Effect of Organic and Inorganic Nutrients for Soil Quality Conservation and Yield of Rainfed Low Land Rice in Sub-tropical Plateau Region

The effect of organic sources of nutrients and inorganic fertilizers, was studied on grain yield of lowland rice and some aspect of soil quality parameters in a field experiment at Agricultural Experimental Farm of Indian Statistical Institute, Giridih, situated at eastern plateau region of India, during consecutive years 1997–2002. Chemical fertilizers and various organic matters were applied to two rice cultivars, Sabita and Subarna. The highest mean grain yield was 3.53 t ha^?1 and maximum agronomic efficiency was 60.3 % with the application of inorganic fertilizer followed by cow dung, where 3.47 t ha^?1 grain yield was recorded with an agronomic efficiency of 57.5 %. Grain yield of rice recorded under organic sources of nutrients was not significantly different from that of inorganic fertilization though there was improvement in soil quality parameters under organic sources. Soil organic carbon (0.72 %), microbial biomass‐C (279.23 μg g^?1 dry soil), urease activity with buffer (33.54 μg urea hydrolyzed g^?1 oven‐dry soil) and non‐buffer (21.97 μg urea hydrolyzed g^?1 of oven‐dry soil) methods and acid phosphatase activity (2.24 μg para‐nitrophenol released g^?1 of oven‐dry soil) analysed following the harvest of the crop were highest under cow dung manure treatment; the most efficient organic source under the experiment. Mean grain yield of rice was significantly higher in Sabita cultivar over Subarna. The regression analyses among the variables have shown that there was linear relationship among soil parameters and grain yield of rice.     

不同水分条件下缓/控释氮肥对水稻干物质量和氮素吸收、运转及分配的影响

为探究缓/控释肥在不同水分条件下提高氮素利用率及增产机制。本研究以杂交中稻F优498为试验材料,在180 kg hm^-2施氮量基础上,采用两因素裂区设计: 主区设控灌、干湿交替灌溉、传统灌水灌溉3种水分管理方式,副区设尿素一道清、尿素常规运筹、硫包膜缓释肥、树脂包膜控释肥4种氮肥种类,研究缓/控释肥和水分管理方式对水稻干物质量和氮素吸收、运转、分配和产量的影响及其互作效应。结果表明, 缓/控释肥和水分管理方式对水稻主要生育期干物质量和氮吸收、转运、分配及产量具显著影响及互作效应,产量构成因素与氮素在结实期转运总量及其分配呈显著正相关。干湿交替灌溉和缓/控释肥均能提高干物质量、氮素吸收及产量并表现出显著互作效应,施用缓/控释肥氮素表观利用率达42%~53%,相较于尿素一道清和传统的尿素常规运筹,氮肥偏生产力提高6%~23%,氮素农学利用率提高26%~71%,增产8%~19%。控灌条件下,缓/控释肥处理氮素有效性高,保证足穗、促进重穗;干湿交替灌溉条件下缓/控释肥处理能保持氮素的高效释放,有利于高产群体的形成,从而提高稻株氮素积累、协调氮素分配;淹水灌溉条件下,缓/控释肥处理无效分蘖减少,氮素入渗、淋溶降低,成穗率提高。综合产量与氮素吸收、运转的表现,干湿交替灌溉条件下施用缓控释肥为本试验最佳处理,能有效提高氮素利用率,促进高产形成。     

水稻产量对氮肥响应的品种间差异及其与根系形态生理的关系

以籼稻天优华占、两优培九和粳稻陵香优18、宁粳1号为材料,研究了水稻产量对氮肥的响应。结果表明,水稻产量对施氮量的反应存在明显的品种间差异。上述4个水稻品种在获得最高产量(10.1~10.3 t hm^-2)时,天优华占和陵香优18所需施氮量为242.5~255.5 kg hm^-2,明显低于两优培九和宁粳1号的327.3~328.0 kg hm^-2。天优华占和陵香优18的氮肥农学利用率和氮肥偏生产力均明显高于两优培九和宁粳1号,表明天优华占和陵香优18产量对氮肥的反应较两优培九和宁粳1号敏感。在高产(10.5~10.9 t hm^-2)条件下,天优华占和陵香优18主要生育期根系的重量、长度和总吸收表面积低于两优培九和宁粳1号,而根系活跃吸收表面积及其占总吸收表面积的比例、根系伤流量以及根系活力则显著高于两优培九和宁粳1号。上述结果表明,通过栽培措施调控或选用根系活跃吸收表面积、根系伤流量和根系活力高的水稻品种将更有利于降低水稻施氮量和提高产量及氮肥利用效率。     

