Critical Yield Factors for Achieving High Grain Yield in Early-Season Rice Grown under Mechanical Transplanting Conditions

Double-season rice cropping systems occupy a large portion of the rice production area in southern China. Because the problem of insufficient labor, mechanical transplanting (in contrast to the manual transplanting) was become more attractive in double-season rice system. However, the decisive yield factors which resulting in high grain yield of early-season rice are unclear under mechanical-transplanted conditions. In present study, the field experiments were conducted in the early season in 2017 and repeated in 2018 in Santang Town, Hunan Province, China. Ten early season rice cultivars (Zhuliangyou 819, Lingliangyou 268, Lingliangyou 104, Luliangyou 996, Xiangzaoxian 24, Xiangzaoxian 32, Xiangzaoxian 45, Xiangzaoxian 42, Zhongjiazao 17, and Zhongzao 39) were used as materials in this study. The difference in grain yield and closelyrelated agronomic and physiological traits of ten tested cultivars were compared. The range of yields (t ha^–1 at 86% dry matter) in 2017 was 6.2 to 8.7 (mean 7.8) and in 2018 was 6.5 to 8.4 (mean 7.8). Grain weight and pre-heading biomass accumulation had potent significant positive correlations with the grain yield. The greater pre-heading biomass accumulation was major attributed to higher apparent radiation use efficiency. Our results suggested that early-season rice cultivars to achieve the high grain yield in mechanical-transplanted conditions depends on apparent radiation use efficiency in the pre-heading period and higher grain weight.     

水分胁迫对水稻籽粒蛋白质积累及营养品质的影响

以生产上广泛使用的水稻(Oryza sativa)品种‘汕优63’、‘扬稻6号’和‘武育粳3号’为材料,研究了水分胁迫对结实期水稻籽粒蛋白质积累及营养品质的影响。结果表明:正常施氮水平下,花后10~20 d的水分胁迫提高了谷氨酰胺合成酶(Glutamine synthetase,GS)和谷氨酸合酶(Glutamate synthase,GOGAT)活性,提高了籽粒自身利用无机氮合成氨基酸的能力,从而利于籽粒内蛋白质的积累,而高氮水平下,水分胁迫降低了籽粒自身合成氨基酸的能力。以重量为基数的蛋白质含有率在整个灌浆过程中呈“V”型消长,正常施氮水平下,水分胁迫明显提高了花后15 d至成熟期蛋白质含有率,而高氮水平下,水分胁迫处理的蛋白质含有率明显低于水层灌溉。与水层灌溉相比,水分胁迫提高了正常施氮水平下精米中醇溶蛋白和谷蛋白含量,但却明显降低了高氮水平下精米中醇溶蛋白和谷蛋白含量。水分胁迫对稻米中赖氨酸含量的影响因品种、植株的氮营养水平的不同而不同,水分胁迫显著降低了两种氮肥水平下‘汕优63’中赖氨酸含量,但却明显提高‘扬稻6号’中赖氨酸含量;而‘武育粳3号’于两种氮肥水平下表现恰好相反,正常施氮水平下赖氨酸含量略有升高;而高氮水平下赖氨酸含量明显降低。     

Effects of exogenous ABA and cytokinin on leaf photosynthesis and grain protein accumulation in wheat ears cultured <Emphasis Type="Italic">in vitro</Emphasis>

A detached culture system and steady-state ¹⁵N labeling technique were used to study the effects of exogenous ABA and ZR on photosynthetic characteristics, nitrogen remobilization and the activities of key enzymes for nitrogen metabolism in detached wheat parts during grain protein accumulation. The differences in net photosynthetic rate, chlorophyll content (SPAD value) and soluble protein content in the flag leaves of detached culture system between the treatments of ABA and ZR showed that ABA facilitates the post-anthesis senescence course compared to the ZR treatment. The differences in the changes of ¹⁵N amount in different organs in the detached culture system between the ABA and ZR treatments showed that nitrogen remobilization from vegetative organs to the grain is accelerated by the ABA treatment but is delayed by ZR. The activities of GS and GPT in grains treated with ABA were significantly higher than those with the control treatment at 5 DAC, but reduced significantly compared with control at 11 DAC. The two enzyme activities in grains were reduced significantly by ZR at 5 DAC and increased significantly at 11 DAC, compared with those treated with ABA. The above changes of enzyme activity showed that the ABA treatment hastens amino acid conversion into grains and protein accumulation in grains, whereas the ZR treatment delays these processes. A significant reduction in grain weight with ABA treatment is associated with the reduction of net photosynthesis, chlorophyll content, and soluble protein content in flag leaves. Compared with the control and ZR treatments, a significant increase in grain protein content with the ABA treatment may result from the accelerating effects of ABA on N remobilization, amino acid conversion into grains and protein accumulation in grains.     

