糯玉米子粒淀粉形态和结构对硬度的影响

以京科糯2000等3个糯玉米品种为试验材料，系统分析糯玉米子粒淀粉形态和结构对硬度的影响及各指标的相关性。结果表明，不同糯玉米品种子粒蒸煮后硬度最低的是京科糯768（2 342.00 g），其次是京科糯2000（2 504.50 g），分别比苏玉糯2号低35.50%和31.02%；蒸煮后子粒回生值以京科糯2000（966.25 g）最低，其次是京科糯768（1 142.25 g），分别比苏玉糯2号低28.56%和15.55%。不同品种糯玉米淀粉结晶度表现，苏玉糯2号（43.64%）>京科糯2000（40.96%）>京科糯768（40.59%）。淀粉颗粒平均粒径以京科糯2000最大，其次是京科糯768，苏玉糯2号淀粉颗粒平均粒径最小。相关分析表明，蒸煮后子粒硬度及蒸煮后子粒回生值与淀粉结晶度呈显著正相关，与淀粉平均粒径呈显著负相关。综合分析表明，淀粉结晶度小、淀粉颗粒大是京科糯768和京科糯2000子粒硬度小的主要原因。     

京科糯2000等系列鲜食糯玉米品种选育及应用

北京市农林科学院玉米研究中心自1996年开展糯玉米种质创制及新品种选育,创制出京糯6、BN2等骨干糯玉米自交系近20个。选育出京科糯2000、京黄糯267、京紫糯218、京科糯569等系列各具特色的优良糯玉米品种21个,其中,通过国审品种6个,省审品种15个,实现了高产与优质的结合,同时具有抗性强、适应性广、用途多等特点。京科糯2000已成为我国种植面积最大、推广范围最广的品种,京科糯569鲜子粒叶酸含量在300μg/100 g以上,属营养强化型糯玉米品种。     

叶面喷硒对糯玉米生理特性及子粒硒含量的影响

采用2因素裂区设计,对4个糯玉米品种在5个供硒水平下的不同生理指标及子粒硒含量进行比较研究。结果表明,60 g/hm2的叶面喷硒处理不仅显著提高糯玉米过氧化物酶(POD)活性、谷胱甘肽(GSH)含量,降低丙二醛(MDA)含量,还能有效提高糯玉米叶片中叶绿素含量,在该处理浓度下4个品种子粒硒含量与对照相比均极显著增加。品种、浓度单一及其互作对子粒硒含量的影响均存在显著差异,各因素对总变异的贡献表现为处理浓度>品种>品种×处理浓度。与不喷硒处理相比,4个品种的子粒硒平均含量分别提高118.0545、139.3179、162.9583和87.1647μg/kg。综合考虑生理特性和子粒硒含量,确定选用CTN1965和JN20作为富硒品种,两个品种推荐叶面喷硒浓度分别为60~61.5529 g/hm2和60~78.8770 g/hm^2,在61.5529、78.8770 g/hm^2阈值下,两个品种子粒硒平均含量可达300μg/kg的安全上限。     

磷素施用对糯玉米子粒产量和磷素积累分配的影响

以苏玉糯5号和渝糯7号为试材,研究不同磷肥施用量和施用时期对糯玉米子粒产量及磷素积累分配的影响。结果表明,糯玉米成熟期子粒产量随施磷量的增加而增加,苏玉糯5号在基施和拔节期分别追施P_2O_575 kg/hm~2处理子粒产量最高;渝糯7号一次性基施P_2O_5150 kg/hm~2的处理子粒产量最高。随着生育进程的推进,两个品种植株磷素积累量均逐渐增加;同一生育时期下,两个品种植株磷素积累量随着施磷量的增加而增加。成熟期苏玉糯5号和渝糯7号两个品种在各施磷处理下子粒中磷素占植株整体的分配比例均最高,达70%左右;雄穗和苞叶中磷素含量相对最低,各仅占植株整体含磷量的2%左右。植株磷素利用效率在基施和拔节期分别追施P2O575 kg/hm~2处理下较低。综合两个品种产量、磷素积累和分配在不同处理的变化趋势,以基施和拔节期分别追施P_2O_575 kg/hm~2较优。     

