低钾胁迫对不同耐性大豆品种干物质积累、转移与分配的影响

选用典型低钾耐性品种和低钾敏感品种进行盆栽试验,设置不同施钾处理,在大豆苗期、分枝期、开花期、结荚期、鼓粒期、成熟期测定根、茎、叶和荚的干质量,应用Logistic方程模拟地上部分干物质积累特征,调查花后光合产物的转移,研究不同低钾耐性大豆干物质在不同器官的积累与分配。研究结果表明,低钾胁迫下降低了平均积累速率和最大积累速率,但耐性品种速率降低少;低钾胁迫降低了花期之后干物质的积累,低钾敏感品种降低更多,并具有较低的干物质转移效率;低钾胁迫下,耐性品种在营养生长阶段将更多干物质集中于叶,生殖生长阶段集中于荚,敏感性品种营养生殖阶段将较多干物质集中于根系,后期根系、叶片干质量/植株干质量显著下降,叶片和根系出现明显早衰,提前丧失功能导致产量明显下降。

酸铝对大麦不同耐性品种形态、生长及元素吸收的影响

通过对耐酸铝性不同的两个大麦品种 (嵊县无芒六棱、浙皮二号 )进行耐酸铝性鉴定表明 ,两品种的苗高、根长及干重受到的影响均存在显著性差异 (P <0 .0 1) .经酸铝培养液处理后 ,敏感品种“嵊县无芒六棱”体内铝元素含量显著增加 (P <0 .0 1) ,而营养元素 (P ,Ca ,K ,Na ,Fe等 )

水稻耐不良土壤因子胁迫品种改良的现状和展望

根据土壤因子是毒害还是缺乏为主 ,可以将水稻生长的不良土壤环境分为两大类。不良土壤类型不同 ,其主要障碍因子存在明显差异 ,改造和利用不良土壤环境的策略也大相径庭。从培育耐不良土壤因子胁迫品种 ,挖掘不良土壤环境的生产潜力考虑 ,育种目标不同 ,育种程序、筛选方法和评价标准有显著差异。从筛选评价技术、育种方法、遗传变异等方面对水稻耐不良土壤因子胁迫品种改良的现状作了评述 ,并对今后的研究趋势作出展望。

潜育化稻田品种耐潜性差异与栽培技术研究

于2012年选取潜育化典型田块为试验田,研究了部分适合于长江中下游地区种植的早晚稻的耐潜性。结果表明,耐潜型的早稻品种为湘早籼45和金优458,敏感型的早稻品种为中嘉早17和湘早籼3号;耐潜型的晚稻品种为湘晚籼13,敏感型的晚稻品种为黄华占和天优华占。通过翻耕及垄畦栽培的方式可提高潜育化稻田水稻品种的有效穗数和每穗粒数,进而提高产量。

Analysis and Evaluation Indicator Selection of Chilling Tolerance of Different Cotton Genotypes

[Objectivc] This study aimed to investigate the chilling tolerance of seedlings of different cotton genotypes and screen appropriate indicators for assess- ing chilling tolerance, to establish reliable mathematical evaluation model for chilling tolerance of cotton, thus providing theoretical basis for breeding and promoting new chilling-tolerant cotton germplasms and large-scale evaluation of chilling tolerance of cotton varieties. [Method] Fifteen cotton varieties （lines） were used as experimental materials. The photosynthetic gas exchange parameters, chlorophyll fluorescence ki- netic parameters, chlorophyll content, relative soluble sugar content, malonaldehyde content, relative proiine content, relative conductivity and other 12 physiological indi- cators of seedling leaves under low temperature treatment （5 ℃, 12 h） and recovery treatment （25 ℃. 24 h） were determined; based on the chilling tolerance coefficient （CTC） of various individual indicators, the comprehensive evaluation of chilling toler- ance was conducled by using principal component analysis, hierarchical cluster anal- ysis and stepwise regression analysis. [Result] The results showed that the 12 indi- vidual physiological indicators could be classified into 7 independent comprehensive components by principal component analysis; 15 cotton varieties （lines） were clus- tered into three categories by using membership function method and hierarchical cluster analysis; the mathematical model for evaluating chilling tolerance of cotton seedlings was established： D =0.275 -0.244Fo1 ＋0.206Fv/Fm1＋0.326g,%-0.056SS ＋ 0.225MDA＋O.O38REC （FF=0.995）, and the evaluation accuracy of the equation was higher than 94.25%,0. Six identification indicators closely related to chilling tolerance were screened, including Fo,, Fv/Fm1, Seedling leaves of cotton varieties （lines） gs2, SS, MDA, and REC. [Conclusion] with high chilling tolerance are less dam- aged under low temperature stress, and are able to maintain relatively high photo- synthetic electron transport capacity and high stomatal conductance after recovery treatment, which is contributed to gas exchange and recovery of photosynthetic ca- pacity. Determination of the six indicators under the same stress condition can be adopted for rapid identification and prediction of the chilling tolerance of other cotton varieties, which provides basis for the breeding, promotion, identification and screen- ing of chilling tolerant germplasms.

