硅对盐胁迫下藜麦生长及抗氧化酶活性的影响

全球气候变暖降水减少加速了土壤盐渍化进程,对农业生产造成了严重影响,低浓度的盐分对藜麦发育没有明显影响,但盐含量较高的土壤则不利于藜麦的生长。前人研究表明,硅能帮助植物在盐胁迫条件下更好的生长。本实验以4种藜麦为研究材料,在300mmol.L_-1^{盐胁迫条件下设置硅浓度梯度(CK、0、0.5、1、1.5、2 mmol.L}_-1^{),研究硅对盐胁迫条件下藜麦幼苗的}生长影响及其生理机制,为提高藜麦耐盐性提供参考。结果表明：(1)与对照相比,盐胁迫条件下藜麦幼苗的芽长均明显降低,根长均显著增加;超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)等抗氧化酶活性有不同程度的增加;可溶性糖(SS)含量降低;超氧阴离子自由基(O_2^.-)产生速率丙二醛(MDA)含量增加。(2)随硅浓度的增加,藜麦幼苗的芽长、根长、SOD、POD、CAT、SS均表现为先增加后降低的趋势,O_2.-^{产生速率和MDA含量先降低后升高。(3)}适当浓度外源硅的添加提高了盐胁迫条件下藜麦幼苗的抗氧化酶活性和SS含量,降低O_2.-^{产生速率和MDA含量,促进了藜麦幼苗在盐胁迫条件下的生长,0.5～1mmol.L}_-1^{硅浓度效果最好。}     

温湿度调控对番茄灰霉病菌产生的细胞壁降解酶的影响

 番茄灰霉病菌在致病过程中能够产生4种细胞壁降解酶,以PMG酶活性最高,其次是β-葡萄糖苷酶和PG酶,Cx最少。灰霉病菌在不同温度下侵染番茄叶片时产生的致病酶活性不同,4种酶在20℃时表现了最高的活性,15℃次之,当温度达到25℃时,各种酶的活性都急剧下降,随着温度的再升高,酶活更低。随着湿度的增高,病菌产生的细胞壁降解酶的活性也增加,当相对湿度达到90%以上时,4种酶的活性也达到最高。温湿度对番茄灰霉病菌产生细胞壁降解酶的影响趋势,与其对发病的影响趋势是一致的。     

硅对盐胁迫下葡萄幼苗生理效应的影响

以酿酒葡萄"赤霞殊"(Cabernet Sauvignon,CS)1年生扦插苗为试材,采用营养液水培系统,研究了根施外源硅(K2SiO3·9H2O,Si)对盐(50 mmol/L NaCl)胁迫下赤霞珠葡萄幼苗叶片生理生化特性的影响.结果表明:盐胁迫处理下,葡萄幼苗叶片超氧阴离子(O2-')产生速率加快,过氧化氢(H2O2)、丙二醛(MDA)含量和相对膜透性增加;超氧化物歧化酶(SOD),过氧化物酶(POD)和过氧化氢酶(CAT)活性增强;组织含水量降低;施用2.0mmol/L Si明显抑制了O2-、H2O2和MDA的积累,增加了组织含水量,并进一步提高了抗氧化酶SOD和POD的活性.说明外源Si可通过提高盐胁迫下葡萄幼苗体内的抗氧化酶活性,从而降低活性氧(ROS)水平,一定程度上减轻盐胁迫对植株所造成的细胞膜脂过氧化伤害,增强其耐盐性.     

花绒寄甲对高温胁迫的适应能力及生理响应

商品化天敌昆虫在我国不同区域释放可能受到极端温度的影响和制约.花绒寄甲Dastarcus helophoroides(Fairmaire)是松墨天牛Monochamus alternatus Hope等蛀干害虫的重要天敌之一,具有良好的应用前景,但其在我国南方应用时控害效果常不稳定.以商品化花绒寄甲成虫为研究对象,并以...     

水分胁迫对抗旱性不同小麦品种叶片光合及根呼吸等生理特性的影响

以两个抗旱性不同的小麦品种西农1043、陕253为材料，采用盆栽与水培试验相结合的方式，研究水分亏缺对小麦不同生育期叶片光合及根呼吸速率等生理指标的影响。结果表明：相同水分处理下，抗旱品种西农1043与水分敏感品种陕253相比，具有较高的光合和根呼吸速率、以及相对较高的保护酶活性；水分胁迫下，两个小麦品种叶片光合和根呼吸速率及苗期叶保护酶活性均降低；两种水分处理下抗旱性强的西农1043根呼吸所占光合的比例相对高于陕253。     

赤霉素A_(4+7)的分子生物学研究进展

目前发现的赤霉素种类已达136种之多,GA4+7以其较高的活性和独特的优势受到人们的广泛关注。因此,就GA4+7的合成途径、关键酶及信号转导过程等方面的研究进展进行了归纳和总结,并指出了今后的发展方向。     