不同颜色糯玉米子粒中花色苷组分及抗氧化活性研究

以5种颜色糯玉米子粒为材料,测定其总花色苷含量、6种花色苷组分含量和色度以及总抗氧化能力。结果表明,深紫灰色、深红色和灰紫色糯玉米子粒中天竺葵色素含量均显著高于淡黄色和淡黄绿色糯玉米子粒中天竺葵色素含量,糯玉米颜色红绿度（a^*值）与天竺葵色素和矮牵牛色素含量呈极显著正相关。深紫灰色糯玉米子粒中矢车菊色素含量显著高于其他4种颜色糯玉米子粒矢车菊色素含量,糯玉米子粒总抗氧化能力与总花色苷含量、矢车菊色素含量、天竺葵色素含量呈极显著正相关。结果表明,可通过提高糯玉米子粒矢车菊色素和天竺葵色素含量,选育高抗氧化能力的深紫灰色糯玉米品种。     

不同类型青贮玉米品种子粒和全株含水率动态变化特性

以8个生产主推青贮玉米品种（专用型4个、粮饲兼用型4个）为研究对象，探究分析不同类型青贮玉米品种的子粒与全株含水率动态变化特性。结果表明，玉米子粒乳线位置处于1/4、2/4、3/4和4/4时，对应处于授粉后36.8 d、47.0 d、56.4 d和63.6 d，子粒平均含水率为48.6%、39.3%、34.2%和31.1%，全株平均含水率为76.9%、70.2%、60.7%和56.5%。8个品种全株含水率由70%降至60%平均需14.0 d，其中专用型品种平均需16.7 d，比粮饲兼用型品种所需时间长5.4 d。专用青贮玉米品种适收期全株含水率70%~60%对应子粒乳线位置1/2~3/4，其适收期较粮饲兼用型品种长5 d；青贮玉米品种收获期内子粒生理降水速率和全株含水率降低速率相对较低，是京科青贮516、雅玉26、郑单958、京科968适收期相对较长的原因。     

南方鲜食玉米区不同糯玉米品种产量和子粒灌浆特性分析

2019年和2020年，以苏科糯1501、苏科糯12、苏科花糯2008、苏科糯11、苏玉糯5号和万糯2000为试验材料，系统分析南方鲜食玉米区不同糯玉米品种产量和子粒灌浆特性差异，为糯玉米高产优质品种选育提供支持。结果表明，产量及产量构成因素品种间差异两年表现基本一致(秃尖长除外)。产量较高的品种为苏科糯12、苏科糯1501、万糯2000和苏科花糯2008，穗粒数和粒重均高于产量较低的品种苏玉糯5号和苏科糯11。糯玉米产量与穗长、穗粒和百粒鲜重呈极显著正相关，百粒鲜重与最大灌浆速率和平均灌浆速率呈极显著正相关，穗粒数与有效灌浆期、最大灌浆速率时的时间和最大灌浆速率时的生长量呈显著正相关。在鲜食玉米高产品种选育时应注重对灌浆速率、最大灌浆速率时的生长量等指标进行选择。     

玉米不同粒位子粒容重与子粒物理性状的相关分析

以普通型品种农大108、郑单958和高淀粉型品种费玉3号、郑单18为试验材料,研究玉米不同粒位子粒容重与子粒物理性状指标间的相关关系。结果表明,高淀粉型玉米的容重高于普通型玉米,不同粒位玉米子粒容重表现为下部子粒上部子粒中部子粒。相关分析结果表明,玉米子粒容重与比重呈极显著正相关,与单粒重呈显著正相关,与粒长、粒长/粒宽、单粒体积以及盛装效率呈正相关,但相关系数未达到显著水平。容重与漂浮率和子粒水分含量均呈显著负相关,玉米上部、中部和下部子粒水分含量平均每下降一个百分点,子粒容重平均上升5.10、5.41和5.63 g/L。     

夏玉米子粒含水率和子粒灌浆的粒位差异及其关系研究

以不同自然脱水类型玉米品种为材料,分析其花后不同部位子粒含水率变化、粒重、体积、灌浆动态以及灌浆参数,明确子粒含水率变化与灌浆动态的关系。结果表明,灌浆后期两个时间节点子粒含水率差异较大,先玉335较蠡玉16子粒含水率分别低4.27和5.49个百分点。子粒含水率、体积和粒重均存在粒位效应,两个玉米品种子粒含水率均表现为下部子粒中部子粒上部子粒,子粒体积和粒重粒位效应表现为下部子粒中部子粒上部子粒。灌浆速率粒位效应存在基因型差异,蠡玉16表现为中部子粒下部子粒上部子粒,先玉335表现为下部子粒中部子粒上部子粒。灌浆启动势均表现为上部子粒下部和中部子粒,活跃灌浆期粒位差异较大,且品种间粒位效应趋势相反,先玉335活跃灌浆期上部子粒略大于下部子粒,蠡玉16下部子粒活跃灌浆期长于中部和上部子粒。灌浆峰值出现时间不同,两个品种最大灌浆速率出现时间相差4.77 d。     

