斜发沸石对干湿交替稻田土壤速效钾和产量的影响

为了进一步探究斜发沸石在干湿交替稻田中的应用潜力,设置不同灌溉模式(淹灌和干湿交替灌溉)和不同斜发沸石用量(0、5、10t/hm2)的大田裂区试验,对2017-2018年稻田土壤速效钾动态变化和产量进行了研究。结果表明:稻田增施斜发沸石显著提高了水稻产量,在10t/hm2水平下产量最高,增产率达8.7%～22.3%。斜发沸石对稻田表层土壤速效钾含量和植株地上部钾素积累的提高有显著正效应,干湿交替灌溉显著提高了各生育期植株地上部钾素积累量,提高幅度分别为11.81%～21.42%(2017年)、9.69%～23.79%(2018年)。通径分析表明,斜发沸石增产是因为其显著增加了分蘖肥期和穂肥期土壤速效钾含量,提高了抽穗开花期和黄熟期地上部钾素积累。研究可为揭示干湿交替灌溉下提高钾肥利用效率的应用潜力,并一定程度上缓解稻田缺钾的局面提供依据。     

Agronomic evaluation of rice cultivation systems for water and grain productivity

Field experiments were conducted during summer (March–July) and kharif (June–September), 2008 at the wetland farm, Tamil Nadu Agricultural University, Coimbatore, India, to study the performance of different rice cultivation methods on productivity and water usage using the hybrid CORH-3 as a test crop. Treatments consisted of different rice cultivation methods, namely, transplanted rice (conventional), direct sown rice (wet seeded), alternate wetting and drying method (AWD), system of rice intensification (SRI) and aerobic rice cultivation. Results revealed that maximum number of tillers m^?2, higher shoot and root length at maturity were recorded under SRI followed by transplanted rice, while aerobic rice produced lower growth parameters in both the seasons. Chlorophyll content at flowering was higher under SRI in two seasons studied (42.74 and 39.48 SPAD value, respectively) and transplanted rice compared to aerobic rice and AWD. In both summer and kharif seasons, SRI produced higher grain yield (6014 and 6682 kg ha^?1), followed by transplanted rice (5732 and 6262 kg ha^?1), while the lowest grain yield (3582 and 3933 kg ha^?1) was recorded under aerobic rice cultivation. Under SRI, 5 and 6.7% increase in grain yield and 12.6 and 14.8% water saving were noticed compared to transplanted rice, respectively, during summer and kharif seasons. In respect to water productivity, the SRI method of rice cultivation registered the highest water productivity (0.43and 0.47 kg m^?3), followed by AWD and aerobic rice cultivation. The conventional rice cultivation and direct sown rice produced lower grain yield per unit quantity of water used.     

