Physio-Morphological Characters of F1 Hybrids of Rice (Oryza sativa L.) in Japonica-Indica Crosses: II. Heterosis for leaf area and dry matter accumulation

Summary

A pot experiment was conducted to investigate the heterosis for morphological characters and to examine the relationship among some characters at active tillering, flowering and dough ripe stages of 12 Fj hybrids from crosses between japonica and indica rice. Heterosis for plant height, number of tillers, green leaf area and dry matter accumulation per plant was positive at all stages. The intensity of heterosis was higher at the active tillering stage for number of tillers, leaf area and dry matter accumulation per plant. A significant positive relationship was found between tiller number and leaf area per plant at active tillering and flowering stages. Significant positive relationships between leaf area and dry matter accumulation, and between tiller number and dry matter accumulation per plant were observed at all stages. A significant positive relationship was found between leaf area per plant at an early stage and dry matter accumulation per plant at a later stage, suggesting that early development of leaf area is an important factor for higher dry matter accumulation in 1 hybrids. Although heterosis for percent dead leaf blade was positive at the flowering stage due to early leaf senescence in some Fx hybrids, a larger leaf area was also found in Fx hybrids at this stage and leaves of Fx hybrids remained green longer compared to parent cultivars up to the dough ripe stage.     

Physio-morphological Studies of F1 Hybrids in Rice (Oryza sativa L.): Photosynthetic ability and yield

Summary

Photosynthetic ability in terms of CO₂ exchange rate and leaf area, dry matter accumulation (dry weight) and other important growth components along with yield and yield contributing characters in two F₁ hybrids of Akebono × Chiyonishiki (A × C) and Zenith × Akebono (Z × A) were studied. The photosynthetic rate at the flowering stage was lower than that at the panicle initiation stage in all the inbred parent cultivars and F₁ hybrids. Heterosis in photosynthetic rate was higher at the panicle initiation stage than that at the flowering stage. Pre-anthesis leaf area in the F₁ hybrid was significantly larger than that in the parent cultivars. However, the post- anthesis decline in leaf area was more rapid in the F₁ hybrids than in the parent cultivars and its magnitude was the highest in the F₁ hybrid of Z × A which was tall having long and curved panicles. Pre-anthesis dry matter accumulation in both hybrids was significantly higher in the F₁ plants than the parental cultivars, but post-anthesis dry matter accumulation in the F₁ hybrid was lower than the mid-parental value in Z × A. The degree of heterosis in grain yield varied with the hybrid combination, an average heterosis being 1.03. Heterosis in grain yield was closely associated with heterosis in harvest index.     

小麦杂种优势群研究：Ⅳ．普通小麦与斯卑尔脱小麦的种间杂种优势

本研究利用6个普通小麦品系与14个从国外引进的斯卑尔脱小麦杂交，研究了种间杂种优势表现，并探讨了扩大杂交小麦育种亲本的遗传基础和构建种间杂种优势群的途径。连续两年的试验结果表明，普通小麦与斯卑尔脱小麦种间杂种存在较强的杂种优势。就平均优势而言，单株产量，单穗产量和千粒重优势最大，分别为111.39%,62.77%,45.72%，单株穗数，株高和主穗粒数优势次之，分别为24．13％，20．18％和12．76％，主穗小穗数和主穗长优势较小，分别为4．08％和0．67％。研究还发现，种间杂种抽穗斯比母本普通小麦晚0－6d，但较父本斯卑尔脱小麦提前20d左右，表明早熟性呈部分显性遗传；蛋白质含量，沉淀值和湿面筋含量的杂种优势比普通小麦分别提高了8．55％，12．13％和9．91％，一些组合沉淀表现超亲优势，说明利用普通小麦与斯卑尔脱尔脱小麦种田杂交既可以扩大小麦亲本间的遗传差异，又可以显著提高小麦的杂种优势潜力。     

Effects of Elevated Atmospheric Carbon Dioxide Concentration on Silica Deposition in Rice (Oryza sativa L.) Panicle

