Comparison and analysis of QTLs for grain and hull thickness related traits in two recombinant inbred line(RIL) populations in rice(Oryza sativa L.)

Grain traits are major constraints in rice production, which are key factors in determining grain yield and market values. This study used two recombinant inbred line（RIL） populations, RIL-JJ（japonica/japonica） and RIL-IJ（indica/japonica） derived from the two crosses Shennong 265/Lijiangxintuanheigu（SN265/LTH） and Shennong 265/Luhui 99（SN265/LH99）. Sixty-eight quantitative trait loci（QTLs） associated with 10 grain traits were consistently detected on the 12 chromosomes across different populations and two environments. Although 61.75% of the QTLs clustered together across two populations, only 16.17% could be detected across two populations. Eight major QTLs were detected on the 9, 10 and 12 chromosomes in RIL-JJ under two environments, a novel QTL clustered on the 10 chromosome, q GT10, q BT10 and q TGW10, have a higher percentage of explained phenotypic variation（PVE） and additive effect; 15 major QTLs were detected on the 5, 8, 9, and 11 chromosomes in RIL-IJ under two environments, a novel clustered QTL, q GT8 and q TGW8, on the 8 chromosome have a higher additive effect. Finally, the analysis of major QTL-BSA mapping narrowed the q TGW10 to a 1.47-Mb region flanked by simple sequence repeat markers RM467 and RM6368 on chromosome 10. A comparison of QTLs for grain traits in two different genetic backgrounds recombinant inbred line populations confirmed that genetic background had a significant impact on grain traits. The identified QTLs were stable across different populations and various environments, and 29.42% of QTLs controlling grain traits were reliably detected in different environments. Fewer QTLs were detected for brown rice traits than for paddy rice traits, 7 and 17 QTLs for brown rice out of 25 and 43 QTLs under RIL-JJ and RILIJ populations, respectively. The identification of genes constituting the QTLs will help to further our understanding of the molecular mechanisms underlying grain shape.

Effect of Excess Fertilizer Phosphorus on Some Chemical Properties of Paddy Soil Derived from Red Soil and Its Relation to Rice Growth

A field experiment with an early rice-late rice rotation was carried out on a paddy soil derived from red soil in the southern part of Zhejiang Province to elucidate the effect of excess P application on some important characteristics of soil properies and its relation to nutrient status and grain yields of rice crops.The experimental results indicated that adequate fertilizer P (15 kg P hm-2) could increase the content of soil available P at the tillering stage of early rice, the contents of N, P and K in the shoots of early rice at primary growth stages, and the grain yield of early rice by increasing valid ears per hectare and weight per thousand grains, which was mainly related to the higher contents of reduced, non-reduced and total sugar in the shoots at the heading stage. And early rice supplied with excessive P could not yield more than that applied with adequate P, due to the reduction in the valid grain percentage and weight per thousand grains.In addition, onestime excess P supply at a rate as high as 90 kg P hm-2 could not improve the soil P fertility in case the soil available P content was lower than the initial (3.74 mg kg-1 soil) after an early rice-late rice rotation, and made a decline in the grain yield increased by per kilogram fertilizer P. Thus, one-time excess P supply should not be adopted for soils with a large P fixation capacity like the paddy soils derived from red soils.

Effect of various crop rotations on rice yield and nitrogen use efficiency in paddy–upland systems in southeastern China