不同酸度酸雨对小麦花后氮硫代谢和籽粒蛋白组分的影响

酸雨是中国重要的环境问题,为研究酸雨对小麦籽粒品质的可能影响,以小麦品种扬麦15和汶农17为材料开展盆栽试验,研究了不同酸度(pH2.5、p H4.0和p H5.6)酸雨对小麦花后氮硫代谢关键酶活性和籽粒蛋白质含量及组分的影响。结果显示:酸雨处理抑制叶片硝酸还原酶(NR)活性,提高了扬麦15整个灌浆期及汶农17灌浆中后期叶片谷氨酰胺合成酶(GS)活性,促进了叶片蛋白的降解,降低了叶片可溶性蛋白含量。不同酸度酸雨提高了成熟期籽粒中蛋白质含量,酸度越强,增加幅度越大,籽粒中各蛋白组分含量和大部分氨基酸含量也有明显提高。酸雨提高了扬麦15叶片丝氨酸乙酰转移酶(SAT)和O-乙酰丝氨酸硫裂解酶(OAS-TL)活性,但对汶农17硫代谢关键酶活性影响较小,酸雨处理还提高了籽粒中二硫键和含硫氨基酸含量。可见酸雨对小麦氮硫代谢有不同程度影响,进而影响了小麦籽粒蛋白质含量和组成,酸度越强影响越大,但不同品种对酸雨响应有一定差异。     

水稻籽粒灌浆过程中蛋白质表达特性及其对氮肥运筹的响应

采用大田栽培的方式,研究了大穗型水稻金辉809籽粒灌浆过程中蛋白质的差异表达变化模式以及同一施氮量下不同的氮肥施用比例(总施氮量225 kg/hm2,基蘖肥:穗粒肥分别为7∶3和6∶4)对强弱势粒灌浆影响的分子机制。获得了水稻不同灌浆时段籽粒总蛋白的表达图谱,共发现32个在灌浆过程中发生显著差异表达的蛋白点,涉及籽粒的淀粉合成,能量代谢,激素信号转导,基因表达调节和抗逆响应等。在此基础上,进一步构建了不同灌浆发育时段水稻强弱势籽粒响应不同氮肥比例调控的蛋白表达图谱,结果发现强势籽粒响应氮肥调控出现差异表达的蛋白点有8个,而弱势籽粒有26个,可见强势籽粒灌浆具有更强的环境稳定性,相对地,弱势籽粒灌浆则易被环境所调节。在总施氮量不变的情况下,适当增加生育后期氮肥的施用量,有利于增强弱势籽粒中信号转导,促进相关基因的表达,提高物质调运与能量代谢速率,增强抗逆性,增强弱势籽粒的代谢水平,延长其灌浆时期,提升弱势籽粒活性和灌浆强度,增加结实率和千粒重,最终实现高产高效。研究结果对于进一步明确氮素调控水稻强弱势粒灌浆的分子生态特性具有重要的理论与实际意义。     

Rice growth improvement and grains bio-fortification through lime and zinc application in zinc deficit tropical acid sulphate soils

A two years field study was conducted to explain the effect of Zn and lime application on morphological characteristics, rice yield and yield components, and more broadly, grains bio-fortification (Zn and protein content (CP), and amino acid profiles). The lime and Zn interaction increased grains and straw yield more than two times (6.64 ton ha^?1) compared to the control (3.20 ton ha^?1). The maximum increase in the Zn content of grain, white rice and bran was obtained about 30% in whole grain, 42% in bran and 56% in white rice. Furthermore, CP increased by about 8% in bran, 12.3% in whole grain, and 27% in white rice compared to control. Also, the Zn and lime application and their interaction were significantly increased the amino acids, especially essential parts.     

