatment， respectively. The volume of oat roots in the unseparated treatment was 17.37%， 38.15% and 106.15% higher than that in the nylon mesh separation treatment， single cropping treatment， and plastic film separation treatment， respectively. In conclusion， oat/pea intercropping significantly affected the root characteristics of both crops， and changed the competitiveness of roots for soil nutrients， thus affecting aboveground biomass. The closer the root interaction， the higher the aboveground biomass of oat and pea plants. Plastic film separation without root interaction resulted in poor root growth， lower soil nutrient contents， and the lowest aboveground biomass of both crops.

Spatiotemporal distribution characteristics and driving factors of livestock feeding structure： A case study in Ningxia

Cong ZHANG, Ya WANG, Li-hua ZHOU, Xiao-dong PEI, Jun-hao LI, Gui SHI

2024, 33(8):  37-49.  DOI: 10.11686/cyxb2023368

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Animal husbandry is a crucial industry that significantly impacts the national economy and people’s livelihoods. Its importance extends to the economy， environment， and food safety. Despite a continuous increase in overall animal production in China in recent years， two problems remain： animals are “large but not strong” and “abundant but not excellent”. This study focuses on the livestock feeding structure， with aims to explore its temporal and spatial distribution characteristics as well as the driving factors. This research holds substantial value for guiding the rational distribution of resources and ensuring the sustainable development of animal husbandry in China. First， the temporal distribution characteristics of effective feeding amount and feeding structure of livestock in Ningxia in 1978-2020 were analyzed. Then， the spatial distribution characteristics of livestock feeding structure were assessed using coefficient of variation and standard deviation ellipse methods. Finally， the core driving factors influencing the spatial differentiation of livestock feeding structure were identified by applying the GeoDetector model. The main findings were as follows： 1） The livestock feeding structure in Ningxia significantly changed around 2002 with a noticeable increase in the proportion of cattle and sheep and a decrease in the proportion of pigs. 2） The proportion of cattle， sheep， and pigs showed spatial differentiation， but each exhibited a distinct trend of spatial heterogeneity. 3） The proportions of cattle， sheep， and pigs displayed a shift from south-north distribution to northeast-southwest distribution. The regions with high proportions of cattle and sheep showed trend of expansion. 4） The core driving factors influencing the proportion of cattle were natural resource conditions and socio-economic conditions and policies. The core driving factors influencing the proportion of sheep were socio-economic conditions and policies. However， the proportion of pigs was only affected by socio-economic conditions. Interactions among most of these core driving factors enhanced the spatial differentiation of livestock feeding structure.

Suitability of five forage sweet sorghum varieties for production in the dry plateau area of Longdong

Zhong-li LI, Cong-ze JIANG, Ren-shi MA, Wei GAO, Na SHOU, Yu-ying SHEN, Xian-long YANG

2024, 33(8):  50-62.  DOI: 10.11686/cyxb2023355

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The aim of this study was to select productive and high-quality forage sweet sorghum （Sorghum bicolor） varieties suitable for cultivation in the Longdong dry Loess Plateau area. A field trial was conducted in 2021-2022 to compare five sweet sorghum varieties in terms of their agronomic traits， dry matter accumulation and partitioning， forage quality， and water- and nitrogen-use efficiencies. The results showed that the variety had significant （P<0.05） effects on the major agronomic traits， forage quality， and water- and nitrogen-use efficiencies of forage sweet sorghum. Among the tested varieties， ‘Lvjuren’ had the greatest plant height and stem thickness at harvest （average of 344.9 cm and 24.2 mm， respectively， over the 2 years）. ‘Hainiu’ had the largest leaf area index （2-year average， 3.6）， whereas ‘Lvjuren’ had the highest fresh and hay yields （2-year averages of 78.4 and 22.1 t·ha^-1， respectively）. ‘Daka’ had the highest crude protein content （2-year average， 7.6%）. ‘Sealion’ had the lowest contents of neutral detergent fiber and acid detergent fiber （2-year averages of 54.9% and 27.6%， respectively）， but the highest relative forage value and relative forage quality （2-year averages of 115.5 and 158.1， respectively）. The dry matter water-use efficiency and partial productivity of nitrogen fertilizer were both highest in ‘Lvjuren’ （2-year averages of 45.7 kg·ha^-1·mm^-1 and 122.7 kg·kg^-1， respectively）. This comprehensive evaluation of five sorghum varieties using the grey correlation analysis method showed that ‘Lvjuren’ is more suitable than other varieties for planting and popularizing in the Longdong dry Loess Plateau area.

