IAA对盐胁迫下大豆幼苗膜伤害及抗盐力的影响

采用溶液培养法研究了ＩＡＡ（吲哚乙酸）对盐胁迫下豆幼苗膜伤害及抗盐力的影响。结果表明：一定浓度的ＩＡＡ处理可促进盐胁迫下大豆幼苗的生长,使其干物质产量增加,叶面积增大,提高叶片光合速率,增强了保护酶系统活性,降低膜脂过氧化产物ＭＤＡ含量及膜相对透性（相对导一）,增强了幼苗对盐渍环境的抵抗能力,缓解了盐害。     

广州城市绿地系统景观异质性分析

选用景观多样性等7个指数对广州城市绿地景观异性质进行了分析.结果表明,广州绿地斑块密度和绿廓道密度分别为11.8和1.87km·km^-2,在老城区绿地具有斑块小,破碎度大,多样性高,以随机分布为主的高异质性空间结构;在新城区,绿地斑块大,以均匀分布为主,因此,在同等大小的区域内,这类绿地空间结构更能提高景观的异质性,更有效地发挥绿地的生态功能.     

Seed germination response to cold stratification period and thermal regime in Phacelia secunda (Hydrophyllaceae) – Altitudinal variation in the mediterranean Andes of central Chile

The ability to germinate under a variety of environmental conditions is essential for plant species inhabiting a wide range of altitudes and latitudes. Phacelia secunda J. F. Gmel. (Hydrophyllaceae) is a perennial herb with wide latitudinal and altitudinal distributional ranges. In the central Chilean Andes (33 °S) P. secunda can be found from 1600 m sealevel up to the vegetation limit at 3400 m. It has been suggested that seeds from populations encountering long periods with snow cover and adverse winter conditions would require longer periods of cold stratification for germination than those from populations exposed to milder winters. Given that the snow-free period decreases with elevation, seeds from high elevation populations could require longer period of cold stratification to germinate. Moreover, it has been shown that seeds from arctic and higher elevations environments are adapted to germinate better under high temperature conditions. Germination response with increasing periods of cold stratification (0–6 mo.) and under two contrasting thermoperiods (20 °/1O °C; 10 °/5 °C; 12 h day/night), were studied for 4 populations of P. secunda located at 1600, 2100, 2900 and 3400 m a.s.l. Initiation of germination required increasingly longer periods of stratification with elevation, and proportionately fewer seeds germinated for any one stratification treatment at the higher elevations. Seeds from higher elevations germinated to a higher percentage under the high than the low temperature thermoperiods. These results illustrates a significant variation in germination characteristics over a spatially short environmental gradient.     

S02对冷藏枇杷果实品质及活性氧和多胺代谢的影响

以"大红袍"枇杷果实为试材,研究了SO2处理对冷藏枇杷果实活性氧代谢和内源多胺含量变化的影响及与果实木质化败坏的关系。结果表明,SO2可提高超氧物歧化酶(SOD)和过氧化氢酶(CAT)活性,抑制过氧化物酶(POD)活性的上升,减少H2O2的积累。经SO2处理的果实,精胺(Spm)和亚精胺(Spd)含量的变化很小,基本维持在贮前水平上,腐胺(Put)的积累则受到极大抑制,贮藏5周后的果实不出现木质化败坏症状。这些结果表明,SO2可能通过维持活性氧代谢的平衡,抑制活性氧的积累,从而防止果实木质化的发生。     

低温、高pH胁迫对水稻幼苗根系质膜、液泡膜ATP酶活性的影响

以耐冷性不同的两个水稻品种为材料,比较研究了幼苗根系质膜、液泡膜ATP酶对低温(8℃)及高pH(8.0)胁迫的反应。结果表明水稻根细胞质膜和液泡膜上均存在Ca3+-ATP酶,但活性远低于H+-ATP酶。耐冷品种武育粳3号经低温(8℃)处理2d,根系质膜和液泡膜H+-ATP酶、Ca2+-ATP酶活性均明显升高,至冷处理12d,H+-ATP酶、Ca2+-ATP酶活性有所下降,但仍与对照相近;而冷敏感品种汕优63经低温(8℃)处理2d,根系质膜H+-ATP酶活性略有升高,而质膜Ca2+-ATP酶以及液泡膜H+-ATP酶、Ca2+-ATP酶活性已明显下降;至冷处理12d,4种酶活性均明显低于对照。高pH胁迫使质膜和液泡膜H+-ATP酶活性下降,而使Ca2+-ATP酶活性上升。高pH胁迫会加剧低温冷害。结果表明,耐冷品种质膜、液泡膜ATP酶比冷敏感品种对低温胁迫有更强的适应能力。     

Effects of Salinity Stress on the Levels of Covalently and Noncovalently Conjugated Polyamines in Plasma Membrane and Tonoplast Isolated from Barley Seedlings

When the 7-d old barley ( Hordeum vulgare L. ) seedlings were treated with different concentrations of NaC1 for 3 d, the levels of the noncovalemly conjugated polyamines (PAs) in the plasma membrane and tonoplast vesicles and the covalently conjugated PAs in the membrane proteins were promoted by NaC1 of low concentrations and suppressed by NaC1 of high concentrations. Among the noncovalenfly conjugated PAs in the vesicles, spennidine (Spd) level was the most abundant, while putrescine (Put) content was predominant among the covalenfly conjugated PAs, accounted for 40%– 70%, 35% – 60%, respectively. In addition, the TLC (thin-layer chromatography) profiles of the benzoylated PAs presented an unknown polyamine with Rf = 0.92 (X0.92), which conjugated covalently and noncovalently in root tonoplast and its content changed as well as Spd with NaC1 treatment. The total PA contents in the roots were higher than that in the leaves, and the types and contents of covalenfly and noncovalently conjugated PAs in the tonoplast were higher than those in the plasma membrane. The results showed that the above two PAs associated with the membrane might be essential in salt adaption of cells and the maintenance of membrane function.     

