The Physiological Basis of Growth Inhibition of Halophytes by Potassium

Salt-dilution halophyte Suaeda salsa, salt-secretory halophytes Atriplex centrMasiatica and Limonium bicolor were treated with different concentrations of KC1 and isosmotic NaC1. It was found that the organic dry weight and net photosynthetic rate of these plants were inhibited by 100--500 and 100--400 mmol/L KC1 respectively, indicating the existance of a relationship between the growth inhibition by K+ and the decrease of photosynthesis in halophytes. After treatment with 100--400 mmol/L KCI, the content of K+ increased while that of Na+ decreased, but there were no change in osmotic potential and ability of osmotic adjustment. It proved that growth inhibition by K+ was related to Na+ deficiency in osmotic adjustment and the toxic effect of high K+ on cells. Further there was no direct relation between the decrease of growth and photosynthesys and the content of sugars in leaves. Moreover, the inhibition of ATPase activity by high K+ concentration was probably related to growth inhibition.     

亚洲玉米螟化性与繁殖力的关系

通过对发生在吉林省的一、二化性玉米螟的繁殖能力研究得出,不同化性越冬代玉米螟的产卵期、成虫寿命、单雌产卵量和最大产卵量差异显著,一化性越冬代玉米螟的产卵量比二化性玉米螟高４５％以上。经虫体大小和重量比较得出,一化性越冬代玉米螟的蛹重比二化性玉米螟的蛹重高３５％以上,人工饲养的一化性玉米螟Ｆ_1代的蛹重也比二化性的蛹重高１０％左右。     

Competitive ability of two Brassica varieties in relation to biomass allocation and morphological plasticity under varying nutrient availability

Green cabbage (Brassica campestris, leafy variety) and turnip (Brassica campestris var. rapifera, rooty variety) were grown in both monocultures and mixtures at three nutrient levels to investigate their responses to nutrient availability with respect to biomass allocation, morphological plasticity and competitive ability. Their allocation parameters and leaf morphological traits were affected by both nutrient availability and developmental stage. Both of the varieties had a smaller biomass allocation to leaf blades, but a greater allocation to petioles at high nutrient levels. Root:shoot ratio (RSR) of green cabbage decreased with increasing nutrient availability, whereas that of turnip increased. Turnip had a smaller leaf blade weight ratio (LBWR) than cabbage, being compensated for by larger leaf area ratio (LAR) and specific leaf area (SLA). Leaf area ratio and SLA of both the varieties increased with increasing nutrient availability as did their mean dry weights. The mean dry weight of turnip was slightly greater than that of green cabbage in their respective monocultures, while that of green cabbage was greater than that of turnip in their 1:1 mixture. Therefore, green cabbage, having inherently greater biomass allocation to leaves, was generally more competitive than turnip with more biomass allocation to roots, especially at higher nutrient levels. However, within a variety, morphological plasticity (variation in LAR and SLA) was more important than the plasticity in biomass allocation (e.g. variation in RSR and LBWR) in determining competitive ability. The implication of our results is that competition models based on biomass allocation pattern alone may fail to predict competitive outcomes and that such models should also take morphological plasticity into full account.     

不同小麦品种对播娘蒿的影响

播娘蒿是黄淮麦区主要田间杂草,在管理粗放的麦田,播娘蒿密度可达100株·ｍ-2以上,严重影响了小麦的产量和品质。因此,对小麦-杂草复合体中杂草的生长发育规律进行研究,寻找降低草害的有效途径引起许多学者极大关注[1,2],而目前有关防除麦田杂草的研究多集中于化学防治方面[3]。然而,出于环境保护和经济成本上的考虑,化学除草受到了挑战。研究人员[4,5]发现,不同物种在竞争力上存在差异,禾谷类作物属于竞争力很强的作物[6],冬小麦及冬黑麦又是其中竞争力最强的物种。就小麦栽培种而言,存在着不同的品种类型,研究不同小麦品种对杂草的抑制作…     

Shift in competitive ability mediated by soil biota in an invasive plant

Understanding the shifts in competitive ability and its driving forces is key to predict the future of plant invasion. Changes in the competition environment and soil biota are two selective forces that impose remarkable influences on competitive ability. By far, evidence of the interactive effects of competition environment and soil biota on competitive ability of invasive species is rare. Here, we investigated their interactive effects using an invasive perennial vine, Mikania micrantha. The competitive performance of seven M. micrantha populations varying in their conspecific and heterospecific abundance were monitored in a greenhouse experiment, by manipulating soil biota (live and sterilized) and competition conditions (competition‐free, intraspecific, and interspecific competition). Our results showed that with increasing conspecific abundance and decreasing heterospecific abundance, (1) M. micrantha increased intraspecific competition tolerance and intra‐ vs. interspecific competitive ability but decreased interspecific competition tolerance; (2) M. micrantha increased tolerance of the negative soil biota effect; and (3) interspecific competition tolerance of M. micrantha was increasingly suppressed by the presence of soil biota, but intraspecific competition tolerance was less affected. These results highlight the importance of the soil biota effect on the evolution of competitive ability during the invasion process. To better control M. micrantha invasion, our results imply that introduction of competition‐tolerant native plants that align with conservation priorities may be effective where M. micrantha populations are long‐established and inferior in inter‐ vs. intraspecific competitive ability, whereas eradication may be effective where populations are newly invaded and fast‐growing.     