Effects of alfalfa green manure on the yield， nitrogen absorption， and nitrogen translocation of feed maize

Zheng WANG, Wei CHANG, Jun-cheng LI, Lian-tai SU, Li GAO, Peng ZHOU, Yuan AN

2024, 33(8):  63-73.  DOI: 10.11686/cyxb2023356

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The use of alfalfa （Medicago sativa） green manure in the cultivation of maize （Zea mays） is an effective way to improve soil quality and increase maize yield， but the mechanism by which alfalfa green manure increases maize production is still unclear. To determine the effects of green manure on maize plants， we conducted a field experiment with the following treatments： maize planted in ryegrass （Lolium perenne） soil and addition of ryegrass green manure （ryegrass green manure treatment）， maize planted in alfalfa soil and addition of alfalfa green manure （alfalfa green manure treatment）， and maize planted in ryegrass soil and addition of nitrogen （N） fertilizer to provide the same amount of N as that in alfalfa green manure （alfalfa-equivalent N treatment）. It was found that both the alfalfa green manure treatment and the alfalfa-equivalent N treatment resulted in significant increases in plant height and the aboveground biomass of maize； the aboveground biomass was 48.77% and 37.73% higher， respectively， in those treatments than in the ryegrass green manure treatment. However， there was a significant difference in N fertilizer partial productivity between the alfalfa green manure treatment and the alfalfa-equivalent N treatment， with an increase of 48.77% and a decrease of 9.61%， respectively， compared with that in the ryegrass green manure treatment. The alfalfa green manure treatment increased the N contents in new leaves， old leaves， and leaf sheaths in maize， which were 9.59%， 9.97%， and 33.90% higher， respectively， than their values in the ryegrass green manure treatment， and these increases were greater than those in the alfalfa-equivalent N treatment. The N content in the root tip was highest in the alfalfa-equivalent N treatment， followed by the alfalfa green manure treatment （78.07% and 23.08% higher， respectively， than that in the ryegrass green manure treatment）. The transcript levels of key genes related to N transport， ZmNPF6.4 and ZmNPF6.6， were upregulated by 96.48% and 234.08%， respectively， in the roots of maize plants in the alfalfa green manure treatment. In the alfalfa green manure treatment， ZmNRT2.1， ZmNRT2.2， and ZmNPF6.6 were significantly upregulated in leaves during daytime （AM 10：00）， whereas ZmNPF6.4 and ZmNPF6.6 were significantly downregulated in leaves during nighttime （PM 10：00）. These results indicate that alfalfa green manure effectively promotes maize plant growth， and increases the aboveground biomass of maize by affecting the absorption and transport of soil N by roots.

Lodging resistance and production performance of 18 autumn-sown forage oat varieties in northern Henan Province

Rui-juan SANG, Chao-jie CUI, Yun HE, Xiao-xia ZHANG, Jin YAO, Chun-yang DONG, Hao SUN, Ying-hua SHI, Xiao-yan ZHU, De-feng LI