To evaluate the effects of various rotation systems on rice grain yield and N use efficiency, a paddy–upland cropping experiment(2013–2016) was conducted in southeastern China. The experiment was designed using six different rice––winter crop rotations: rice–fallow(RF),rice–wheat(RW), rice–potato with rice straw mulch(RP), rice–green manure(Chinese milk vetch; RC–G), rice–oilseed rape(RO), and rice–green manure crop(oilseed rape with fresh straw incorporated into soil at flowering; RO–G) and three N rates, N0(0 kg N ha-1), N1(142.5 kg N ha-1), and N2(202.5 kg N ha-1). Average rice yields in the RF(5.93 t ha-1) rotation were significantly lower than those in the rotations with winter crops(7.20–7.48 t ha-1)under the N0 treatment, suggesting that incorporation of straw might be more effective for increasing soil N than winter fallow. The rice yield differences among the rotations varied by year with the N input. In general, the grain yields in the RP and RO–G rotations –were respectively 11.6–28.5% and 14.80–37.19% higher than those in the RF in plots with N applied. Increasing the N rate may have tended to minimize the average yield gap between the RF and the other rotations; the yield gaps were 18.55%, 4.14%, and 0.23% in N0, N1, and N2, respectively. However, the N recovery efficiency in the RF was significantly lower than that in other rotations, except for 2015 under both N1 and N2 rates, a finding that implies a large amount of chemical N loss. No significant differences in nitrogen agronomic efficiency(NAE) and physiological efficiency(NPE) were found between the rotations with legume(RC–G) and non–legume(RO and RW) winter crops, a result that may be due partly to straw incorporation. For this reason, we concluded that the return of straw could reduce differences in N use efficiency between rotations with and without legume crops. The degree of synchrony between the crop N demand and the N supply was evaluated by comparison of nitrogen balance degree(NBD) values. The NBD values in the RP and RW were significantly lower than those in the other rotations under both N1 and N2 rates. Thus,in view of the higher grain yield in the RP compared to the RW under the N1 rate, the RP rotation might be a promising practice with comparable grain yield and greater N use efficiency under reduced N input relative to the other rotations. The primary yield components of the RF and RP were identified as number of panicles m-2 and numbers of kernels panicle-1, respectively. The NAE and NPE were positively correlated with harvest index, possibly providing a useful indicator for evaluating N use efficiency.

Screening of Rice Cultivars for Morpho-Physiological Responses to Early-Season Soil Moisture Stress

The majority of rice(Oryza sativa L.) produced in the southern USA is drill-seeded and grown under upland-like conditions because permanent flooding is established after the four-leaf stage. Therefore, rice during the seedling growth stage will be subjected to variable soil moisture content. A greenhouse experiment was conducted to evaluate the performance of 15 rice cultivars commonly grown in Mississippi of USA under early-season soil moisture stress. Twenty morpho-physiological parameters of rice seedlings subjected to three different levels(100%, 66% and 33% field capacity) of soil moisture, from 10 to 30 d after sowing, were measured. Significant moisture stress × treatment interaction(P < 0.001) was observed for most of the parameters. Further, the total drought response index(TDRI) was developed to score the cultivars for drought tolerance with the variation from 26.88 to 36.21. Accordingly, the cultivars were classified into different groups of tolerance. The cultivars CL152 and CL142-AR were classified as the least and the most tolerant to drought based on TDRI and standard deviation, respectively. Even though both total root(R^2 = 0.98) or shoot(R^2 = 0.76) drought responses indices were positively correlated with TDRI, root traits were important in deriving the indices. Therefore, TDRI could be used to select cultivars for drought tolerance in a given environment and develop rice varieties with early-season drought tolerance. However, further research is needed to identify and characterize tolerance at other stages to assist breeding programs in rice.

Effects of Farm Yard Manure and Lime on Cadmium Uptake by Rice Grown in Two Contaminated Soils of Chittagong

A pot experiment was conducted to evaluate the efficiency of farm yard manure （FYM） and lime （calcium carbonate） on reducing the uptake of Cd by rice in two Cd contaminated soils of Chittagong. The effects of farm yard manure, lime and farm yard manure mixed with lime （FYM ＋ Lime） on rice （Oryza sativa L.） growth, Cd uptake by rice and 0.1 N HC1 extractable Cd in soil were investigated. Results showed that addition of lime and farm yard manure mixed with lime significantly decreased 0.1 N HCl extractable Cd in the city sewage soil. Application of farm yard manure significantly decreased Cd concentration in rice in the city sewage soil. Lime and farm yard manure mixed with lime significantly reduced Cd concentration in rice m both the contaminated soils. Lime was more efficient than farm yard manure in reducing the uptake of Cd by rice.

