夏季遮荫改善大田牡丹叶片光合功能的研究

利用气体交换和叶绿素荧光分析技术,研究大田牡丹叶片在自然光照和夏季遮荫处理下光合作用日变化.结果表明:自然光下夏季牡丹叶片的净光合速率(Pn)明显低于春季,2个生长季节Pn日变化差异明显,即春季的Pn日变化呈"单峰型"曲线,夏季的Pn日变化为"双峰型"曲线,有明显的光合"午休";羧化效率(CE)变化趋势与Pn相似;表观量子效率(AQY)中午降低,下午逐渐回升;光系统Ⅱ(PSⅡ)最大光化学效率Fv/Fm和最大荧光Fm日变化为倒"单峰型"曲线,中午明显降低;与夏季自然光下相比,夏季遮荫处理(遮光50%)的牡丹叶片Pn、AQY、CE升高;气孔限制值(Ls)和叶温(t1)降低;Fv/Fm和Fm中午下降幅度显著减小.这些结果说明:夏季晴天中午高温、强光下,牡丹叶片PSⅡ反应中心发生了可逆失活,PSⅡ功能下调,光合作用的光抑制明显发生,遮荫可减轻光抑制,改善光合功能以增加光合产物积累.     

1—MCP对苹果梨采后生理效应和品质的影响

以苹果梨为试验材料,研究了300 nl.l-1和600 nl.l-1浓度的1—MCP对苹果梨在贮藏条件下果实的呼吸速率、乙烯释放速度、果实硬度、可溶性固形物和可滴定酸的影响。结果表明:1—MCP对延缓果实衰老、抑制乙烯生成有很好的作用;可明显推迟果实硬度下降,维持果实较高的可溶性固形物含量(TSS)和可滴定酸含量。600 nl.l-1浓度处理比300 nl.l-1浓度处理效果明显,但差异不是很显著。     

樟树幼林生物化学参数与高光谱遥感特征参数相关分析

高光谱遥感在植被研究中的应用使定量估算植被的生物化学参数和生物物理参数成为可能.分析了樟树幼林生物化学参数与高光谱特征变量之间的相关关系.结果表明:樟树幼林的大部分生物化学参数(叶绿素a含量、叶绿素b含量、叶绿素总含量、类胡萝卜素含量和总磷含量)与高光谱遥感特征参数(蓝边内最大的一阶微分、绿峰反射率、红边位置、蓝边面积、绿峰反射率和红谷反射率构成的比值与归一化植被指数、红边面积和蓝边面积构成的比值和归一化植被指数)之间的相关系数达到了0.01极显著性检验水平;纤维素、总氮含量与高光谱特征参数的相关系数没有达到显著性检验水平.因此,可以利用相关系数达到了0.01极显著性检验水平的高光谱特征参数建立樟树幼林生物化学参数的高光谱遥感估算模型.     

探测树势的电测技术--电容法

1994－1999年，对油松、侧柏、桧柏、白皮松、黑松、银杏等树种进行了树林电容测定。结果表明：树体电容参数不仅能准确地反映树木当时的生理状况，而且可将一个抽象的生长势概念变成一个具体数量，来进行数量比较与统计分析，在林业生产管理上有广泛的应用前景。     

多胺在果蔬冷藏中生理效应和作用机制

本文在总结前人研究的基础上，对多胺的代谢特点和冷藏中的生理效应进行了分析，提出多胺抑制冷害发生可能的作用机制，为多胺在果蔬贮藏中的应用和研究提供理论探讨。     

“果畜结合”生态果园调查报告

果畜结合是改善洛川县果园土壤有机质含量低、土壤肥力不足,提高苹果产量和质量有效途径。     

11 种城市木本植物叶片生理物质对遮荫的响应

通过遮光率45%、75%和全光照3种光生境的植物栽培试验,测定了11种城市木本植物叶片叶绿素、花青素、可溶性糖、淀粉和蛋白质的变化,分析了遮荫对不同木本植物生理物质变化的影响,结果表明,遮荫能增加多数植物的叶绿素含量,明显降低花青素含量,特别是色叶植物,从而影响色叶植物的叶色效果,遮荫可减少色叶植物可溶性糖的含量,而增加非色叶植物可溶性糖含量,但对不同类型植物可溶性糖含量的影响幅度不一;遮荫能减少大多数植物的淀粉含量,但使部分色叶植物的淀粉含量增加,而不同遮荫程度对植物叶片淀粉含量的影响没有明显的规律性;光生境变化对植物叶片蛋白质影响缺乏明显的规律性,影响幅度也不一。     

Cold tolerance of Acacia karroo and A. nilotica, two tree species from South Africa, in Beijing

Fynbos plant communities developed under geographic and climatic conditions unique to South Africa. Acacia karroo is the most widespread tree species, well known for its drought tolerance. A. nilotica exudes a good quality gum which is edible and suitable for confectionery. The two species have been introduced to China but little is known about their adaptability under the new environmental conditions. For our present study, the growth potential and physiological and biochemical parameters of the two species in response to cold stress were investigated. The results, measured as seed qualities (purity, thousand seed weights, germination, etc.) show differences between A. karroo and A. nilotica. The seed germination rate was between 10% and 60%. Seedlings were established in fields, pots and plugs. Those in the field grew well during the growing season but completely died in the winter. Those in pots or plugs were moved to and managed in the greenhouse. The plants were green in winter. The electrical conductivity of cells, the contents of water soluble sugars, proteins, malondialdehyde (MDA) increased during eight hours of low temperature treatment at 4℃. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) decreased markedly during the eight hours of 4℃treatment. We conclude that A. karroo and A. nilotica have little adaptability to the cold winter weather and cannot survive in the outdoors in the Beijing area, but could grow well indoors as ornamentals.     

几种药剂浸种处理对西瓜幼苗生长的影响

采用黄腐酸盐、绿风95、稀土、爱多收、油菜素内酯等几种药剂对西瓜进行浸种处理,测定其对西瓜幼苗某些生长、生理指标的影响。结果表明:采用几种药剂处理后,与相应的对照相比,均可提高叶绿素含量、增加根系活力、促进幼苗生长,从而有利于西瓜的壮苗培育。从几种药剂处理对西瓜的营养生长及生理指标的影响进行综合判断可知,以爱多收处理为最好。     

Power spectrum density and experimental modal analysis of wide belt sander applied in domestic wood industry

This paper took the upper-lower wide belt sander B229 with four-feet wide belts, manufactured in China, as the study target. By means of framework dynamic design, we study its vibration characteristics by commencing from the place having horizontal defects and used experimental modal analysis (EMA) and power spectrum density (PSD) to observe the sanding parts and the whole machine, respectively. In the modal test, we mainly adopted the cross spots testing method to get the frequency response function of the fixed spots to every excitation vibration spot, then applied the SISO frequency response function and the frequency response function fitting method to identify and complete parameter recognition, respectively. The typical frequency response function chart of the whole machine and its sanding parts, as well as its second-order mode charts of contacting roller, were obtained. Through PSD analysis, we can get the amplitude-frequency spectrum and drive frequency. Translated from Scientia Silvae Sinicae, 2005, 41(6): 132–137 [译自: 林业科学]