Iron Toxicity Tolerance of Rice Genotypes in Relation to Growth,Yield and Physiochemical Characters

Iron(Fe)toxicity,generated from excess reduced ferrous Fe(Fe^(2+))ion formation within the soil under submerged condition,is a potent environmental stress that limits lowland rice production.Total 11 diverse Thai rice genotypes,including a recognized tolerant genotype Azucena and a susceptible genotype IR64,were evaluated against 5 Fe^(2+)levels[0(control),150,300,600 and 900 mg/L]to screen the tested genotypes for their Fe-toxicity tolerance and to classify them as a sensitive/tolerant category.The evaluation was conducted by a germination study,followed by a polyhouse study on growth,yield and physiochemical performances.Results showed significant variations in Fe^(2+)-tolerance across genotypes.Increasing Fe^(2+)level beyond 300 mg/L was detrimental for germination and growth of all the tested genotypes,although germination responses were negatively affected at Fe^(2+)≥300 mg/L.Physiochemical responses in the form of leaf greenness,net photosynthetic rate,membrane stability index and Fe contents in leaf and root were the most representative of Fe^(2+)-toxicity-mediated impairments on overall growth and yield.Difference in physiochemical responses was effectively correlated with the contrasting ability of the genotypes on lowering excess Fe^(2+)in tissues.Analysis of average tolerance and stress tolerance index unveiled that the genotypes RD85 and RD31 were the closest to the tolerant check Azucena and the sensitive check IR64,respectively.The unweighted pair group method with arithmetic means clustering revealed three major clusters,with cluster Ⅱ(four genotypes)being Fe^(2+)tolerant and cluster Ⅰ(four genotypes)being Fe^(2+)sensitive.Principal component(PC)analysis and genotype by trait-biplot analysis showed that the first two components explained 90.5%of the total variation,with PC1 accounting for 56.6%and PC2 for 33.9%of the total variation.The identified tolerant rice genotypes show potentials for cultivation in Fe^(2+)-toxic lowlands for increased productivity.The findings contribute to the present understanding on Fe^(2+)-toxicity response and provide a basis for future genotype selection or rice crop improvement programs against Fe^(2+)-toxicity.

Selection of Cowpea [(Vigna unguiculata (L.) WALP] Genotypes for Drought Tolerance Using Selection Indices

Cowpea [(Vigna unguiculata (L.)] is one of the most important arid legumes cultivated for pulse and forage production. However, in cowpea, not much is known about the base index selection method in breeding for drought tolerance. Consequently, the present study has been conducted to: 1) evaluate the yield performance of cowpea genotypes under artificial drought and well-watered condition;2) develop a base index using multiple traits for ranking genotype performance. The experiment was a 25 × 2 factorial laid out in a Randomized Complete Block Design (RCBD) with three replications. The experiment was carried out in the screen house at the Department of Horticulture at KNUST. The result showed that KPR1-96-73, Simbo, CZ06-4-16, Wilibaly and Agyenkwa were high yielding in well-water condition while Ghana Shoba, Sangaraka, NKetewade, Ghana-Shoni and Korobalen were high yielding genotypes in water stress condition. The average yield reduction was 60.6% for grain respectively. The biplot displays revealed four groups among the genotypes tested which was based on their yielding capacity and drought tolerance. In cluster B high yielding and drought tolerant genotypes were identified, high yielding and drought susceptible have been identified in cluster A, low yielding and drought tolerant in cluster D, and lastly low yielding and drought susceptible in cluster C. Genotypes in cluster B, were the best due to the fact that it combines high yield and tolerance to drought. They were Ghana Shoni, Nketewade, Sangaraka and Ghana shoba. These genotypes might be suitably employed in further drought tolerance breeding program of cowpea.