2024, 33(8):  74-85.  DOI: 10.11686/cyxb2023362

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The aim of this study was to compare the lodging resistance and production performance of 18 autumn-sown forage oat （Avena sativa） varieties in northern Henan Province. A field study was conducted to determine the lodging incidence at different growth stages， hay yield， tillering characteristics， and winter survival of 18 oat varieties. Then， the relationships between lodging and plant height， ear height， and stem morphology were evaluated. The results showed that： 80% of oat varieties began to show lodging from the heading stage， and the lodging incidence ranged from 10% to 95% at the mid-milk maturity stage. Among the 18 varieties， ‘Baler’ and ‘Millionaire’ had the lowest lodging incidence. The lodging incidence was negatively correlated with stem morphological indexes including stem base diameter （1^st and 2^nd internode diameters） and 2^nd internode dry weight （P<0.05）. The 18 varieties were able to complete the entire growth and development process in the experimental area， and the growth period ranged from 182 to 207 days. Among the 18 varieties， the number of tillers at the greening stage， hay yield， plant height， and winter survival rate ranged from 5.3 to 8.5 per plant， 11.99 to 20.46 t·ha^-1， 1.11 to 1.52 m， and 83.7% to 96.6%， respectively. The hay yields of ‘Baler’， ‘Everleaf’， and ‘Forage Plus’ were significantly higher than those of other varieties， and the hay yield of these three varieties exceeded 20 t·ha^-1. Based on a multivariate evaluation of lodging resistance， hay yield， and nutritional quality， ‘Baler’， ‘Forage Plus’， and ‘Millionaire’ were identified as suitable varieties for autumn sowing in northern Henan Province.

Effects of a fermentation bed on the growth， digestion， and blood physiological and biochemical indices of suckling Hu lambs

Dong-yao SU, Yong-liang LI, Qing DONG, Xin-nian ZHAO, Xiao-yu LI, Xiao-dong JIN, Ya-nan WANG, Shu-jun TIAN, Yu-hong GAO, Xin-sheng SUN

2024, 33(8):  86-97.  DOI: 10.11686/cyxb2023303

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At present， there is a high incidence of diarrhea and death in suckling lambs in the sheep industry. During the suckling period， the lambs and ewes are usually kept in farm sheds with an exposed soil floor. In this study， the soil floor was reformed into a fermentation bed， to determine whether this affected the health of lambs during the early suckling period. The temperature of the fermentation bed， and the effect of the fermentation bed on diarrhea incidence， growth， digestion， blood physiological and biochemical parameters in lambs were investigated in different seasons （cold， warm， and hot season）. Three batches of Hu ewes （30 ewes·batch^-1） and their newborn twins were randomly assigned to two farm sheds with the same building structure. One farm shed had a fermentation bed （sawdust∶rice husk=7∶3） and the other （control） had a traditional soil floor， with each ewe and its own lambs kept in individual pens. At 7 days after parturition， all sheep were transferred to a semi-open farm shed with a soil floor and were continually fed until weaning at 60 days. The results were as follows： 1） The surface temperature of the fermentation bed was significantly higher （P<0.05） than that of the control soil floor in each season. In the cold season， compared with the temperature of the control soil floor， the temperature of the fermentation bed was 1.80 ℃ higher in the morning， 0.97 ℃ higher at noon， and 1.09 ℃ higher in the evening. 2） The diarrhea incidence in lambs during both the cold and warm seasons was lower in the treatment group （P<0.05） than in the control group （19.99% lower in the cold season and 28.09% lower in the warm season during the 60 days after birth）. Moreover， compared with lambs in the control group， those in the treatment group showed 15.04% higher average daily weight gain （ADG） during the cold season and 7.88% higher ADG during the warm season. However， there was no significant difference （P>0.05） in diarrhea incidence or ADG between the two groups in the hot season. 3） The apparent digestibility of dry matter， crude protein， crude fat， and calcium were increased （P<0.05） on weaning day when the fermentation bed was used within 7 days of birth in the cold season. 4） Analyses of blood physiological and chemical parameters showed that， in the cold season， serum glucose （GLU）， albumin， and globulin contents， and the percentage of lymphocytes in the whole blood of lambs were significantly higher （P<0.05） in the treatment group than in the control group. In the warm season， the GLU content was significantly higher （P<0.05） in the treatment group than in the control group. In the hot season， however， there were no significant differences （P>0.05） in blood indexes between the two groups. In summary， the use of the fermentation bed for the first week after birth effectively improved the growth and digestive performance of lambs in both the cold season and the warm season.