Differences in Grain Ultrastructure,Phytochemical and Proteomic Profiles between the Two Contrasting Grain Cd-Accumulation Barley Genotypes

To reveal grain physio-chemical and proteomic differences between two barley genotypes, Zhenong8 and W6nk2 of high- and low- grain-Cd-accumulation, grain profiles of ultrastructure, amino acid and proteins were compared. Results showed that W6nk2 possesses significantly lower protein content, with hordein depicting the greatest genotypic difference, compared with Zhenong8, and lower amino acid contents with especially lower proportion of Glu, Tyr, Phe and Pro. Both scanning and transmission electron microscopy observation declared that the size of A-type starch molecule in W6nk2 was considerably larger than that of Zhenong8. Grains of Zhenong8 exhibited more protein-rich deposits around starch granules, with some A-type granules having surface pits. Seventeen proteins were identified in grains, using 2-DE coupled with mass spectrometry, with higher expression in Zhenong8 than that in W6nk2; including z-type serpin, serpin-Z7 and alpha-amylase/trypsin inhibitor CM, carbohydrate metabolism, protein synthesis and signal transduction related proteins. Twelve proteins were less expressed in Zhenong8 than that in W6nk2; including barley trypsin inhibitor chloroform/methanol-soluble protein (BTI-CMe2.1, BTI-CMe2.2), trypsin inhibitor, dehydroascorbate reductase (DHAR), pericentrin, dynein heavy chain and some antiviral related proteins. The data extend our understanding of mechanisms underlying Cd accumulation/tolerance and provides possible utilization of elite genetic resources in developing low-grain-Cd barley cultivars.     

高产水稻品种及种植方式对稻田甲烷排放的影响

采用大田试验研究了不同水稻品种（早稻：超级稻“陆两优996”和常规稻“创丰1号”;晚稻：T优259）及不同种植方式（直播和移栽）对稻田甲烷排放通量的影响.结果表明：早稻晒田前甲烷排放量占排放总量的52%～73%,排水晒田减少了甲烷排放通量;晚稻生育前期甲烷排放量占生长期间甲烷排放总量的70%.早稻直播方式的甲烷排放通量均值低于移栽种植方式,但甲烷排放总量大于移栽种植方式;晚稻直播方式的甲烷排放通量均值与排放总量都大于移栽种植方式.早、晚稻直播方式的单位稻谷甲烷排放量与移栽种植方式间均存在显著差异,早稻中超级稻和常规稻直播方式的单位稻谷甲烷排放量分别比移栽方式高4.84和3.48 g·kg^-1稻谷,常规稻的甲烷排放量高于超级稻;晚稻直播方式的单位稻谷甲烷排放量比移栽方式高6.67 g·kg^-1稻谷.相同面积、相同时间不同种植方式的稻田甲烷排放量、单位经济产量甲烷排放量表现为：早稻：常规稻直播＞常规稻移栽＞超级稻直播＞超级稻移栽;晚稻：直播＞移栽.     

Free and bound amino acids and proteins in developing grains of rice with enhanced lysine/proteins

 Free amino acids were determined in developing seed of a rice mutant with enhanced grain lysine. This phenotype frequently has enhanced protein. Some free amino acids of developing seed are inversely related to the level of total amino acids in proteins of the mature grain. Amino acids that were enhanced in protein, including aspartic acid, threonine, methionine and lysine, were notably lower in the free amino-acid pool. Our conclusion is that mutant-developing grains process aspartate amino acids more rapidly than the controls. Conversely, arginine, valine and glutamic acid/glutamine accumulate as free amino acids with mutant/control ratios of 1.39, 1.29 and 1.12, respectively. Glutamic acid/glutamine in proteins of mature seeds is lower in the mutant than the control. ³H-lysine incorporation showed enhanced isotope incorporation into at least four proteins. One mutant protein was less actively labelled than analogous controls. The ³Hlysine pattern indicates processing modifications in this useful rice mutant. Received: 14 October 1996/Accepted: 8 November 1996     