Research Progress of Heat-tolerance of Brassica campestris ssp. Chinensis

Brassica campestris ssp. chinensis, also known as non-heading Chinese cabbage, is an important vegetable widely distributed in southern China. High temperature is the most common adversity factor in vegetable production, because Brassica campestris ssp. chinensis is a thermophilic vegetable, which can＇t well grow at high temperature. In summer and autumn, high temperature stress would prevent Brassica campestris ssp. chinensis from growing and result in poor quality of its seedlings, seriously influencing yield and quality of the vegetable in later period. In this paper, present situation and latest advances in heat resistance research of Brassica campestris ssp. chinensis in recent years were reviewed at home and abroad. The research tendency in Bassica campestris ssp. chinensis was also described, providing reference for breeding of heat-resistant Brassica campestris ssp. chinensis.

Evaluation on Chinese Bread Wheat Landraces for Low pH and Aluminum Tolerance Using Hydroponic Screening

Aluminum （Al） toxicity often takes place in acidic soils with a pH of 5.5 or lower. Breeding and cultivation of Al tolerance wheat can partially protect wheat escaping from Al toxicity. The scarcity of the tolerant sources impedes the wheat breeding. In order to find new Al tolerance sources, we screened 173 bread wheat landraces from Tibet of China using hydroponic screening. It was indicated that： （1） There were diversities on the root regenerate length （RRL）. The RRL of a large of landraces were longer than 7.00 cm in pH 7 （58.38%） and pH 4.5 （66.47%）, but shorter than 5.00 cm in pH 4.5 ＋50μM Al^3＋ （80.93%）. The low pH showed either promotion or restraining effects depend on landraces, but Al toxicity under low pH only showed restraining effects on the root elongation. （2） There were also diversities on root tolerance index of low pH （RTI 1） or root aluminum tolerance index （RTI2） among cultivars. The RTI1 varied from a narrow range but with relatively high value （0.8722-1.2953） in comparison with that of RTI2 （0.3829-1.0058）, and the RTI1 of approximately 60% landraces was higher than 1.0000, the RTI2 of only 19.07% landraces was higher than 0.7000, suggesting that Al toxicity acted as an important factor for the reduction of the root elongation under acidic soils. （3） The RTI 1 of many wheats was higher than 1.0000, and As2256 and As2295 were the most tolerant for low pH, with RTI1 1.2953 and 1.2925, respectively. （4） Based on RTI2, seven wheats showed similar or higher tolerance to Al toxicity than Chinese Spring （CS）, a known tolerance wheat. Much better tolerance existed in landraces of As1543 and As1242, which can be used as the new parents for Al tolerant breeding.

Antibiotic Resistance and Heavy Metals Tolerance in Gram-Negative Bacteria from Diseased American Bullfrog (Rana catesbeiana) Cultured in Malaysia

A total of 140 bacterial isolates have been successfully isolated from various organs of diseased American bullfrog （Rana catesbeiana） cultured in Malaysia. The most frequently isolated bacteria was Edwardsiella spp. （46 isolates） followed by Aeromonas spp. （33 isolates）, Flavobacterium spp. （31 isolates）, and Vibrio spp. （30 isolates）. Majority of the bacterial isolates were found sensitive to furazolidone （85.0%）, chloramphenicol （85.0%）, oxolinic acid （90.0%）, florfenicol （95.0%）, and flumequine （97.5%）. On the other hand, most of the bacterial isolates were resistant to oleandomycin （77.5%） and lincomycin （87.5%）. Nitrofurantoin and flumequine can be inhibited the growth of all of Vibrio spp. whereas all isolates of Edwardsiella spp. were found sensitive to florfenicol and flumequine. Multiple antibiotic resistance （MAR） index were in range of 0.30-0.40, indicating that bacterial isolates from cultured bullfrogs may have received high risk exposure to the tested antibiotics. In addition, 90-100% of the isolates were resistant to copper, cadmium, and chromium. These results provided insight information on tolerance level of bacterial isolates from cultured bullfrogs to 21 antibiotics as well as heavy metals.