稻秆生物炭添加对红壤性水稻土磷素生物有效性的影响

为明确稻秆生物炭添加对红壤性水稻土磷生物有效性组分的影响,基于水稻种植的盆栽试验,采用模拟生物活化的磷素分析方法(BBP法),分析了生物炭在不施加(CK)、施加一年(B1)和两年(B2)条件下,不同水稻生育期稻田土壤中可溶性磷(CaCl_(2)-P)、易被酶矿化的有机磷(Enzyme-P)、易被有机酸活化释放的磷(Citrate-P)和潜在无机磷(HCl-P)4个组分磷与全磷(TP)、有效磷(Bray-P)及磷素活化系数(PAC)的变化差异和影响因素。研究表明:与CK相比,B1处理的稻田土壤TP、Bray-P及BBP磷组分均无显著变化;B2处理稻田土壤TP、Bray-P、Citrate-P和HCl-P含量均显著增加,而CaCl_(2)-P、Enzyme-P含量无显著变化。随着水稻生育期的延长,各处理HCl-P/TP均显著上升;B2处理下CaCl_(2)-P/TP与Enzyme-P/TP均显著上升。相关分析表明:生物炭添加后稻田土壤Bray-P、TP与土壤pH显著正相关;CaCl_(2)-P与HCl-P、TP显著正相关,与土壤有效铁呈显著负相关;Citrate-P与TP、HCl-P极显著正相关,与Enzyme-P、pH显著正相关,与土壤有效铝极显著负相关。稻秆生物炭通过影响稻田土壤pH、有效铁和有效铝含量,间接地调控且显著增加了红壤性稻田土壤中TP、Bray-P、PAC及生物有效磷组分含量,稻秆生物炭的合理施用有利于农田生态环境保护和土壤磷素有效性的提升。

硅基叶面阻控剂对水稻的控镉效应

在中轻度Cd污染区域开展大田试验,探索不同用量的硅基叶面阻控剂对土壤有效Cd、水稻(Oryza sativa L.)不同器官Cd含量及Cd转运的影响。结果表明,叶面阻控剂不能降低土壤有效Cd含量,但能调控Cd在水稻器官中的转运与富集,与不施叶面阻控剂对照相比,水稻根、茎、叶与稻米中Cd含量分别降低13.06%~27.03%、17.39%~36.96%、14.89%~42.55%、11.11%~32.83%,水稻对Cd的富集从高到低依次为根、茎、叶、稻米。水稻植株中Cd从根到茎(TF根-茎)、茎到叶(TF茎-叶)、叶到稻米(TF叶-稻米)的转运系数分别为0.36~0.42、0.47~0.53、0.42~0.50,其中根到茎的转运系数最低,且随叶面阻控剂用量的增加其转运系数逐渐降低。施用一定量的叶面阻控剂在一定程度上能提高水稻产量,从经济成本和降镉效果等因素综合考虑,用量为4 500 mL/hm~2时,成本低廉且效果较佳。

水稻旱育稀植高产栽培的生理生态研究Ⅰ.早稻肥床旱育秧苗素质及其生态生理特性

本研究表明 ,旱育秧床中土壤好气微生物总量高于对照 ,其中好气性固氮菌、纤维分解菌、氨化细菌、有机磷分解菌、亚硝酸细菌增加了 1 .40、2 0 .67、8.0 4、74.0 0、0 .69倍 ,除脱氢酶外土壤蛋白酶、纤维素酶、磷酸酶、尿酶和蔗糖转化酶活性比对照增加77.5%、51 .1 5%、47.1 2 %、43.59%、6.88% ,这有利于土壤物能转化 ,提高土壤养分的有效性 ,使旱育秧床土壤硝态氮、速效N、P、K比对照增加 2 7.9、2 .0 8、0 .97、0 .7倍 .同时还表明 ,旱育秧白根率高 ,根系氧化能力强 ,低节位分蘖多 ,并表现出强大的生理生化优势 ,淀粉酶、硝酸还原酶、ATP酶以及过氧化物酶、过氧化氢酶、超氧物歧化酶等保护酶含量增加 ,而丙二醛含量和膜透性比对照降低了 7.1 2 %和 43.42 % .

