优质籼稻育种中F1代生理优势的研究

对优质／优质、优质／非优质、非优质／非优质１０个不同籼稻组合杂种Ｆ１与其亲本植株生理特性进行了研究。结果表明：分蘖期Ｆ１植株叶片硝酸还原酶活性超中亲值,并与穗数呈正相关。始穗期Ｆ１植株剑叶叶绿素含量和光合速率超中亲值或近中亲值;呼吸速率低于中亲值或近中亲值;乙醇酸氧化酶活性超中亲值或低于中亲值,但以低于中亲值的组合居多。所有Ｆ１植株剑叶的呼吸速率和乙醇酸氧化酶活性都低于高亲值。试验结果还表明,七桂早／新丝苗、七桂早／早优占和七桂早／金占可以作为优质高产稻育种的最佳组合。     

籼型杂交早稻优Ⅰ 66的选育与应用

优Ⅰ６６是中国水稻研究所用印水型不育系优ⅠＡ与早籼恢复系６６配组选育而成的籼型杂交早稻新组合。该组合具有产量高、抗稻瘟病、米质优、制种易获高产、适应性广等特点,适宜在长江以南各省和桂北、粤北、闽北作双季早稻种植。１９９７年３月通过江西省品种审定委员会审定     

Effect of nitrogen application during ripening period on photosynthesis and dry matter production and its impact on yield and yield components of semidwarf iniica rice varieties under water culture conditions

Abstract

A water culture pot experiment was conducted to analyze the effects of N application during the ripening period (RP) on photosynthesis, dry matter production, and its impact on grain ripening and yield in two semidwarf indica type varieties viz. Gui Zhao 2 (GZ) and BR3 (BR) compared with a japonica type variety Koganemasari (KO) under four N rates viz. 0 (N₀), 10 (N₁₀), 20 (N₂₀), and 40 (N₄₀) mg L^?1. Results showed that N application enabled to maintain a higher leaf area and delay leaf senescence in both indica and japonica type varieties but the decrease in the rate, of leaf area was higher in the former than in the latter and the rate was reduced with increasing N rates. Flag leaf photosynthesis and SPAD values of N treated plants were higher throughout the RP, showing the presence of a significant correlation either for each variety or all the varieties together. Higher photosynthetic rate was supported by higher leaf chlorophyll (SPAD value basis) content, stomatai conductance, and N concentration in leaf blades. Top dry matter content increased with increasing N rates mainly due to mean leaf area rather than NAR except for BR during RP but it was higher in KO than in GZ and BR. Reduction of shoot weight due to translocation of dry matter to panicles during RP was suppressed by N rates both in GZ and BR while shoot weight increased in the N-treated plants in KO. The dependency of KO on current photosynthates for panicle weight was found to be almost hundred percent while the contribution of stored carbohydrates in shoot before heading to panicle weight in GZ and BR was in the range of 4-27 and 33-54%, respectively and the rest was contributed by current photosynthates. The percentage increased with increasing N rates. Percentage of ripened grains (PRG) increased with increasing N rates in GZ and BR due to the increase in dry matter production and in the photosynthetic rates of apex leaves, despite the larger spikelet number and larger hull size. However, KO showed almost no variation although it had the highest PRG among the varieties. Brown rice yield followed the same pattern as that of PRG in GZ and BR and the highest yield was produced by BR followed by GZ and KO. These results suggest that N application during RP was more effective in increasing yield in the semidwarf indica type varieties than in the japonica type variety.     

Interactions between rodents and weeds in a lowland rice agro‐ecosystem: the need for an integrated approach to management

Rodents and weeds are important pests to rice crops in Southeast Asia. The interaction between these 2 major pests is poorly documented. In temperate cereal systems, seeds of grass weeds can be an important food source for rodents and weed cover along crop margins provides important refuge for rodents. In 2012 and 2013, a replicated study (n = 4) in Bago, Myanmar compared 4 treatments (rodents and weeds; no rodents and weeds; rodents and no weeds; no rodents and no weeds) each of 0.25 ha in transplanted rice. Weeds were managed with hand weeding in the wet season, and hand weeding and herbicides in the dry season. Plastic fences were installed to exclude rodents. We examined the weed cover and relative abundance of weed species, rodent damage, rodent population dynamics and rice yield loss caused by rodents and weeds. The dominant rodent species was Bandicota bengalensis. In the dry season, Cyperus difformis was dominant at the tillering stage and Echinochloa crus‐galli was the dominant weed species at the booting stage. In the wet season E. crus‐galli was a dominant weed throughout the season. Damage by rodents was higher in the dry season. There were larger economic benefits for best weed management and effective rodent control in the dry season (258 US$/ha) than in the wet season (30 US$/ha). Concurrent control of weeds in and around rice fields combined with coordinated community trapping of rodents during the early tillering stage and ripening stage of rice are recommended management options.     

