不同密度群体对寒地水稻分蘖及产量的影响

在不同栽培密度条件下,对黑龙江2个主栽品种的分蘖、10株主茎干重、成穗率及产量进行研究。结果表明:随平方米穴数的减少,主栽品种的分蘖数增加;不同密度群体对10株主茎干重前期影响较小,后期影响较大,密度越稀的群体,后期每穴或每株主茎干物质积累越多,对空育131影响较垦稻12号大,成穗率差异不显著;不同密度群体下,空育131产量差异显著,垦稻12号差异不显著,空育131适宜密植。     

氮肥一次性基施对不同成穗方式下直播常规粳稻产量的影响

在江苏省稻麦两熟轮作地区,以南粳9108为材料,在控释氮肥配方(40 d释放期控释氮肥∶l00d释放期控释氮肥=1∶4)和速效氮肥的不同配比下,研究全程氮素一次性基施条件下控释氮肥施用比例对不同成穗方式下直播常规粳稻产量的影响.试验为裂区设计,主区设置3种不同基本苗处理,在成熟期调查其主茎占有效穗数的比例,以分别代表主...     

水稻特大穗种质DR108航天诱变后代的选育研究

通过航天育种途径对特大穗恢复系材料DR108进行株叶形态改良,选育出新的恢复系,对新选育恢复系HR227及其配制组合的株叶形态进行比较分析,显示了航天育种在水稻种质创建上的独特优势。     

中国高粱地方品种和育成品种穗部表型性状精准鉴定及综合评价

【目的】 通过对高粱种质资源穗部表型多样性与遗传变异规律的研究,筛选高粱优异种质,丰富高粱穗部相关性状的遗传信息,为现有种质资源的保护、高效利用及新品种的选育等提供参考。【方法】 以320份来源于中国各地的高粱种质为供试材料,对其在2个不同生态环境下的12个穗部性状（粒长、粒宽、千粒重、籽粒硬度、籽粒容重、角质率、穗粒重、穗长、穗柄长、穗柄直径、一级枝梗长和一级枝梗数）进行精准鉴定。运用相关性分析、主成分分析、聚类分析等方法对高粱种质资源进行综合评价,并根据综合评价F值及目标性状筛选出不同突出特点的优异高粱种质。【结果】 各数量性状分布频次呈中间高两边低的分布趋势,籽粒硬度、穗粒重和籽粒容重、角质率2年间的频次分布和曲线走势分别在保定和晋中试验点较为相似,多数性状只在一个年份或单个试验点呈正态分布;除穗长和一级枝梗数外,其余性状的均值在同年两点间存在差异;12个穗部性状的平均多样性指数（H'）分布范围为1.72—2.11,其中,籽粒硬度的多样性指数均值最高,一级枝梗长的多样性指数均值最低;籽粒硬度、角质率、穗粒重、一级枝梗长和一级枝梗数的变异系数均高于30.00%;所提取的4个主成分累计贡献率为65.39%;聚类分析将320份种质划分为3个类群,第Ⅰ类可作为筛选工艺（帚）用高粱的种质类,第Ⅱ类适用于粒用（酿造）高粱优异种质的选育,第Ⅲ类为穗部性状表现较差的种质;依据综合得分F值及目标性状筛选出具有不同突出特点的29份优异种质。【结论】 参试高粱种质资源穗部性状表型变异丰富,多样性程度较高;角质率和一级枝梗长的变异系数较高;粒长、粒宽、籽粒硬度、籽粒容重和穗粒重受环境条件影响较大,一级枝梗长相对稳定;筛选出优异种质29份。     

水稻穗粒数及相关性状的遗传研究进展

大穗是水稻高产品种选育的主攻方向，揭示大穗形成遗传机制是品种选育的理论基础。综述水稻穗粒数基因/QTL定位和克隆以及与穗粒数有关的穗长、一次枝梗数和二次枝梗数等性状的遗传研究进展。     

结实前水分供应对寒地水稻穗部性状和产量的影响

以垦鉴稻5号和垦稻12号为材料,采用负压式土壤湿度计监测盆栽控水试验土壤水势.研究了结实前水分供应对寒地水稻穗部性状和产量的影响.结果表明:结实前进行-8～ - 10 kPa的间歇控水处理,两品种的收获穗数减少,穗粒数极显著地减少,结实率和千粒重增加;垦鉴稻5号的经济产量增加,垦稻12号的经济产量降低.结实前进行- 1...     

