Systematic Characterization of Long Non-Coding RNAs and Their Responses to Drought Stress in Dongxiang Wild Rice

Long non-coding RNAs(lncRNAs) play important roles in response to various biotic and abiotic stresses. So far, systematic identification and characterization of lncRNAs have been reported in a few model plant species and major crops, but their roles in abiotic stress response have not yet been reported in common wild rice(Oryza rufipogon). Dongxiang wild rice(DXWR) possesses a high degree of drought resistance and has been well recognized as a precious genetic resource for drought resistant rice breeding. We presented the reference catalog of 1 655 novel lncRNA transcripts in DXWR using strand-specific RNA sequencing and bioinformatics approaches. Meanwhile, a total of 1092 lncRNAs were determined as differentially expressed lncRNAs under drought stress. Quantitative real-time PCR results exhibited a high concordance with RNA sequencing data, which confirmed that the expression patterns of lncRNAs based on RNA sequencing were highly reliable. Furthermore, 8 711 transcripts were predicted as target genes of the differentially expressed lncRNAs. Functional annotation analysis based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases showed that the target genes were significantly enriched in cellular and metabolic processes, cell part, binding and plant hormone signal transduction, as well as many other terms related to abiotic stress resistance. These results expanded our understanding of lncRNA biology and provided candidate regulators for genetic improvement of drought resistance in rice cultivars.

Discrepancy in Response of Rice Yield and Soil Fertility to Long-Term Chemical Fertilization and Organic Amendments in Paddy Soils Cultivated from Infertile Upland in Subtropical China

From 1990,over 17 years field experiment was carried out in paddy field cultivated from infertile upland to evaluate the response of rice productivity,soil organic carbon（SOC）,and total N to long-term NPK fertilization or NPK combined with organic amendments.The field trials included NPK（N,P,K fertilizer）,NPKRS（NPK combined with rice straw）,NPK2RS（NPK combined with double amount of rice straw）,NPKPM（NPK combined with pig manure） and NPKGM（NPK combined with green manure） and the cropping system was rice-rice（Oryza sativa L.） rotation.Annual rice yield,straw biomass,and harvesting index increased steadily with cultivation time in all treatments.Average annual rice yield from 1991 to 2006 was ranged from 7 795 to 8 572 kg ha-1 among treatments.Rice yields in treatments with organic amendments were usually higher than that in treatment with NPK.Contents of SOC and total N also increased gradually in the cultivation years and reached the level of 7.82 to 9.45 and 0.85 to 1.03 g kg-1,respectively,in 2006.Soil fertilities in treatments with chemical fertilization combined with organic amendments were relatively appropriate than those in treatment with NPK.There was obvious discrepancy between cumulative characters of rice yield and soil organic fertility in newly formed paddy field.Compared with relatively high rate of crop productivity improvement,cumulative rates of SOC and total N were much lower in our study.SOC and total N contents were still less than half of those in local highly productive paddy soils after 17 years cultivation in subtropical China.Present work helps to better understand the development of infertile paddy soils and to estimate the potential of yield improvement in this region.

Soil carbon sequestration under long-term rice-based cropping systems of purple soil in Southwest China

Carbon sequestration in agricultural soils is a complex process controlled by farming practices, climate and some other environment factors. Since purple soils are unique in China and used as the main cropland in Sichuan Basin of China, it is of great importance to study and understand the impacts of different fertilizer amendments on soil organic carbon（SOC） changes with time. A research was carried out to investigate the relationship between soil carbon sequestration and organic carbon input as affected by different fertilizer treatments at two long-term rice-based cropping system experiments set up in early 1980 s. Each experiment consisted of six identical treatments, including（1） no fertilizer（CK）,（2） nitrogen and phosphorus fertilizers（NP）,（3） nitrogen, phosphorus and potassium fertilizers（NPK）,（4） fresh pig manure（M）,（5） nitrogen and phosphorus fertilizers plus manure（MNP）, and（6） nitrogen, phosphorus and potassium fertilizers plus manure（MNPK）. The results showed that annual harvestable carbon biomass was the highest in the treatment of MNPK, followed by MNP and NPK, then M and NP, and the lowest in CK. Most of fertilizer treatments resulted in a significant gain in SOC ranging from 6.48 to 2 9.13% compared with the CK, and raised soil carbon sequestration rate to 0.10–0.53 t ha–1 yr-1. Especially, addition of manure on the basis of mineral fertilizers was very conducive to SOC maintenance in this soil. SOC content and soil carbon sequestration rate under balanced fertilizer treatments（NPK and MNPK） in the calcareous purple soil（Suining） were higher than that in the acid purple soil（Leshan）. But carbon conversion rate at Leshan was 11.00%, almost 1.5 times of that（7.80%） at Suining. Significant linear correlations between soil carbon sequestration and carbon input were observed at both sites, signifying that the purple soil was not carbon-saturated and still had considerable potential to se questrate more carbon.