Abstract

The effects of elevated carbon dioxide concentration ([CO₂]) on silica deposition on husk epidermis of rice (Oryza sativa L. cv. Akitakomachi) during the flowering stage were investigated in this study. The study was motivated by the concept that the rice yield maybe affected by global warming as a result of elevated [CO₂] environment since sterility of rice is related to the panicle silica content that influences transpiration, and elevated [CO₂] could affect plant transpiration. Silica deposition analysis was focused on the flowering stage of the rice crop grown hydroponically under two [CO₂] conditions: 350 μmol mol-¹ (ambient) and 700 μmol mol-¹ (elevated). Silica deposition on the husk epidermis from three parts of the panicle at four flowering stages were examined using a scanning electron microscope (SEM) combined with an energy dispersive X-ray microanalyzer (EDX). The results demonstrated that elevated [CO₂] significantly suppressed silica deposition on the husk epidermis at the lower part of the panicle, and at the early flowering stage when 1/3 of the panicle emerged from the leaf sheath. In the transverse section analysis of the husk, silica deposition on the husk epidermis under elevated [CO₂] was less than that under ambient [CO₂] at the late flowering stage. The less silica deposition observed on the husks at the late flowering stage under elevated [CO₂] might be related to the suppressed transpiration from the panicle by elevated [CO₂] found in a previous study.     

Genotypic Differences in Dry Matter Accumulation,Nitrogen Use Efficiency and Harvest Index in Recombinant Inbred Lines of Rice under Hydroponic Culture

Abstract

To examine the possibility of breeding high-yielding cultivars with high nitrogen use efficiency for dry matter accumulation (NUEd) and to provide simple criteria for the selecting and breeding high-yielding cultivars with high NUEd as well as useful information for the mapping of quantitative trait loci (QTL) controlling NUEd, we cultured recombinant inbred lines (RILs) of rice hydroponically in 2000 and 2001. RILs with a higher grain yield tended to show greater total dry matter accumulation (TDMA) and higher harvest index (HI), while increasing TDMA resulted in a decrease in HI. The contribution ratio of the TDMA to grain yield (2000 : 67.3%, 2001 : 68.2%) was higher than that of HI in both 2000 and 2001. Even at the same high-yielding level, there was a significant difference in the TDMA and HI values. In both years, the contribution ratios of NUEd and total nitrogen absorption (NTA) to TDMA were about 62.0 and 38.0%, respectively. The contribution ratio of the NUEd to grain yield was higher than those of the NTA and HI in both 2000 (41.6%) and 2001 (42.9%). These results suggested that the high-yielding rice plants generally displayed high TDMA and HI values. Further increase in rice grain yield should be based on the further increase in TDMA than in HI, and to increase TDMA leading to a high grain yield, the emphasis also should be put on improving NUEd in RILs.     

晚籼夜公和野败雄性不育细胞质对杂交水稻农艺性状的影响

 由夜公和野败的两个异质同核不育系分别与两个恢复系杂交，配制8个组合进行随机区组试验，在相同核背景下比较不同雄性不育细胞质对杂交水稻的影响。结果表明，夜公雄性不育细胞质对杂交水稻产量和主要农艺性状的影响优于野败，是一个可以开发利用的雄性不育细胞质。     

晚籼夜公和野败雄性不育细胞质对杂交水稻农艺性状的影响

由夜公和野败的两个异质同核不育系分别与两个恢复系杂交，配制8个组合进行随机区组试验，在相同核背景下比较不同雄性不育细胞质对杂交水稻的影响。结果表明，夜公雄性不育细胞质对杂交水稻产量和主要农艺性状的影响优于野败，是一个可以开发利用的雄性不育细胞质。     

Insect-mediated cross-pollination in soybean [Glycine max (L.) Merrill] : I. Agronomic performance

In soybean, manual cross-pollination to produce large quantities of F₁ hybrid seed for yield trials is difficult and time-consuming. Conversely, insect-mediated cross-pollination has been shown to produce large quantities of hybrid seed in soybean and could facilitate the identification of heterotic patterns. The objective of our study was: (1) evaluate F₁ hybrid soybean plants from single crosses for yield and agronomic traits over several environments and (2) compare hybrid performance of the single crosses to lines developed from three-way crosses and backcrosses. In 2003, F₁ seed of single-crosses and their parent lines were evaluated in replicated experiments at three locations. Also in 2003, three-way crosses, and BC₁F₁ seed were produced. In 2004, three-way crosses, BC₁F₁ crosses, and their parent lines were evaluated at one location. High-parent heterosis (HPH) in single-crosses for grain yield ranged from −41.11% to +11.19%; for protein content from −4.34% to +3.53%, and for oil content from −13.22% to −0.84%. In three-way crosses, HPH for yield ranged from −25.21% to −4.50%, for protein from −2.72% to +1.92%, and for oil from −5.87% to −1.20%. For BC₁F₁ crosses, HPH for yield ranged from −15.65% to +41.97%, for protein from −2.57% to +1.69%, and for oil from −2.47% to +2.22%. Although positive heterosis levels were observed across all populations tested to determine the economic feasibility it is imperative that more tests of more cross-combinations be evaluated in replicated environments. Extensive research in different environments must be conducted to determine what parental combinations will produce the highest heterosis levels, and to develop criteria for selecting the parents with the best combining ability. This will be important to maximize agronomic performance that can economically justify the use of hybrids in soybean production.     