不同质地土壤下缓释尿素与常规尿素配施对水稻产量及其生长发育的影响

以早熟晚粳南粳44为材料,分别在2种质地的土壤上,研究270 kg hm^-2施氮条件下, 2种缓释尿素(硫包衣尿素SCU)单施及与常规尿素(PU)按2种不同比例混配一次性基施对水稻产量及其生长发育的影响。结果表明,与PU分施相比,SCU2单施与SCU1+PU(1∶1)、SCU1+PU(2∶1)及SCU2+PU(2∶1)配施处理水稻产量、生长中后期氮素吸收量、氮素吸收利用率与偏生产力、干物质积累以及茎鞘可用性糖颖花比均显著提高,抽穗后期根系α-萘胺氧化量维持较高水平,下降幅度小;产量、氮素吸收量、氮肥吸收利用率、偏生产力及干物质积累量在黏土上略高于在沙土上;抽穗期与抽穗后10 d根系α-萘胺氧化量在黏土上低于在沙土上,抽穗后20 d、30 d在两种土上差异不大。SCU单施及与PU配施基本上能满足水稻生长需求,SCU1与PU配施效果明显优于单施;SCU2单施效果最佳,SCU2+PU(2∶1)次之,SCU2+PU(1∶1)效果不显著。     

养分管理对直播稻产量和氮肥利用率的影响

为探明不同养分管理模式在实地农户种植条件下对直播水稻产量和氮肥利用率的影响。本试验于2011年6月至2013年11月在江苏省兴化市茅山镇基本农田保护区的田间稻麦轮作条件下,分别选取茅山东村、茅山西村和冯顾村各8个农户,开展3个不同养分管理模式试验,设置了不施肥对照(CK)、农民习惯施肥(FFP)和优化施肥(OPT1和OPT2)4个处理,主要研究了水稻产量及构成因子、氮累积分配和氮肥利用率等对不同养分管理模式的响应。结果表明：(1)施肥较不施肥显著提高水稻产量,优化施肥(226 kg N hm^-2)在较习惯施肥(333 kg N hm^-2)平均减氮32.1%的基础上显著提高水稻产量5.5%,增产原因是提高了穗粒数、结实率和千粒重;OPT2较OPT1平均增产3.1%,其原因是在孕穗期增施了钾肥(18 kg hm^-2 K₂O)。(2)优化施肥水稻植株各部位氮浓度、百千克籽粒需氮量和秸秆氮累积均显著低于习惯施肥,且降低营养器官的氮素分配比例。(3)优化施肥较习惯施肥显著提高水稻氮肥利用率,其氮肥偏生产力(PFP_N)、氮肥农学效率(AE_N)、氮肥回收效率(RE_N)和氮肥生理效率(PE_N)分别平均增加55.5%、79.1%、18.7%和48.7%。(4)水稻植株氮累积与产量呈显著正相关,且优化施肥单位氮累积的增产效果高于习惯施肥。因此,基于氮肥总量控制、分期调控和增施钾肥的养分优化管理措施可在实地农户直播稻种植上协同实现水稻高产和氮肥高效。     

QTL-based analysis of genotype-by-environment interaction for grain yield of rice in stress and non-stress environments