锌肥品种与施用方法对水稻产量和锌含量的影响

【目的】 鉴于在缺锌土壤上施用锌肥不仅可提高水稻产量,而且也能显著提高水稻籽粒锌含量,本研究旨在揭示不同品种锌肥和施用方法在提高水稻产量和籽粒锌含量方面的差异。 【方法】 以水稻品种‘镇稻 11 号’为供试材料,于 2011 年 5 月至 2012 年 11 月在大田条件下设置 4 组试验:试验 1,富锌稻种的生产制备与籽粒锌含量的染色鉴定试验,设水稻常规种植(CK)和生育期连续喷施 5 次硫酸锌(ZnSO₄·7H₂O,Zn) 2 个处理;试验 2,不同品种锌肥土壤施用试验,设不施锌肥对照(S1)、土施 ZnSO₄·7H₂O (S2)、土施氮锌复合肥(Urea-Zn,S3)、土施磷锌复合肥(Mosaic-Zn,S4)、土施钾锌复合肥(Kali-Zn,S5)、富锌种苗移栽(S6)和 ZnSO₄·7H₂O 蘸秧根移栽(S7) 7 个处理;试验 3,不同品种锌肥叶面喷施试验,设不施锌肥对照(F1)、孕穗期喷施 ZnSO₄·7H₂O (F2)、开花期喷施 ZnSO₄·7H₂O (F3)、孕穗期和开花期各喷施 ZnSO₄·7H₂O (F4)、开花期与农药一起喷施 ZnSO₄·7H₂O (F5)、开花期喷施 Kali-EPSO-Zn(F6)和开花期喷施 ADOB-IDHA-Zn(F7) 7 个处理;试验 4,富锌稻种育苗种植比较试验,设常规稻种(CK-grain)和富锌稻种(Zn-grain)育苗种植 2 个处理,研究其对水稻产量及构成、各器官(叶片、茎秆和籽粒)锌含量和累积分配的影响。 【结果】 1) 在水稻生育期进行叶面高浓度和高强度的喷锌方式可制备富锌稻种,且可采用双硫腙(DTZ)染色直观鉴定籽粒锌含量。2) 施用锌肥显著提高水稻产量和锌含量,且不同锌肥品种和施用方法间差异显著。3) 土壤施锌各处理平均增产效果显著高于叶面喷锌 5.2%;与土壤施锌处理相比,叶面喷锌各处理的叶片、茎秆和籽粒锌含量的平均值则分别显著提高 224.6%、78.5% 和 12.1%。4) 在土壤施锌条件下,不同锌肥品种中氮锌复合肥 (S3) 和钾锌复合肥 (S5) 的增产效果显著高于磷锌复合肥 (S4),而在叶面喷锌条件下,以 Kali-EPSO-Zn 处理 (F6) 提高水稻各器官锌含量的能力显著高于 ADOB-IDHA-Zn 处理 (F7) 和 ZnSO₄·7H₂O 处理 (F3)。5) 较常规稻种 (CK-grain),应用富锌稻种 (Zn-grain) 育苗种植的水稻产量和籽粒锌含量分别提高 4.6% 和 3.9%。 【结论】 结合锌肥土施增加水稻产量和喷施增加籽粒锌含量的田间应用效果,因地制宜地综合采用土施氮锌复合肥和喷施钾锌复合肥的配合施肥方法以及选用富锌稻种育苗种植,可协同实现最佳的锌肥利用效率、最大程度地稳产增产和提高稻米的锌营养品质。      

氮锌互作对水稻产量及籽粒氮、锌含量的影响

为探明氮锌互作对水稻产量及氮、锌含量的影响,以镇稻11号为供试材料,在大田条件下研究了2个氮肥用量（N 200、300 kg/hm2）下6个施锌水平（ZnSO47H2O 0、10、25、50、100、150 kg/hm2） 对水稻产量及成熟期植株氮、锌浓度及累积量的影响。试验结果表明: 在本试验条件下,锌肥的施用对水稻产量的增加不显著,但施锌能显著提高水稻各部位的锌浓度和籽粒锌累积量,并能提高水稻籽粒的氮浓度和粗蛋白含量,且表现出随施锌量的增加籽粒的氮浓度和粗蛋白含量增加的趋势; 高施氮量有利于水稻的增产及对锌的吸收与累积。因此,氮锌配施具有增加籽粒锌富集和提高蛋白质含量的双重效益。     

Zinc nutrition of rice as influenced by crop establishment methods,rates of nitrogen and phosphorus fertilization and inoculation with microbial consortia

Abstract

Zinc (Zn) fertilization in rice is important to enhance productivity and increase Zn concentration in rice grain to improve its nutritional status. A field experiment was conducted in wet seasons of 2013 and 2014 to study Zn nutrition of rice in three different crop establishment methods (CEMs) viz. puddled transplanted rice (PTR), system of rice intensification (SRI) and aerobic rice system (ARS), under three different rates of nitrogen (N) and phosphorus (P) viz. 0, 75 and 100% of recommended dose of fertilizer (RDF) (120?kg N ha^?1 and 25.8?kg P ha^?1) and two different sources of N and P viz. chemical fertilizer and microbial inoculation (MI). Concentration and uptake of Zn at different growth stages and in straw and milled rice was significantly higher in PTR and SRI than ARS. Soil DTPA–extractable Zn content of soil was increased by 1142.4, 1140.3 and 755.8?g ha^?1 in PTR, SRI and ARS after two year of Zn fertilization (soil application of 5?kg Zn ha^?1). Zinc nutrition increase its Zn concentration in straw and milled rice and improvement in total uptake was 38.1, 40.3 and 40.8?g ha^?1 when Zn was applied with RDF, 75% RDF + Anabaena sp. (CR1) + Providencia sp (PR3) consortia (MI1) and 75% RDF + Anabaena-Pseudomonas biofilmed bio-fertilizer (MI2), respectively. Positive correlation between milled rice yield and Zn concentration (R²= 0.95 and 0.97) showed the importance of Zn nutrition in improving rice yield. Zinc concentration at 70?days after sowing (DAS) and 100 DAS was also found positively correlated with dehydrogenase activity and microbial biomass carbon in soil.     