水稻重要农艺性状的两年QTL剖析

 利用水稻汕优63（珍汕97 × 明恢63）重组自交系群体241个株系，对株高、生育期、产量及其产量构成因子等9个重要农艺性状进行了年度间的QTL定位和比较。结果表明，9个性状的表现型在两年均为连续分布，且都存在一定数量的双向超亲遗传类型。两年共检测到64个QTL，分布于水稻除第4染色体外的其余11条染色体，其中1999年检测到45个，2000年检测到35个，两年相同的QTL共16个。2000年检测到的QTL贡献率介于283%~1499%，且大多低于1999年。不同环境可以影响QTL的表达，但表达差异并不全是QTL×环境(QE)互作结果，也可能是由于该性状的遗传力偏低、QTL本身效应偏低或QE互作等原因共同造成的。另外，检测到8个显著的QE互作，但其互作效应明显低于对应的QTL效应。     

Effect of a Bio-decomposer on Utilization by Rice (Oryza sativa L.) of 15N Derived from Rice Chaff or Straw

Abstract

The ¹⁵N - labeled technique was used to study the stock, transformation, fate and utilization efficiency of N in the farming–pig husbandry–biogas ecosystem in rice areas. It was shown that the crude protein digestibility of the ensilaged milk vetch by pig was 53.76%, the recovery rates of ensilaged milk vetch N from the pig feces and urine were 39.36% and 24.71%, respectively. The recovery rate of biogas fermentation N of pig feces and urine was 97.9%. The quantity of alkali-hydrolysable N was 2.6 times as great as before the fermentation. The mixed application of milk vetch, biogas-tank sludge and chemical fertilizer could promote N partitioning to rice grain, therefore it was advantageous to yield improvement. The residual quantity in soil of the fertilizer N was equivalent to 2.0 - 2.5 times that of only chemical fertilizer and yet gaseous loss N of the latter was 2.6-8.2 times that of the former. The comprehensive economic effect of the whole ecosystem increased by times, compared with the only milk vetch-early rice-late rice pattern, and ecological effect and social effect were also very prominent.     

水稻短根的遗传分析

 用水稻短根突变化RM1、RM2与原品种Ohchikara杂交配成两个组合的P₁、 P₂、 F₁、 F₂、 B₁₁、B'₁₁、B₁₂、 B'₁₂ 以及F₃世代，调查冠根长度，研究短根性状的遗传。结果表明，RM1和RM2的短根性状均受单个位点稳性核基因（srt1srt1），并且RM1和RM2的短根基因是等位的。讨论了srt1基因在杂交稻和中子纯度快速鉴定中的应用。     

大麦单株产量性状的杂种优势及其稳定性分析

为研究不同环境下大麦单株产量性状的杂种优势及其稳定性,以113个(Nasonijo×泰兴9425)DH系配制226个杂交种构建的永久F_2群体及亲本为材料,分别调查参试材料在4个环境下的单株穗数、主穗粒数、千粒重、单株产量和单株生物量,利用方差分析、聚类分析及稳定性分析对大麦单株产量性状的杂种优势及其稳定性进行了分析。结果表明,大麦杂种F_1各被测性状大多表现中亲优势,超亲优势组合出现率相对较低。各被测性状的杂种优势不仅受自身遗传因素影响,而且受试点生态条件及年度气候条件的影响。杂种优势的稳定性因性状不同而异,千粒重和主穗粒数杂种优势的稳定性较好,单株生物量和单株产量杂种优势的稳定性较差,仅有2个组合在多环境下表现出稳定的强杂种优势。     

QTL Analysis for Traits Associated with Feeding Value of Straw in Rice(Oryza sativa L.)