闽南丘陵山地引种栽培树木的物候期与抗寒力调查

本试验以厦门同安祥溪国有林场为试验点,进行为期30多年的引种驯化试验。对35种主要树种的物候观测表明,引种树木叶芽及幼叶的生长集中在每年3月,花期集中在2~6月,果熟期集中在7~10月。寒害调查结果表明,引种保存的117个树种中,未受寒害或受寒害轻、能在同安正常越冬的有83种,占70.9%;中度冻害的有八宝树、石笔木等16种,占13.7%;而受冻严重和地上部分冻死的有柚木、白格等18种,占15.4%。绝大部分树种均可顺利渡夏,90多种已开花结实;无病虫害或危害轻微不影响生长发育的有109种,占93.2%;病虫影响严重的有桔红、细子龙等8种,占6.8%;造林成活率大于80%的有110种,占93.8%。试验结果表明,闽南丘陵山地收集保存的树种种质资源的生态适应性是多样的,这些树种在生长发育和适应性等方面表现出较大的差异性。     

Changes in Parameters of the Plasmalemma ATPase during Peach Vegetative Bud Dormancy

Plant dormancy and dormancy breaking depend, at least partially, on close relationships between buds and tissues underlying bud (bud stands). In Prunus persica, the dormancy was related to high nutrient absorption in bud stands linked to high plasmalemma ATPase (EC 3.6.1.3) activity. Two plasmalemma fractions was isolated from peach vegetative buds and bud stands using aqueous phase partitioning and ultracentrifugation. Results of markers enzyme assays indicated that both plasmalemma enriched fractions obtained were highly purified. During the dormancy period plasma membrane ATPase amount and activity were higher in bud stands than in buds. Moreover, assays performed at different temperatures (4, 18, 30 °C) indicated modifications of kinetic parameters (K_m, V_m) in both tissues during dormancy release. In buds, from November to February, K_m declined at 4°C and increased at 30 °C whereas no changes was measured at 18 °C and V_m increased at all temperature. In bud stands, no changes of K_m was measured at 4 °C and 18 °C whereas an increase occurred at 30 °C and V_m decreased at all temperature. According to the results, it can be postulated that dormancy release in peach-tree could be related to modifications of plasma membrane ATPase properties, in buds and bud stands, during winter time.     

Photoperiodic and Thermal Regulation of Development and Cold Hardiness in Larvae of the Clover Leaf Weevil, Hypera punctata

Effects of photoperiod and temperature on the development and cold hardiness were investigated in larvae of Hypera punctata. At a relatively low temperature (15°C), the larvae fed less and developed more slowly under a 12L:12D (SD) photoperiod than under a 16L:8D photoperiod (LD). SD larvae had lower gut weight against the whole body weight and lower supercooling point (SCP) than the LD counterparts for the same instar and same body weight. This was because the larval SCP is markedly affected by the quantity of the gut content. Laboratory experiments indicated that the low temperature mortality of this larvae occurred mainly due to freezing irrespective of the photoperiod and temperature, suggesting that the lower lethal temperature (LLT) depends on the supercooling ability of larvae. The SD larvae tended to have a lower SCP and hence a lower LLT than the LD counterparts at 15 or 10°C, unlike at 20°C. Thus, the slower larval development under SD conditions at relatively low temperatures may prevent larvae from reaching the later instar, which have a higher SCP and thus less cold tolerance, during the coldest season. The suppressed feeding activity under SD conditions would lower the SCP, thereby reducing the possibility of lethal tissue freezing. Such a photoperiodic and thermal regulation of the larval development and the supercooling ability appear to represent adaptive mechanisms for winter survival in this beetle.     

Effects of Wind Speed and Atmospheric Pressure on Mate Searching Behavior in the Aphid Parasitoid Aphidius nigripes (Hymenoptera: Aphidiidae)

The effects of wind speed and atmospheric pressure on male mate searching behavior, modulated by a female sex pheromone, were investigated in the aphid parasitoid Aphidius nigripes (Hymenoptera: Aphidiidae). Male A. nigripe generally did not reach females at wind speeds of 100 cm/sec, as the majority of individuals taking flight in the pheromone plume (81.8%) were unable to sustain upwind flight. At lower wind velocities, male responsiveness to females generally decreased with distance from the source. However, wind speeds approaching the upper threshold (100 cm/sec) tended to eliminate this distance effect. Therefore, there appears to be a trade-off between the need for higher wind speeds to detect the pheromone source from long distances, and a reduction in male flight capacity as wind velocity increases. Our results also indicate that chemical communication in A. nigripes could be affected by variations in atmospheric pressure, as we observed a relationship between pressure fluctuations in the 24 hr prior to testing and male responsiveness to females. The importance of these abiotic factors on mate searching behavior is discussed within the context of the reproductive biology of A. nigripes.