Zinc Concentration in Rice (Oryza sativa L.) Grains and Allocation in Plants as Affected by Different Zinc Fertilization Strategies

Concern over the food chain transfer of zinc (Zn) is increasing because of its importance in human health. A field experiment was conducted on a low Zn soil to determine the effect of different Zn fertilization strategies on grain Zn concentration and Zn allocation in different plant tissues of rice. Six treatments were used: (1) no Zn fertilization; (2) soil fertilization at transplanting; (3) Zn soil fertilization at transplanting and flowering; (4) foliar application during grain filling; (5) foliar applications during tillering, flowering, and grain filling; and (6) combination of treatments 3 and 5. Zn fertilization significantly increased Zn concentration in brown rice. The largest effect on grain Zn was observed by combination of soil and foliar applications. The increase in brown rice was much smaller (20%) than the increase in the vegetative parts (100%), indicating that grain Zn concentration of rice is not strongly increased by Zn fertilization. More increased Zn by Zn fertilization was allocated into straw not into grain. From the perspective of human nutrition, it seems that there is too little scope to enhance Zn concentration in rice by fertilization alone. the major bottleneck to increase Zn concentration in rice grain seems to be internal translocation/retranslocation of Zn from shoot to panicle or from rachis to grain, rather than root uptake of Zn from the soil.     

钾肥用量对寒地水稻产量和品质的影响

以粳稻品种空育131为试材,研究不同钾肥用量对其产量构成和品质性状的影响,为寒地水稻生产的合理施肥提供依据。结果表明,施用钾肥显著提高了有效穗数、穗粒数、稻谷产量和整精米率,降低了垩白粒率和胚乳直链淀粉含量,而对结实率、千粒重、糙米率、垩白面积和垩白度的影响较小;施钾使胚乳中总氮和蛋白氮含量增加,并提高蛋白氮比例,改善营养品质;施钾降低了糊化开始温度、冷胶黏度、回复值和消减值,提高了最高黏度、热浆黏度和崩解值,各特征值以回复值受影响最大。钾肥对水稻产量构成、品质指标及淀粉黏滞性谱特性的影响,在一定的范围内随施用量增加变化较明显,达到一定用量后继续增施钾肥效应减弱;试验条件下,以90.0kghm-2K2O的施用量较佳。     