Selection of Maize Genotypes with Tolerance to Osmotic Stress Associated with Salinity

Thirteen different inbred lines in relation to the type of grain and life cycles were characterized by testing for osmotic stress associated with salinity. The identification of tolerant genotypes would be an effective strategy to overcome the saline stress. Osmotic stress reduces immediately the expansion of the roots and young leaves which determine a reduction in the size of the plant. A completely randomized design was adopted to test seedlings under controlled conditions of light and temperature. Two treatments were used: 0 mM NaCl (as control) and 100 mM NaCl. After 15 days of complete salinization, the seedlings were harvested and several morphological traits were measured. The morphological traits of growth were leaf growth (Ar1, Ar2, Ar3 and Ar4), dry masses of shoot and root (SDM and RDM, respectively). Also, traits associated with water economy were registered: leaf water loss (LWL) and relative water content (RWC). The morphological traits were expressed in relative terms, while the traits associated with the economy of water were expressed in absolute terms. Uni and multivariate techniques were applied to identify genotypes with divergent behaviors to osmotic stress tolerance. Also, a Tolerance Index was employed to identify superior genotypes. Four clusters were obtained after applying a Cluster Analysis and Principal Component Analysis (PCA). The genotypes were compared to each other with a test of DMS. The results obtained with different statistical techniques converged. Some variables presented a differential weight classification of genotypes. The morphological traits like RDM, SDM, Ar3, Ar4 and Ar5 were the most discriminating. Tolerance Index allowed to classify genotypes, thus SC2 and AD3 lines were that reached highest value of the index and therefore would be tolerant lines, while AF3 and LP3 had a low index and were seen as sensible.

Cold tolerance of Acacia karroo and A.nilotica,two tree species from South Africa,in Beijing

Fynbos plant communities developed under geographic and climatic conditions unique to South Africa. Acacia karroo is the most widespread tree species, well known for its drought tolerance. A. nilotica exudes a good quality gum which is edible and suitable for confectionery. The two species have been introduced to China but little is known about their adaptability under the new environmental conditions. For our present study, the growth potential and physiological and biochemical parameters of the two spe- cies in response to cold stress were investigated. The results, measured as seed qualities （purity, thousand seed weights, germination, etc.） show differences between A. karroo and A. nilotica. The seed germination rate was between 10% and 60%. Seedlings were es- tablished in fields, pots and plugs. Those in the field grew well during the growing season but completely died in the winter. Those in pots or plugs were moved to and managed in the greenhouse. The plants were green in winter. The electrical conductivity of cells, the contents of water soluble sugars, proteins, malondialdehyde （MDA） increased during eight hours of low temperature treatment at 4℃ The activities of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） decreased markedly during the eight hours of 4℃ treatment. We conclude that A. karroo and A. nilotica have little adaptability to the cold winter weather and cannot survive in the outdoors in the Beijing area, but could grow well indoors as ornamentals.

Predictive models of drought tolerance indices based on physiological,morphological and biochemical markers for the selection of cotton(Gossypium hirsutum L.)varieties

The use of tolerant crop varieties is a strategy that mitigates the water deficit effect in a sustainable way.The generation of these varieties is more efficient when variables associated with this tolerance have been identified,since they can facilitate the breeding processes.This study aimed to establish the relationships between water deficit tolerance of four cotton varieties(Nevada-123,Oasis-129,Guatapuri,and Festivalle)and morphological variables(monopodial branches,boll weight,root/shoot ratio,and leaf and root dry matter),physiological variables(relative water content,net photosynthesis,stomatal conductance,electron transport rate,photochemical quenching,photochemical efficiency of PSII,chlorophyll a/b ratio(Chl a/b),C^(12)/C^(13)isotope ratio,and electrolyte leakage),and biochemical variables(contents of sugars,proline,carotenoids,and malondialdehyde).Furthermore,calibrated predictive models of the drought tolerance indices were developed based on the key variables identified.For this purpose,a pot experiment was established where plants were subjected to a moderate or severe water deficit during the blooming stage for 12 days.The stress tolerance index(STI)and mean productivity(MP)were calculated.For the evaluated variables,the differences between well-watered and water deficit plants(Δ)were calculated and ANOVA,partial least squares,Pearson’s correlation,and multiple linear regression analyzes were performed.A model was generated that explained 95% of the STI and was composed of Δmalondialdehyde,Δproline,and Δboll weight.For MP,the model was comprised of Δstomatal conductance,Δroot/shoot ratio,and ΔChl a/b,and explained 89% of the MP.The analysis of the assessed variables allowed the identification of key variables and the development of calibrated predictive models that can be used in screening to obtain cotton varieties with different levels of water deficit tolerance.