夏谷籽粒蛋白质积累和旗叶蛋白质周转的关系

谷子灌浆期旗叶蛋白水解酶活性、籽粒和旗叶游离氨基酸含量均呈双峰曲线变化。第一峰在花后１３天;第二峰分别在２５、２８天。籽粒和旗叶游离氨基酸峰稍滞后,且后者不明显。籽粒总蛋白积累和干重增加均为Ｓ型变化,与旗叶总蛋白和可溶性蛋白变化趋势相反。花后２２─２５天上述物质和酶活变化均出现─转折。转折点之前,蛋白质合成和周转活跃;之后,由叶片蛋白酶活性升高引起的旗叶氮素撤离对籽粒蛋白质积累仍有一定贡献（约１０％）。     

Biochemical factors affecting protein accumulation in the rice grain

Rice grains (Oryza sativa L.) from three varieties and three pairs of lines with different protein content were collected at 4-day intervals from 4 to 32 days after flowering. The samples were analyzed for protein, free amino nitrogen, ribonucleic acid, protease activity, and ribonuclease activity. In addition, the capacity of the intact grain to incorporate amino acids was determined for the three pairs of lines. The maximal level of free amino nitrogen and the capacity of the developing grain to incorporate amino acids were consistently found to be higher in the samples with the high protein content in the mature grain. The ribonucleic acid content of the grain tended to be higher in the high protein samples.     

Wheat nitrogen metabolism during grain filling: comparative role of glumes and the flag leaf

The mobilization of nitrogen (N) compounds and the roles played by glumes and the flag leaf during grain filling were studied in bread wheat (Triticum aestivum L. cv. Florida) grown under field conditions. Glumes lost twice as much of their total N content as that lost by the flag leaf between the milk and early dough stages. In the flag leaf, glumes and grains, Glu, Asp, Ser and Ala accounted for 85% of all the reductions in the free amino acid pool. Principal component analysis of free amino acid pools separated grains from the glumes and the flag leaf, suggesting grain specific regulations in the use of free amino acids in protein synthesis. In all three organs, no decrease in Gln was detected, probably due to steady glutamine synthetase (GS; EC 6.3.1.2) activities per soluble protein in both the flag leaf and glumes. Compared with the flag leaf, glumes presented relatively smaller amounts of the chloroplast GS associated isoform. This we show is due to a lower relative number of mesophyll cells in glumes as supported by the different anatomy and the cellular pattern of the GS immunolocalization. We argue that cellular distribution plays a key role in supporting metabolism to enable the various functions undertaken by glume tissue.     

Physiological and metabolic enzymes activity changes in transgenic rice plants with increased phosphoenolpyruvate carboxylase activity during the flowering stage

To compare the differences in physiology and metabolism between phosphoenolpyruvate carboxylase (PEPC) transgenic rice and its control, untransformed wild rice, dry matter accumulation, soluble sugar, starch and protein contents and enzyme activities were determined in different plant parts during flowering. Results revealed that PEPC transgenic rice had higher dry weights for leaf, stem and sheath as well as panicle than the untransformed wild rice did, with the largest increase in the panicle. Soluble sugar and protein content in the grains of PEPC transgenic rice were significantly enhanced while starch content changed less. PEPC transgenic rice exhibited high levels of PEPC activity, manifesting in high net photosynthetic rates during flowering. Moreover, transgenic rice with high PEPC expression levels also had elevated levels of the enzymes such as sucrose-p-synthase and sucrose synthase, which may confer a higher capacity to assimilate CO₂ into sucrose. Little increase in grain starch content was observed in transgenic plants due to the stable activities of starch synthase and Q enzyme. However, the PEPC transgenic rice plant induced the activities of nitrate reductase, glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, glutamine synthetase, and asparagine synthase to high levels, as compared with the untransformed rice plant. PEPC activity was correlated with protein content in grains and the enzymes of nitrogen metabolism, suggesting that high PEPC activity in transgenic rice might be able to redirect carbon and nitrogen flow by regulating some enzymes related to carbon or nitrogen metabolisms. These results may help to understand how the C₃ plants possessing a C₄-like photosynthesis pathway worked by expression of PEPC.     

