五种藏医药用植物叶解剖结构特征的研究

通过对分布于青藏高原东北部海拔 380 0～ 440 0m处生长的五种高山藏医药用植物结构进行的显微观察。进一步探讨青藏高原高山植物独特生理结构与自然环境间的相互影响及适应性。结果表明 :五种植物的叶表皮细胞单层 ,有的叶表面密被表皮毛 ,角质层厚 ;叶肉组织中栅栏组织均多层 ,并普遍形成发达的通气组织。这些特征是高寒地区低氧、低温、强辐射等自然条件长期作用的结果。     

塑料大棚内黄瓜叶片露时的计算方法

1.采用单叶的能量平衡方法,建立大棚黄瓜叶片的露时模式。模式运行结果:结露期间的叶片温度计算值与测量值差异极不显著(|t|0.50,S=0.291,n=25);结露时间、露干时间和露时的计算值与观测值差异不显著(|t|0.40,平均差异分别为21、-6和-25分钟。2.根据叶湿频率与相对湿度的关系,得出大棚黄瓜叶片结露的临界相对湿度为93％。用此临界相对湿度估算露时,误差一般不超出1小时。     

Quality of different mulch materials and their decomposition and N release under low moisture regimes

During the dry season in the tropics, agriculture which is solely dependent upon rainfall as its source of water is frequently affected by soil moisture stress, resulting in crop failures. Farmers therefore depend mainly on other sources of limited water supply during this period, such as ground water. Soil moisture conservation measures, especially surface mulching with loppings and, occasionally, leaf litter and crop residues, are practised. Our objective was to study the decomposition and nitrogen (N) release from these plant materials under continuously wet, low moisture regimes, i.e. comparable to those which prevail in the mulches used in the agriculture. A greenhouse experiment was conducted with fresh, chopped leaves of six leguminous trees, wild sunflower and rice, which were spread as a mulch on a layer of soil. They were maintained at eight moisture levels (a total of between zero and 43l water m^–2 applied over 8 weeks) by spraying water. Different optimal moisture requirements for the rapid decomposition of these species were observed. These were presumably determined by different physical and chemical properties of the leaves. The amount of water received to the mulches and their soluble polyphenolic and carbon (C) concentrations played an important role in determining the decomposition and the mode of N release under non-limiting conditions of leaf N. Specifically, the C concentration governed N release, while the effect of polyphenolics was important when their concentration was low, as a result of leaching under relatively high moisture regimes. Leaves with a high polyphenolic and C content, which were subjected to high leaching losses of these fractions, underwent a change in their N dynamics from net immobilization to mineralization. This study indicates that leaves with a fast rate of decomposition should be mixed with other species, leaves which decompose more slowly in order to increase the conservation of soil moisture and also improve the synchronization between N release from the mulch and its demand by crops. Received: 6 January 1997     

The Machine Recognition for Population Feature of Wheat Images Based on BP Neural Network

Recognition and analysis of dynamic information about population images during wheat growth periods can be taken for the base of quantitative diagnosis for wheat growth. A recognition system based on self-learning BP neural network for feature data of wheat population images, such as total green areas and leaves areas was designed in this paper. In addition, some techniques to create favorable conditions for image recognition was discussed, which were as follows: (1) The method of collecting images by a digital camera and assistant equipment under natural conditions in fields. (2) An algorithm of pixei labeling was used to segment image and extract feature. (3)A high pass filter based on Laplacian was used to strengthen image information. The results showed that the ANN system was availability for image recognition of wheat population feature.     