Drought Tolerance Identification and Eevluation of Maize during Flowering Stage in Guangxi

Total 20 maize varieties were subjected to drought stress at flowering stage,and then the relative water content,soluble sugar content,chlorophyll content,malondialdehyde( MDA) content and superoxide dismutase( SOD) activity in their leaves,as well as their yields were determined. The drought tolerance of the physiological and biochemical indexes was scored by five-level scoring method,and the drought tolerance index was calculated by the yield index to comprehensively evaluate the drought tolerance of maize during flowering stage. The results showed that the scores of drought tolerance of the maize varieties ranged from 1. 929 3 to 5. 659 5. Among them,the scores of Zhengda 619,Guidan 162 and Guidan 0810 were greater than 5. 0,followed by Dika 008,Xianyu 30 T60,Xianzhengda 901,Qingnong 68,South America No. 1 and Wanchuan 1306 of which the scores were in the range of 4. 0-5. 0. The drought tolerance indexes were in the range of 0. 410 4-1. 096 3. Among the test maize varieties,the drought tolerance indexes of Guidan 0810,Pacific 99 and Zhengda 619 were greater than 1. 0,and those of Xianyu 30 T60,Dika 008 and South America No. 1 were in the range of 0. 9-1. 0. The correlation between the two kinds of evaluation results was 0. 588 7 and was extremely significant. The five-level scoring method and the drought tolerance index can be used simultaneously for the evaluation of drought tolerance of maize during flowering stage. The two aspects of evaluation results showed that Guidan 0810,Zhengda 619,Xianyu 30 T60,Dika 008 and South America No. 1 were drought-tolerant varieties,among which Guidan 0810 and Zhengda 619 were extremely highly drought-tolerant varieties.

Switchgrass (Panicum virgatum L.) Intraspecific Variation and Thermotolerance Classification Using in Vitro Seed Germination Assay

Cardinal temperatures for plant processes have been used for thermotolerance screening of geNotypes, geoclimatic adaptability determination and pheNological prediction. Current simulation models for switchgrass (Panicum virga-tum L.) utilize single cardinal temperatures across geNotypes for both vegetative and reproductive processes although intra-specific variation exists among geNotypes. An experiment was conducted to estimate the cardinal temperatures for seed germination of 14 diverse switchgrass geNotypes and to classify geNotypes for temperature tolerance. Strati-fied seeds of each geNotype were germinated at eight constant temperatures from 10oC to 45oC under a constant light intensity of 35 μmol m-2 s-1 for 12 h d-1. Germination was recorded at 6-h intervals in all treatments. Maximum seed germination (MSG) and germination rate (GR), estimated by fitting Sigmoidal function to germination-time series data, varied among geNotypes. Quadratic and bilinear models best described the MSG and GR responses to temperature, respectively. The mean cardinal temperatures, Tmin, Topt and Tmax, were 8.1, 26.6, and 45.1oC for MSG and 11.1, 33.1, and 46.0oC for GR, respectively. Cardinal temperatures for MSG and GR;however, varied significantly among geNotypes. GeNotypes were classified as sensitive (‘Cave-in-rock’, ‘Dacotah’, ‘Expresso’, ‘Forestburg’, ‘Kanlow’, ‘Sunburst’, ‘Trailblazer’, and ‘Warrior’), intermediate (‘Alamo’, ‘Blackwell’, ‘Carthage’, ‘Shawnee’, and ‘Shelter’) and tolerant (‘Summer’) to high temperature based on cumulative temperature response index (CTRI) estimated by summing individual response indices estimated from the MSG and GR cardinal temperatures. Similarly, geNotypes were also classified as sensitive (Alamo, Blackwell, Carthage, Dacotah, Shawnee, Shelter, and Summer), moderately sensitive (Cave-in-rock, Forestburg, Kanlow, Sunburst, and Warrior), moderately tolerant (Trailblazer), and tolerant (Expresso) to low temperatures. The cardinal temperature estimates would be useful to improve switchgrass models for field applications. Additionally, the identified cold- and heat-tolerant geNotypes can be selected for niche environments and in switchgrass breeding programs to develop new geNotypes for low and high temperature environments.

