Indicators of Cotton Nitrogen Status

ABSTRACT

Nitrogen (N) deficiency limits cotton yields, while too much N causes excessive vegetative growth hurting yields, wastes expensive inputs, and causes environmental pollution. Diagnostic indicators are needed to assess cotton N status so that yields can be optimized as efficiently as possible. This study evaluated selected tools for predicting cotton responses to N fertilizer application. Petiole nitrate (NO₃)-N (PNN) concentration was found to correlate with cotton N status and a good indicator of potential for response to N application. Critical PNN concentrations for irrigated cotton in subtropical South Texas at first bloom, and 10, 20 and 30 d later were determined to be 15.0, 9.0, 4.5, and 2.0 g kg^{? 1}, respectively. These critical PNN levels are higher than in more humid areas of the traditional southern US Cotton Belt, probably due to the effects of the subtropical climate. Cotton plants in this area tend to be less vegetative, possibly due to shorter growing season day lengths, and therefore need to be “pushed” slightly harder with greater N fertilization. Leaf total N concentrations were found to be less responsive to changes in applied N than were PNN levels. Although leaf N tended to be more stable over time, there was no consistent pattern between years. Leaf N values of 35 g kg^{? 1} or less appear to represent a deficiency at any time, and optimum levels may be slightly higher. Nodes above white flower showed very small responses to N fertilization and the differences occurred late in the bloom period. Chlorophyll meter readings showed a good relationship with N fertilizer application within a given sampling date, but much greater variability occurred between dates and due to other factors. The most effective indicator of cotton N status was found to be PNN, and to a lesser extent leaf N, but none of other parameters could be recommended for purposes of making inferences as to N status of cotton.     

福建乌龙茶种质离体保存研究Ⅰ.成年茎段无菌系建立

以代表性乌龙茶品种铁观音成年新梢茎段为外植体,初步探讨了茶树成年茎段离体培养无菌系的建立.结果表明,外植体的适宜消毒方法为0.1%升汞浸泡11 min;适宜取材气候条件是连续晴天5 d以上;适宜取材部位是第二腋芽的茎段;适宜的诱导培养基为MS+2.0 mg.L-16-BA+0.5 mg.L-1IAA+0.5 mg.L-1GA3.     

福建乌龙茶种质离体保存研究Ⅱ 无菌系继代增殖与生根

本试验以铁观音茶树成年茎段离体培养诱导的丛生芽作为研究材料,探讨无菌系的继代增殖和生根。试验结果表明：适宜茶树成年茎段无菌系继代增殖的培养基为1/2MS＋1.0mg/L6-BA＋0.2mg/LIAA＋0.2mg/LGA3,培养基中附加8g/L琼脂糖,30g/L蔗糖,pH5.6。在此继代培养基上进行增殖,茶树成年茎段平均增殖率为7.57,最高增殖率可达13。适合茶树成年茎段离体培养生根的培养基是1/2MS＋3mg/LIBA＋30g/L蔗糖＋7g/L琼脂糖;研究还表明随着继代生长时间的延长,生根率提高,最早生根的天数缩短。     

在前临床期检测金仓鼠羊痒病淋巴结中病理型朊蛋白PrP（Sc）

12只雌性5周龄金仓鼠腹腔注射50μL羊痒病（SCRAPIE）263K株10%的脑组织匀浆。在临床前期,感染后第2、4、6、8、10、12周和临床末期第20周,金仓鼠被分别处死,取大脑、淋巴组织、脾脏、肾脏、肝脏、心脏和肌肉等组织,进行蛋白质免疫印迹杂交实验检测朊病毒病理型朊蛋白PrPSc。研究结果显示在临床前期,通过改进后的纯化技术,我们能够检测出淋巴组织和脾脏组织中的PrPSc,但是在肾脏、肝脏、心脏和肌肉等组织中仍然没有检测到PrPSc。     

