水稻大库容遗传群体源库性状、物质生产与分配的基本特征

在大田条件下,以染色体单片段代换系水稻群体114个株系为供试材料,采用聚类分析的方法依据供试群体库容量大小将其分为6种类型。结果表明:1)供试群体库容量变幅为676.80~1326.43g/m^2,666.7m^2产量变幅为311.74~763.35kg,供试材料间差异较大,同时随着库容量的增大,产量呈明显增加趋势;2)大库容量水稻抽穗期LAI、成熟期LAI均显著大于其他类型,结实期叶面积下降比例较其他类型小;3)大库容量水稻库容量大,库容量形成速率大,粒叶比大,结实期净同化率高;4)大库容量水稻主要生育时期(抽穗期、结实期、成熟期等)群体干物质积累量均具有较大的优势,结实期的优势更明显,其单茎干质量及单穗干质量亦具有相似的特征;5)大库容量水稻抽穗期茎鞘叶干质量比例大,穗干质量中等,成熟期这2个性状均为中等水平,经济系数中等偏上。大库容量水稻源足、库大,产量优势明显,但经济系数中等表明其库容量有进一步充实的潜力。

不同氮敏感性粳稻品种的氮代谢与光合特性比较

本文旨在探明不同氮敏感性粳稻品种氮代谢与光合特性。以2个氮敏感高产品种淮稻5号和连粳7号,2个氮钝感品种宁粳1号和扬粳4038为材料,设置0和200 kg hm–2 2个施氮水平,研究其产量、氮肥利用效率以及地上部生理性状的变化特点。结果表明,在2种施氮水平下,氮敏感品种的产量和氮肥利用效率显著高于氮钝感品种。与氮钝感品种相比,氮敏感品种具有较高的光合速率和氮素积累,较强的氮代谢酶活性和较高的光合氮素利用效率,抽穗期茎叶中积累较多的可溶性糖和淀粉,抽穗至成熟期茎鞘中非结构性碳水化合物向籽粒转运率较高。表明氮敏感品种在较低施氮量下具有较高的生理活性和物质生产效率;这些特征可作为筛选高产氮敏感水稻品种的重要生理指标。

Source-Sink and Grain-Filling Characteristics of Two-Line Hybrid Rice Yangliangyou 6

With two-line hybrid rice Yangliangyou 6 (YLY6) and Liangyoupeijiu (LYPJ) and three-line hybrid rice Shanyou 63 (SY63) as materials, the source, sink and flow characteristics in association with grain filling were investigated. The seed-setting rate, grain filling degree and grain yield of YLY6 and SY63 were significantly higher than those of LYPJ. The export and transformation percentages of the matter in culms and sheaths of YLY6 and SY63 were significantly higher than those of LYPJ. Activities of sucrose synthase, adenosine diphosphoglucose pyrophosphorylase, starch synthase and starch branching enzyme in grains were higher for YLY6 and SY63 than for LYPJ, and were very significantly correlated with maximum grain filling rate, mean grain filling rate, grain filling degree and grain weight. The spikelet number, grain yield and total sink load per area of vascular bundle and phloem of YLY6 and SY63 were significantly smaller than those of LYPJ, and the greater the load, the lower seed-setting rate and the poorer grain filling. The transportation rate per area phloem of YLY6 was greater than that of LYPJ or SY63. The results suggest that YLY6 possesses strong source, great sink activity and efficient flow, which lay a physiological base for its high seed-setting rate and good grain filling.

Causes of Poor Grain Plumpness of Two-Line Hybrids and Their Relationships to the Contents of Hormones in the Rice Grain

This study was designed to elucidate the grain filling characteristics and the causes of poor grain plumpness of some two-line hybrid rice combinations and their hormonal mechanism. Six varieties, including three two-line hybrid rice combinations, that show differences in seed-setting and grain filling, were used. And the contents of starch, sucrose, zeatin (Z) + zeatin riboside (ZR), indole-3-acetic acid (IAA), and abscisic acid (ABA), the ethylene evolution rate, activities of sucrose synthase (SuSase) and starch synthase (StSase) in grains, the seed-setting and grain filling rate were investigated. The correlations amongst these were analyzed. The results showed that the poor grain filling of two-line hybrids was mainly attributed to the higher unfilled grain rate and the lower filling degree of inferior grains. During the early and mid grain filling periods, the sucrose content in inferior grains was greater than that in superior grains for the combinations with poor grain filling, indicating that the substrate concentration was not the principal factor for their slow grain filling and poor grain plumpness of the inferior grains of two-line hybrids. Z + ZR, IAA, and ABA in superior grains were obviously greater than those in inferior grains at early grain filling stage. The maximum and mean contents of Z + ZR, IAA, and ABA were positively very significantly correlated with the maximum and mean grain-filling rate, filling degree, and grain weight. The evolution rate of ethylene was greater in inferior grains than in superior grains and greater for the combinations with poor grain plumpness than those with good grain plumpness at the early or mid filling stages. The evolution rate of ethylene was negatively and significantly correlated with the grain filling rate, the grain filling degree, and the grain weight. Spraying ethephon (ethylene-releasing agent) at the early grain filling stage increased the evolution rate of ethylene, reduced the ABA content and activities of SuSase and StSase, and decreased the grain filling degree and the grain weight. The results were reversed when cobatous nitrate (an inhibitor of ethylene synthesis) was applied. The results suggested that the hormones and their balance play a role in the regulation of grain filling and enzymatic activities, and the poor grain filling is attributed to the low contents of Z + ZR, IAA, and ABA, and the high evolution rate of ethylene in the inferior grains of some two-line hybrid rice combinations. The results suggested that hormones play important roles in the grain filling of some two-line hybrid rice combinations, and their filling degree can be improved by regulating the hormonal contents.

起重机主梁变形原因分析及修复

针对一台冶金桥式起重机电气梁水平弯曲严重超差的问题,本文对造成其产生变形的原因进行了分析,结合设备使用现场情况及业主要求,采用预应力法对水平弯曲超差的主梁进行了修复,修复后检测结果符合设计及标准要求。