Physiological Response to High Temperature and Evaluation of Heat Tolerance of Different Grape Cultivars

[Objectives]This study was conducted to investigate the differences in the physiological responses of different grape cultivars to high temperature.[Methods]The 19 tested cultivars were selected from the grape germplasm resources pool of Turpan Research Institute of Xinjiang Academy of Agricultural Sciences.Twelve physiological indexes including gas exchange parameters,chlorophyll content,antioxidant enzyme activity and proline content were determined in grape leaves under field conditions during the middle period of local natural high temperature period(July,daily maximum air temperature>35℃).The heat tolerance of different cultivars was evaluated by fuzzy membership function analysis and optimum partitioning clustering of ordered samples.[Results](1)Under natural high temperature conditions in Turpan,the 19 tested grape cultivars responded differently to high temperature.‘Red Globe’,‘Fujiminori’,‘Beta’,‘Hetianhuang’had strong heat tolerance,while‘Thompson Seedless’,‘Hongqi Tezaomeigui’,‘Shuijing Wuhe’,‘Victoria’,‘Yatomi Rosa’and‘Crimson Seedless’had weak heat tolerance.(2)Among the 12 physiological indexes,malondialdehyde content and antioxidant enzyme activity were mostly different among various grape cultivars.The grape cultivars with strong heat tolerance,‘Red Globe’and‘Fujiminori’,had relatively lower malondialdehyde contents,while‘Beta’and‘Hetianhuang’had relatively higher malondialdehyde contents.But they had higher activity of antioxidant enzymes.(3)The results of fuzzy membership function analysis showed that the cumulative membership value(AR)of each physiological index was consistent with its apparent heat tolerance performance,suggesting that AR can be a potential index for the evaluation of heat tolerance of grape cultivars.Further cluster analysis classified the tested cultivars as strong,medium and weak.‘Red Globe’,‘Fujiminori’,‘Beta’and‘Hetianhuang’had strong heat tolerance.[Conclusions]This study provides a reference for grape cultivation under high temperature and stress and breeding of heat-tolerant varieties.

Study on Cold Tolerance Identification Indices for Bitter Gourd Germplasms

The selection of cold tolerance identification indices for bitter gourd germplasms is an important basis for the breeding of cold-tolerant bitter gourd varieties. In this study, with six bitter gourd germplasms as experimental materials, the cold injury index of bitter gourd was analyzed under low temperature treatment, the changes in physiological indices were revealed, and the main agronomic traits were measured. The results showed that the cold injury index of bitter gourd was in very significant negative correlation with SOD activity, POD activity and PRO content, in significant negative correlation with CAT activity, in very significant negative correlation with flowering node and commodity rate, but in significant positive correlation with female flower ratio. It was found that that cold injury index, SOD activity, POD activity, CAT activity and PRO content could serve as the cold tolerance identification indices for bitter gourd at seedling stage, and flowering node and commodity rate could be used as the auxiliary indices for field cold tolerance identification.

