Airborne laser scanning in forest management: Individual tree identification and laser pulse penetration in a stand with different levels of thinning

This study examined the ability of an airborne laser scanner to identify individual trees in the canopy of a Chamaecyparis obtusa stand and investigated the relationship between the penetration rate of the laser pulses and stand attributes under different canopy conditions caused by different levels of thinning. Individual tree crowns were identified from a digital canopy model (DCM) derived from airborne laser scanner data by the watershed segmentation method. The identification rate of individual trees in blocks with heavy thinning (ratio of the basal area of the felled trees to the total basal area, hereinafter thinning ratio of the basal area, 38.0%), moderate thinning (30.4%), and no thinning was 95.3%, 89.2%, and 60.0%, respectively. Individual tree heights were estimated from the DCM values by local maximum filtering within identified individual crowns. Tree height in the three blocks was estimated with a root-mean-square error of 0.95, 0.65, and 0.68 m, respectively. Tree heights determined in a field survey were regressed against those estimated from the DCM, yielding coefficients of determination (r²) of 0.71, 0.87, and 0.85, respectively, for the blocks with heavy thinning, moderate thinning, and no thinning, respectively, and 0.86 overall. The respective penetration rates of the laser pulses through the canopy to the ground were 50.6%, 43.1%, and 9.2%. Regression of the laser pulse penetration rate against the thinning ratio of the basal area and against the total basal area of the remaining trees in 25 quadrats established in the blocks, yielded r² values of 0.89 and 0.74, respectively.     

剪根与水分胁迫对小麦单根和细胞导水率及TaPIP基因表达的影响

剪去小麦部分根系能瞬间打破其水分平衡,研究根系导水特性对剪根的响应有助于解释静水压对作物根系吸水的调节机制。通过对苗期小麦(Triticum aestivum)剪根与水分胁迫处理,用压力探针技术测定单根和细胞两种尺度上的根导水特性变化,以及根中TaPIP1;2和TaPIP2;5的转录调节变化。结果显示,剪根处理或水分胁迫处理使叶片蒸腾速率和气孔导度均显著低于对照,而单根导水率和细胞导水率均与对照无显著差异。剪根处理的叶片蒸腾速率、气孔导度、叶水势、单根导水率和细胞导水率均显著高于水分胁迫处理,而剪根且水分胁迫处理的各参数均显著低于其他处理。各处理的单根导水率与细胞导水率显著正相关。各处理根中TaPIP1;2和TaPIP2;5相对mRNA含量的变化规律与单根和细胞导水率的变化规律相似。剪根处理显著上调了TaPIP1;2和TaPIP2;5转录,水分胁迫处理显著下调了其转录,但TaPIP1;2和TaPIP2;5在剪根且水分胁迫处理中的转录水平最低。这些结果表明,小麦的根导水特性在单根尺度和细胞尺度上具有一致性;剪根短期内能够增加小麦幼苗的水分敏感性。推测TaPIP1;2和TaPIP2;5参与了静水压对小麦根导水特性的调节过程。     

不同处理对锦橙贮藏效果的影响

为了测定不同处理对柑橘的贮藏效果,以锦橙果实为材料,对经不同果蜡(402F、自备蜡A、自备虫胶蜡B、自备蜡A与虫胶蜡B混合蜡液(A∶B=3∶7))及苹果包装处理后置于常温下贮藏果实的理化指标进行分析.结果表明,涂蜡和单果包装处理均能提高果实亮度、减少果实失重、降低腐烂率,其中以自备虫胶蜡B处理提高亮度最好,单果包装处理抑制果实失重显著优于其他处理,自备虫胶蜡B和自备蜡A与虫胶蜡B混合蜡液(A∶B=3∶7)降低腐烂率作用较为显著.     