冬水田杂交中稻品种适应氮肥后移的筛选指标

【目的】水稻采用前氮后移的施肥方式有利于提高氮肥利用效率并获得高产,但不同杂交组合是否适应尚无研究报道。为此,本文以20个杂交中稻组合为材料,研究了施氮方式与杂交组合间的产量及库源结构的互作效应。【方法】在冬水田高产栽培条件下,试验设前氮后移(底肥:促花肥:保花肥=6:2:2)与重底早追(底:蘖=7:3)两种施氮方式,采用裂区设计,以施氮方式为主处理,杂交组合为副处理进行田间试验。对两种施氮方式的产量差值与各施氮方式下产量性状间进行了相关、 回归与通径分析。【结果】20个杂交组合分别在两种施氮方式下的产量相关性状均达极显著,方差分析F值8.89~149.08(P＜0.01)。两种施氮方式下,20个杂交组合的产量性状及粒叶比的成对数据平均值的差异显著性分析表明,前氮后移处理的有效穗数比重底早追显著降低,但其结实率和千粒重分别显著或极显著提高,最高苗数、 穗粒数和粒叶比在两种施氮方式间差异不显著。不同杂交组合在两种施氮方式间的产量表现不尽相同。20个杂交组合前氮后移平均产量8981.90 kg/hm2,比重底早追增产1.62%;前氮后移处理中,内5优306、 蓉18优447、 内5优317和川谷优7329四个组合不仅产量较高,而且均分别比重底早追法极显著增产。前氮后移比重底早追的增产效果与两种施氮方式下杂交组合的穗粒数呈极显著负相关,相关系数分别为-0.7870和-0.7986(P＜0.01)。其原因在于,穗粒数较少的组合,其分蘖力较强,在前氮后移情况下,仍能确保较多的有效穗数,而且穗粒数和结实率因施用穗肥有一定提高,最终表现为前氮后移比重底早追法显著或极显著增产;而穗粒数过大的组合,其分蘖力较弱,在前氮后移前期施氮量较少情况下,因最高苗数明显不够,有效穗数显著下降,加之穗粒数有所降低而减产。【结论】前氮后移增产量(y)与杂交组合穗粒数(x)的关系可表述为 y =2607.9-11.02x (R2=0.6308)。大面积生产中,穗粒数237粒可作为采用前氮后移施肥法的杂交组合品种的选择指标。     

不同时期施锌对旱稻籽粒锌积累的影响

为了探明不同时期施锌肥对旱稻籽粒锌积累的影响,在田间条件下对两个旱稻供试品种(巴西陆稻和旱稻502)进行不同时期施锌肥(100 kg/hm~2 ZnSO_4·7H_2O)处理(基施或花前7 d土壤追施),收获期对旱稻各器官锌含量进行测定和分析.结果表明,与对照(未施锌)和基施锌肥相比,花前7 d追施锌肥能显著增加地上部生物量和籽粒产量.施锌肥两处理均显著提高了旱稻地上部锌积累量.与基施锌肥相比,花前7 d施锌肥更能增加旱稻糙米中锌的含量,但在巴西陆稻上两种施锌方法对籽粒产量的增加均不显著.     

水稻对~(65)Zn吸收和分配的比较研究

本试验以籽粒高锌含量基因型水稻V5 6和低锌含量基因型水稻湘早籼 1 7为材料 ,运用溶液培养和同位素示踪技术 ,探讨了水稻不同时期对65Zn吸收、运转和分配 ,特别是往籽粒的运输与分配。试验结果表明 :V5 6苗期根系吸收65Zn的能力和往地上部运转65Zn的能力强 ,累积的65Zn较少 ;生殖阶段分配到剑叶的65Zn低 ,籽粒的65Zn分配率高 ,籽粒65Zn累积高。湘早籼 1 7的结果恰恰相反     