A multi-trait evaluation of cold resistance of 14 native Pennisetum alopecuroides germplasm lines at the seedling stage

Jiao-yun LU, Hong TIAN, Jun-bo XIONG, Xin-jiang WU, Yang LIU, He-shan ZHANG

2024, 33(8):  98-111.  DOI: 10.11686/cyxb2023433

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The aim of this study was to explore the effects of low temperature stress on the physiological characteristics of Pennisetum alopecuroides seedlings and to develop a multivariate evaluation of the cold resistance of different P. alopecuroides germplasm lines. Seedlings of 14 native P. alopecuroides germplasm lines were grown in peat soil in pots and subjected to low-temperature stress （25 °C as the control， and cold treatments at 4， 0， -5 °C）. Then， the contents of chlorophylls， carotenoids， malondialdehyde， and osmoregulatory substances were determined， as well as antioxidant enzyme activity. The cold resistance of the 14 materials was evaluated by principal component analysis and the membership function method. As the low temperature stress became more severe， the contents of chlorophylls， soluble sugars， and proline as well as catalase （CAT） activity in the test seedlings first increased and then decreased， the carotenoid content and superoxide dismutase （SOD） activity increased gradually， the soluble protein content first increased， then decreased， and then slightly increased， whereas peroxidase （POD） activity showed a different trend. There were significant positive correlations among the photosynthesis-related indexes. The results of principal component analysis showed that photosynthetic factors， plasma membrane system factors， and osmotic regulatory factors of P. alopecuroides under low temperature stress could be used as traits for multivariate evaluation of cold resistance. On the basis of the D values obtained using the membership function multivariate evaluation method， L₁₀ had strong cold resistance， while L₄， L₁， and L₂ had weak cold resistance. The results obtained by the membership function evaluation method are accurate， objective， and reliable. Therefore， this method can be used for the evaluation of cold resistance and for screening low temperature-tolerant germplasm resources of P. alopecuroides.

A broomrape seed germination recognition method based on convolutional neural networks

Qi-rong SHEN, Jun YAN, Xiao-xin YE, Yu-ying SANG, Qi-ling SHAN, Qi-teng ZHANG

2024, 33(8):  112-121.  DOI: 10.11686/cyxb2023358

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Broomrape （Orobanche spp.） is an exceedingly pernicious parasitic weed that is difficult to eradicate using conventional methods. Inducing “suicidal germination” in broomrape seeds through the application of germination stimulants is a crucial control method. However， the current method to evaluate broomrape seed germination based on human visual inspection using a microscope is time-consuming and produces inconsistent results. To address these issues， we propose a broomrape seed germination recognition algorithm based on convolutional neural networks. First， we cultivated broomrape seeds and collected images of germinated and ungerminated seeds under a microscope to construct a broomrape image library. Then， we developed a convolutional neural network， named OB-Net， to extract features from broomrape images and recognize seed germination. Through comparative analysis and optimization， we carefully selected the hyperparameters of the OB-Net model. Our experimental results demonstrated that the model achieved a recognition accuracy of 95.2%. Comparative analysis with existing mainstream network models confirmed that the proposed OB-Net model exhibited the highest accuracy and fastest detection speed in recognizing germinated broomrape seeds. The broomrape seed germination recognition method proposed in this study offers effective theoretical support for further research on other seeds and germination stimulants.