基于密度划分的分布式数据容错存储算法研究

为保证数据安全性,缓解数据存储空间,提出基于密度划分的分布式数据容错存储算法。过滤分布式数据高密度数据区域,将具有高度相似的目标划分到不同区域,通过数据来源样本点描述数据的密度分布,设定数据弹性,利用概率以及数据粒度推算出对应的存储梯度和强度指数,并在信息存储中引入数据存储梯度和数据弹性,完成分布式数据容错存储。实验证明,所提算法有较高的容错性,带宽吞吐量平稳,平均路径长度较小,能提高网络数据的安全性。

高产乳酸耐热克鲁维酵母的筛选及其在葡萄酒中增酸潜力研究

通过比较16株耐热克鲁维酵母(Lachancea thermotolerans)的产乳酸能力及耐受性,筛选高产乳酸的优良菌株,并将其与商业酿酒酵母(Saccharomyces cerevisiae)EC1118按1∶1配比共发酵制备霞多丽葡萄酒,评估其酿造特性。结果表明,耐热克鲁维酵母菌株LT-XJ24、LT-XJ59、LT-ZX03与LT-GS27的耐受性较好,且产乳酸能力较强,在葡萄汁中的乳酸产量分别为6.41 g/L、6.52 g/L、7.89 g/L和6.21 g/L。优选的4株耐热克鲁维酵母与商业酿酒酵母共发酵均能完成霞多丽葡萄酒的酒精发酵,且均具有良好的生物增酸能力,其中菌株LT-ZX03混合发酵的霞多丽葡萄酒中的乳酸产量最高,达6.66 g/L。尽管混合发酵组提高了葡萄酒的挥发酸含量,但仍然符合相关标准要求(≤1.2 g/L)。从霞多丽葡萄酒样品中共检出41种香气物质,包括23种酯类、11种醇类、5种酸类以及2种其他类化合物,其中13种物质的香气活度值(OAV)>1。不同耐热克鲁维酵母对霞多丽葡萄酒中挥发性香气物质的影响存在差异,其中菌株LT-GS27和LT-ZX03影响较大,能够提高葡萄酒中具有花果香气的丁酸乙酯、己酸乙酯、辛酸乙酯和癸酸乙酯等物质含量。

不同木豆幼苗低温胁迫下的生理响应及耐寒性鉴定

木豆[Cajanus cajan (L.) Millsp.]为热区重要的粮饲兼用作物。为解析木豆响应低温胁迫生理特性及耐寒能力,本研究以8份木豆种质幼苗为试验材料,通过低温胁迫(4℃)处理,对木豆8个生理指标测定分析,运用隶属函数综合分析法鉴定其耐寒性。结果表明:随低温胁迫时间的延长,木豆相对电导率(REC)和可溶性糖(SS)、丙二醛(MDA)、脯氨酸(Pro)的含量呈升高趋势,超氧化物气化酶(SOD)、过氧化物酶(POD)活性随低温处理时间的延长呈先升后降之势,叶绿素(Chl)含量总体呈下降趋,过氧化氢酶(CAT)活性变化存在差异,仅P_(2)中CAT活性差异显著。运用隶属函数综合评价木豆耐寒性强弱为:缅甸木豆>海南儋州木豆>木豆(170306001)>木豆(060302216)>ICPL7086>木豆(南02137)>广西木豆>海南琼中木豆,且木豆耐寒性与Chl含量、SOD和POD活性呈显著相关,这些指标可以作为木豆耐寒性评价的可信指标。

甘蓝型油菜耐密性综合评价及其鉴定指标筛选

以从江西省油菜主产区收集到的109个甘蓝型油菜品种(系)为材料,分析了不同密度条件下根茎粗、株高、角果层厚度、分枝数、主花序长、主花序角果数、结角密度、单株角果数、角果粒数、千粒重、角粒重、单位角果皮面积、单株生物量、经济系数、产量等性状的基因型差异,以各性状的耐密系数作为衡量耐密性的指标,利用主成分分析、隶属函数、聚类分析和逐步回归分析法,对不同基因型油菜进行了耐密性综合评价。结果表明,不同基因型油菜品种(系)各性状对密度的反应不同,基因型间差异显著。利用主成分分析法将15个单项指标综合成7个相互独立的综合指标,可代表油菜耐密性86.62%的原始数据信息量。通过隶属函数法得到了各品种的耐密性综合评价值(D),并对D值进行聚类分析,将109个油菜品种划分为4种耐密类型。通过建立耐密性评价的数学模型进行了耐密性预测,筛选出角果层厚度、主花序角果数、角果粒数、单位角果皮面积、经济系数、产量等6个对耐密性有显著影响的指标,可作为油菜耐密性的鉴定指标。