不同冬小麦品种在3种质地土壤中氮代谢特征及利用效率分析

为明确不同土壤质地条件下不同品种冬小麦(Triticum aestivum)的氮代谢和利用特征, 筛选与土壤质地相适宜的高产和氮高效利用的优质小麦品种, 采用大田试验的方法, 在同一生态类型区砂土、壤土和黏土3种质地土壤上, 以当地生产上大面积应用的强筋小麦‘郑麦366’ (‘ZM366’)和中筋小麦‘矮抗58’ (‘AK58’)、‘周麦22’ (‘ZM22’)为材料, 系统地研究了土壤质地对不同冬小麦品种主要生育时期叶片氨同化关键酶谷氨酰胺合成酶(GS)活性、游离氨基酸含量、花前和花后不同器官氮素积累和分配、氮素再分配等氮代谢过程及产量、品质和氮素利用效率等的影响。结果表明: 在这3种土壤质地上, 不同品种冬小麦旗叶GS活性和游离氨基酸含量均呈倒“V”型变化特征。各品种小麦旗叶GS活性、游离氨基酸含量大小及达到最大值的时期不一样, 砂土条件下峰值早于壤土10天左右出现, 且在5月22日已检测不到GS活性和游离氨基酸含量。花前和花后小麦地上部及各器官氮积累量(NA)、氮再分配量(NR)、成熟期籽粒产量和氮素当季利用率(NUE)均以壤土上为最高。氮素转运率(NRE)、花前再分配氮素对籽粒氮素的贡献率(NRC)、氮素生理效率(NPE)、氮收获指数(NHI)以砂土上为最高。其中, 砂土上NRC达82.46%-95.84%, 是花后的7倍左右; 壤土和黏土条件下花后吸收的氮素在籽粒氮素的积累中占有较大的比例, 贡献率分别为36.6%和29.2%。同一土壤质地上3个品种比较, 在砂土上, GS活性、游离氨基酸含量、籽粒产量、蛋白质含量及NUE和NPE以‘郑麦366’最高, 而壤土上以‘矮抗58’最高, 黏土上则以‘周麦22’最高。因此, 在生产上应培育和选择与土壤质地相适应的小麦品种, 砂土地种植‘郑麦366’, 壤土条件下种植‘矮抗58’, 黏土条件下种植‘周麦22’, 可以在获得较高产量和品质的同时, 提高氮素利用效率。     

The 14‐3‐3 protein GF14f negatively affects grain filling of inferior spikelets of rice (Oryza sativa L.)

In rice (Oryza sativa L.), later flowering inferior spikelets (IS), which are located on proximal secondary branches, fill slowly and produce smaller and lighter grains than earlier flowering superior spikelets (SS). Many genes have been reported to be involved in poor grain filling of IS, however the underlying molecular mechanisms remain unclear. The present study determined that GF14f, a member of the 14‐3‐3 protein family, showed temporal and spatial differences in expression patterns between SS and IS. Using GF14f–RNAi plants, we observed that a reduction in GF14f expression in the endosperm resulted in a significant increase in both grain length and weight, which in turn improved grain yield. Furthermore, pull‐down assays indicated that GF14f interacts with enzymes that are involved in sucrose breakdown, starch synthesis, tricarboxylic acid (TCA) cycle and glycolysis. At the same time, an increase in the activity of sucrose synthase (SuSase), adenosine diphosphate‐glucose pyrophosphorylase (AGPase), and starch synthase (StSase) was observed in the GF14f–RNAi grains. Comprehensive analysis of the proteome and metabolite profiling revealed that the abundance of proteins related to the TCA cycle, and glycolysis increased in the GF14f–RNAi grains together with several carbohydrate intermediates. These results suggested that GF14f negatively affected grain development and filling, and the observed higher abundance of the GF14f protein in IS compared with SS may be responsible for poor IS grain filling. The study provides insights into the molecular mechanisms underlying poor grain filling of IS and suggests that GF14f could serve as a potential tool for improving rice grain filling.     

Incorporation of 15N labelled urea and ammonium into proteins and amino acids of Sorghum

Protein fractionation studies in developing Sorghum kernel indicated a considerable decrease in the proportion of albumin and increase in prolamin, glutelin and residue proteins during grain development. The globulin fraction remained more or less constant. ¹⁵N analysis indicated a turnover of albumin and globulin fractions. The nitrogen present in these fractions appeared into glutelin and residue proteins. At an early maturation stage ¹⁵N from ammonium was detected in the residue fraction while that from urea was incorporated in both albumin and residue fractions. However, this difference disappeared as the grains matured. Incorporation of ¹⁵N into basic amino acids was lower when compared to that in neutral and acidic amino acids at all stages of grain development.     