Effects of different exogenous substances on the seed germination， seedling growth， and physiology of Melilotus suaveolens under salt， alkali， and drought stress

Ting-ting ZHANG, Yu-le LIU, Hong CHEN, Ling-xin XU, Xiang-wei CHEN, En-heng WANG, Jun-xin YAN

2024, 33(8):  122-132.  DOI: 10.11686/cyxb2023369

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The aim of this study was to determine the best exogenous substance， and its optimal concentration， to promote the seed germination and seedling growth of Melilotus suaveolens under salt， alkali， and drought stress. Seeds of M. suaveolens were germinated in Petri dishes on filter paper with gibberellin （GA） and melatonin （MT） at various concentrations. The effects of these substances on the seed germination and seedling growth of M. suaveolens， as well its responses to 6-h salt， alkali， and drought stress treatments， were evaluated. The results showed that 200 mg·L^-1 GA was the best treatment to promote seed germination， and 50 μmol·L^-1 MT was the best treatment to improve the activities of superoxide dismutase （SOD）， peroxidase （POD）， and catalase （CAT） in seedlings under salt stress. Under alkali stress， the maximum hypocotyl length of seedlings was in the 200 μmol·L^-1 MT treatment. Under drought stress， the maximum germination rate and radicle length were in the 100 mg·L^-1 GA treatment. According to a multivariate evaluation using a membership function method， the best exogenous substance for alleviating salt stress was GA， and the optimal concentration was 200 mg·L^-1. The best exogenous substance for alleviating alkali stress and drought stress was MT， and the optimal concentration was 50 and 100 μmol·L^-1， respectively. In conclusion， MT and GA can promote the seed germination and seedling growth of M. suaveolens under salt， alkali， and drought stress. These findings provide reference data for improving the tolerance of M. suaveolens to salt， alkali， and drought stress.

Leaf structure and photosynthetic properties of alfalfa in response to bacteria and phosphorus addition

Ying-ying ZHANG, Dan-dan HU, Chun-hui MA, Qian-bing ZHANG

2024, 33(8):  133-144.  DOI: 10.11686/cyxb2023354

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In this study， we investigated the effects of bacteria-phosphorus interactions on the anatomical structure and photosynthetic properties of alfalfa （Medicago sativa） leaves， and explored the relationship between alfalfa leaf structure and photosynthetic parameters. A two-factor randomized block design was adopted， with single inoculation of Bacillus mucilaginosus （J₁）， Bacillus megaterium （J₂）， a mixture of both bacteria （J₃）， and no bacteria （J₀）， with phosphorus application （P₂O₅ at 100 mg·kg^-1） （P₁） or without phosphorus application （P₀）. The leaf photosynthetic indexes and anatomical structure indexes were measured， and the relationship between leaf photosynthetic characteristics and anatomical structure was clarified using regression analyses. It was found that under the same bacterial inoculation conditions， the leaf thickness， upper epidermal thickness， lower epidermal thickness， palisade parenchyma thickness （PPT）， spongy parenchyma thickness （SPT）， vessel diameter and diameter of sieve tubes， and the daily mean values of net photosynthetic rate （P_n）， transpiration rate （T_r）， stomatal conductance （G_s） of alfalfa leaves were higher in the P₁ treatment than in the P₀ treatment； the relative chlorophyll content （SPAD value） was significantly higher in the P₁ treatment than in the P₀ treatment （P<0.05）； and the daily mean values of intercellular CO₂ concentration （C_i） were lower in the P₁ treatment than in the P₀ treatment. Under the same phosphorus application conditions， the leaf thickness， upper epidermal thickness， lower epidermal thickness， PPT， SPT， vessel diameter and diameter of sieve tubes， and daily mean values of P_n， T_r， G_s， and SPAD of alfalfa leaves were higher in bacteria-inoculated treatments than in the uninoculated treatment， with maximum values in the J₃ treatment. The daily mean value of C_i was lower in bacteria-inoculated treatments than in the uninoculated treatment. Bacteria and phosphorus had highly significant effects on alfalfa leaf thickness， upper epidermal thickness， lower epidermal thickness， PPT， SPT， and vessel diameter （P<0.01）. Bacteria×phosphorus interactions were significant for alfalfa leaf thickness and palisade tissue thickness （P<0.05）. The daily mean values of P_n were significantly and positively correlated with leaf thickness， vessel diameter， sieve tubes diameter， PPT， and SPT （P<0.05）， and significantly negatively correlated with PPT∶SPT ratio （P<0.05）. In a multivariate evaluation based on the structural and photosynthetic properties of alfalfa leaves， the treatments were ranked， from most to least conducive to leaf development and photosynthesis， as follows： J₃P₁ > J₁P₁ > J₂P₁ > J₃P₀ > J₀P₁ > J₁P₀ > J₂P₀ > J₀P₀. Therefore， a phosphorus application rate of 100 mg·kg^-1 and double inoculation with B. mucilaginosus and B. megaterium was most conducive to the photosynthetic process of alfalfa leaves， with strong positive effects on growth and physiological development.