Response to Low Temperature and Evaluation on Cold Tolerance of Sugarcane at Seedling Stage

This study aimed to screen out cold-tolerant sugarcane cultivars through acomprehensive cold tolerance evaluation. A total of 9 sugarcane cultivars with good agronomic traits, bred by the Yunnan Agricultural University, were selected. They were treated by low temperaturestress （3 ℃）, and the changes of their cold-tolerant physiological and biochemical indices were monitored. The cold tolerance of the sugarcane cultivars was evaluated comprehensively by polar ordination. The results showed that the low temperature stress increased the averagemembrane conductivi- ty, soluble sugar content, MDA content, proline content, soluble protein content, chlorophyll content and peroxidase （POD） activity in sugarcane leaves by 21.21%, 134.1%, 83.60%, 35.47%, 47.72%, 9.07% and 565.2%, respectively, but decreased the superoxide dismutase （SOD） activity in sugarcane leaves by 19.67%. Among the 9 sugarcane cultivars, Dianzhe 03-91 showed the strongest cold tolerance, while Dianzhe 02-39 showed the poorest cold tolerance; the cold tolerance of Dianzhe 08-5, Dianzhe 05-103 and Dianzhe 01-58 was stronger than that of Dianzhe 04- 14, Dianzhe 04-429, Dianzhe 05-522 and Dianzhe 02-227.

Salt Tolerance of 15 Rice （Oryza sativa L.） Varieties in the Office du Niger Zone of Mali

From 2003 to 2005, in pot and field experiments, rice response to salinity stress of 15 rice varieties was studied at germination and young seedling stages using salt affected soils collected from rice production areas in the Office du Niger zone of Mali. The rice varieties were composed of 10 rice genotypes from the breeding program of Mali and five from West African Rice Development Association （WARDA） program （Saint Louis, Senegal）. Soil samples were collected from the visually affected soils which were characterized by the appearance of white or black efflorescence on the soil surface. In pot experiments, the genotypes were allowed to germinate in both affected soil types （white efflorescence and black efflorescence） and salt effects on plant seedling growth were observed. Results showed that all varieties were significantly sensitive to salinity stress based on germination, young seedling shoot and root dry weights. Among the rice varieties, the most salt tolerant variety was BG90-2 （a high yielding genotype from the Institut d＇Economie Rurale （IER） breeding program） while the most sensitive variety was Telimani （also from the breeding program of IER）. All other varieties were intermediary between these two genotypes. A three year field experiment conducted in a highly affected area near Niono confirmed the results of the pot experiment. The relatively salt tolerant genotypes were found in both Malian （BG90-2, Kogoni91-1, SK51-5-2） and WARDA （Was30-11-1-1-4-6-1B） rice breeding programs.

Recombinants for Enhanced Productivity and Drought Tolerance in Barley （Hordeum vulgare L.）

In an attempt to enhance productivity as well as drought tolerance of barley cultivar, a 5 × 5 diallel cross involving rainfed cultivars was made. Of the 10 crosses, cross K603 x K560 was most promising as it yielded highest number of recombinants （21 in irrigated and 36 in rainfed conditions）; the cultivar K506 was considered as drought resistant （drought susceptibility index 〈 1）. A total of 22 out of 64 and 18 out of 59 most promising F2 recombinants in irrigated and rainfed conditions, respectively from 6 crosses were evaluated for yield, harvest index as well as proline content. All the recombinants selected under rainfed condition （including a few from irrigated condition） showed enhanced level of proline content coupled with high grain yield and harvest index. Further, a total of twenty-nine segregants （12 rainfed and 17 irrigated derived cultures） showing significantly higher values of proline content and grain yield were grown during 2007-2008 under both the environments, rainfed and irrigated to determine the geometric mean （GM） and drought susceptibility index （S）. The segregants （Culture No. 8, 10 ＆ 13） derived from cross K 603 × K 560 and culture No. 5 from K 560 × RD 2508 gave maximum mean yield under rainfed and geometric mean coupled with lower drought susceptibility index （S）. Also, it has been observed that the transgressive segregants selected from limited water environment （rainfed） performed better than those selected from irrigated environment for higher grain yield and drought tolerance.