灌溉稻田水稻旱作技术要素及产量形成

研究灌溉稻田水稻旱作法旨在构建类似旱地作物高产的稻作技术体系,以旱作求节水、以高产求效益。水稻旱作法是吸取我国稻作传统技术、新应用技术及强化栽培技术之精华整合而成,其核心是限量用水、湿栽旱管与选用超级杂交稻、培育短龄壮秧带土移栽及稀植等4个要素。研究结果表明,灌溉稻田水稻旱作法的技术框架基本可行,收到了高产、节水与改善稻米品质的效果。超级杂交稻组合两优培九、协优9308的旱作产量达9～10 tha-1,节约用水45%,灌溉水利用率高达3.0～4.0 kgt-1,并提高稻米的加工品质与营养品质。但与常规灌溉水稻相比,旱作水稻的穗型变小,结实率与千粒重下降。因此,本旱作法的几个主要技术要素有待改进,如超稀植的程度与提高结实率的方法。初步提出“湿栽护苗、旱管培根、沟水育穗、干润防衰”的湿栽旱管、限量用水技术的16字诀,就灌溉田旱作稻产量形成的特点作了初步的描述。

不同种植方式对土壤肥力和水稻根系生长的影响

以冈优22、Ⅱ优162和K优047为材料,通过大田试验研究了不同种植方式对土壤肥力、根系特征、根系伤流液和地上部干物质积累的影响。结果表明:免耕高留茬抛秧处理促进了土壤肥力提高,水稻成熟期其有机质含量、全氮含量、全钾均高于常耕插秧、常耕抛秧和移栽前的基础肥力,同时速效氮、钾含量也有明显提高。免耕高留茬抛秧前期根系和地上部的生长量均较低,拔节期总根长和根数均大大低于常耕插秧,也低于常耕抛秧。但免耕高留茬抛秧延缓了后期根系和地上部衰老,抽穗后30 d根系伤流液强度显著或极显著高于常耕抛秧和插秧。

免耕高留茬抛秧稻的产量及若干生理特性研究

通过与常耕插秧和抛秧的比较,分析了免耕高留茬抛秧分蘖消长、根系生长、籽粒灌浆和产量特性;同时研究了不同育秧方式和秧龄对免耕高留茬抛秧稻产量及产量构成的影响。结果表明,免耕高留茬抛秧分蘖缓慢,有效穗数较少。抽穗前植株发根力较低,但抽穗后10d植株发根力高于其他种植方式,抽穗后30d根系伤流强度显著高于常耕插秧和抛秧,后期植株衰老延缓。强势粒灌浆过程差异较小,但免耕高留茬抛秧延长了弱势粒灌浆时间,增加了弱势粒重,提高了单穗颖花数、籽粒充实率和千粒重。产量与其他处理差异不显著。在免耕与前作秸秆高留茬还田条件下,旱育带泥抛栽根多活力高,促进了水稻分蘖早生快发,比塑盘育秧抛栽极显著增产;3个抛栽秧龄中,以秧龄40d处理产量最高。

水稻砷污染及其对砷的吸收和代谢机制

水稻是当今世界大部分地区(尤其是东南亚)的主要的粮食作物之一,同时也是砷(As)进入食物链的主要途径之一。日益严重的水稻田As污染,不但影响了稻米的产量和品质,而且通过食物链威胁着人体健康。如何减少水稻地上部(尤其是米粒)As的含量和降低其毒性,及提高水稻As耐性是亟需解决的世界食品安全问题。深入了解水稻对As的吸收、积累和代谢的生理及分子生物学机制是解决水稻As污染的关键途径。综述国内外研究,对今后深入研究提出建议。

3种不同性质改良剂对镉锌污染水稻土的修复效果及评价

采用盆栽试验,研究施用石灰、有机肥、海泡石3种不同改良剂对水稻土培养的小油菜生物量、镉锌吸收量、吸收系数的影响。结果表明:施用改良剂,小油菜(Brassica campestris Linn)连种3季的生物产量都显著提高,对镉锌的吸收量降低,其中以石灰和有机肥配施的效果最好,增产170%以上;单施改良剂降低小油菜对镉锌的吸收以石灰的效果较好,海泡石的最差。小油菜对镉的吸收系数大于锌的吸收系数,说明镉在土壤中的移动性比锌大,施用石灰降低吸收系数的效果最好;施有石灰的使小油菜中镉、锌含量达到食品卫生标准;改良剂对镉的后效好于对锌的后效。

