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121.
采用菌丝生长速率法用金银花的花、黄花蒿的地上部分、蓝桉果实和黄柏果实的乙醇提取物及其不同极性的组分对杨树溃疡病菌菌丝生长的抑制作用进行了测定。以黄柏果实的抗菌活性最强,其次是金银花的花。抗菌活性成分主要存在于金银花的正丁醇组分、黄花蒿的石油醚组分和乙酸乙酯组分、蓝桉的水部分、黄柏的正丁醇组分。当培养基中碳酸钠和碳酸氢钠的浓度分别为8g/L时(对应的pH值分别为10.24和7.71),菌丝生长抑制率分别为100.00%和79.68%。如果用1mol/L氢氧化钠溶液调节培养基的pH值至10.00,菌丝生长抑制率为40.58%。说明碳酸钠或碳酸氢钠对菌丝生长的抑制作用,一方面是由于改变了培养基的pH值,另一方面可能是由于碳酸根和碳酸氢根离子抑制了菌丝的生长。 相似文献
122.
123.
不同钠盐胁迫对高冰草种子萌发的影响 总被引:12,自引:0,他引:12
通过对高冰草种子在不同钠盐(NaCl、NaHCO3、Na2CO3)溶液中萌发情况的研究,旨在探明高冰草种子在不同盐胁迫下的萌发特性。结果表明:碱性盐(NaHCO3、Na2CO3)胁迫较中性盐(NaCl)胁迫显著降低了高冰草的发芽率。高冰草种子在NaCl浓度150mmol/L、NaHCO3浓度100mmol/L和Na2CO3浓度50mmol/L时萌发受到明显抑制。不同钠盐胁迫下高冰草种子胚根和胚芽的受抑制大小顺序为,中性盐NaCl胁迫:胚根<胚芽;碱性盐NaHCO3和Na2CO3胁迫:胚根>胚芽。 相似文献
124.
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126.
《Communications in Soil Science and Plant Analysis》2012,43(19-20):2827-2838
Vertisols in the Sudan occur under different climatic zones, ranging from arid in the north to tropical monsoon in the south, with rainfall varying from 150 mm to 1000 mm per annum. In this study, the exchangeable sodium percentage (ESP) was estimated from the sodium adsorption ratio (SAR); values of SAR and ESP for all identified soil series of Vertisols in the Sudan were extracted from the available data. These data were used to examine the variability in SAR and ESP in these soils using coefficient of variation (CV) as an index and then to regress ESP on SAR for the three master horizons (A, AC, C) and pooled data for all horizon. Curvilinear, linear, quadratic, and cubic equations were used to examine the relation between ESP and SAR. The significance of the F ratio and correlation coefficient was tested for individual equation. The soil series were then sorted out into saline and nonsaline, sodic and nonsodic, and the ESP was regressed on SAR once again. The equations used for the regression were curvilinear and first‐, second‐, and third‐degree polynomial equations. Then analysis of variance (ANOVA) was used to screen any significant difference between the estimated values of ESP (using these equations and USDA salinity laboratory equation) on one hand and the actual (measured) values of ESP. The results revealed that ESP and SAR are highly variable irrespective of depth despite slight decrease with depth. Furthermore, ESP is more variable than SAR in horizons A and AC but less variable in horizon C. The regression equations indicated that ESP might be reasonably estimated from SAR. However, different equations were appropriate for different horizons. Moreover, the result indicated that in most of the cases the relation between ESP and SAR better fits quadratic equations. But for simplicity, linear equations for all horizons could be used to estimate ESP from SAR. 相似文献
127.
Selective absorption (SA) of K over Na (i.e. the preferential absorption of K over Na) has been proposed as a Na tolerance mechanism but genotypic variation for this trait has not been assessed with sugar beet in the field. Thus, the aim of this study was to explore the variation of SA in 14 sugar beet cultivars and to relate SA with yield and root quality in two sites of central Greece (Amfithea and Pyrgetos). Genotypic variation for SA was significant and the SA values were higher in Pyrgetos, the site with the lower soil K and Na concentrations. In Pyrgetos, a favourable environment for sugar beet growth, cultivars yielded more and root quality was better. In that site, a negative relationship between SA and yield (fresh root weight, sugar yield) was found indicating that strong Na exclusion from root is a disadvantage for high yielding. Negative SA–yield relationships were evident in Amfithea when five cultivars with very low SA values (<1.00) were excluded from the analysis. Combined all the cultivars, curvilinear functions were the best-fitted curves for the SA–yield relationships. In Amfithea, where sugar beets had lower water content in root (WCR), a significant, positive correlation between SA and % sucrose content in fresh root weight was found. This finding was ascribed to the dilution of sucrose in roots due to the increased WCR as a result of the increased root Na concentration. In both sites, SA was positively related with root K concentration and negatively with Na concentration. The positive correlations between SA and root α-amino N concentration indicated that sugar beet N nutrition could be affected by the genotypic ability to exclude Na from the root. 相似文献
128.
十二烷基硫酸钠对大豆基木材胶黏剂的改性作用 总被引:3,自引:0,他引:3
采用10.0g·kg^-1的十二烷基硫酸钠(SDS)改性质量分数为250.0g·kg^-1的大豆粉浆液,制成SDS改性大豆基木材胶黏剂(SF),运用单因素和正交试验法考察了pH值、反应温度和反应时间对改性SF胶耐水胶合强度的影响。试验结果表明,SDS改性大豆基木材胶黏剂的最佳工艺:pH8,反应温度35℃,反应时间4h。改性后的SF胶Ⅱ类耐水胶合强度为0.70MPa。由红外光谱分析可知,SDS改性使大豆蛋白质分子大量的非极性基团外露,增加了蛋白质分子的疏水性,提高了改性SF胶的耐水胶合强度。图4表3参10 相似文献
129.
Blood samples were taken at weekly intervals from 54 dairy cows (mainly Friesians and Jerseys) during the periods 8 weeks before and 8 weeks after calving. The cows were divided into two age groups; group 1 consisting of 26 cows aged 2 1/2 years and group 2 consisting of 28 cows aged 5–9 years. The changes in the erythrocyte sodium (ENa) and the erythrocyte potassium (EK) concentrations before and after calving were expressed as the slopes for each component regressed on weeks. In the older cows the concentration of ENa decreased (p<0.05) while that of EK increased (p<0.05) after calving. Both the ENa and EK concentrations varied significantly (p<0.01) between cows in the two age groups. The prepartum and postpartum ENa and the postpartum EK concentrations varied significantly (p<0.05) between weeks. EK type did not influence the changes in ENa or EK concentrations before or after calving. 相似文献
130.
无水氯化钙可代替硫酸催化酯化反应,探讨了氯化钙催化9-羟基芴-9-甲酸甲酯的条件,操作简便,反应温和,无腐蚀,减少了污染与产品纯化。 相似文献