杂交水稻根系生理优势及其与地上部性状的关联研究

 连晚杂交水稻汕优6号根系的生长、氮吸收、氨基酸合成能力以及根系活力均超过其亲本三系和常规品种。干种子中α-淀粉酶的存在是杂种幼苗根系生长优势的重要生理基础。营养吸收优势表现在单株氮吸收速率上,并与地上部干物质生产有紧密的联系。从杂交水稻伤流液中分离出31种游离氨基酸,而氨基酸种类和浓度则受地上部营养的制约。生育中、后期缺氮和通气不良会导致根系活力降低;适施氮肥和改善通气条件可有效地提高根系活力,并防止早衰。此外,对杂种优势的早期诊断指标和产量预测指标进行了讨论。     

复烤烟叶异地醇化过程中生物活性的变化

以复烤烟叶为试验材料,研究了异地醇化过程中生物活性的变化.结果表明:复烤烟叶异地醇化过程中,醇化初期叶面微生物数量和生物酶活性迅速上升,之后随着醇化的进行而逐渐下降;中部烟叶叶面微生物数量总体大于上部和下部烟叶,并可检出蛋白酶活性,而上部和下部烟叶均未能检出其活性,纤维素酶和淀粉酶活性均为中部＞上部＞下部烟叶,而蔗糖酶活性为下部＞中部＞上部烟叶;同等级复烤烟叶存放于西昌烟叶仓库的生物活性水平高于成都烟叶仓库.     

陈化烟叶中1株果胶酶高产菌的分离、筛选与鉴定

烤烟中的高果胶含量严重影响烟草吸食品质和陈化速度。为降低烟草中的果胶含量,提高烟草及烟草制品的品质及安全性,从不同年份和不同产地的18份复烤烟草中共分离筛选出有降解果胶能力的细菌38株和真菌9株。其中,XC-8、XC-30、SMXP-57、SMXP-58、SMXP-62共5株细菌具有较高的降解果胶的能力,在发酵时间24 h、发酵温度30℃、接种量10%条件下果胶酶活性分别为176、179、143、192、121 U/mL。其中,菌株SMXP-58酶活性最高(192 U/mL),通过16S r DNA序列分析并结合形态、理化特性分析,确定SMXP-58菌株为枯草芽孢杆菌(Bacillus subtilis)。将SMXP-58菌株制成的菌剂(9.6×107个/mL)喷施于100 g烟叶表面,发酵3 d的烟叶评吸总分提高了1.02,进一步优化发酵条件,在发酵时间60 h、菌液量1 mL、水量20 mL的条件下,烟叶中果胶含量最低(7.45%)。     

Cation binding in a soil with low exchange capacity: Implication for the structural rigidity of soil organic matter

Two previous studies suggested that part of the cation sorption sites in soil organic matter with low exchange capacity have to be considered as “lonely”, i.e., too far from each other to allow direct cross‐linking by bivalent cations. The objective of this contribution was to understand the mechanisms controlling structural rigidity and physicochemical aging of the SOM (soil organic matter) and the role of water molecule bridges (WaMB) therein. For this, we evaluated the matrix rigidity of an organic surface layer of a Haplic Podzol on a quantitative basis, by assessing WaMB transition temperature (T*) directly after treatment with bivalent cations (Mg²⁺, Ca²⁺, or Ba²⁺) and after eight weeks of aging. Cation loading as well as cation type influenced matrix rigidity. Ba²⁺ induced the most rigid matrix and Mg²⁺ the weakest, which is in line with their binding strength in terms of Langmuir coefficient. The matrix rigidity increased with the cross‐linking activity, which is the product of loading and Langmuir constant of the respective cation. The aging process, however, was slowed down by the initial matrix rigidity, and the rigidity of the aged matrix decreased with increasing Langmuir constant. The degree of aging increased with increasing hydration enthalpy of the cation and decreased with increasing cation loading. Thus, directly after cation treatment, direct cross‐links by multivalent cations were most relevant, but WaMB increasingly gained influence on the matrix rigidity during aging. The untreated sample revealed a considerable number of WaMB, resulting in a fairly rigid and strongly cross‐linked matrix which, however, flexibly reacts on external influences like change in cation concentration or relative humidity. With these findings, the ideas on the relevance of indirect CaB‐WaMB associations between distant sorption sites for the rigidity and flexibility of the OM matrix as proposed in previous studies were confirmed on a mechanistic basis in this study.     

Effect of accelerated aging on maize, sorghum, and sorghum meal

Accelerated aging at 50 °C significantly affected the physical and chemical properties of sorghum and maize. Aging caused associations between starch granules, protein matrix, and cell walls. During aging, floury areas of the endosperm became more corneous; as the endosperm hardened, strong associations between starch and protein developed, causing the endosperm to fracture through endosperm cells instead of along cell walls, which is common for non-aged maize. Aging significantly decreased the pasting viscosity of starch, molecular solubility at 85 °C and the molecular weight of solubilized starch. Solubility of albumins and globulins decreased while solubility of proteins extracted by a reducing agent and/or in alkaline pH increased during aging. Decreased solubility and functionality of starch and protein in aged grain appear to be due to protein oxidation.     

