几种落叶果树H2O2含量变化与自然休眠关系的研究

 以设施栽培中常见的几种核果类果树品种和两个葡萄品种为试材, 分析了芽休眠期间 H₂O₂含量变化动态, 并探讨了温度、生长调节剂及化学破眠物质对H₂O₂含量影响的效应。结果表明: 休眠期间,不同树种( 品种) 芽内 H₂O₂含量存在差异, 基本趋势是晚熟品种高于早熟品种, 花芽高于叶芽, 但葡萄品种相反, 早熟的‘京秀’高于晚熟的‘巨峰’; 休眠期芽内 H₂O₂含量基本呈稳步上升后急剧下降的趋势,不同品种急剧下降的时间略有差别, 且与自然休眠解除的时间相吻合。低温(5 ℃) 处理显著增加了芽中 H₂O₂含量, 中温(10 ℃) 使 H₂O₂含量略有增加, 而高温(20 ℃) 却导致 H₂O₂含量降低。休眠前期50 mg.L^-1 ABA 处理显著提高了芽中H₂O₂含量, 而100 mg.L^-1的GA₃和6-BA 处理有减少 H₂O₂含量的趋势, 但二者差异不明显。热带地区常用的化学破眠物质对芽 H₂O₂的影响因树种( 品种) 、使用时期不同而异, 硫脲、KNO₃前期使用对核果类果树影响明显, CaCN₂对核果类无明显效应, 但对葡萄品种作用显著。果树芽 H₂O₂含量的动态变化表明, H₂O₂可能是低温解除自然休眠的原因。     

云南特有野生果树资源及其分布特点

 云南有各类野生果树资源约500 余种, 其中云南特有的164种, 分属35科54属, 多为热带、亚热带果树和浆果类果树, 形成滇南—滇东南、滇西—滇西北和滇中—滇东北3个特有野生果树集中分布中心。这些果树资源用途广泛, 优异性状明显, 有待深入研究和综合开发利用。     

苹果粗皮病与锰含量的关系

对胶东半岛部分发生苹果粗皮病(IBN)的果园的土壤和植株进行了分析测定,结果表明:发生苹果粗皮病的果园土壤有效锰含量较高,而且粗皮病严重果园高于粗皮病较轻果园。发生粗皮病的苹果树花器官中锰含量较高,粗皮病最严重的姜格庄果园苹果树花器官中锰平均含量比观水镇高出139.28mg/kg,比季家埠重病园和轻病园分别高122.34和182.19mg/kg。从4月到10月,苹果粗皮病逐渐加重,叶片中锰含量逐步增高。10月份姜格庄果园最高锰含量达1717.85mg/kg,平均锰含量达1119.69mg/kg,而粗皮病较轻的季家埠果园则仅306.03mg/kg,前者比后者高265.88%。对不同部位锰含量测定表明,锰含量在叶片中最高,其次是韧皮部,木质部最低。表明胶东半岛苹果粗皮病的发生是因为锰过量。可能是土壤锰含量高,pH值低,降雨多,施肥不合理等,造成土壤锰有效性增加.导致树体吸收过量而出现粗皮病害。     

Effects of platelet-derived growth factor on DNA and collagen protein synthesis in human vascular fibroblasts

AIM: To investigate the effects of platelet-derived growth factor on DNA and collagen protein synthesis in human vascular fibroblasts. METHODS: In the present experiment, the human vascular fibroblasts were cultured and effects of platelet-derived growth factor-BB on DNA and collagen protein synthesis in human vascular fibroblasts were observed by using [³H]-TdR incorporation and [³H]-proline incorporation in vitro. RESULTS: Platelet-derived growth factor-BB significantly promoted NDA synthesis and collagen protein synthesis of quiescent human vascular fibroblasts, with a maximal response at a concentration of 30μg·L^-1at 24 h and 36 h, respectively. CONCLUSION: Platelet-derived growth factor-BB promotes DNA and collagen protein synthesis in cultured human vascular fibroblasts.     

Variation of Parthenium hysterophorus in response to soil quality: implications for invasiveness

Summary The performance of Parthenium hysterophorus , native to the tropical Americas and invasive to several countries, was evaluated for response to soil quality. Phenological (six stages) and quantitative growth variables [relative growth rates in height (R_h) and diameter (R_d)] were measured every fortnight. Based on harvest data, the variables, root:shoot (R:S) ratio, specific leaf area (SLA), relative growth rate in biomass (R_w), net assimilation rate (NAR) and dry matter allocation to plant components, were determined. High clay content in soils prolonged the rosette stage, enhanced R_h and R_d and hampered root growth, but promoted biomass allocation to shoots. The extreme degree of plant mortality was observed, with only 33.3% individuals surviving to reproduce in the soils with highest clay contents. This appears to be one of the most important findings that certainly has a major bearing on the range of adaptation of the weed. Seed mass declined whereas seed production increased in relatively coarser soils with the exception of nearly pure sand. In soils rich in clay, plants produced a smaller number of larger seeds. These data suggest that variation in fundamental functional traits would enable P. hysterophorus to adjust to a variety of habitat conditions.     