Use of DNA-based markers can accelerate cultivar development in variable cultivation environments since, in contrast to phenotype, DNA markers are environment-independent. In an effort to elucidate the genetic basis of genotype-by-environment interaction (G × E) for yield of rice (Oryza sativa L.), the associations between 139 AFLP markers and grain yield were determined for rice grown in fresh water (EC of 0.65 dS m⁻¹) and saline conditions (EC of 4–8 dS m⁻¹) with 0 kg ha⁻¹ or 100 kg ha⁻¹ nitrogen fertilizer in the years 2000 and 2001. A population of recombinant inbred lines of rice, developed from an IR29 × Pokkali cross, was used in the study. Both genotype × salinity and genotype × nitrogen level interactions were significant, with the genotype × salinity interaction being stronger. Through multiple regression analysis using a stepwise procedure for selecting markers, 36 markers were detected for grain yield in the four test conditions and of these 28 were detected in only one test condition implying strong environmental specificity for yield QTL expression. However, the fact that eight QTLs were detected in more than one test condition points to the existence of wide-adaptability genes in this cross. Markers with significant associations with yield explained between 37% and 48% of the yield variation in each test condition. Superior genotypes of rice were identified in all four test conditions based on their marker signatures. Furthermore, across N fertilizer regimes, yield predicted from summed additive effects of QTLs were significantly correlated with observed yield in the same year and across years. Thus marker-assisted selection can help breeders overcome the problem of low selection efficiency encountered during phenotypic selection for yield in stress environments.     

Photosynthetic ability,grain yield and an esterase band in rice genotypes

Summary Four Indica and one Japonica (Tainung 67) of rice (Oryza sativa L.) varieties had an esterase band (tentatively designated as E₁), and also had higher photosynthetic ability than other five Japonica varieties without E₁ band. The F₁ plants of Tainung 67 × Mineyutaka (low photosynthetic ability, no E₁ band) showed E₁ band and a low photosynthetic ability. Of 34 F₂ plants, 28 had E₁ band, but 6 had no E₁ band of which 5 plants showed a low photosynthetic ability. These results suggest that an esterase gene and one of the photosynthesis gene are linked, and the gene for low photosynthetic ability is dominant.Among 42 new Japonica strains and 2 control varieties bred in Taiwan, most genotypes with E₁ band showed higher grain yield potential (grain field/growth days) in local test.Esterase band may be used as a marker for high photosynthesis and grain yield ability in breeding.     

Identification and crop performance of acid sulfate soil-tolerant rice varieties

The present study aims to: 1) identify acid sulfate soil (ASS)-tolerant rice varieties from the genetic stock of Korean rice (Oryza sativa L.) varieties under ASS conditions; 2) to evaluate their yield performance, and elucidate the physiological mechanism for ASS tolerance with the identified tolerant varieties. Two hundred sixty-six rice varieties were screened for ASS tolerance, and we identified two japonica-indica hybrid varieties, Geumgang (GG) and Pungsan (PS), as having high tolerance under ASS paddy conditions (pH 3). We first conducted a yield trial of GG and PS grown in Wagner pots to determine their potential yields under ASS conditions. A yield trial under paddy field condition followed. In the pot experiment, the ASS-tolerant varieties, GG and PS, showed significantly higher yields than PT-1, which is a local reference variety in mildly improved soil pH conditions (pH 4.1–4.6). Al and Fe content in GG and PS were significantly lower than that of PT-1, so there might be some mechanism that inhibits the absorption of toxic metal ions in the tolerant varieties. In the paddy conditions, the grain yields more than 5 t ha⁻¹ of the two tolerant varieties under mildly improved soil pH condition were significantly higher than PT-1. Dry matter weights of above ground parts also showed the same trend as grain yield. The study demonstrated that the ASS-tolerant japonica-indica rice varieties with high yielding potential could contribute to the improvement of rice yield in ASS regions, and will be good materials for the development of acid soil-tolerant rice varieties.     