脱水速率和灌浆速率对玉米收获期子粒含水量的影响

以黑龙江省极早熟和早熟玉米种植区域两对收获期含水量差异显著的玉米主栽品种及其亲本自交系为试材,极早熟玉米种植区域品种为德美亚2号和克玉17,早熟玉米种植区域品种为德美亚3号和哲单37,对比调查子粒含水量动态变化、灌浆速率、生理成熟前后脱水速率等,分析与收获期子粒含水量的关系。结果表明,收获期含水量低的德美亚2号和德美亚3号,与同熟期含水量高的克玉17和哲单37相比,均提前3 d达到生理成熟期,此时期两对杂交种间子粒含水量均无显著差异,灌浆速率平均快0.12 g/d,灌浆时间缩短3 d,各自的母本自交系间呈现出同样的变化;生理成熟后德美亚2号和德美亚3号与克玉17和哲单37相比,随着子粒脱水速率的加快,子粒含水量差异逐渐增大,收获期差异达到极显著水平,父母本自交系间也具有同样的表现。玉米收获期子粒含水量与生理成熟后子粒脱水速率和子粒灌浆速率均呈极显著和显著负相关,相关系数分别为-0.767和-0.589。     

水稻特大粒种质BG1和优质恢复系华占的粒形基因研究及相关功能标记开发

【目的】特异种质资源的发掘与利用是水稻优质高产育种的重要手段之一。明确特大籽粒种质BG1（Big Grain 1）和育种上广泛配组的优质恢复系华占携带的部分粒形基因等位变异类型,并开发相应基因的功能标记,有助于加快粒形基因的育种应用,提高水稻粒形精准改良的效率。【方法】对BG1和华占中的9个主效粒形基因（GS3、qLGY3、qGL3、GW2、GW8、GW5、TGW3、TGW6、GS9）的目的片段进行测序分析。并根据GW2、GS3、qGL3、TGW3、TGW6、qLGY3、GW8和GW5的测序结果,开发了鉴定其基因分型的功能标记。【结果】与日本晴相比,特大粒种质BG1在检测的9个主效粒形基因中有5个表现为功能缺失型（gs3、GW8、gw2、tgw3、tgw6）,1个稀有等位变异（qgl3）和1个外显子可变剪切型（qlgy3）;与日本晴相比,华占在检测的9个主效粒形基因中有3个（gs3、GW8、GW5）存在差异。根据测序结果开发了GW2、GS3、qGL3、TGW3、TGW6、qLGY3、GW8和GW5的功能标记,并利用15个水稻种质进行检测,检测结果中除了TGW6 的标记TGW6-Del 仅可用于鉴定是否含有功能缺失型的等位变异tgw6外,另外7个标记均为可准确鉴定基因型。【结论】与日本晴相比,特大粒种质BG1中调控粒长的基因gs3、qgl3、qlgy3、tgw3、GW8和tgw6之间可能存在复杂的互作调控通路,而不是简单的效应累加,粒宽特征可能是gw2、GW8的累加效应。优质恢复系华占的细长粒形可能是gs3、GW5和 GW8的互作效应所致。本研究中开发的功能标记可以用于水稻分子标记辅助育种。     

烯效唑对杂交水稻籽粒灌浆及产量的影响研究

以杂交稻组合汕优63为材料,探讨了不同施药时期(浸种、孕穗期喷施)和不同质量浓度(0,10,20,40,80 mg/L)烯效唑处理对籽粒生长过程及产量的影响.结果表明,烯效唑对强势粒生长有一定抑制作用,但同时却促进了弱势粒的生长,在一定程度上具有协调强、弱势粒灌浆的作用,降低成熟期强势粒单粒重而提高弱势粒单粒重;使强势粒的终极生长量降低,达最大生长速率的时间延后,从而延长弱势粒的灌浆时间,提高弱势粒的灌浆速率及最大干重;由于烯效唑对弱势粒生长的促进作用,显著提高了其穗实粒数,进而提高了单穗籽粒干重及水稻产量.处理时期不同,其最佳浓度不同;浸种处理以质量浓度为40mg/L时产量最高,喷施处理以20mg/L时的产量最高.     