南方粳型超级稻氮肥群体最高生产力及其形成特征的研究

在大田机插条件下,以南方稻区5个粳型超级稻(南粳44、宁粳1号、宁粳3号、扬粳4038、武粳15)为材料,同生育期常规粳稻武运粳7号为对照,在其他栽培措施统一在最佳技术指标前提下,设置7个氮肥水平(0、150.0、187.5、225.0、262.5、300.0和337.5kg.hm-2),从中得出各品种在这7个氮肥水平下出现的最高生产力,并将其定义为氮肥群体最高生产力。对5个超级稻氮肥群体最高生产力及其构成、群体生长发育动态、株型以及倒伏性状等方面进行系统的比较研究。结果表明,超级稻氮肥群体最高生产力为10.51(10.30～10.68)t.hm-2,极显著高于对照(9.77～9.82t.hm-2),增产幅度达5.2%～8.7%。与对照相比,超级稻氮肥群体最高生产力群体穗数多,穗型大,群体颖花量高(42442.11～44873.23×104.hm-2),结实率和千粒重与之相当;群体茎蘖机插后早发快长,有效分蘖临界叶龄期苗数略高于预期穗数,有效分蘖临界叶龄到拔节期茎蘖增长平缓,高峰苗出现在拔节期,数量适中,为预期穗数的1.4～1.5倍,此后群体平缓下降,至抽穗期基本稳定,最终成穗率高(66.9%～70.4%);其群体叶面积动态与茎蘖动态基本一致,最大叶面积指数出现在孕穗期,为7.72～7.97,此后平缓下降,成熟期保持在较高的水平上(3.30～3.74);干物重积累方面,移栽到有效分蘖临界叶龄期较对照高,有效分蘖临界叶龄到拔节期较对照低,拔节后积累速度较快,至抽穗期为10.80～11.08t.hm-2,抽穗到成熟期干物质积累量6.78～7.22t.hm-2,成熟期总干物重17.58～18.29t.hm-2,显著或极显著高于对照;根冠比和根系干重均高于对照,随着生育期的推移,超级稻优势更为明显,生育后期根系活力强(抽穗到蜡熟期平均伤流量3.53～3.74g.m-2.h-1)。超级稻群体形成特征:高秧苗素质促进低位分蘖发生,精确群体起点稳定提高穗数;生育中期干物质积累高,叶面积大,株型直挺,有效叶面积率和高效叶面积率高,源库流畅;生育后期茎鞘输出大,2次增重高,根群强健,支撑着高光效灌浆结实层的安全充实。氮肥群体最高生产力水平下,超级稻穗多粒大,群体颖花量大,需氮量大,产量潜力高;生育中后期光合生产能力强,充实量大;群体株型改善,抗倒支撑强,适宜用作机插。     

Zinc fertilization of lentil for grain yield and grain zinc concentration in ten Saskatchewan soils

Fertilization of grain legumes with zinc (Zn) can affect both marketable yield and Zn content of the grain, which is important in addressing human nutritional deficiencies in certain regions of the world. A pot experiment was conducted to determine the response of three different market classes of lentil to Zn fertilization using ten surface soils from Saskatchewan (Canada). The distribution of Zn among labile and stable fractions chemically separated from the soil was also determined in the ten prairie soils and related to the lentil responses observed. The three market classes of lentils (large and small green, small red) were grown without Zn (control), and with 2.5 and 5 kg Zn ha^?1 added as zinc sulfate to each soil prior to planting. Zinc fertilizer application significantly influenced grain yield and was soil dependent. A significant increase in grain yield over the control was observed from application of Zn on some low organic matter, high pH Brown Chernozem soils whereas a decrease in grain yield over control was observed in other soils such as a Black Chernozem of high organic matter content and low (<7) pH. Lack of positive yield response to addition of Zn were related to measured high diethylene triamine pentaacetic acid (DTPA) extractable and plant root simulator (PRS) resin membrane probe Zn, and large amounts of native Zn in exchangeable and iron/manganese (Fe/Mn) oxide bound fractions. Application of Zn fertilizer generally increased the grain concentration of Zn. For example, an increase of ～20% in Zn concentration over control was observed when 5 kg Zn ha^?1 was added to a loamy textured low organic matter Brown Chernozem soil. Overall, small green lentil was more consistent in producing a positive response to Zn fertilizer application on soils with low plant available Zn compared to large green lentil and small red lentil.     

Zinc fertilization in rice-wheat cropping system under upland calcareous soil

Zinc (Zn) fertilization is important for Zn crop biofortification as well as increasing yields, thus proper Zn recommendations for soil application is needed for Zn deficient soils. The effectiveness of Zn applications was evaluated in different combinations of rates (2.5, 5.0, 7.5, and 10.0?kg?ha^?1 per year) and frequencies (initial, alternate, and every year) in rice (Oriza sativa L.) – wheat (Triticum aestivum L.) cropping system in a Zn-deficient upland calcareous soil in the fourth year. Zn applications to rice at 7.5 and 10?kg?ha^?1 of alternate year and 5.0 to 10?kg?ha^?1 of every year had the highest rice equivalent yield as compared to no-Zn treatment. Hence, Zn application to rice at 7.5?kg?ha^?1 at alternate years is the lowest rate at which highest rice equivalent yield of rice-wheat cropping system can be obtained.     