长江中下游地区糯玉米花期耐热性鉴定及评价指标筛选

全球气候变暖趋势日趋明显,高温热害已成为限制糯玉米丰产稳产的主要非生物胁迫之一。鉴定糯玉米的耐热性,筛选耐高温评价指标,可为耐热糯玉米品种的选育提供理论支撑。本研究以长江中下游地区主推品种为试验材料,设置2种增温方式(覆膜增温处理和延迟播种处理)以及自然对照处理(CK),测定了13个与耐热相关的指标,采用主成分分析、隶属函数法、聚类分析和逐步回归分析相结合的方法,对糯玉米花期耐热性进行综合评价。结果显示,与对照相比,除叶绿素a和光系统II最大光化学效率外,各指标在高温处理下的降低幅度均达到显著或极显著水平。利用主成分分析将13个单项指标转换为3个相互独立的综合指标,其贡献率分别为64.46%、15.06%和7.76%,代表了糯玉米耐热性87.28%的原始数据信息量;通过隶属函数计算综合耐热评价值(D值),将10个参试糯玉米品种划分为3类,分别为3个耐热型、4个中等耐热型和3个热敏感型。筛选出的耐热型品种为苏玉糯2号、中糯2号和苏玉糯901,生产中应用这些品种可能在一定程度上减轻高温热害对糯玉米生长发育造成的不利影响。最后,利用逐步回归分析建立了糯玉米耐热性评价方程预测供试材料的耐热性,预测值(PV)与D值基本一致,确定了产量、F_v/F_m、叶面积指数和花粉活力作为糯玉米花期耐热性评价指标。本研究筛选出的耐热品种和鉴定指标可为今后耐热糯玉米品种的选育提供理论依据。

不同油麦菜品种萌发期耐热指标筛选及耐热性评价

为筛选油麦菜萌发期耐热性的鉴定指标,初步构建耐热性评价体系,为生产上快速筛选耐热的油麦菜品种及提高耐热油麦菜育种效率提供依据,本研究以15个油麦菜品种为试材,以筛选出的35℃高温胁迫条件为基础,通过设置正常和35℃高温2个处理,测定不同油麦菜品种萌发期的7个形态指标,并计算耐热系数;以各指标的耐热系数为基础,利用相关性分析、主成分分析、隶属函数分析、逐步回归分析、聚类分析等方法对各参试油麦菜品种萌发期的耐热性进行综合评价并对耐热指标进行筛选,并结合各参试油麦菜品种田间耐热性对萌发期的耐热性鉴定结果进行验证。结果表明,35℃高温处理后,不同品种的发芽率、发芽势、发芽指数、活力指数、芽根比、芽粗及鲜质量等均显著下降。对这7个单项指标进行多元统计综合评价及相关性分析发现,除芽根比外,其余单项指标耐热性系数之间存在极显著正相关。主成分分析从这7个指标提取出2个相互独立的主成分,可概括参试油麦菜品种萌发期耐热性原始信息量的90.70%。通过隶属函数分析得出耐热性综合评价值(D值),并进行排序得出‘脆香油麦菜’耐热性最强、‘圣美紫油麦菜’耐热性最差。通过聚类分析将15个参试品种分为耐热型、中等耐热型、不耐热型3类,综合主成分分析和逐步回归分析的结果得出,发芽率、芽根比、活力指数为油麦菜萌发期耐热性鉴定重要指标。各参试品种萌发期耐热性鉴定结果与田间成株期鉴定结果基本一致。