The effects of nitrogen uptake before and after heading on grain protein content and the occurrence of basal- and back-white grains in rice (Oryza sativa L.)

Chalky rice (Oryza sativa L.) grains are induced by high temperature during the grain-filling period. Plant nitrogen status also affects the occurrence of basal- and back-white grains (BBWG). The objective of this study was to elucidate the relations between nitrogen availability per spikelet during the grain-filling period (N_GF) and each of the percentage of BBWG and grain protein content (GPC). We further compared the effect of the components of N_GF determined before heading (N_BH) and after heading (N_AH) on BBWG and GPC. We grew the rice cultivar ‘Koshihikari’ in pots in 2012 and 2013, and top-dressed nitrogen at the panicle formation and heading stages, under two (2012) or three (2013) temperature regimes during the grain-filling period. GPC was explained well by N_GF, but BBWG was not. BBWG was best explained in a multiple-regression equation by mean air temperature after heading and by N_BH and N_AH. The partial correlation coefficients for N_BH were 1.6 and 3.0 times those for N_AH in 2012 and 2013, respectively. On the other hand, in a multiple-regression equation for GPC, the partial correlation coefficients for N_BH were 0.91 and 0.71 times those for N_AH in 2012 and 2013, respectively. These results suggest that rice grains are most sensitive to plant nitrogen status before heading for BBWG but after heading for GPC, and that there is an optimal timing for nitrogen top-dressing that would maximize the reduction in BBWG per unit increment of GPC.     

晚粳稻籽粒中砷、镉、铬、镍、铅等重金属含量的品种和粒位效应

 选用籽粒着粒密度差异较大的密穗型品种秀水63和散穗型品种秀水11，种植于受重金属轻度污染的土壤，研究了晚粳稻籽粒中有毒重金属As、Cd、Cr、Ni、Pb含量的品种与粒位效应。结果表明，重金属含量的粒位间差异秀水63明显大于秀水11，As、Cd、Cr、Pb含量粒位间差异显著， Ni含量差异较小。穗上部籽粒As、Cd、Ni含量高于中部籽粒，穗下部籽粒最低，而Cr、Pb则正好相反。稻米中几种重金属含量与粒重的关系因重金属种类不同存在着差异，籽粒As、Cd、Ni含量与粒重呈正相关，而Cr和Pb含量与粒重呈负相关。秀水63和秀水11不同粒位的籽粒灌浆模式存在差异，下位粒灌浆速率较低，使粒重较上、中位粒低，导致粒重有较大的粒位差异，而这种差异也与穗部着粒密度有关，秀水63明显大于秀水11。籽粒As、Cd、Ni含量与最大灌浆速率（GRm）呈正相关，与到达最大灌浆速率时间（Tpoi）呈负相关，而Cr和Pb含量与以上两个籽粒灌浆特性参数分别呈负相关和正相关，说明籽粒As、Cd、Ni的积累与碳水化合物的积累具有相同或相近的模式，而Cr和Pb表现为不同的积累模式。     

Effects of GS3 and GL3.1 for Grain Size Editing by CRISPR/Cas9 in Rice

Grain size is one of key agronomic traits associated with grain yield and grain quality. Both major quantitative trait loci GS3 and GL3.1 play a predominant role in negative regulation of grain size. In this study, a CRISPR/Cas9-mediated multiplex genome editing system was used to simultaneously edit GS3 and GL3.1 in a typical japonica rice Nipponbare. In T_1 generation, we found that gs3 formed slender grain with lower chalkiness percentage, while gs3gl3.1 produced larger grain with higher chalkiness percentage. In terms of other agronomic traits, flag leaf size, grain number and grain yield of both gs3 and gs3gl3.1 mutants were affected. It is noteworthy that gs3 and gs3gl3.1 mutants both led to dramatical reduction of grain number, thereby decreased grain yield. In conclusion, these results indicated that knockout of GS3 and GL3.1 could rapidly improve grain size, but probably have some negative influences on grain quality and grain yield.     