氮肥用量及钾肥施用对稻麦周年产量及效益的影响

为探明优化施氮量与高施氮量下不同钾肥施用处理对稻麦周年产量及效益的影响。本试验于2010年5月–2011年7月在江苏省如皋市农业科学研究所试验基地的田间稻麦轮作条件下,对常规粳稻品种镇稻11和春性中筋品种扬麦16设置了两个氮肥用量下不同钾肥用量及施用方法处理,测定稻麦周年的产量和组成因子,成熟期不同器官的氮、钾浓度和累积量,氮、钾利用效率及经济效益。试验结果表明,钾肥的施用显著提高了周年稻麦的产量,同时提高了稻麦的有效穗数、穗粒数和结实率,钾肥的利用效率和经济效益。稻麦周年钾肥(K₂O)的偏生产力(PFP)、农学效率(AE)、回收利用率(RE)和经济效益均以周年钾肥(K2O)土壤施用150 kg hm^-2 + 叶面喷施16.2 kg hm^-2 (K_S150 + K_F16.2)处理最高。氮肥用量的结果表明,相对于优化施氮量,高施氮量有利于提高水稻的氮素营养而增产,但对稻麦周年产量的影响不显著,且优化施氮量的氮肥利用效率及经济效益均高于高施氮量。因此,综合考虑土壤环境因素、经济效益和肥料资源管理,本地区最佳氮肥(N)用量为水稻200 kg hm^-2,小麦180 kg hm^-2;最佳钾肥(K₂O)用量及方法为水稻土壤施用90 kg hm^-2 + 叶面喷施9.7 kg hm^-2 (K_S90 + K_F9.7),小麦土壤施用60 kg hm^-2 + 叶面喷施6.5 kg hm^-2 (K_S60 + K_F6.5)。     

Development of high yielding IR64 × <Emphasis Type="Italic">Oryza rufipogon</Emphasis> (Griff.) introgression lines and identification of introgressed alien chromosome segments using SSR markers

Modern rice varieties that ushered in the green revolution brought about dramatic increase in rice production worldwide but at the cost of genetic diversity at the farmers’ fields. The wild species germplasm can be used for broadening the genetic base and improving productivity. Mining of alleles at productivity QTL from related wild species under simultaneous backcrossing and evaluation, accompanied by molecular marker analysis has emerged as an effective plant breeding strategy for utilization of wild species germplasm. In the present study, a limited backcross strategy was used to introgress QTL associated with yield and yield components from Oryza rufipogon (acc. IRGC 105491) to cultivated rice, O. sativa cv IR64. A set of 12 BC₂F₆ progenies, selected from among more than 100 BC₂F₅ progenies were evaluated for yield and yield components. For plant height, days to 50% flowering and tillers/plant, the introgression lines did not show any significant change compared to the recurrent parent IR64. For yield, 9 of the 12 introgression lines showed significantly higher yield (19–38%) than the recurrent parent IR64. Four of these lines originating from a common lineage showed higher yield due to increase in grain weight and another three also from a common lineage showed yield increase due to increase in grain number per panicle. For analyzing the introgression at molecular level all the 12 lines were analyzed for 259 polymorphic SSR markers. Of the total 259 SSR markers analyzed, only 18 (7.0%) showed introgression from O. rufipogon for chromosomes 1, 2, 3, 5, 6 and 11. Graphical genotypes have been prepared for each line and association between the introgression regions and the traits that increased yield is reported. Based on marker trait association it appears that some of the QTL are stable across the environments and genetic backgrounds and can be exploited universally.     

Organic fertilizer effects on pea yield,nutrient uptake,microbial root colonization and soil microbial biomass indices in organic farming systems

In the present field experiment, horse manure and compost derived from shrub and garden cuttings were supplied at nearly equivalent N amounts but different C amounts to field peas (Pisum sativum L.), either as a sole crop or intercropped with oat (Avena sativa L.). The objectives were: (1) to evaluate the beneficial effects of C-rich manure and compost on pea productivity in different cropping systems (2) to investigate whether these effects were reflected by microbial root colonization, microbial biomass and CO₂ production and (3) to study the residual effects of the organic fertilizers on the yield of succeeding crop. Short term application of horse manure and compost greatly stimulated soil microbial biomass C, N, P, fungal ergosterol and CO₂ evolution, but failed to stimulate productivity of the current crops. However, significant positive residual effects of organic fertilizer, especially horse manure were observed on the grain yield of the succeeding winter wheat. Mycorrhizal colonization and ergosterol concentration were significantly higher in pea than in oat roots. Intercropping is an important tool for controlling weeds on pea plots under organic farming conditions, but did not affect microbial root colonization, soil microbial biomass indices or CO₂ evolution from the soil surface. According to the extrapolation of the CO₂ evolution rates into amounts per hectare, approximately 40% of the manure C and 24% of the compost C were mineralized to CO₂ during the 124-day experimental period. There were close relationships between grain N and P concentrations in both crops and microbial biomass C, N and P, suggesting that soil microbial biomass can be used as an indicator of nutrient availability to plants.     