Study Frequency of Antibiotic Resistance Enzymes in Bacillus Species in Some of Foods

The subject of this study was to survey prevalence Beta lactamase enzyme in Bacillus species isolated from foods in Isfahan city in Iran. This is a laboratory study performed during 2009-2010 years in Isfahan. In this study, 150 samples of food, including juice ketchup, mayonnaise,

Antioxidant Defense System in Wheat （Triticum aestivum L.） Seedlings under Heat Stress and Revival Conditions

The present investigation was carried out to investigate the effect of heat stress and revival on some antioxidative enzymes and metabolites in leaves of the wheat （Triticum aestivum L.） seedlings of heat susceptible （cv. WH 147 and HS 277） and heat tolerant （cv. WH 1021 and HW 2045） cultivars. Seven days old seedlings grown at 25 ℃ were exposed to 40 ℃ for 6 h and these seedlings were again brought to 25 ℃. The observations were recorded in the leaves of control, stressed and revived seedlings on 2nd and 4th day of revival. For the selection ofthermo-tolerant cultivars, screening of the thirty-six cultivars was done based on wilting of primary leaf and values of chlorophyll fluorescence. The MDA （malondialdehyde） and H2O2 concentration in leaves of wheat seedlings increased at the high temperature. There was enhancement in the activities of antioxidative enzymes, viz. CAT （catalase）, POX （peroxidase）, GR （glutathione reductase） and APX （ascorbate peroxidase） in leaves of the tolerant and susceptible cultivars under heat stress, however, higher percent increase was observed in tolerant cultivars. Heat stress increased the SOD （superoxide dismutase） activity in tolerant cultivars but activity declined in susceptible cultivars. On revival, the activities of the CAT, POX and GR declined in comparison to stressed seedlings but remained higher as compared to control. Ascorbate peroxidase activity remained higher on 2nd day and 4th day of revival in all the cultivars.

Characterization in Greenhouse Conditions of Two Salt Tolerant Citrumelo （Citrus paradisi Macf. x Poncirus trifoliata （L.） Raf.） Cultivars

Increasing salinity in Mediterranean soils and the wide spread of citrus tristeza virus have challenged the use of sour orange （Citrus aurantium） and have accelerated the process of seeking alternative rootstocks. In the present study, nine cultivars of citrumelo （Citrus paradisi Macf. x Poncirus trifoliata （L.） Raf.） were evaluated for salt tolerance. Two month-old seedlings were raised under greenhouse conditions and irrigated with a half strength Hoagland solution supplemented with different concentrations of NaCI, i.e., 0 mM, 35 mM and 85 mM. Tolerance was assessed after two months of stress by measuring stem growth, number of leaves, fresh and dry weight organs and leaf water, chlorophyll and chloride contents. A differential behavior was noticed among the seedlings we studied. When using increased concentration of salt in irrigation water, all the parameters were significantly reduced except for leaf chloride content which highly increased in response to stress. At 85 mM, the cultivar SC2 showed a high tolerance resulting in less apparent leaf symptoms, higher growth and higher leaf chlorophyll content when compared to other seedlings. Similarly, the cultivar C4475-C was shown to be a strong root chloride excluder with less than 2.6% DW （dry weight） chloride accumulation at leaf level. By contrast, our results suggest that C4475-A and C4475-B are salt sensitive cultivars regarding to all the parameters studied while the other citrumelos were considered as moderately tolerant.

Variation in Salt Tolerance of Wheat Cultivars:Role of Glycinebetaine and Ethylene

Four wheat （Triticum aestivum L.） cultivars 711, PBW343, 3765 and WH542 were screened for studying variations in glycinebetaine （GB） content and plant dry mass under 100 mmol L-1 NaCl stress. A tolerance index was calculated using plant dry mass data to select salt-tolerant and salt-sensitive types and find association between tolerance index and GB content. Tolerance index has been used as a good criterion to select the tolerant types under high salinity stress. Further, physiological differences in salt-tolerant cultivar 711 and salt-sensitive cultivar WH542 were examined. The salt-tolerant cultivar exhibited greater CB content, which was found correlative with ethylene. The cultivar also showed higher nitrogen （N） content and nitrate reductase activity, reduced glutathione and higher redox state resulting in maximal protection of plant dry mass than the salt-sensitive type. Thus, the content of CB may be considered as important physiological criteria for selecting salt-tolerant wheat types.