3种类型红檵木叶总黄酮含量测定及花与叶红色素的TLC比较

对3种类型红檵木的幼叶与老叶进行了总黄酮提取及分光光度比色法测定,并进行了嫩叶红红檵木品种的花和幼叶红色素的硅胶G薄层层析(TLC)比较分析。结果表明:总黄酮含量以嫩叶红红檵木幼叶为最高,达1.02%;3类品种之间的总黄酮含量排序是:嫩叶红幼叶>透骨红幼叶>双面红幼叶,嫩叶红老叶>双面红老叶>透骨红老叶。TLC分析结果表明:嫩叶红幼叶与花的红色素含有相同的颜色成分。     

柑桔枝叶形态解剖特征与抗寒性的关系

将35个柑桔品种、类型的枝叶形态解剖观测的数值,分别与冻害级数进行相关回归分析。春梢越冬期木栓层厚度与冻害级数极显著的负相关(r=-0.9266),春叶叶面积与冻害级数呈极显著的正相关(r=0.8144),均可作为柑桔抗寒性鉴定的主要指标。春叶栅栏组织厚度与叶厚的比值与冻害级数呈极显著负相关(r=-0.5455),可作为柑桔抗寒性鉴定的重要补充指标。叶下表皮气孔密度与冻害级数呈极显著正相关(r=0.4748),可作为抗寒性鉴定的参考指标。上述指标测试较为简便且准确。     

Plant species identification using Elliptic Fourier leaf shape analysis

Elliptic Fourier (EF) and discriminant analyses were used to identify young soybean (Glycine max (L.) merrill), sunflower (Helianthus pumilus), redroot pigweed (Amaranthus retroflexus) and velvetleaf (Abutilon theophrasti Medicus) plants, based on leaf shape. Chain encoded, Elliptic Fourier harmonic functions were generated based on leaf boundary. A complexity index of the leaf shape was computed using the variation between consecutive EF functions. Principle component analysis was used to select the Fourier coefficients with the best discriminatory power. Canonical discriminant analysis was used to develop species identification models based on leaf shapes extracted from plant color images during the second and third weeks after germination. The classification results showed that plant species during the third week were successfully identified with an average of correct classification rate of 89.4%. The discriminant model correctly classified on average: 77.9% of redroot pigweed, 93.8% of sunflower, 89.4% of velvetleaf and 96.5% of soybean. Using all of the leaves extracted from the second and the third weeks, the overall classification accuracy was 89.2%. The discriminant model correctly classified 76.4% of redroot pigweed, 93.6% of sunflower, 81.6% of velvetleaf, 91.5% of soybean leaf extracted from trifoliolate and 90.9% of soybean unifoliolate leaves. The Elliptic Fourier shape feature analysis could be an important and accurate tool for weed species identification and mapping.     

低温弱光对西葫芦叶片解剖结构的影响

研究了不同温度和光照条件对西葫芦幼苗叶片解剖结构的影响。研究结果表明,低温弱光处理使得西葫芦叶片上下表皮细胞密度、细胞直径、气孔密度以及气孔长度均变小,叶片厚度变薄,栅栏组织厚度及叶片厚度均减小,海绵组织也变得更为疏松,栅栏组织/海绵组织的比值减小,细胞间隙变大。     

菱湖公园3种阔叶树种叶片叶绿素含量对比

对菱湖公园3种阔叶树叶片进行一系列的研究。结果表明：①3种阔叶树叶片叶绿素含量对比中,女贞的叶绿素a、叶绿素b的含量最高;②3种阔叶树叶片叶绿素光合作用对比中,女贞叶片光合作用最高;③3种阔叶树叶片含水量对比中,法国冬青的含水量最高。     

南方红豆杉叶片性状的遗传变异及相关性研究

为了选育南方红豆杉优良品种,研究南方红豆杉实生后代的遗传变异规律,对福建明溪的南方红豆杉实生后代叶片性状5个方面的遗传变异情况进行调查分析。结果表明:叶宽变异度最大,变异系数为19.05%,其他性状的变异系数在10.46%～16.77%。叶片性状变异表现为连续性变异,属于数量性状遗传;叶片性状的分布表现为正态分布规律,偏倚系数较小;叶片性状多个指标的相关性显著,其中叶长与叶宽呈现极显著性正相关,叶长与叶厚、单位叶片数量,叶宽与叶厚、叶型指数呈现极显著性负相关。