不同施肥水平对不同品种小麦籽粒蛋白质和地上器官游离氨基酸含量的影响

研究了小麦不同品种开花后各地上器官游离氨基酸含量的变化动态及其与籽粒蛋白质含量的关系,以及氮素营养的调节作用。结果表明,小麦叶片和颖壳十穗轴游离氨基酸含量均在开花后持续增加,至花后14d达到最大值,之后开始下降。茎和叶鞘游离氨基酸含量则在开花后上升较缓慢,至花后21d达最大值。籽粒游离氨基酸含量一般在开花后就持续降低。各地上器官游离氨基酸含量与成熟期籽粒蛋白质含量均呈显著或极显著正相关,说明源器宫中游离氨基酸供应充足,有利于籽粒蛋白质积累。增施氮肥能够提高各地上器官中的游离氨基酸含量,进而促进籽粒蛋白质的合成,提高籽粒蛋白质含量。品种之间籽粒蛋白质含量的差异,是由各地上营养器官向籽粒运输氨基酸的综合作用所造成的。     

稻田温室气体减排措施对稻米氨基酸含量的影响

为探索稻田中温室气体减排措施对稻米氨基酸含量的影响,用10个不同方法对双季稻田进行处理,并使用高效液相色谱分别测定了各处理稻田中所产稻米中的16种氨基酸的含量,其中色谱柱为Agilent Zorbax AAA分析柱,柱前衍生使用邻苯二甲醛(OPA)和9-芴甲基氯甲酸酯(FMOC-CL)为衍生试剂。结果发现:1)10个处理中的稻米16种氨基酸种类齐全,施氮肥+添加生物质炭48 t/hm2+间歇灌溉(NPK+HBC+IF)处理中所得氨基酸总量为6520.7 mg/100g,效果最佳;对照组处理(不施加氮肥+无稻草还田+间歇灌溉)所得氨基酸含量4338.0 mg/100g为最低。以对照组处理所得必需氨基酸百分含量36.8%为最高值;无稻草还田+长期淹水(NPK+CF)处理方法所得必需氨基酸百分含量33.1%为最低值。10个处理中16种氨基酸中含量较高的氨基酸均为天冬氨酸、谷氨酸和精氨酸,含量最低的均为甲硫氨酸;2)施氮肥量相同时,长期淹水与间歇灌溉相比,氨基酸总量增加185.1 mg/100g,非必需氨基酸百分含量增加3%,谷氨酸、组氨酸和丝氨酸含量明显升高,但亮氨酸含量显著降低;3)施用氮肥能提高稻米中的氨基酸含量,且随着氮肥使用量的增加,氨基酸含量也随之增加,组氨酸含量增加显著;4)供氮量相同时,添加猪粪使氨基酸总含量升高了286.0 mg/100g,此结果表明,在供氮量相同的情况下,施用猪粪更有利于稻米氨基酸含量的提高;5)灌溉模式相同时,稻草还田配施氮肥对必需氨基酸和氨基酸总量均有提高,天冬氨酸、谷氨酸和组氨酸的含量增加较多,甲硫氨酸含量略有下降;随着稻草还田量的增加,对非必需氨基酸影响较为明显;当稻草半量还田(还田量为3 t/hm2)时,稻米中氨基酸总量增加最多;稻草全量还田+长期淹水(NPK+HRS+CF)与稻草半量还田+间歇灌溉(NPK+LRS+IF)处理中的氨基酸含量基本接近,但必需氨基酸含量前者略高于后者,说明稻草还田与水肥管理对氨基酸含量影响可能存在交互作用;6)添加生物质炭配施氮肥提高了稻米必需氨基酸与非必需氨基酸含量,且随着生物质炭添加量的增加而增加;与稻草还田、添加猪粪处理相比,生物质炭的添加对氨基酸总含量提升的效果最为显著,对稻田实际生产具有指导意义且具有一定的环境效益。