Integrated Nitrogen Management with Green Manures in Rice-Chickpea Cropping System

A field experiment was conducted during wet and dry seasons of 1987–88 and 1988–89 to evaluate the performance of green manures with and without fertilizer nitrogen in lowland rice and their residual effect on succeeding crop of chickpea grown under rice-chickpea cropping system. Incorporation of Ipomea carnea (green leaves), Cassia tora and Parthenium hysterophorus (green young plants) ca. 5 t/ha fresh weight significantly improved yield and yield components namely panicles per hill, panicle length, grains per panicle and test weight of transplanted rice. The results showed that at least 20 kg/ha fertilizer nitrogen applied to rice could be replaced by incorporation of 5 t/ha fresh weight green manure. Supplementation of 60 kg N/ha through urea to the green manures treated plots proved to be the best in respect of grain yield and was comparable to the yield obtained under 80 kg N/ha as urea alone. Plant N-uptake followed the similar pattern of rice grain yield. Residual fertility in terms of available nitrogen increased under the green manure treatments, whereas urea nitrogen alone made no impact on fertility build-up. Green manures showed significantly higher residual response than fertilizer N alone to seed yield and N uptake of chickpea.     

Transgressive segregation for yield traits in Oryza sativa IR58025B X Oryza meridionalis Ng. Bc2F3population under irrigated and aerobic conditions

Wild species of the genus Oryza are a good source of beneficial alleles for enhancing rice yield under normal and adverse conditions. BC₂F₃ population was derived from a cross between Oryza sativa IR58025B and Oryza meridionalis Ng. (2n = 24, AA) a heat tolerant wild species to evaluate 12 yield traits under irrigated and aerobic conditions. Analysis of variance and genetic estimates indicated there is substantial genetic variation among progenies under both conditions. Grain yield had high heritability (61.9%) and genetic advance (36.4%) under irrigated conditions but moderate heritability (49.6%) and genetic advance (13.3%) under aerobic conditions indicating that selection for yield will be effective under both conditions. Panicle number, grain number, spikelet fertility, and test weight showed significant positive correlation with grain yield under both conditions. Families out-performing IR58025B for yield under both conditions were obtained providing evidence that phenotypically inferior O. meridionalis contributed to yield increase. This species can be a novel source of natural genetic variation for the improvement of rice under irrigated as well as under aerobic condition.     

Seed priming improves stand establishment and productivity of no till wheat grown after direct seeded aerobic and transplanted flooded rice

No tillage (NT) in wheat (Triticum aestivum L.) offers a pragmatic option for resolving the time and edaphic conflicts in rice (Oryza sativa L.)–wheat cropping system (RWS). However, poor stand establishment is an issue in NT wheat, which adversely affects crop growth, grain yield, and profitability. Therefore, a 2-year field study was conducted to assess the potential role of seed priming in improving the stand establishment, grain yield, water productivity and profitability of NT and plough till (PT) wheat grown after direct seeded aerobic (conservation) and puddled transplanted flooded (conventional) rice-based systems. For seed priming, wheat seeds were soaked in aerated water (hydropriming) or solution of CaCl₂ (ψs −1.25 MPa; osmopriming) for 12 h, and non-primed seeds were used as control. After harvest of rice, grown as direct seeded aerobic and puddled transplanted flooded crop, primed and non-primed wheat seeds were sown following NT and PT. In both years, stand establishment of NT wheat after direct seeded aerobic and puddled transplanted flooded rice was impeded. Nonetheless, seed priming improved the stand establishment which was visible through earliness and better uniformity of seedling emergence. Overall, primed seeds completed 50% emergence in 6.4 days, against 7.8 days taken by non-primed seeds in NT wheat. The highest emergence index (41.7) was recorded in primed seeds versus 32.0 for non-primed seeds. Improved stand establishment enhanced growth, grain yield, water productivity and profitability in NT wheat. In this regard, osmopriming was the most effective, and produced grain yield of 4.5 Mg ha⁻¹ against 3.8 Mg ha⁻¹ for non-primed seeds in NT wheat. Water productivity of the NT wheat grown from osmoprimed seeds was 8.72 kg ha⁻¹ mm⁻¹ while that from non-primed seeds was 7.21 kg ha⁻¹ mm⁻¹. Among the RWSs, the maximum wheat biomass was produced with PT after direct seeded aerobic rice. However, grain yield, water productivity, and profitability were the highest in NT wheat following direct seeded aerobic rice. Wheat yields grown after direct seeded aerobic rice and transplanted flooded rice were 4.4 and 4.2 Mg ha⁻¹ respectively. Planting NT wheat after direct seeded aerobic rice provided the highest system productivity (1.80) than other RWSs. Thus, seed priming is a viable option to improve the stand establishment, grain yield, water productivity and profitability of NT wheat in the RWS. Nonetheless, osmopriming was a better option than hydropriming in this regard.     