Soil organic matter, microbial biomass and enzyme activities in a tropical agroforestry system

 The effects of growing trees in combination with field crops on soil organic matter, microbial biomass C, basal respiration and dehydrogenase and alkaline phosphatase activities were studied in soils under a 12-year-old Dalbergia sissoo (a N₂-fixing tree) plantation intercropped with a wheat (Triticum aestivum) – cowpea (Vigna sinensis) cropping sequence. The inputs of organic matter through D. sissoo leaf litter increased and crop roots decreased with the increase in tree density. Higher organic C and total N, microbial biomass C, basal soil respiration and activities of dehydrogenase and alkaline phosphatase were observed in treatments with tree-crop combination than in the treatment without trees. Soil organic matter, microbial biomass C and soil enzyme activities increased with the decrease in the spacing of the D. sissoo plantation. The results indicate that adoption of the agroforestry practices led to an improved organic matter status of the soil, which is also reflected in the increased nutrient pool and microbial activities necessary for long-term productivity of the soil. However, tree spacing should be properly maintained to minimize the effects of shading on the intercrops. Received: 21 February 1997     

棉花秸秆纤维素降解菌的筛选鉴定 与降解棉秆效果研究

【目的】 利用微生物学和分子生物学手段筛选和鉴定棉秆表面附着的真菌,获得具有高效纤维素分解能力的真菌。【方法】 通过将棉花秸秆接种至不同选择性培养基中,分离挑选水解圈较大的菌株,进行镜检和分子生物学鉴定;并同时对菌株进行滤纸酶活性(FPA)和羧甲基纤维素钠(CMC-Na)糖化活力的测定,以及连续(25 d)观测棉秆纤维的失重率。【结果】 主要4株菌种水解圈直径大小排序为,SN-1＞SN-4＞SN-3＞SN-4(P=0.013)。对于CMC-Na糖化活力,24~96 h时SN-1菌种显著低于其它3个菌种(P＜0.05),120 h时,各菌种处理间差异不显著(P＞0.05)。对于FPA活性,第24和120 h时,SN-1和SN-4菌种显著高于SN-2和SN-3菌种(P＜0.05);其它时间点,各菌种按活性高低排序为:SN-1、SN-4＞SN-3＞SN-2(P＜0.05)。通过镜检和分子生物学鉴定,得到4株菌种分别为:SN-1为黑曲霉(Aspergillus niger),SN-2为赤霉(Gibberella moniliformis),SN-3为链格孢霉(Alternaria nees),SN-4为青霉菌(Penicillium italicum)。【结论】 黑曲霉降解棉花秸秆的效果最为显著。对于CMC-Na糖化酶活力、滤纸酶活性以及棉花秸秆的实际失重率(降解率),接种黑曲霉或青霉菌时表现均最佳。     

控释氮肥对水稻氮代谢关键酶活性及糙米蛋白质含量的影响

为了探明控释氮肥提高氮素利用率的作用机理，研究了控释氮肥对水稻氮代谢关键酶活性以及糙米蛋白质含量的影响。结果表明，施用控释氮肥能显著增强齐穗期和乳熟期叶片中的硝酸还原酶、谷氨酰胺合成酶和谷氨酰胺转化酶活性，且其增强作用可持续到蜡熟期。施用控释氮肥还能提高乳熟期和蜡熟期叶片中的蛋白水解酶活性，对水稻籽粒中谷氨酰胺合成酶和谷氨酰胺转化酶活性有明显的促进作用，可增加糙米的全氮和蛋白氮含量，提高水稻产量。     

An inter-laboratory comparison of multi-enzyme and multiple substrate-induced respiration assays to assess method consistency in soil monitoring

The use of indicators in soil monitoring schemes to detect changes in soil quality is receiving increased attention, particularly the application of soil biological methods. However, to date, the ability to compare information from different laboratories applying soil microbiological techniques in broad-scale monitoring has rarely been taken into account. This study aimed to assess the consistency and repeatability of two techniques that are being evaluated for use as microbiological indicators of soil quality: multi-enzyme activity assay and multiple substrate-induced respiration (MSIR). Data were tested for intrinsic (within-assay plate) variation, inter-laboratory repeatability (geometric mean regression and correlation coefficient) and land-use discrimination (principal components analysis). Intrinsic variation was large for both assays suggesting that high replicate numbers are required. Inter-laboratory repeatability showed diverging patterns for the enzyme assay and MSIR. Discrimination of soils was significant for both techniques with relatively consistent patterns; however, combined laboratory discrimination analyses for each technique showed inconsistent correspondence between the laboratories. These issues could be addressed through the adoption of reliable analytical standards for biological methods along with adequate replication. However, until the former is addressed, dispersed analyses are not currently advisable for monitoring schemes.