Decreased panicle N application alleviates the negative effects of shading on rice grain yield and grain quality

Light deficiency is a growing abiotic stress in rice production. However, few studies focus on shading effects on grain yield and quality of rice in East China. It is also essential to investigate proper nitrogen (N) application strategies that can effectively alleviate the negative impacts of light deficiency on grain yield and quality in rice. A two-year field experiment was conducted to explore the effects of shading (non-shading and shading from heading to maturity) and panicle N application (N_DP, decreased panicle N rate; N_MP, medium panicle N rate; N_IP, increased panicle N rate) treatments on rice yield- and quality-related characteristics. Compared with non-shading, shading resulted in a 9.5–14.8% yield loss (P<0.05), mainly due to lower filled-grain percentage and grain weight. N_MP and N_IP had higher (P<0.05) grain yield than N_DP under non-shading, and no significant difference was observed in rice grain yield among N_DP, N_MP, and N_IP under shading. Compared with N_MP and N_IP, N_DP achieved less yield loss under shading because of the increased filled-grain percentage and grain weight. Shading reduced leaf photosynthetic rate after heading, as well as shoot biomass weight at maturity, shoot biomass accumulation from heading to maturity, and nonstructural carbohydrate (NSC) content in the stem at maturity (P<0.05). The harvest index and NSC remobilization reserve of N_DP were increased under shading. Shading decreased (P<0.05) percentages of brown rice, milled rice, head rice, and amylose content while increasing (P<0.05) chalky rice percentage, chalky area, chalky degree, and grain protein. N_MP demonstrated a better milling quality under non-shading, while N_DP demonstrated under shading. N_DP exhibited both lower chalky rice percentage, chalky area, and chalky degree under non-shading and shading, compared with N_MP and N_IP. N_DP under shading decreased amylose content and breakdown but increased grain protein content and setback, contributing to similar overall palatability to non-shading. Our results suggested severe grain yield and quality penalty of rice when subjected to shading after heading. N_DP improved NSC remobilization, harvest index, and sink-filling efficiency and alleviated yield loss under shading. Besides, N_DP would maintain rice’s milling, appearance, and cooking and eating qualities under shading. Proper N management with a decreased panicle N rate could be adopted to mitigate the negative effects of shading on rice grain yield and quality.     

Brassinosteroids Mediate Endogenous Phytohormone Metabolism to Alleviate High Temperature Injury at Panicle Initiation Stage in Rice

High temperatures cause physiological and biochemical changes and significantly affect young panicle development of rice (Oryza sativa L.). Brassinosteroids play important roles in enhancing crop stress resistance. In this study, we subjected rice cultivars Huanghuazhan (heat-resistant) and IR36 (heat-sensitive) to high temperature (HT, 40 ºC) or normal temperature (NT, 33 ºC) for 7 d at the panicle initiation stage, in conjunction with application of 24-epibrassinolide [EBR, a synthetic brassinolide (BR)] or brassinazole (BRZ, a BR biosynthesis inhibitor) at the beginning of the treatments. HT exacerbated spikelet degeneration and inhibited young panicle growth, which were partially prevented by EBR application, while BRZ application aggravated the reduction in spikelet number. HT decreased the contents of BR, active cytokinins (aCTK), active gibberellins (aGA) and indole-3-acetic acid (IAA), but increased the content of abscisic acid (ABA) in young panicles. The activities of key enzymes involved in sucrose hydrolysis, glycolysis and the tricarboxylic acid cycle in young panicles were decreased with the change of endogenous hormone levels under HT. In addition, the contents of H₂O₂ and malondialdehyde (MDA) were increased and the activities of antioxidant enzymes were decreased in young panicles. Exogenous application of EBR induced the expression of phytohormone biosynthesis-related genes and down-regulated the expression of phytohormone catabolism-related genes to increase the contents of endogenous BR, aCTK, aGA and ABA, thus promoting the decomposition and utilization of sucrose in young panicles, enhancing the activities of superoxide dismutase, catalase and peroxidase, and reducing the accumulation of H₂O₂ and MDA in young panicles, whereas application of BRZ had the opposite physiological effects. These results showed that brassinosteroids mediate endogenous phytohormone metabolism to alleviate HT injury at the panicle initiation stage in rice.