Identification of the oat sHSP gene family and its transcript profiles in response to high temperature and aging

Yuan MA, Huan LIU, Gui-qin ZHAO, Jing-long WANG, Ran ZHANG, Rui-rui YAO

2024, 33(8):  145-158.  DOI: 10.11686/cyxb2023346

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Small heat shock proteins （sHSPs） are a type of protein that is encoded by nuclear genes in plants. The sHSPs are ubiquitous in plants， contain conserved ACD domains， and play important roles in aging as well as in responses to stresses such as high temperature and drought. In this study， 24 HSP20 （AsHSP20.1-AsHSP20.24） genes were identified in the oat genome using bioinformatics methods. The physical and chemical properties， protein structure， subcellular localization， phylogeny， conserved motifs， and conserved domains of the putative AsHSP20 family members were determined， and the chromosomal locations of their encoding genes and gene transcription profiles in response to high temperature and aging were systematically analyzed. The AsHSP20 genes were distributed on 17 chromosomes. The genes encoded polypeptides consisting of 136-529 amino acids， with molecular weights ranging from 14.9 to 58.1 kDa， and theoretical isoelectric points ranging from 5.30 to 8.79. Most HSP20 members were predicted to localize in the nucleus， cytoplasm， or chloroplast， and a few were predicted to localize in the plasma membrane， mitochondria， peroxisome， or extracellular space. Protein secondary and tertiary structure analyses showed that AsHSP20 members have β-folded structures. Based on analyses of conserved motif composition and phylogenetic relationships， the AsHSP20 gene family was classified into 11 subgroups. The conserved motifs were similar or identical among the members of the same subgroup， indicative of functional similarity among proteins in the same subgroup. Further analysis of AsHSP20 transcript profiles in seeds showed that AsHSP20.20 and AsHSP20.24 were down-regulated under both natural and artificial aging conditions. It is speculated that AsHSP20.20 and AsHSP20.24 are involved in regulating the reduction in oat seed viability during aging， and are candidate genes related to oat seed longevity. These genes have potential applications in anti-aging germplasm breeding. The results of this study provide valuable information on the regulatory mechanism of the AsHSP20 gene family in the aging process of oat， and also provide theoretical support for further research on oat HSP20 genes and the molecular mechanism of delayed aging in oat seeds.

Functional analysis of the MaERF058 gene in response to drought stress in Melilotus albus

Na WEI, Wen-mao JING, Er-wen XU, Rong-xin WANG, Jing-zhong ZHAO, Xue-e MA, Ji-yu ZHANG, Wen-xian LIU