Laboratory evaluation of the insect growth regulator lufenuron againstHelicoverpa armigera on cotton

An insect growth regulator (IGR), lufenuron (Match 5EC), was tested for its toxicity toHelicoverpa armigera on cotton. Potency of the IGR against the larval stage of the pest was demonstrated with respect to larval instars; the LC₉₀ values of 1st, 2nd, 3rd, 4th and 5th instar larvae were 5.63, 7.89, 8.03, 11.39 and 14.76 mg a.i.l ⁻¹, respectively. However, different larval instars did not differ significantly with respect to LC₅₀ and LC₁₀. IGR-treated larvae had swollen heads and were significantly smaller (1.5–2.3 mm) than the untreated control (2.9 mm). Larval weight was significantly reduced from 190 mg in the control to 50–70 mg in the lufenuron treatment. IGR treatment in the larval stage significantly affected both pupal length and pupal weight. Pupal duration of the test insect was significantly extended by IGR treatment. Pupal deformities, including an inability to shed the last larval skin and formation of larval-pupal intermediates, occurred following treatment. A significant reduction in adult emergence was recorded. In addition, abnormalities in the form of development of cavities in the forewings of adult were evident. A significant decline in fecundity was noted in the studies. http://www.phytoparasitica.org posting Feb. 3, 2003.     

The ecological fitness of ALS-resistant Amaranthus retroflexus and multiple-resistant Amaranthus blitoides

Summary Field studies were conducted to evaluate the ecological fitness of Amaranthus spp. biotypes that evolved resistance to either acetolactate synthase (ALS) inhibitors ( A. retroflexus , SuR), to triazine herbicides ( A. blitoides , SuS/TR), or to both ( A. blitoides , SuR/TR), and estimate their ecological fitness under competitive conditions. The plants were grown in monoculture and in replacement series experiments. The examined mixtures were 100%S, 75%S/25%R, 50%S/50%R, 25%S/75%R and 100%R, at a constant stand of 400 plants m⁻². The SuR and SuS A. retroflexus biotypes attained similar shoot dry biomass per plant, biomass per plot and relative yield total (RYT) = 1. In monoculture, the final shoot biomass of A. blitoides biotypes SuS/TS plants was higher than that of SuR/TR and SuS/TR. A negative effect of association was observed, amensalism, when SuS/TS was grown in mixture with SuR/TR, in favour of the wild type. However, SuR/TR and SuS/TR biomass was not influenced by the presence of the competitor. These data support the hypothesis that the ALS-resistance trait in A. retroflexus and A. blitoides is not associated with growth penalty and did not incur ecological cost in the field. We suggest that the cause of the observed reduction in growth rendering the SuS/TR and SuR/TR less fit than the wild type is due to the triazine resistance, and may facilitate their dissipation.     

Restoration of tuber production by exposure to unshaded daylight in Eleocharis kuroguwai Ohwi shaded during the early tuber formation period

The loss of final tuber weight of Eleocharis kuroguwai Ohwi by shading during the early tuber formation period (TFP) is overcome by exposure to unshaded daylight thereafter (late TFP). In the present study, the growth parameters that contribute to the dry matter increase (DMI) per day of tubers in the late TFP were examined. DMI of the tuber during the late TFP was determined by that of the whole plant and the ratio of the DMI of the tuber to that of the whole plant during this period. The ratio of the DMI of the tuber to that of the whole plant during the late TFP was significantly correlated with the DMI of the whole plant during the first 14 days of the late TFP. During the late TFP after the exposure to unshaded daylight, DMI of the whole plant correlated with the surface area of the stem (SAS) and net assimilation ratio (NAR), and the SAS correlated with the stem dry weight (DW) and specific stem-surface area (SSA). SSA negatively influenced NAR, but NAR was increased by unshading. During the late TFP after shading, the effect of the decrease of the stem DW due to shading on the DMI of the whole plant was mitigated by the large SAS and high NAR. These results indicate that the growth parameters that contribute to the DMI of tuber during the late TFP after exposure to unshaded daylight are SAS and NAR just after unshading, and SSA during this period.     

土壤改良对越桔生长的影响

在盆栽条件下,对生长越桔的土壤进行改良。通过土壤pH值的变化、生长量及相关指标的分析对比,获得适合越桔生长的土壤改良类型。试验研究表明,pH值4.0～5.0的苔藓 草炭 原土 S土壤改良类型适合于越桔的生长,植株的高度、粗度、基生枝数等都明显增加。从各指标上观察,原土 2S的土壤改良类型也具有一定优势,说明在土壤有机质充足的基础上,只需调酸,越桔就能正常生长。     

荔枝环剥时期对新梢生长及碳素储备的影响

 枝梢环剥显著抑制了‘怀枝’荔枝新梢的生长，并导致射线细胞和髓部大量积累淀粉。梢芽萌发或伸长前环剥可完全抑制新梢生长，而新梢快速伸长期环剥对其抑制效应最弱。秋季环剥对新梢的抑制和对淀粉积累的促进效应明显高于春季环剥。环剥口以上的老叶面积和环剥位置并不影响环剥对新梢生长的抑制效应和促进淀粉的积累效应，但环剥口以上单位枝梢长度的叶面积与淀粉含量呈显著正相关。