籼稻稻米外观品质与其它品质性状的相关性分析

利用６个籼型不育系和３个籼型恢复系按不完全双列杂交方式配制杂交组合，考察稻米外观品质等米质性状，采用种子胚乳模型分析成对性状间的多种遗传相关。结果表明，粒长与长宽比、长宽比与直链淀粉含量、垩白面积与胶稠度、垩白面积与蛋白质指数以及垩白面积与赖氨酸指数性状间具有明显的种子直接加性相关、母体植株加性相关以及种子直接加性与母体植株加性相关，但也受制于一些显性相关分量，而粒长与粒宽、粒宽与长宽比、粒宽与垩白面积、粒宽与精米率、粒宽与直链淀粉含量、长宽比与精米率、垩白面积与蛋白质含量以及至白面积与赖氨酸／蛋白质比例的相关则以显性相关为主。对于以加性相关为主的成对性状，间接改良的效果较好。     

华南早晚造籼稻品质变化规律与定级探讨

应用国家优质稻谷标准GB／T17891-1999对华南籼稻早晚两造种植的稻谷样品进行了品质指标系统测定，结果表明：不同品种(组合)早晚造品质变化具有特异性。     

优质早籼不育系早红突A的选育

早红突Ａ是浙江省台州市农科所新育成的一个优质早籼不育系，具有熟期早、配合力好、米质优、异文结实率高等特点，在高产、优质杂文早稻的选育中具有较好的应用前景。     

Studies on the Developmental Genetics of Tiller Number in Three-line Indica Hybrid Rice

Following NC Ⅱ design, the developmental genetic behavior of tiller number (TN) in three-line indica hybrid rice was studied using additive-dominance developmental genetic models and the corresponding statistical methods. The results showed that dominance effects were predominant for TN. The expression of those additive effects were affected by environment and genotype interaction, but the expression of dominance effects were not affected. Heterosis was the strongest in the middle developmental periods of TN. Additive effects and dominance effects were selectively expressed throughout in the entire tillering developmental stage.Analysis of genetic correlation between TN at different stages and the productive panicles indicated that a close correlation appeared earlier in the populations with higher heterosis than in those with less heterosis. Utilization of heterosis at the middle tillering stage might enhance the final biomass but reduce the percentage of productive panicles.     

水稻籼粳杂种一代稻米加工和外观品质性状研究

采用不同稻米品质3个粳稻和4个籼稻按完全双列模型设计进行杂交，配组了24个籼粳杂种一代F1，对其主要稻米加工和外观品质性状进行研究。加工品质中糙米率和精米率均接近粳稻品种，与籼稻无关，无胞质效应；整精米率差异很大，但大多介于籼粳双亲之间，并且随粳稻亲本不同，其胞质效应表现不一致。外现品质中垩白度和透明度，大多数介于双亲之间．而垩白率多倾向于亲本的高值。     

Genetic studies on the interspecific cytoplasm substitution lines of an Asian perennial strain of Oryza rufipogon Griff. and O. glaberrima Steud.

Summary It is shown that the restorer gene Rf _j extracted from the Japanese rice variety Akebono is effective on pollen restoration in the cytoplasm substitution line having the nucleus of Oryza glaberrima and japonica or indica cytoplasm of O. sativa, and is of the sporophytic type.The Asian perennial type of the wild rice species O. rufipogon is considered to be the progenitor of O. sativa. Two substitution lines having the cytoplasm of a perennial strain of O. rufipogon from Sri Lanka and the nucleus of O. glaberrima with or without the gene Rf _j in homozygous condition have been bred by means of successive backcrosses. These lines have now reached the BC₅ generation. Plants of the lines resemble morphologically the recurrent parent, but do not show pollen restoration, indicating that the cytoplasm of the rufipogon strain induced male sterility and that the gene Rf _j does not act as the restorer.