恒定磁场对小麦种子的生物物理机制研究

根据恒定磁场促进小麦种子三磷酸腺甙（ＡＴＰ）含量增加的作用,建立了线粒体在恒定磁场中的理论模型,并应用物理和生物化学的方法对模型进行了讨论,得出线粒体在恒定磁场下获得能量,得种子ＡＴＰ增加的根本原因。     

Optimal utilisation of natural resources for agricultural sustainability in rainfed hill plateaus of Orissa

The climatic data for 17 years from 1988 to 2004 of the rainfed hill plateaus of Kandhamal district of Orissa (India) were analyzed to find out the monthly climatic index from the calculated values of effective rainfall and evapotranspiration. The 80% dependable monthly climatic index was correlated with crop coefficient and suitable cropping period and sequences for the study area were suggested based on it. The extent of investment, net return and soil loss from agriculture were estimated as per the present condition and for the suggested cropping patterns. A mathematical model was formulated for optimal allocation of area to different crop sequences with different objectives viz. minimization of soil loss, minimization of investment and maximization of net return from agriculture and was solved using linear goal programming technique. The model suggested to take up food crops in area of 1,30,777 ha and perennial grass cover in 3223 ha with a cropping intensity of 1.61 resulting in a net return of Rs 1064.775 millions sustaining soil loss to a tune of 9489.67 thousand tons per year. The model was found to be favourable in respect of higher net return of Rs 8862.34 and lesser soil loss of 23.41 tons/ha than the corresponding present values. But more investment of Rs 4489.01 per ha was required to fulfill the objectives.     

海水淡化泵水润滑轴承间隙的优化设计

针对海水淡化高压泵水润滑轴承存在的润滑问题,设计了6种不同轴承半径间隙的水润滑轴承;用三维造型软件Pro/E建立了滑动轴承内部三维流动水膜数学模型;利用Fluent 6.2进行非结构化六面体/楔形网格划分,采用RNGk-ε湍流模型和SIMPLE算法,对不同轴承半径间隙内水膜的三维流场和同一轴承半径间隙不同偏心距下的水润滑轴承的动特性进行了模拟,得到了轴承内部动压力分布以及流量、承载力、刚度与轴承半径间隙之间的关系.结果表明,所研究的水润滑轴承在半径间隙为0.2 mm时性能最佳.模拟结果可以对水润滑轴承的润滑特性进行预测,可为高压泵水润滑轴承的优化设计和安全运行提供参考.     

南方水田耕整机械发展趋势及探讨

我国南方水田耕整机械经过了30多年的发展,已基本形成了多功能、多机型的格局.随着科学技术的创新与进步,水田耕整机械正朝高标准、智能化、自动化方向发展;但实现这一目标的任务还很艰巨,政府须给予政策和资金支持,保障科研成果及时转化、推进农机研发"产学研"结合.     

节水灌溉下秸秆还田形式对黑土区稻田N2O排放与产量的影响

为探寻不同灌溉模式下秸秆还田形式对黑土区稻田N2O排放与产量的影响,于2023年进行大田试验,设置常规灌溉（F）与控制灌溉（C）两种灌溉模式,同时设置秸秆还田（S）、秸秆炭化为生物炭还田（B）、秸秆过牛腹为有机肥还田（O）3种还田形式,以及秸秆不还田（N）作为对照组,共计8个处理。分析不同灌溉模式下秸秆还田形式对稻田N2O排放通量与水稻产量的影响,测定了水稻各生育期稻田土壤铵态氮含量、硝态氮含量、微生物氮含量、pH值,并分析了N2O排放总量和水稻产量与土壤环境因子之间的关系。结果表明：除返青期外,与秸秆不还田处理相比,秸秆还田与有机肥还田处理土壤铵态氮含量、硝态氮含量、微生物氮含量均表现为增加。相同秸秆还田形式下,控制灌溉模式下各处理生育期内土壤平均铵态氮含量、硝态氮含量较常规灌溉模式高36.23%~60.82%、14.16%~19.61%。同时,秸秆还田与生物炭还田能提高稻田土壤pH值。相同灌溉模式下,与秸秆不还田处理相比较,秸秆还田与有机肥还田处理N2O排放总量分别增加14.44%~24.09%、8.22%~14.44%,生物炭还田处理N2O排放总量降低14.31%~23.90%。生物炭还田与有机肥还田各处理水稻产量提高3.28%~13.07%,其中控制灌溉模式下生物炭还田处理产量最高。综上所述,控制灌溉下生物炭还田可以实现节水、增产、减排的目的。     

A critical appraisal of appendage disparity and homology in fishes

Fishes are both extremely diverse and morphologically disparate. Part of this disparity can be observed in the numerous possible fin configurations that may differ in terms of the number of fins as well as fin shapes, sizes and relative positions on the body. Here, we thoroughly review the major patterns of disparity in fin configurations for each major group of fishes and discuss how median and paired fin homologies have been interpreted over time. When taking into account the entire span of fish diversity, including both extant and fossil taxa, the disparity in fin morphologies greatly complicates inferring homologies for individual fins. Given the phylogenetic scope of this review, structural and topological criteria appear to be the most useful indicators of fin identity. We further suggest that it may be advantageous to consider some of these fin homologies as nested within the larger framework of homologous fin‐forming morphogenetic fields. We also discuss scenarios of appendage evolution and suggest that modularity may have played a key role in appendage disparification. Fin modules re‐expressed within the boundaries of fin‐forming fields could explain how some fins may have evolved numerous times independently in separate lineages (e.g., adipose fin), or how new fins may have evolved over time (e.g., anterior and posterior dorsal fins, pectoral and pelvic fins). We favour an evolutionary scenario whereby median appendages appeared from a unique field of competence first positioned throughout the dorsal and ventral midlines, which was then redeployed laterally leading to paired appendages.     

