Post-molt processes of cuticle formation and calcification in the Japanese mitten crab <Emphasis Type="Italic">Eriocheir japonicus</Emphasis>

This study examines the following in the Japanese mitten crab: (1) the structure of the exoskeleton with special reference to its calcification; (2) the progression of post-molt cuticle formation and calcification. In the crab, the structure and calcification state of the exoskeleton at the molt and during the inter-molt stage were similar to those of other crustaceans. During the inter-molt, the exoskeleton consisted of four cuticle layers; the outermost epicuticle, the exocuticle, the endocuticle and the innermost membrane layer. Intense calcification was observed in the exo- and endocuticle. At the molt, the synthesis of the epi- and exocuticle was already complete, and the addition of the endocuticle began after the molt. Calcification of the exocuticle initiated soon after the molt, but there was a delay between endocuticle matrix synthesis and calcification. Histology showed that the process of calcification was similar to that in other crustaceans. However, calcium concentrations within the exoskeleton continued to increase and never reached the levels of the inter-molt stage at the end of the experiment. This suggests that the Japanese mitten crab is relatively slow to calcify compared to other crustaceans.     

The progamic phase and seed formation in Armoracia rusticana

The progamic phase is a period of specific interaction between the male gametophyte and the pistil tissues and is very important for proper seed development in plants. The aims of this study were to investigate the events during the progamic phase in Armoracia rusticana, to examine a plant’s capability of sexual reproduction and to obtain vital seeds under natural conditions. There were very few pollen grains on the stigmas at anthesis stage. The incompatibility reaction between the stigma cells and pollen grains was observed by using fluorescence microscopy. A series of ovary cross‐sections revealed a high accumulation of Periodic Acid Schiff (PAS)‐positive globules in all the embryo sacs. About 33% of ovules in the ovary were fertilized, but only 3% of them were able to germinate into seedlings.     

高温对黄瓜生殖生长及产量形成的影响

黄瓜不同品系的耐热方式存在多样性。与不耐热品系新泰密刺相比 ,高温下品系EP 6通过较高的雌花节率和较强的单性结果能力耐热 ;品系XC 1通过较多的总生长节位和较高的雄蕊及花粉活力耐热 ;品系NY 1则在上述产量形成的诸因子中均有一定优势。在播种后 10～ 50d内 ,黄瓜遭遇高温的苗龄越小 ,产量下降就越多。高温减少黄瓜雌花的效应具有后作效果。     

激光诊断技术在内燃机研究中的应用及其分析

论述了在内燃机缸内速度测量、喷雾粒子粒度测量及燃烧过程温度和组分浓度测量中常用的激光诊断技术和测试方法,并对其工作原理、适用范围与场合、优缺点等进行了比较和分析。相位多谱勒粒子测速(PDPA)技术比较适合于单点速度、粒子尺寸及其分布的测量;粒子图像测速(PIV)技术适合于缸内二维平面速度场的测量;激光全息术是分析喷雾特性的有效途径和测量喷雾液滴尺寸的标准方法;平面激光诱导荧光(PLIF)法已成为喷雾、燃烧过程组分浓度及火焰结构研究的重要工具。     

影响黄瓜未授粉子房培养胚发生因素的研究

以不同基因型黄瓜为试材,研究了子房发育时期、热激处理时间、TDZ和AgNO3对黄瓜未授粉子房培养过程中胚发生的影响.结果表明处于开花前2～3 d的子房胚发生率相对较高,达83.8%;在子房培养开始阶段进行35 ℃处理的胚发生率显著高于对照(0 d),其中处理3 d 的效果最好;添加0.01～0.04 mg·L-1 TDZ的诱导培养基培养的胚发生率为20.0%～72.7%,其中添加0.04 mg·L-1 TDZ的胚发生效果较好;在诱导培养基中添加AgNO3可以提高胚发生率,同时能缩短胚出现的时间并提高胚产量.     

Progress and Yield Bottleneck of Aerobic Rice in the North China Plain: A Case Study of Varieties Handao 297 and Handao 502

Aerobic rice has been considered a promising rice cultivation system as water scarcity is increasing in the world. This article summarizes the advances in aerobic rice management researches in the North China Plain, focusing on yield formation and its bottleneck. High-yielding and good-quality aerobic rice varieties adapted to aerobic soil conditions have been released officially and adopted by farmers in North China. The varieties Handao 502 and Handao 297 have been recognized as the most promising varieties reaching a yield level ranging 3.5-5.0 t ha-1 with 450-650 mm water input. Compared with lowland rice, water input in aerobic rice was more than 50% lower, and water productivity was 60% higher. Researches on responses of rice cultivars to nitrate nitrogen （N） and ammonium N supplied at early growth stages provided the first evidence for a preference of aerobic rice HD297 for nitrate N supply, compared with the lowland rice variety. Zinc uptake studies demonstrated that introduction of aerobic rice system on calcareous soils may increase zinc deficiency problems. Sink size was identified as the limitation of aerobic rice yield, because its spikelet number m-2 was too low （20000-24 000） compared with the lowland rice. For future research, more attention is suggested to be paid to yield formation focusing on effects of water regimes on tiller dynamics. Understanding of nutrient uptake and response to fertilization effects are also urgently required to establish optimized crop management technology. Additionally, alternative cropping systems based on aerobic rice should be established, and key sustainability and environmental impact issues in the systems need to be identified.     

酥梨产量构成因素的通径分析

两年定树调查测定44株次的酥梨产量及其相关的树高/冠径、花芽数、总果数、座果率、枝/果,叶面积系数、每果叶面积、平均单果重等8个性状。应用逐步回归法逐个别除对于产量没有显著线性效应的性状,得到包括总果数、每果叶面积和平均单果重在内的最优多元线性回归方程。再对入选的各个主要性状进行通径分析,明确其对产量构成的直接和间接效应。结果说明,提高酥梨单株产量。首先要具有一定的果量,其次是增加平均单果重,再次是维持叶面积与果实的适当比例。在树冠大小基本稳定的情形下,增加每果叶面积会造成果量减少而使产量下降,同时又可提高平均单果重而使产量上升。每果最佳叶面积应是提高平均单果重而使产量的上升量大于因果量减少而使产量的下降量,这样不仅可以增加产量,而且可提高果实的商品竞争力。     

玉米雌穗小花类型,形态,决定时期及其与成粒的关系

玉米雌穗有完全花与不完全花之分,不完全花又分退化花和畸形花。总花数受品种遗传性制约,栽培措施影响较小,吐丝前后的温光条件影响较大。性器官形成期是不完全花发生的重要时期。夏播时品种间花数变幅为543——840朵。雌穗分化终止期因品种而异,大多于吐丝前7d至吐丝后1—2d。结实率达总花数80%,其中11—17%为败育粒,是影响小花成粒的首要因素,败育花影响甚微。高产栽培时花数较稳定,减少籽粒败育是提高产量的有效途径,中低产区增花增粒和保花增粒亦不可忽视。     

番茄不同花药长短及花粉发育时期其愈伤组织诱导率的相关性

研究了番茄花药长短与花粉发育时期及其与愈伤组织诱导率的相关性.结果发现,小果型番茄品种中,同一花粉囊内,小孢子母细胞的发育过程基本同步,而大中果型番茄品种,则不完全同步.不同果型番茄品种,花粉发育与花药长度成正相关.作者观察并用照片记录了不同果型番茄品种花粉的发育过程.进一步研究发现,当番茄花粉发育处于单核靠边期时进行花药培养,诱导愈伤组织的频率最高,是最适时期.