不同水分条件下水稻籽粒形态及其与粒重的关系

运用机器视觉检测技术,以普通杂交稻汕优63和超级杂交稻国稻6号为材料,在幼穗分化开始至分化后30d分别设置不同的控水处理,通过水分仪结合称重法控制土壤含水量,研究了稻穗及穗上不同部位籽粒的形态性状,并分析各性状与粒重的关系。结果表明:水稻的籽粒面积、长度及千粒重对水分反应较明显,水分亏缺对籽粒面积和粒重的影响引起比粒重(单位籽粒面积的重量)变化,长宽比对水分也有一定反应,宽度对水分的响应因品种而异。籽粒形态性状、产量及其构成因素均随水分亏缺的加重而有不同程度下降,穗生长发育全阶段的控水处理影响最大,其次是中期的重度和中度控水处理以及前期、后期的重度控水处理,各时段控水对不同部位籽粒形态的影响与穗分化发育的顺序历期基本吻合。除粒宽与其他形态性状之间呈极显著或显著负相关以外,其余各籽粒形态性状之间均呈极显著正相关。籽粒面积、长度及长宽比与千粒重之间存在极显著或显著的相关关系,可以作为水稻抗旱性鉴定有效的籽粒形态指标。

土壤水分与氮素对水稻地上器官脱落酸和细胞分裂素含量的影响

在盆栽和土培池条件下，研究了结实期轻度土壤水分胁迫与氮素营养对水稻地上部脱落酸和细胞分裂素含量及籽粒灌浆的影响。轻度土壤水分胁迫提高了籽粒的灌浆速率，缩短了灌浆期。在高氮（HN）水平下，轻度土壤水分胁迫处理使结实率、粒重和产量较正常灌溉条件下提高。土壤水分胁迫降低了稻株中的玉米素（Z）＋玉米素核苷（ZR）含量，显著增加了稻株中特别是籽粒中脱落酸（ABA）含量。籽粒灌浆速率与籽粒ABA含量极显著正相关，而与籽粒中Z＋ZR含量的相关不显著。灌浆前期（花后9～13d）对在HN和正常灌水下生长的稻株喷施ABA，显著提高了籽粒中蔗糖合成酶、淀粉合成酶、淀粉分支酶、可溶性酸性转化酶和腺苷二磷酸葡萄糖焦磷酸化酶的活性，增加了粒重。喷施氟草酮（ABA合成抑制剂）的结果与喷施ABA相反。表明轻度土壤水分胁迫促进籽粒灌浆，ABA起重要的调控作用。

有机物料对污染土壤上水稻重金属吸收的调控效应

采用重金属污染水稻土开展盆栽试验，研究施用有机碳源、菜籽饼和猪粪对不同水稻（汕优63，简称“SY63”；中浙优1号，简称“ZZYl”）重金属吸收的调控效应。结果表明，在重金属污染土壤上ZZYl具有一定的耐性，相同处理时ZZYl糙米、砻糠、秸秆中重金属含量均低于SY63品种，糙米中Cd含量较SY63低57．5％～83．8％，Cu含量低37．8％～69．1％，Zn含量低0．88％～31．7％，食物链风险较SY63品种低。3种有机物料中，施用菜籽饼使两水稻品种糙米中重金属含量明显低于其他处理；与对照相比，施用菜籽饼使SY63糙米中Cd、Cu和zn含量降低73．5％、52．6％和32．1％，ZZYl糙米Cd含量降低30．5％。在供试重金属污染土壤上可选择具有一定重金属耐性的水稻品种ZZYl进行粮食生产，同时施用适量的菜籽饼以增强其抵御重金属毒害的能力，降低糙米中Cd、Cu和Zn含量及其食物链污染风险。

紫云英还田对土壤肥力、水稻产量及其经济效益的影响

为研究紫云英还田与配施不同量化肥对土壤肥力、水稻产量、产量构成要素以及经济效益的影响,采用田间小区试验,设置了不施肥(CK)、仅施当地常规化肥施用量(G0N225P135K135)、紫云英还田与当地常规化肥施用量的100%、80%、60%、40%配施(GN225P135K135、GN180P108K108、GN135P81K81、G90P54K54)6个处理。结果表明,紫云英与不同量化肥配施,均能明显提高耕层土壤有效氮、有效磷、有效钾和有机质的含量。且紫云英与当地常规施肥量100%、80%、60%、40%配施,稻谷产量比仅施化肥处理分别增产4.5%、5.2%、2.8%、0.5%,其中,80%化肥量与紫云英配施的产量显著高于仅施化肥处理(P<0.05)。同时紫云英和80%、60%当地常规施肥量配施,其总净收益均高于仅施化肥的处理。从稻谷产量、净收益和产投比及环境友好性综合来看,紫云英还田与当地化肥施用量的80%和60%配施是最优组合。