氨基多糖水溶肥对小麦生理特性、产量及籽粒品质的影响

为了探明氨基多糖水溶肥对小麦生理特性、产量及籽粒品质的影响,以'淮麦33'为试验材料,研究小麦不同生育期叶面喷施氨基多糖水溶肥1次、2次和3次对小麦产量和品质的影响,并在处理后12天测定小麦旗叶净光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)、气孔导度(Gs),叶绿素(Ch1)、可溶性糖、可溶性蛋白和丙二醛...     

硫包衣尿素对水稻养分吸收利用及土壤反应的影响

采用盆栽结合部分大田论证的试验方法,研究了硫包衣尿素(SCU)和常规尿素对水稻生长、营养元素吸收利用及增产效应和土壤反应的影响。结果表明:大田上SCU和常规尿素处理其产量分别是对照的1.20,1.11倍,盆栽试验下为对照的1.92,1.48倍;施肥量相同的SCU处理水稻产量比常规尿素处理增加10.93%~22.23%,SCU提高水稻产量的优势在于千粒重;同常规尿素相比,SCU促进了水稻对磷的吸收,对钾的影响不大。盆栽试验表明,施常规尿素和SCU的处理氮收获指数都随施氮量的增加而增加,等N量(N 0.15 g/kg土)和等施肥量(0.66 g/kg土)下,SCU处理其氮收获指数显著高于对应的常规尿素处理,施用SCU的处理其氮素的利用率也比常规尿素提高11.79%~20.25%,其氮肥利用率最高达57.58%;短期内适宜施氮量下SCU未降低土壤pH,但随着SCU施用量的增加,土壤酸化明显,且趋势超过常规尿素。     

Mapping quantitative trait loci influencing panicle‐related traits from Chinese common wild rice (Oryza rufipogon) using introgression lines

Panicle‐related traits are important agronomic traits which directly associated with grain yield. In this study, we investigated quantitative trait loci (QTLs) associated with panicle‐related traits using a set of 265 introgression lines (ILs) of common wild rice (Oryza rufipogon Griff.) in the background of Indica high‐yielding cultivar Guichao 2 (O. sativa L.). A total of 39 QTLs associated with panicle‐related traits including panicle length (PL), primary branch number (PBN), secondary branch number (SBN), spikelet number per panicle (SPP) and spikelet density (SD), were detected in the ILs with single‐point analysis. The alleles of 20 QTLs derived from wild rice showed positive effects, and some QTLs, such as, QPl1b for PL, QPbn8 for PBN, QSd4 and QSd11b for SD and QSpp4 for SPP showed larger positive effects, providing good candidates and useful information for marker‐aided improvement of yield potential of rice. Most of the QTLs controlling SPP, SBN and SD were located in cluster or closely linked on chromosomes, and the directions of their additive effects were consistent, which explained the genetic basis of significant correlations between their phenotypic characters.     