Effect of Grain Position within a Panicle and Variety on As, Cd, Cr, Ni, Pb Concentrations in japonica Rice

Two japonica rice varieties, a compact panicle (CP) Xiushui 63 and a loose panicle (LP) Xiushui 11 were grown in a slightly contaminated paddy field, to determine the effect of grain positions within a panicle and variety on grain As, Cd, Cr, Ni and Pb concentrations. There was a significant difference in grain As, Cd, Cr, Ni and Pb concentrations among grain positions, and the extent of the difference was variety- and metal-specific; Xiushui 63 showed greater difference than Xiushui 11, and As, Cd, Cr and Pb being greater than Ni. The top grains (TG) of a panicle had higher As, Cd and Ni concentrations than the middle ones (MG), and the bottom ones (BG) contained the lowest. With regard to Cr and Pb, the case was opposite. Significantly positive correlations were found between grain weight and As, Cd, Ni concentrations, but there was a negative correlation between grain weight and Cr, and Pb concentrations. There was a remarkable variation in grain filling pattern among grains within a panicle, and between Xiushui 63 and Xiushui 11. In comparison with MG and TG, BG had the lowest grain filling rate and grain weight, leading to obvious difference in grain weight among grains within a panicle, and a greater difference for Xiushui 63 than for Xiushui 11. The regression analysis showed that grain As and Cd concentrations were positively correlated with the maximum grain filling rate (GRm),while negatively correlated with the required time for reaching the maximum grain filling rate (Tpol). Concerning Cr and Pb, the case was just reverse. It is suggested that As and Cd accumulation in grains might be accompanied by the carbohydrate accumulations, while Cr and Pb accumulation displayed a different pattern.     

Modeling the effects of N application on growth,yield and plant properties associated with the occurrence of chalky grains of rice

The objective of this study was to propose a model for explaining rice responses to a wide range of N application rates in various growth attributes associated with the occurrence of chalky grains. We improved the sub-model for N uptake process of a previous rice model which was originally developed for explaining genotypic and environmental variations in the whole growth processes, considering the difference in the rate of N loss from the plant-soil system between indigenously supplied soil mineral N and fertilizer N. A total of 80 growth datasets of cultivar ‘Koshihikari’ grown at Shiga prefecture, Japan, in 2010 was utilized for the calibration and validation of the model. The rice growth model well explained the above-ground biomass growth (RMSD = 78.7 g m^?2) and rough dry grain yield (RMSD = 83.2 g m^?2) for the validation data-set, simultaneously. The simulated carbohydrate content available per single spikelet was negatively correlated with the observed percentage of the milky-white grain which includes white-cored grain (r = ?.77, p < .001) for all the data-sets of calibration and validation. On the other hand, the observed percentage of the sum of white-back and white-base grains was closely correlated with the simulated plant N content available per single spikelet (r = ?.59, p < .001). It was suggested that the present rice growth model would rationally explain the effects of N application on the occurrence of the chalky grains through the dynamic change of the carbohydrate content and plant N content available per single spikelet.     

施磷量对超级稻南粳44产量和品质的影响

 以超级稻南粳44为材料,研究施磷量对水稻产量和品质的影响。结果表明,大田基施磷肥(P2O5)  0.0~225.0  kg/hm2,单位面积穗数、每穗粒数随着施磷量的增加而降低,结实率、千粒重则先升后降。各品质指标值与施磷量的相关均未达到显著水平,但施磷能提高糙米率、整精米率、垩白面积、垩白度,降低峰值黏度、热浆黏度、崩解值、冷胶黏度和回复值,而精米率、垩白米率、蛋白质含量、直链淀粉含量、起始糊化温度、消减值和到达峰值黏度时间对磷素的反应不明显。施磷主要是增加垩白面积从而增加垩白度,对垩白面积、垩白度、消减值影响较大,而糙米率、到达峰值黏度时间和起始糊化温度基本不受影响。综合产量和品质性状,水稻生产中应适量施磷(在土壤营养中等或偏上土壤上施85.7 kg/hm2为宜),过量施用不仅低产低效,还会加重生态污染。     

水稻强弱势籽粒核酸和蛋白质代谢差异

以两系杂交稻两优培九和培两优500为试验材料,对强弱势粒核酸和蛋白质含量进行了测定。水稻抽穗当天,强势粒单位质量子房中总RNA、mRNA含量都高于弱势粒,蛋白质含量却低于弱势粒。抽穗后第5天,强势粒单位质量子房中总RNA含量仍然高于弱势粒,mRNA含量两者差异不大,蛋白质含量依然低于弱势粒。不论是强势粒还是弱势粒,从抽穗到开花后第5天,其总RNA、mRNA和蛋白质单粒含量都有显著的增加,且各时期强势粒都高于弱势粒。抽穗当天强势粒有两条特异蛋白质带出现,而弱势粒没有,抽穗后第5天弱势粒才出现其中的一条。这说明强势粒与籽粒灌浆有关的基因表达比弱势粒早,强度高。