稻-稻-油菜轮作对土壤微生物活性和多样性的影响

水稻(Oryza sativa L.)和油菜(Brassica campestris L.)轮作是中国南方地区常见的耕作制度,其优点在于能够提高农业土地利用率和增强土壤生产力,且能改变土壤生态环境。轮作栽培土壤生态环境的改变对作物生长具有益的作用,而土壤中微生物的变化是土壤生态环境改变的重要因素。因此,研究土壤微生物活性和多样性可为水稻和油菜轮作栽培对土壤质地的影响能够提供理论依据,对维持良好的土壤环境生态系统和农田可持续耕作具有重要的现实意义。以浏阳(短期试验:3 a)和安仁(长期试验:30 a)两地的稻-稻-油菜轮作土壤为研究对象,选取稻-稻连作土壤作为对照比较,分别于2015年7月、10月和2016年4月取样测定稻-稻-油菜轮作和稻-稻连作土壤微生物量碳、氮含量。结果表明:就所测得的浏阳土壤微生物量碳含量而言,稻-稻-油菜轮作比稻-稻连作分别高出16.99%、15.26%、32.33%,安仁土壤则分别高出26.38%、20.18%、35.74%;就所测得的浏阳土壤微生物量氮含量而言,稻-稻-油菜轮作比稻-稻连作分别高出34.63%、17.80%、33.81%,安仁土壤则分别高出14.29%、15.31%、14.58%。采用Biolog ECO技术分析土壤微生物多样性,结果表明浏阳和安仁两地稻-稻-油菜轮作和稻-稻连作土壤平均吸光值(AWCD)变化趋势相同,稻-稻-油菜轮作土壤AWCD值大于稻-稻连作,表明稻-稻-油菜轮作提高了土壤微生物对碳源的利用能力。研究结果表明稻-稻-油菜轮作显著提高了土壤微生物丰富度指数,而对均匀度和优势度指数影响不显著。通过主成分分析可知,3个不同时期土壤微生物对碳源的利用以糖类、羧酸类、氨基酸类为主。

珠江三角洲稻田土壤砷及其向水稻籽粒迁移特征

采集珠江三角洲区域水稻（Oryza sativa L.）植株的根系、秸秆、稻谷和对应的耕层土壤（015cm）样品,分析土壤和水稻植株中砷含量,初步研究土壤砷与土壤基本理化性质的关系及砷在土壤-水稻系统中的迁移规律。结果表明,土壤砷含量在1.8318.14mg·kg^-1之间,土壤砷与土壤有机质、砂粒含量呈显著负相关,与土壤粉粒含量呈显著正相关。糙米中的砷含量在0.210.43mg·kg^-1之间,均未超过国家食品卫生标准（0.7mg·kg^-1）,砷在水稻植株中的分布规律为根〉秸秆〉颖壳〉糙米。糙米砷含量与秸秆砷含量呈极显著正相关,与秸秆中P/As、Si/As摩尔比呈极显著负相关,因此,降低秸秆中As的积累、增加秸秆中P、Si的积累可降低水稻籽粒中的砷含量。

水稻化感品种对土壤微生物的影响

通过盆栽实验研究三叶期水稻化感品种对土壤微生物种群数量的影响。结果显示,土壤细菌、放线菌、真菌、氨化细菌和好气性自生固氮菌数量在水稻化感品种PI312777和水稻非化感品种“辽粳九”、“秋光”的土壤中存在显著差异,土壤中大多数微生物被水稻化感品种所抑制,但化感品种土壤中的放线菌和好气性纤维素分解菌数量则介于两种非化感品种之间。这一研究表明,水稻化感品种能显著地影响土壤微生物种群数量。