~(32)P、~(14)C在杂交水稻分蘖和穗中的分布与谷粒产量的关系

研究结果表明,高产杂交水稻有较多的~(32)P和~(14)C积集在分蘖和孔熟期的稻穗中,杂交水稻F_1乳熟期同化的~(14)C-葡萄糖向稻穗输送的百分率高。观察发现,杂交稻谷粒产量与~(14)C-葡萄糖在稻穗中分布及与IAP(输入积)之间的相关性高。低产杂交稻没有上述特性。放射性同位素~(32)P、~(14)C在分蘖和稻穗中的分布可作为预测杂交水稻F_1谷粒产量的指标。     

Zinc-Use Efficiency in Upland Rice Genotypes

Zinc (Zn) deficiency is very common in annual crops grown on Brazilian Oxisols. A greenhouse experiment was conducted to evaluate Zn-use efficiency of 20 upland rice genotypes. The Zn levels used were 0 mg kg^?1 (natural level of the soil) and 20 mg kg^?1 of soil applied with zinc sulfate (ZnSO₄). Zinc × genotype interactions were significant for grain yield, panicle number, panicle length, root dry weight, and specific root length, indicating different responses of genotypes with the variation of Zn levels and that selection for Zn-use efficiency is necessary at low as well as at high Zn rates. Based on Zn-use efficiency index, 11 genotypes were classified as efficient and nine were classified as moderately efficient. The most Zn-efficient genotypes were BRA 01596, BRA 042156, BRA 052053, BRA Primavera, and BRA 01506. The most inefficient genotypes in Zn-use efficiency were BRA 042094, BRA 052045, BRA 052034, and BRA 052023. Grain yield and most of the yield attributing characteristics have significant Zn × genotype interactions, which indicate that genotypes respond differently under different Zn levels. Thus, genotype selection is an important strategy for upland rice production in Brazilian Oxisols.     

Zinc fertilization approaches for agronomic biofortification and estimated human bioavailability of zinc in maize grain

Maize (Zea mays L.) is generally low in bioavailable zinc (Zn); however, agronomic biofortification can cure human Zn deficiency. In the present experiment, Zn was applied in pots as ZnSO₄ · 7H₂O to maize cultivar DK-6142 as foliar spray (0.5% w/v Zn sprayed 25 days after sowing and 0.25% w/v at tasseling), surface broadcasting (16 kg Zn ha^?1), subsurface banding (16 kg Zn ha^?1 at the depth of 15 cm), surface broadcasting + foliar and subsurface banding + foliar in comparison to an unfertilized control. As compared to control, all treatments significantly (P ≤ 0.05) increased growth, yield and nutritional attributes in maize. Grain Zn and protein concentrations were correlated and ranged from 22.3 to 41.9 mg kg^?1 and 9 to 12 %, respectively. Zinc fertilization also significantly reduced grain phytate and increased grain Zn concentration. Zinc fertilization, especially broadcasting and subsurface banding combined with foliar spray decreased grain [phytate]:[Zn] ratio to 28 and 21 and increased Zn bioavailability by trivariate model of Zn absorption to 2.04 to 2.40, respectively. Conclusively, broadcasting and subsurface banding combined with foliar spray is suitable for optimal maize yield and agronomic Zn biofortification of maize grain. This would also be helpful to optimize Zn and protein concentration in maize grain.     

Zinc Nutrition of Lowland Rice

Zinc (Zn) deficiency in rice has been widely reported in many rice-growing regions of the world. A greenhouse experiment was conducted with the objective of determining Zn requirements of lowland rice. Zinc rates used were 0, 5, 10 20, 40, 80, and 120 mg Zn kg^?1 of soil applied to an Inceptisol. Zinc application significantly affected shoot dry weight and grain yield as well as concentrations and uptakes of Zn in soil and plant. Maximum yield of shoot dry weight and grain yield were achieved at 5 and 20 mg Zn kg^?1 of soil, respectively. Zinc concentration and uptake in shoot as well as Zn uptake in grain had significant quadratic increases as Zn concentration increased in the soil solution. Zinc concentration as well as uptake was greater in the shoot as compared with concentration and uptake in the grain. Zinc-use efficiencies significantly decreased with increasing Zn rates in the soil except agrophysiological efficiency, which had significant quadratic increases with increasing Zn rates. On average, about 6% of the applied Zn was recovered by the lowland rice plants. Mehlich 1 extracting solution extracted much more Zn than diethylenetriaminepentaacetic acid (DTPA). However, Mehlich 1 as well as DTPA-extractable Zn had significant positive correlations with each other as well as with Zn uptake in grain and shoot.     