2024, 33(8):  159-169.  DOI: 10.11686/cyxb2023338

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Drought is one of the most common stresses in agricultural production. It has a deleterious effect on plant growth and many aspects of development， such as photosynthetic function， stomatal aperture， osmotic balance， and hormone regulation， thereby affecting crop yield and quality. Melilotusalbus is a high-quality forage legume that is widely grown in the northern arid regions of China because of its high protein content and tolerance to drought， salinity， and barren environments. Transcription factors （TFs） are important proteins that regulate gene expression. They bind to specific cis-elements in the promoter regions of their target genes to activate or repress their transcription， thereby regulating plant growth and development in response to abiotic stress. Genes in the plant ethylene response factor （ERF） TF family respond to various abiotic stresses， and are important components of plant stress resistance mechanisms. MaERF058 is a key drought tolerance gene in M.albus. In this study， we analyzed the subcellular localization of MaERF058 in tobacco （Nicotiana tabacum）， and found that the expressed protein was located in the nucleus. Overexpression of MaERF058 in Arabidopsisthaliana significantly increased its drought tolerance， compared with that of wild type. Compared with the wild type， the MaERF058-overexpressinglines showed significantly increased proline content （P<0.01） and catalase activity （P<0.05） and significantly decreased malondialdehyde content （P<0.01） under drought conditions. Monoamine oxidase staining using the nitroblue tetrazolium method showed that the reactive oxygen content in the roots was higher in the MaERF058-overexpressinglines than in the control. These results suggest that the TF encoded by MaERF058 in M. albus has a positive regulatory role in the drought stress response.

Diversity of seed-borne fungi on four Trifolium pratense cultivars

Rong-chun ZHENG, Zhi-biao NAN, Ting-yu DUAN

2024, 33(8):  170-180.  DOI: 10.11686/cyxb2023392

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Red clover （Trifolium pratense） is an important leguminous forage and green manure crop. However， seed-borne fungi severely affect the seed quality of red clover， and are among the major limiting factors for red clover production. In this study， four varieties of red clover were selected to investigate the species and diversity of seed-borne fungi using indoor isolation and high-throughput sequencing methods. A total of 26 species from 15 genera of seedborne fungi were identified from the four tested varieties， including 14 species from nine genera in T. pratense （cv. Minshan）， seven species from five genera in T. pratense （cv. Ruide）， nine species from nine genera in T. pratense （cv. VNS）， and 11 species from seven genera in T. pratense （cv. Honglong）. High-throughput sequencing of fungi from the seed samples of the four red clover varieties identified a total of 87 species from 30 genera， including Cladosporium， Alternaria， Penicillium， Aspergillus， Stemphylium， Sporobolomyces， Filobasidium， Udeniomyces， and other genera. Among them， several species of the genera Stemphylium， Alternaria， Cladosporium， Acremonium， Botrytis， Fusarium， and Erysiphe were identified as potential pathogens. Alpha and beta diversity analyses revealed significant differences in fungal community composition and abundance among the red clover varieties， with T. pratense （cv. Minshan） exhibiting higher diversity of seed-borne fungi compared with that of the other three red clover varieties.

Responses to temperature of population parameters of the pest mite Sancassania alfalfa fed on alfalfa

Wei LI, Han WANG, Chang-qing WANG, Yu-xin PAN, Jian-rong HOU, Wen-juan KANG, Su-qin SHANG, Shang-li SHI

2024, 33(8):  181-189.  DOI: 10.11686/cyxb2023347

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The occurrence of subterranean pests in alfalfa （Medicago sativa） fields has become one of the major constraints of alfalfa quality and yield. Sancassania alfalfa， which was identified and described based on its morphology and molecular markers， is a newly discovered pest mite that causes serious damage to alfalfa roots. The occurrence of this pest reduced the growth， yield， and quality of alfalfa at the Jiuquan alfalfa base in Gansu Province. To date， little is known about the population biology of this pest. To explore aspects of the population biology of this pest， its growth， development， and fecundity were determined under a range of temperatures in an artificial incubator. The insects were kept in the dark and supplied with dry yeast as feed， the relative humidity （RH） was maintained at （90±5） %， and the temperature was controlled at 15， 20， 25， 30， or 35 ℃. The results showed that the eggs did not hatch at 35 ℃， and only a few the mites survived to the larval stage at 15 ℃. In contrast， S. alfalfa successfully completed egg-to-adult development at temperatures of 20-30 ℃. The developmental period of immature stage female mites was 19.42， 16.98， and 9.91 days， and that of immature stage male mites was 18.50， 16.31， and 10.16 days at 20， 25， and 30 ℃， respectively. As the temperature increased， the lifespan of female and male mites became progressively shorter and differed significantly between 20 and 25 ℃ （P<0.05）. The duration of each developmental period shortened as the temperature increased， and the longevity of female mites was significantly greater than that of male mites at the same temperature （P<0.05）. The mean total spawning and daily spawning values were highest at 25 ℃ and differed significantly between 20 and 30 ℃ （P<0.05）. The highest net reproduction rate （R₀）， 233.3， was at 25 ℃. The mean generation time （T） was longest at 20 ℃ （26.24 days） and shortest at 30 ℃ （14.07 days）. The maximum innate rate of increase （r_m） was 0.329 at 30 ℃. These results provide basic data for indoor-reared S. alfalfa， and lay a foundation for devising strategies to control this important alfalfa pest mite.