不同播期和密度处理对超短季棉个体形态发育的影响

[目的]探讨不同播期和密度处理对超短季棉品种个体发育动态的影响,明晰它们对棉花营养生长和生殖生长的效应,为黄河流域冀东棉区棉花种植的播期和密度管理提供理论和实践指导。[方法]以超短季抗虫棉546系为材料,探讨了不同播期（播期I：5月20日．播期Ⅱ：6月2日,播期Ⅲ：6月14日）和密度（低密度：127万株／hm^2,中密度：15万株／hm＾2,高密度：18万株/hm＾2）处理对其个体生长发育动态的影响。[结果]不同的播期和密度处理对超短季棉546系的个体生长发育具有明显的影响,其中播期的影响效力要高于密度的影响效力,而播期对于棉株个体果枝数量发育的影响效力又明显高于对主茎伸长生长和加粗生长的影响效力。[结论]在黄河流域的冀中棉区对超短季棉546系栽培过程中,可以通过播期和密度的调控,有效地促进其营养生长和生殖生长,夯实其产量基础。     

基于大比例尺航片的单株立木坐标提取

以凉水林场1:8 000大比例尺航片上的树冠影像为基础,通过栅格矢量转换、转换算法调整及图层矢量编辑生成了红松(Pinus koraiensis)树冠多边形图层。在ArcGIS中对该图层通过VBA(Visual Basic For Applica-tions)编程调用多边形属性算法,提取红松树冠多边形的重心作为红松立木的坐标,并与实地实时动态差分法RTK(Real-Time Kinematic)精确定位面积为9 hm2的阔叶红松林样地内红松立木坐标数据进行了检验与分析。结果表明,对于胸径(HDB)达到30 cm以上的红松,其坐标提取精度达到90%以上,且径阶越高,提取精度越高。     

Influence of Storage Environment,Surface Coating,and Individual Shrink Wrapping on Quality Assurance of Guava (<Emphasis Type="Italic">Psidium guajava</Emphasis>) Fruits

Guava (Psidium guajava) fruits of cv. L-49 with individual shrink wrapping using 9 LLDPE film could be successfully stored up to 12 days at ambient and 18 days in evaporative cool chamber with negligible loss in vitamin C content. The untreated fruits lose 25–30% of ascorbic acid within 1week after harvest. Delay in senescence and metabolic activities as supported by less changes in soluble solids, sugars, acidity, respiration, and ethylene evaluation rate was also observed in individual shrink wrapped fruits in cool chamber. The spoilage of fruits by Fusarium rots was significantly less in cool chamber in individually shrink wrapped fruits followed by Sta-fresh treatment. Sta-fresh was more effective in cool chamber than ambient. Individually stored wrapped fruits scored a better value of sensory score than Sta-fresh under both the storage condition.     

农村籍女大学生教育个人直接成本实证研究——以西北农林科技大学为例

以西北农林科技大学为例,进行了农村女大学生教育直接成本的实证研究,并得出高等教育对于农民仍是不轻的负担这一结论.     

2个马铃薯杂交组合F1的SSR鉴定

杂交育种是马铃薯新品种选育的重要方法, 其杂种F₁真实性鉴定是获得目标性状单株的关键环节。为选育优质、高产、抗病性及抗旱性强的马铃薯新品种, 用马铃薯品种"费乌瑞它"(Favorita)分别与"J07-6"和"陇薯3号"杂交, 获得了杂种F1代。本试验利用SSR标记技术对"Favorita"×"J07-6"、"Favorita"×"陇薯3号"2个杂交组合F1共86个单株的真实性进行了鉴定。试验从43对SSR引物中筛选出2对适宜引物STM1049和S7。利用这2对引物进行PCR扩增, 将"Favorita"×"J07-6"杂交种F1和"Favorita"×"陇薯3号"杂交种F1的SSR带型划分为双亲互补型、缺失型、父本型和母本型4种类型。依据SSR带型特征, 从"Favorita"×"J07-6"和"Favorita"×"陇薯3号"2个杂交组合F₁单株中分别鉴定出真杂种34个和27个, SSR分子标记技术用于马铃薯杂交种真实性鉴定是可靠的。该研究结果可为马铃薯杂交种优良株系选育提供依据。     

农产品区域品牌“伞品牌”与“个别品牌”的互动机制研究

在相关文献的基础上,围绕农产品的区域品牌展开研究,通过对农产品区域品牌“伞品牌”与“个别品牌”进行定义,具体分析二者之间的互动关系,从而探讨农产品区域品牌中伞品牌的覆盖效应,以及品牌伞下子品牌对其的影响.以“凤桥水蜜桃”区域品牌的发展为例,通过实例分析进一步提出通过建立伞品牌与个别品牌的互动机制,更好地发展农产品区域品牌的策略.     

转Bt基因棉花对棉田天敌的影响

就转Bt基因棉花对棉田害虫寄生性天敌、捕食性天敌的个体发育和种群的影响进行了综述,并且分析了影响机理。