N-酰基高丝氨酸内酯酶在肉鸡中应用的耐受性评价

本试验依据《饲料和饲料添加剂畜禽靶动物耐受性评价试验指南(试行)》对N-酰基高丝氨酸内酯酶(AHLase)在肉鸡中的应用进行耐受性评价。采用双因素试验设计,选取健康、体重接近的1日龄科宝肉仔鸡360只,随机分为3组,每组6个重复,每个重复20只鸡,公母各占1/2且分笼饲养。对照组饲喂基础饲粮,试验组在基础饲粮中分别添加500(AHLase-500)和5000 mg/kg(AHLase-5000)的AHLase。试验期42 d。结果表明:1)与对照组相比,AHLase-5000组公鸡1~21日龄的平均日采食量显著提高(P<0.05),22~42日龄以及1~42日龄的料重比显著降低(P<0.05);AHLase-5000组母鸡22~42日龄末重显著提高(P<0.05),而AHLase-500、AHLase-5000组1~42日龄母鸡的平均日采食量显著降低(P<0.05)。2)试验期内公鸡的平均日增重、平均日采食量显著高于母鸡(P<0.05)。1~21日龄公鸡的料重比有高于母鸡的趋势(P=0.075)。性别对1~21日龄肉鸡末重表现出趋于显著的影响(P=0.079)。3)随着AHLase添加水平的增加,1~21日龄肉鸡的平均日采食量显著提高(P<0.05),平均日增重有提高的趋势(P=0.052),而料重比显著降低(P<0.05);22~42日龄肉鸡的末重显著提高(P<0.05)。4)AHLase添加水平和性别在1~21日龄平均日采食量、22~42日龄平均日采食量以及1~42日龄料重比中均表现出显著互作效应(P<0.05);在22~42日龄料重比(P=0.069)以及1~42日龄平均日增重(P=0.064)中表现出互作趋势。5)饲粮中添加AHLase对肉鸡血常规和血清生化指标无显著影响(P>0.05)。6)饲粮中添加AHLase对肉鸡器官指数无显著影响(P>0.05),组织未观察到形态结构变化。由此可见,饲粮中添加5000 mg/kg的AHLase改善了肉鸡生长性能,对血液生理生化指标和内脏器官发育无显著影响,表明肉鸡对AHLase的耐受剂量在5000 mg/kg以上。

二甲酸钾在肉鸡应用中的耐受性评价

本试验旨在根据《饲料原料和饲料添加剂畜禽靶动物耐受性评价试验指南(试行)》,评价肉鸡对二甲酸钾(KDF)的耐受性。试验选取360只1日龄爱拔益加(AA)肉鸡,随机分为3组,每组6个重复,每个重复20只鸡,公母各占1/2且分笼饲养。对照组饲喂基础饲粮,试验组在基础饲粮中分别添加4和40 g/kg的二甲酸钾。试验期42 d。结果表明:1)与4 g/kg二甲酸钾组相比,40 g/kg二甲酸钾组肉鸡的平均日增重显著降低(P<0.05),料重比显著提高(P<0.05);40 g/kg二甲酸钾组公鸡平均日采食量显著低于4 g/kg二甲酸钾组(P<0.05)。2)与对照组相比,饲粮中添加40 g/kg二甲酸钾显著提高了21日龄公鸡血液中红细胞数量(P<0.05),并降低母鸡血液中间细胞比例(P<0.05)。42日龄时,与对照组相比,饲粮中添加40 g/kg二甲酸钾显著降低公鸡的血小板压积(P<0.05);添加4和40 g/kg二甲酸钾显著降低母鸡血小板数量和血小板压积(P<0.05)。3)与对照组相比,饲粮中添加40 g/kg二甲酸钾显著提高了21日龄公鸡血清尿素含量(P<0.05),显著降低血清尿酸含量(P<0.05)。4)与对照组相比,饲粮中添加二甲酸钾对肉鸡器官指数无显著影响(P>0.05),且组织未出现病理变化。综上所述,饲粮中添加40 g/kg二甲酸钾虽然提高机体对蛋白质的代谢,未对器官发育造成影响,但显著降低了肉鸡的生长性能,证实肉鸡对二甲酸钾的耐受性在40 g/kg以下。