Research progress on the hydraulic structure characteristics of xerophytes

Yan-xia PAN, Hao XU, Ya-feng ZHANG, Hong-xia ZHANG

2024, 33(8):  190-198.  DOI: 10.11686/cyxb2023367

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The survival of xerophytes is mainly dependent on water conditions. The responses and adaptation strategies of plants to drought stress and rehydration determine their growth and distribution characteristics. The hydraulic structure of plants is a complex hydraulic connection system that forms during plant growth. It reflects the water supply strategy formed in the Soil-Plant-Atmosphere Continuum （SPAC） circulation process of water uptake by roots， water transport via the xylem， and water lost by transpiration. It is the key internal factor determining the drought resistance of plants， and is also the focus of research on plant-water relationships. In this study， we reviewed recent research on the characteristics of plant hydraulic structure. The results of recent studies have revealed the coordination and trade-off mechanisms of plant hydraulic characteristics， and clarified the coupling relationship between hydraulic and economic traits. This review discusses the shortcomings in plant supply-demand hydraulics model simulations and the evaluation systems used to evaluate plant drought resistance and rehydration resilience. From the perspective of hydraulic structure， we discuss the existing problems in research on plant drought resistance and adaptation mechanisms， and propose key points for future research. Studies addressing these key problems will provide a theoretical basis and supporting data for vegetation restoration and reconstruction in arid conditions.

Allelopathic effects of different artificial economic forest litter extracts on Fabaceae and Poaceae species

Bang-yin HE, Jing-hong PEI, Qi-rui YE, Jia-jia HU, Cai-xue ZHENG, Jiang-wen LI

2024, 33(8):  199-208.  DOI: 10.11686/cyxb2023359

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Ziziphus jujuba， Juglans regia， and Malus pumila are dominant artificial economic forest tree species in northern Shaanxi， while they are usually planted as pure plantations. To explore the allelopathic effects of these artificial economic forests on the growth of forage species， Medicago sativa and Lolium perenne were used as receptors. These receptors were treated using Z. jujuba， J. regia and M. pumila leaf extracts with different concentrations to analyse their effects on seed germination and seedling growth of forage species. The results showed that：1） The germination rate and germination potential of M. sativa and L. perenne decreased significantly with the increase of the concentration of the leaching solution （P<0.05）； 2） Higher concentrations of M. pumila and Z. jujuba leaf litter extract led to lower root activity and chlorophyll content of M. sativa and L. perenne. The chlorophyll content of L. perenne seedlings treated with J. regia leaf extract was significantly higher than that of the control group， and the root activity was significantly lower than that of the control group （P<0.05）； 3） The biochemical indicators of two forage species indicated that the antioxidant capacity of L. perenne was significantly stronger than that of M. sativa. There were differences in the allelopathic responses of the seed germination and seedling growth of Fabaceae and Poaceae species to different tree species and different concentrations of leaf litter extracts. Overall， the allelopathic effects of artificial economic forest leaf litter extracts on M. sativa was stronger than those on L. perenne. This study aimed to provide a theoretical basis for the mixed planting of economic tree sand forage species in northern Shaanxi， and the combination of Fabaceae and Poaceae forage species and economic forests should be fully considered during the planting process.