小田块变量施肥系统优化设计与应用

针对苏南地区推广变量施肥存在的施肥策略过于精细化导致高密度土壤信息不易获取和普通的施肥机械难以达到播量精度等主要技术障碍,该文建立了一种简单实用的变量施肥方案,在现有机械式播种施肥机基础上进行了自动化改造,构建了一套基于简易电子处方图系统的变量施肥系统;变量施肥作业时,以单个自然田块为处理单元,依托所建立的简单实用的电子处方图系统,实现多种肥料按需配比、同一田块均匀施肥、不同田块变量施肥的功能。为提高播量精度和播量稳定性,对普通精度GPS模块的数据进行了差分和卡尔曼滤波处理,对外槽轮施肥播种器结构进行了优化设计。田间试验结果表明:电子处方图运行结果准确,施肥播种机工作稳定,种子和肥料的最大和平均播量误差分别为3.91%和2.09%,最大和平均动态误差分别为4.52%和1.48%。该研究可为苏南小田块地区推广变量施肥提供技术参考。     

云南哈尼梯田红米地方品种遗传多样性分析

云南元阳哈尼梯田有丰富的水稻品种,特别是红米资源。本研究利用均匀分布于水稻基因组的100对简单序列重复（SSR）标记分析元阳哈尼梯田60份红米地方品种遗传多样性。100对SSR引物共扩增条带477个,平均每对引物扩增4.770个条带;有效等位基因数（Ne）从1.035~6.000,平均为2.518;香农多样性指数（I）为0.086~1.912,平均为1.016;多态性信息含量（PIC）范围为0.064~0.838,平均为0.519;基因杂合度（H）从0到0.950,平均为0.167;聚类分析可将60个红米品种分为两大类,第一类为籼稻亚种,包括57个水稻品种,第二类只有3个品种,为粳稻亚种。研究表明云南哈尼梯田水稻红米品种具有丰富的遗传多样性。     

玉米田养鹅对土壤理化性状、杂草多样性及玉米生长的影响

为探究"玉米田养鹅"对农田生态系统杂草多样性、土壤理化性质及玉米生长状况的影响,以林芝市八一镇章麦村试验田为研究对象,运用对比方法,研究玉米田养鹅(Raising geese in cornfield,RGC)和对照(Control,CK)土壤理化性质、杂草多样性及玉米生长的异同,旨在通过田间状态的描述和中间状态的研究,为以后优化玉米田调控措施提供依据。结果表明:1)RGC处理有19种杂草,其中以菊科植物最多,对照组仅有9种。不同功能群杂草密度相差很大,双子叶一年生或越年生被子植物功能群杂草密度远远高于其他5种功能群;RGC处理提高了杂草群落Shannon-Wiener和Simpson多样性指数,但降低了Pielou均匀度指数和Margalef物种丰富度指数;2)RGC处理土壤含水率较对照高1.27%,与对照相比差异不显著(P0.05);3)随着土层加深,RGC和对照土壤紧实度均呈逐渐增加趋势,且RGC对紧实度影响显著;4)对照土壤碱解氮含量为86.48mg/kg,略高于RGC处理2.67mg/kg(P0.05),速效钾含量为161.07mg/kg,略高于RGC处理28.66mg/kg(P0.05),而RGC的土壤中速效磷含量为120.98mg/kg,是对照(106.25mg/kg)的1.14倍(P0.05)。结论:RGC处理增加了农田系统杂草数量、种类和生物量,提高了生物多样性,使土壤紧实度明显减小、土壤含水率增加及土壤养分含量出现差异,且玉米各项农艺性状低于对照。     

50%禾草丹·异丙隆WP在直播水稻田中的消解动态

【目的】评价禾草丹和异丙隆在直播水稻田施用后的生态环境和糙米的安全性。【方法】进行2年3地田间试验,采用高效液相色谱-串联质谱法(HPLC-MS/MS)测定稻田土壤中禾草丹和异丙隆的消解动态及其在糙米和土壤中的最终残留。【结果】在0.01~0.5mg/kg添加水平下,禾草丹和异丙隆在土壤和糙米中的平均回收率为80.4%~108.8%,变异系数为0.6%~12.6%。田间试验结果表明:禾草丹和异丙隆在稻田土壤中施药2h后的原始沉积量分别为0.141~1.134mg/kg和0.066~0.543mg/kg,半衰期分别为1.1~4.2d和0.4~4.4d。收获期稻田土壤和糙米中两者的最终残留量均未检出。【结论】禾草丹和异丙隆均属于易降解农药,50%禾草丹·异丙隆WP按推荐剂量(900g a.i./hm2,即1 800g/hm2)施用于直播水稻田中,施药1次,收获的糙米安全。