Genetic improvement of the digestibility of rice strew for increasing the utilization of the whole rice plant as feedstuffs is an important way to solve the feedstuffs shortage in southeastem China. To elucidate the genetic basis of the traits affecting the digestibility of rice straw, a rice population of 111 recombinant inbred lines (RILs) derived from a cross of Nekken 2xGaya was used to map the quantitative traits loci (QTLs) for in vitro dry matter digestion (IVDMD), the percentages of nonstructurel carbohydrate (NSC) and acid detergent fiber (exclusive of residual ash, ADFom) in 2005 and 2006. IVDMD was positively correlated with NSC, and negatively correlated with ADFom. A total of 16 QTLs were detected in the two years, and the amounts of variation explained by individual QTLs ranged from 6.9% to 15.5%. Some QTLs for IVDMD and ADFom on chromosome 2 were detected in the two years. On chromosome 2, the interval RM475-RM3515 contained QTLs for IVDMD in the two years and for NSC in 2006 only, while the interval RM3874-RM5305 influenced ADFom in the two years and NSC in 2005 only. At those loci, Gaya contributed favorable alleles to IVDMD and NSC, while Nekken 2 contributed positive alleles to ADFom.     

广东高州普通野生稻与粳稻杂交F1胚囊育性及发育特点

利用整体染色激光扫描共聚焦显微术(WE CLSM), 对广东高州普通野生稻与粳稻台中65杂交F1的成熟胚囊育性、胚囊形成发育及受精特点进行研究。杂种F1成熟胚囊平均育性为64.61%。不同杂种的成熟胚囊均存在不同程度的异常现象, 异常的主要类型有：胚囊退化、小胚囊、雌性生殖单位退化、卵器退化、极核数目或位置异常及其他异常等类型。其中频率最高的异常类型为雌性生殖单位退化（10.49%）,其次是胚囊退化（9.80%）。杂种F1的胚囊发育过程与高州野生稻原种基本一致,育性低的杂种F1胚囊发育过程出现多种异常现象。对3个杂种F1受粉后1 d的胚囊进行观察发现,除正常受精膨大的胚囊外,还存在结构正常未受精和结构异常未受精等异常现象。受粉后7 d的胚囊基本上与受粉后1 d的相似。研究结果表明,广东高州普通野生稻可能具有决定杂种F1胚囊育性的不同基因,包括中性基因等。     

Salinity-Induced Ultrastructural Alterations in Leaf Cells of Rice (Oryza sativa L.)

Summary

High concentrations of NaCl significantly reduced the fresh and dry weights and lengths of roots and shoots. NaCl exhibited a more rapid effect in water culture than in soil culture. In both water and solid cultures, root growth was suppressed more severely than shoot growth. Electron microscopic studies revealed that NaCl caused swelling of thylakoids, accumulation of starch grains and lipid droplets, distortion of grana stacking, increase in the size and number of plastoglobuli and vesiculation of cellular membrane. Mitochondria became deficient in cristae, swelled and the matrix appeared pale in salt-treated plants as compared with control plants. Disappearance of nucleolus and nuclear chromatin and destruction of vascular tissues were occasionally observed in salt-treated plants.     

BT型杂交粳稻育性及其三系的若干蛋白质标记

 用十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）方法，对粳稻BT 细胞质雄性不育系六千辛A，保持系六千辛B，恢复系六千辛R、77302-1，以及杂交组合六千辛A/77302-1的F1和F2 种子的胚乳贮藏蛋白进行了分析。结果表明，在谷蛋白α3区域，恢复系有两条带α3a 和α3b,而六千辛A和六千辛B只有一条带α3。 F2代具有α3的种子和具有α3a 加α3b的种子1∶1分离。谷蛋白α4带的移动速率，恢复系比六千辛A快。把较快的α4带记为α4f。 F2代具有α4的种子和具有α4 加α4f的种子也是1∶1分离，与配子体不育类型的F2代花粉育性恢复基因分离比一致。系谱分析表明六千辛R中α3a 和α3b来源于IR8。六千辛A比六千辛B容易提取醇溶蛋白。     