Immobilization of Zinc Fertilizer in Flooded Soils Monitored by Adapted DTPA Soil Test

Zinc (Zn) deficiency is a persistent problem in flooded rice (Oryza sativa L.). Severe Zn deficiency causes loss of grain yield, and rice grains with low Zn content contribute to human nutritional Zn deficiencies. The objectives of this study were to evaluate the diethylenetriaminepentaacetic acid (DTPA) extraction method for use with reduced soils and to assess differences in plant availability of native and fertilizer Zn from oxidized and reduced soils. The DTPA‐extractable Zn decreased by 60% through time after flooding when the extraction was done on field‐moist soil but remained at original levels when air‐dried prior to extraction. In a pot experiment with one calcareous and one noncalcareous soil, moist‐soil DTPA‐extractable Zn and plant Zn uptake both decreased after flooding compared with the oxidized soil treatment for both soils. In the flooded treatment of the calcareous soil, both plant and soil Zn concentrations were equal to or less than critical deficiency levels even after fertilization with 50 kg Zn ha^?1. We concluded that Zn availability measurements for rice at low redox potentials should be made on reduced soil rather than air‐dry soil and that applied Zn fertilizer may become unavailable to plants after flooding.     

Direct and Residual Effects of Zinc on Zinc-Efficient and Zinc-Inefficient Rice Genotypes Grown under Low-Zinc-Content Submerged Acidic Conditions

Zinc (Zn) deficiency has been identified as a major cause of poor yield in rice. Flooding and submergence bring about a decline in available Zn due to pH changes and the formation of insoluble Zn compounds. A field experiment (undisturbed randomized complete block design with three replications) was conducted in farmers’ fields of Kedah state during 2008 and 2009 to determine the direct and residual response of Zn on rice genotypes at the rates of 0 and 15 kg Zn ha^?1 in low-Zn-content acidic submerged soil. The genotypes differed significantly in grain yield and its components. Single application of Zn significantly increased the growth and yield of the crop for two seasons. Based on the grain yield efficiency index, the most Zn-efficient genotypes were MR 106 and Seri Malaysia Dua. Two genotypes, MR 220 and MR 219, were moderately efficient, but MR 211 and Bahagia were classified as inefficient.     

Nitrogen Application in Irrigated Rice Grown in Mediterranean Conditions: Effects on Grain Yield,Dry Matter Production,Nitrogen Uptake,and Nitrogen Use Efficiency

ABSTRACT

Field experiments were conducted in the major rice growing area of Chile to evaluate the effects of nitrogen (N) fertilization and site on grain yield and some yield components, dry matter production, N uptake, and N use efficiency in rice cultivar ‘Diamante’. Two sites (indicated as sites 1 and 2) and six N rates (0, 50, 100, 150, 200, and 300 kg N ha^?1) were compared. Nitrogen fertilization increased yield, panicle density, spikelet sterility, dry matter production, and N uptake at maturity. 90% of maximum yield was obtained with 200 kg N ha^?1 in site 1 (12,810 kg ha^?1) and with 100 kg N ha^?1 in site 2 (8,000 kg ha^?1). These differences were explained by lower panicle density, and the resulting lower dry matter production and N uptake in site 2. Nitrogen use efficiency for biomass and grain production, and grain yield per unit of grain N decreased with N fertilization. While, agronomic N use efficiency and N harvest index were not affected. All N use efficiency indices were significantly higher in site 1, except grain yield per unit of grain N. The observed variation in N use efficiency indices between sites would reflect site-specific differences in temperature and solar radiation, which in turn, determined yield potentials of each site. On the basis of these results, cultivar ‘Diamante’ would correspond to a high-N use efficiency genotype for grain yield.