春大豆种子在贮藏期间的一些生理生化变化

四个春大豆品种在8个月的贮藏过程中,随着贮藏时间延长,种子不断老化劣变,发芽率降低,脱氨酶活性和过氧化物酶活性下降,以及膜透性增大。种皮黑色的品种较黄色的品种抗劣变能力强。四个品种耐贮藏力大小顺序为:泰兴黑豆>矮脚早>湘春豆10号>吉林21号。     

有机酸对As(Ⅴ)在土壤中老化的影响

为了明确不同类型有机酸对土壤中砷释放及迁移转化等行为的影响,应用模拟试验方法,研究了添加乙酸、草酸、柠檬酸和腐植酸对砷在第四纪红壤中老化的影响。研究结果表明,在温度为25℃、湿度为最大田间持水量70%条件下,有机酸类型对砷在第四纪红壤中老化过程的影响不显著,但有机酸添加量对培养期间土壤有效态和结合态砷的含量具有显著影响。当乙酸的添加量为50、100 mg·kg~(-1)时,对As(Ⅴ)在土壤中的老化均有抑制作用;添加量达到200 mg·kg~(-1)时,对As(Ⅴ)的老化具有促进作用。而草酸和柠檬酸的添加量为50 mg·kg~(-1)时,对As(Ⅴ)的老化具有促进作用;添加量为100、200 mg·kg~(-1)时均抑制As(Ⅴ)的老化。腐植酸对外源砷在土壤中的老化具有抑制作用,且其对砷老化的影响远大于其他类型有机酸。当添加量在50~200 mg·kg~(-1)时,乙酸和草酸对土壤中专性吸附态砷含量有显著影响;添加量为50、100 mg·kg~(-1)时,柠檬酸和腐植酸对弱结晶水合铁铝氧化物结合态砷均有显著影响;添加量为200 mg·kg~(-1)时,乙酸、柠檬酸和腐植酸对结晶水合铁铝氧化物态砷影响显著。综上,在本试验条件下,As(Ⅴ)在第四纪红壤上老化不受有机酸类型的影响,而受有机酸添加量的影响。     

部分玉米自交系根际线虫群体数量与玉米早衰病相关性研究

1999－2000年对10个玉米自交系早衰病与根际线虫群体变化的相关性进行了系统研究，结果表明：玉米自交系早衰病的发生和根际线虫的群体变化具有一定关系，玉米根际存在大量的线虫，其中重要的植物内寄生线虫－－短体线虫的种群数量与玉米早衰病的群体数量与玉米早衰病的发生呈正相关，其中543和嫩297两个感病自交系根际短体线虫出现的频率较高，而玉米根际的取食真菌和细菌的腐生线虫的群体数量与玉米早衰病的发生呈负相关。     

Post‐ovulatory aging of mouse oocytes in vivo and in vitro: Effects of caffeine on exocytosis and translocation of cortical granules

The developmental potential of post‐ovulatory oocytes decreases with aging in vivo and in vitro. In this study, we aimed to investigate the effects of a potent antioxidant caffeine on cortical granules (CGs) distribution in mouse oocytes aging in vivo and in vitro. We found that in vivo administration of 150 mg/kg caffeine caused ovulation of some morphologically abnormal oocytes showing premature exocytosis or congregation of CGs, but significantly decreased abnormal distribution of CGs in oocytes aging for 6 h, 12 h and 18 h in vivo compared to those without caffeine treatment. Unexpectedly, supplementation of oocyte culture medium with 10 mmol/L caffeine accelerated CGs release of oocytes and the normal CG distribution rate dramatically decreased from 6 h in oocytes aging in vitro. It appeared that oocytes showed a high degree of abnormal CG distribution by aging for 18 h, and caffeine might delay oocyte CG exocytosis in vivo, but accelerates CG exocytosis in vitro. Our findings may have implications for improving assisted reproduction technologies.     

吸湿-回干处理对人工老化翠菊种子活力的影响

[目的]研究人工老化及吸湿一回干处理对翠菊种子活力的影响,旨在为合理的贮存与使用翠菊种子提供科学依据。[方法]供试种子在45℃、100％RH下进行老化处理。老化后种子在20℃条件下进行吸湿,25℃下回干及发芽测定。[结果]试验结果表明,在45℃、100％RH高温高湿条件下处理翠菊种子,对翠菊种子有快速老化的作用,其主要的活力指标呈明显降低趋势,随着老化处理时间的延长,种子的发芽指数（F=1257．73〉F0.01=4.82）与活力指数（F=385614.42〉F0.01=4.82）明显下降。老化处理时间达到60h后,翠菊种子的发芽率只剩下50％。对经过人工老化后吸湿一回干处理的翠菊种子进行发芽率（F=600．06〉F0.01=4．82）和发芽势（F=543．44〉F0.01=4．82）的测定显示,经吸湿-回干处理后可以明显缓解高温对种子劣变的影响,不同程度地提高发芽率与发芽势。[结论]吸湿-回干处理可部分消除高温高湿对翠菊种子所造成的伤害,明显提高翠菊种子的活力。