施氮量对济麦20旗叶光合特性和蔗糖合成及籽粒产量的影响

在田间高产条件下,研究了施氮量对强筋小麦品种济麦20旗叶光合特性、蔗糖合成及籽粒产量的影响。结果表明,在0～168 kg hm^-2施氮量范围内,随施氮量的增加,旗叶蒸腾速率提高,气孔导度增大,细胞间隙二氧化碳浓度降低,旗叶净光合速率与蔗糖磷酸合酶活性显著提高,从而促进旗叶蔗糖合成,提高生物产量、籽粒产量和氮肥利用率;施氮量增加至240 kg hm^-2,旗叶净光合速率、蔗糖磷酸合酶活性、蔗糖含量和生物产量显著提高,但收获指数降低,籽粒产量和氮肥利用率无显著变化。施氮量继续增加至275 kg hm^-2,旗叶蒸腾速率、气孔导度、气孔限制值和净光合速率均显著降低,细胞间隙二氧化碳浓度则显著升高,旗叶光合作用受非气孔限制,蔗糖磷酸合酶活性、蔗糖含量、生物产量和收获指数均显著降低,籽粒产量减少,氮肥利用率降低。在本试验条件下,济麦20的适宜施氮量为168~240 kg hm^-2。     

Effectiveness of Sulphuric Acid and Gypsum for the Reclamation of a Calcareous Saline-Sodic Soil Under Four Crop Rotations

As a low‐cost strategy, the cultivation of certain salt‐tolerant crop species on calcareous saline‐sodic soils, i.e. phytoreclamation, has enjoyed great attention in recent years. A lysimeter study was carried out to evaluate whether a phytoreclamation approach alone, or in combination with some booster dose of either gypsum or sulphuric acid, is sufficient to reclaim a calcareous, moderately saline‐sodic soil. Four crop rotations, rice (Oryza sativa L.)–wheat (Triticum aestivum L.)–sesbania (Sesbania aculeata L.); rice–berseem (Trifolium alexandrinum L.); Kallar grass (Leptochloa fusca L.)–alfalfa (Medicago sativa L.) and sesbania–berseem were tested against three treatments: (T₁) control, (T₂) sulphuric acid application 25 % of soil gypsum requirement (SGR), and (T₃) application of gypsum 25 % SGR. To decrease the sodium adsorption ratio of the saline‐sodic soil well below the threshold level, especially from deeper depth, a booster dose of gypsum or sulphuric acid 25 % SGR was quite effective. Rice–berseem and Kallar grass–alfalfa rotations were more promising in combination with inorganic amendments than the rest of the rotations. The study also suggests that better yields of wheat and rice crops can be obtained with the application of inorganic amendments like gypsum or sulphuric acid. However, Kallar grass yield was somewhat suppressed with these amendments.     

Rice dry matter and nitrogen accumulation,soil mineral N around root and N leaching,with increasing application rates of fertilizer

Rice morphology and N leaching, together with mineral N in the soil and soil solution around root, were determined at different growth stages in a 3-year experiment located in the Taihu Lake region, China. The results showed that the N application rates had little impact on the soil mineral N around root, but increased the dry matter and N accumulation aboveground in the high fertility soil (55.3 mg kg⁻¹ of soil mineral N before rice season in 2008). However, no significant difference in grain yield was observed in all N treatments in these 3 years. Path analysis showed that spikelet per panicle made the greatest direct contribution (0.781) and total contribution (0.309) to grain yield compared to other yield components. And a higher panicle per m² and dry matter accumulation resulted in yield decline later in the season due to a decline in the percentage of filled grains.No significant increases in plant N uptake, regardless of N application rates, were observed at the seedling stage, which indicated that lower N application rates could suffice during the rice early growing stages. Nitrate contents, in spite of high N rates input, in the percolation water were all below 1.0 mg L⁻¹ throughout the rice growing season. The increased N rates showed an increment of total N leaching through the percolation water, but not significant. The cumulative total N leaching only accounted for 1.86–4.96% of N fertilizer input, which suggested the N leaching should not be considered as main pollution resources in paddy filed in summer rice season. However, the evaluation of N leaching in different stages indicated that N leaching at seedling stage was larger in dominant (averaged 39.8% of total N leaching) than other stages. For the lower absorbing ability of rice seedling and more N leaching risk, suggestions on N fertilizer reduction should be made at rice early growing stage in this region.