Stay-Green in Rice (Oryza sativa L.) of Drought-Prone Areas in Desiccated Soils

Abstract

Stay-green in the post-anthesis period is thought to be an efficient drought-tolerance trait in crops, but its effectiveness in rice (Oryza sativa L.) is unknown. Our objectives were to determine whether the stay-green trait exists in rice cultivars in drought-prone areas. Twenty-four cultivars from Japan and Vietnam were grown in pots of 0.08 m in diameter and 1.00 m deep. At heading, irrigation was terminated in half of the pots and continued in the remaining pots. Every four days during the grain-filling period, we measured the leaf green color with a chlorophyll meter (SPAD), the green leaf area (GLA) and the fraction of transpirable soil water (FTSW). The capacity for maintenance of SPAD-value and GLA in desiccated soils was evaluated by determining the ratio of integrated SPAD-value and GLA in desiccated (D) plants to those in irrigated (I) plants (SPAD_d/I or GLA_d/I, respectively). The SPAD_d/I and GLA_d/I in 24 cultivars showed diverse frequency distributions. Cultivars belonging to higher ranges of the distribution in SPAD_d/I and GLA_d/I tended to show higher ratios of plant dry weight at harvest in D to in I plants. SPAD_d/I and GLA_d/I in the grain-filling period were poorly correlated with those in the seedling period in desiccated soils, and hence the capacity for maintenance of green leaves in the grain-filling period would differ from that in the seedling period. These results suggest that the stay-green trait exists as the capacity for maintaining green leaves and benefits dry matter production in desiccated soils in rice cultivars in drought-prone areas.     

水稻柱头外露率的QTL分析

以高柱头外露率的50S作母本,低柱头外露率的三系粳稻保持系连B作父本杂交,种植F2群体,调查单株调查柱头外露率,分析表明群体柱头外露率值接近正态分布;以SSR标记建立了该群体的基因分子连锁图谱,使用该群体分子连锁图谱进行柱头外露率的QTL分析,共检测到3个控制水稻柱头外露率的QTL(qPES-3,qPES-9,qPES-12),分别位于第3、第9、第12染色体,其增效基因均来自50S。并对选育高柱头外露率粳稻保持系进行了探讨。     

利用同工酶标记水稻亲本遗传差异及其在杂交水稻育种中的利用

利用淀粉凝胶和聚丙烯酰胺凝胶电泳显示的同工酶差异，分析17个杂交水稻亲本、3个新株型株系和22个光壳稻、爪哇稻品种的遗传差异，研究光壳稻和爪哇稻及其与温带粳稻之间的关系，探索同工酶标记水稻亲本遗传差异在杂交稻育种中利用的可能性。在本研究中，8个同工酶18个多态性位点至少在2个基因型间存在差异。每个具有多态性的酶谱带分别以1和0记录存在与否，由同工酶数据计算的Nei’s遗传距离创建聚类树状图。聚类分析结果表明，籼稻和粳稻容易被分开，普通粳稻与光壳稻、爪哇稻混合聚在一起；光壳稻与爪哇稻之间的遗传距离要比它们与普通粳稻之间的遗传距离小。利用光壳稻、爪哇稻选育不同生态群方向的恢复系和不育系，已配组育成了强优势的杂交稻组合。     

Effect of Soil Compaction on Dry Matter Production and Water Use of Rice (Oryza sativa L.) under Water Deficit Stress during the Reproductive Stage

Abstract

The effect of a long term of soil compaction on dry matter production (DMP) and water use in rice cultivated under limited water supply during the reproductive stage is unknown. Our objectives were to determine which of the transpiration (Tr) or water use efficiency (WUE) is dominant in determining DMP under compacted and desiccated soil conditions. When irrigation in the period around the reproductive stage was terminated in artificially compacted and non-compacted fields, the rate of suppression of DMP by soil compaction was similar in the three rice cultivars, but DMP was higher in drought resistant cultivars having deep root density at the heading stage. Six cultivars were grown in pots of 1.0 m in depth containing the soils of three levels of soil bulk density (SBD). Water supply was restricted by keeping the water table in the pot deep without irrigation during the reproductive stage. DMP and Tr in all cultivars decreased with increasing SBD, and a close relationship was seen between DMP and Tr. WUE was thus a fairly stable factor for all cultivars examined. Tr was positively correlated with root length density and was relatively maintained at a high SBD in drought-resistant cultivars having a higher root length density. We concluded that water shortage under compacted soil conditions during reproductive stage suppressed the DMP, and DMP suppression accompanied a reduction of Tr due to poor root development rather than the reduction of WUE. In the drought-resistant cultivars reduction of DMP was relatively small due to their highly developed root systems that allowed high water absorption from the deep layers in the compacted soil.