Birth rate and mortality rate of infants with congenital malformations of the limbs in the Awajishima free-ranging group of Japanese monkeys (Macaca fuscata)

The birth rate and mortality rate of infants with congenital malformations of the limbs were examined in the Awajishima free-ranging group of Japanese macaques (Macaca fuscata). Of the 606 infants born between 1978 and 1995, 86 (14.2%) were malformed. The male-female ratio did not differ between malformed and normal infants. Most kin-groups included females who gave birth to malformed infants at least once. The mortality rate within the first year after birth for malformed infants (28.2%) was significantly higher than that for normal infants (10.0%). However, this indicates that more than 70% of malformed infants were able to survive for the first year of life, even though they were unable to cling to their mothers ventrum due to their limb deformities. This finding indicates that maternal care-taking is sufficient to enable malformed infants to survive during the early stages of development and that clinging by the infant is not necessary for the display of maternal care. Am. J. Primatol. 42:225–234, 1997. © 1997 Wiley-Liss, Inc.     

聚四氟乙烯对温带臭虫爬行能力的影响

温带臭虫Cimex lectularius L.是一种重要的卫生害虫,严重影响人们的生活和健康。目前有关该虫的防治措施主要以喷洒化学杀虫剂为主,而杀虫剂的使用不当极易导致该虫抗药性的产生或进一步加重,还将对人身安全构成极大的威胁。因此,探索高效、安全的防治方法成为当前温带臭虫防治过程中亟待解决的问题。本研究在实验室条件下采用行为观察法评估了高分子聚合物-聚四氟乙烯对温带臭虫垂直和水平爬行能力的影响。结果表明,随着聚四氟乙烯涂层宽度的增加,温带臭虫的垂直攀爬能力逐渐降低,当涂层宽度为6 cm时可100%阻隔温带臭虫垂直攀爬,且涂层的持效期可达112 d以上。而聚四氟乙烯涂层无法阻止温带臭虫的水平扩散。研究结果可为温带臭虫的高效、安全物理预防提供理论依据和技术支持。     

基于4种光响应模型模拟不同砧木对夏黑葡萄耐弱光能力的影响

采用直角双曲线模型、非直角双曲线模型、直角双曲线修正模型和指数模型4种光响应模型分别拟合夏黑/贝达、夏黑/1103P、夏黑/101-14、夏黑/3309C、夏黑/140Ru、夏黑/5C、夏黑/5BB、夏黑/420A、夏黑/SO4、夏黑/抗砧1号、夏黑/华葡1号11种砧穗组合的光响应曲线,通过拟合程度、光补偿点、光饱和点、初始量子效率、最大净光合速率、暗呼吸速率等6个参数分析比较其拟合效果.结果表明: 4种模型拟合系数都在0.98以上,在光补偿点上,4种模型拟合效果相差不大,但直角双曲线修正模型在光饱和点、初始量子效率、最大净光合速率和暗呼吸速率方面拟合程度最好,运用赤池信息量准则计算,直角双曲线修正模型赤池信息量准则(AIC)值也最小,因此,直角双曲线修正模型为最佳拟合模型.通过聚类分析发现,夏黑/SO4、夏黑/420A两砧穗组合的表观量子效率高、光补偿点低、暗呼吸速率低,说明两者对弱光的利用效率高,耐弱光能力强,呼吸消耗少.通过Topsis (Technique for Order Prefe-rence by Similarity to an Ideal Solution)方法综合排名发现,夏黑/SO4、夏黑/420A组合耐弱光能力分别为第1、2名,与聚类分析结果一致.因此,夏黑以SO4或420A作为砧木的耐弱光能力最突出,更适合设施栽培.     

Effect of delayed first feeding on development and feeding ability of Paralabrax maculatofasciatus larvae

The impact of delayed feeding early in development on late feeding ability and development of spotted sand bass Paralabrax maculatofasciatus larvae was examined. Larvae were sampled from hatching until day 19 after delayed feeding for zero (control), 1, 2, or 3 days. Feeding incidence was evaluated as the percentage of larvae with food in the gut and feeding intensity was measured by direct counting of prey after dissection of the gut. Delayed feeding effects due to starvation were observed early in development. By day 5, significant differences ( P  < 0·05) were observed between controls and larvae submitted to degrees of delayed feeding, including total length ( L _T), eye diameter, and the size of the head, liver, gut, muscles and body. Differences were still apparent in L _T, and body, liver and muscle heights at the end of the studied period. Larvae under total starvation did not survive beyond day 5. Initial feeding incidence was 35, 60, 90 and 10% for larvae first fed on day 2, 3, 4 or 5, respectively. Mean ±  s . d . feeding intensity was 3·6 ± 0·8, 2·8 ± 1·3, 5·2 ± 0·3, and 10·2 ± 1·5 rotifers per larva depending on whether larvae were initially fed on day 2, 3, 4 or 5, respectively. The point of no return occurred between 4 and 5 days after hatching.     

Extraction of defatted rice bran by subcritical water treatment

Defatted rice bran was treated with subcritical water in the temperature range of 180–280 °C for 5 min using 117 mL and 9 mL vessels to produce the extracts. The total sugar and protein contents and radical scavenging activity of the extracts were then estimated for both vessels. The total sugar concentration of ca. 0.3 g/L-extract was the highest for the extracts at 200 °C, and it significantly decreased at the higher temperatures. The protein concentration and radical scavenging activity were higher at the higher temperatures. Extraction was also done at 200 °C and 260 °C for various times using the small vessel. The total sugar concentration decreased with the increasing extraction time, while the protein concentration and radical scavenging activity only slightly depended on the extraction time. The extracts at 200 °C or lower temperatures using the large vessel possessed the emulsifying and emulsion-stabilizing activities. The HPLC analysis of the extract at 260 °C for 5 min using the small vessel indicated that it contained both hydrophilic and hydrophobic substances. The hydrophilic fraction of the extract mainly contained low-molecular-mass substances.