松嫩平原野古草无性系种群的营养繁殖特征

野古草是典型的无怀系禾草,分蘖节存活时间最多为４ａ。割草场和放牧场野古草无性系种群的分蘖株为增长型的年龄结构;放牧能增加２、３龄分蘖株的形成与存活;野古草无性系种群１龄级分蘖株的生产力明显高于２龄级;割草场和放牧场的野古草无性系潜在种群均于增长的年龄结构。以硌潜在种群的数量估计,割草场将保护翌年群落的优势种地位和作用;放牧场具有向优势和演替的潜在趋势。     

99mTc-labeled dextran for mammary lymphoscintigraphy in dogs

Lymphoscintigraphy is the technique of choice for sentinel lymph node detection in women with early breast cancer, but there is limited information evaluating the value of this technique in animals. We investigated mammary lymphatic drainage in 25 young female mongrel dogs by intramammary injection of 18.5 MBq of 99mTc-dextran (70,000 Da). Lymph node anatomical referencing was obtained using an external marker, bone scintigraphy, or scintiscanning the body contour. Cranial and caudal thoracic mammary glands drained into the cranial sternal lymph node and axillary lymph center. The cranial thoracic mammary gland also drained into the superficial cervical lymph node in two of five animals. The cranial abdominal gland was drained by the axillary lymph center. The caudal abdominal mammary gland was drained by the superficial inguinal lymph node in all animals and simultaneously by medial iliac lymph nodes in four of five animals. In one dog, this mammary gland was also drained by the mediastinal and the superficial cervical lymph nodes. The inguinal mammary gland was drained by superficial inguinal lymph nodes and simultaneously via the medial iliac lymph node in one animal. Lymphatic communications between lymph nodes were identified in 11 of 25 (44%) animals. 99mTc-dextran mammary lymphoscintigraphy was easy and rapid to perform and may provide valuable information for further studies.     

基于传染病动力学模型的P2P文件传播研究

利用具有空间动力的多种群传染病传播模型的构建方法,充分考虑了P2P文件共享系统中节点的不同状态和变化,提出一种P2P文件传播模型.同时,给出了可以描述P2P文件传播效率的基本再生数计算公式.试验结果表明,该模型对于流行文件的下载情况符合较好,具有良好的应用价值.     

Immunophenotypic comparison of blood and lymph node from dogs with lymphoma

Peripheral blood and lymph node tissue from 12 dogs with lymphoma was immunophenotyped. Additionally, the bone marrow was immunophenotyped in 6 dogs. The lymphomas were characterized as B-cell in 11 dogs and T-cell in 1 dog. Immunophenotypic patterns in the peripheral blood and bone marrow were variable. The trend in dogs with B-cell lymphoma was normal to increased percentage of IgG-positive cells, decreased percentage of pan-T-positive cells, decreased percentage of CD4-positive cells, and decreased CD4/CD8 ratio. Simultaneous immunophenotyping of lymph node, blood and bone marrow cannot be recommended routinely without further studies to document its value as an independent prognostic indicator. However, it is potentially useful for tumor staging and monitoring remission, especially in lymphoma patients with a leukemic phase.     

福建乌龙茶种质离体保存研究Ⅱ 无菌系继代增殖与生根

试验以铁观音茶树成年茎段离体培养诱导的丛生芽作为研究材料,探讨无菌系的继代增殖和生根.试验结果表明:适宜茶树成年茎段无菌系继代增殖的培养基为1/2MS 1.0mg/L6-BA 0.2mg/LIAA 0.2mg/LGA3,培养基中附加8g/L琼脂糖,30g/L蔗糖,pH5.6.在此继代培养基上进行增殖,茶树成年茎段平均增殖率为7.57,最高增殖率可达13.适合茶树成年茎段离体培养生根的培养基是1/2MS 3mg/LIBA 30g/L蔗糖 7g/L琼脂糖;研究还表明随着继代生长时间的延长,生根率提高,最早生根的天数缩短.