Effects of Long-Term Application of Sulfur-Containing and Chloride-Containing Chemical Fertilizers on Rice Yield and Its Components

Impacts of 33-yr of application of S-containing and Cl-containing chemical fertilizers on rice （Oryza sativa L.） yield and its components were investigated in a red paddy field experiment,south China.The treatments included：1） adding 302 kg SO42--S ha-1 yr-1 with application of （NH4）2SO4-,K2SO4,and calcium superphosphate （SO42-）;2） adding 56 kg SO42--S and 176 kg Cl ha-1 yr-1 with application of urea,calcium superphosphate,and KCl （Cl-＋SO42-）;3） adding 516 kg Cl ha-1 yr-1 with application of NH4Cl,KCl,and KH2PO4 （Cl-）.Under each treatment,the applied N,P,and K nutrients were controlled at conventional rates of 150 kg N ha-1 yr-1,75 kg P2O5 ha-1 yr-1,225 kg K2O ha-1 yr-1,respectively.Under the S-containing fertilizer application,soil SO42--S content showed a first increasing then decreasing trend with years,and was significantly negatively correlated with annual rice yield.Average annual yield significantly declined in an order of Cl-,Cl-＋SO42-,and SO42-.Under the Cl-treatment,soil SO42--S content was maintained at about 26.5 mg kg-1,not showing deficiency.From 1990 to 2000,rice yield declined rapidly under the SO42- treatment,and was significantly lower than that under the Cltreatment.After then,there was no significant difference in yield among the treatments.Our results demonstrated that long-term application of S- containing fertilizer could result in excessive accumulation of SO42--S in the red paddy soils of south China,therefore producing a certain threat to rice growth.The Cl- containing fertilizer could be relatively safe.

Impact of Long-Term Fertilization on Community Structure of Ammonia Oxidizing and Denitrifying Bacteria Based on amoA and nirK Genes in a Rice Paddy from Tai Lake Region,China

Ammonia oxidizing （AOB） and denitrifying bacteria （DNB） play an important role in soil nitrogen transformation in natural and agricultural ecosystems. Effects of long-term fertilization on abundance and community composition of AOB and DNB were studied with targeting ammonia monooxygenase （amoA） and nitrite reductase （nirK） genes using polymerase chain reaction- denaturing gradient gel electrophoresis （PCR-DGGE） and real-time PCR, respectively. A field trial with different fertilization treatments in a rice paddy from Tai Lake region, centre East China was used in this study, including no fertilizer application （NF）, balanced chemical fertilizers （CF）, combined organic/inorganic fertilizer of balanced chemical fertilizers plus pig manure （CFM）, and plus rice straw return （CFS）. The abundances and riehnesses of amoA and nirK were increased in CF, CFM and CFS compared to NF. Principle component analysis of DGGE profiles showed significant difference in nirK and amoA genes composition between organic amended （CFS and CFM） and the non-organic amended （CF and NF） plots. Number of amoA copies was significantly positively correlated with normalized soil nutrient richness （NSNR） of soil organic carbon （SOC） and total nitrogen （T-N）, and that of nirK copies was with NSNR of SOC, T-N plus total phosphorus. Moreover, nitrification potential showed a positive correlation with SOC content, while a significantly lower denitrification potential was found under CFM compared to under CFS. Therefore, SOC accumulation accompanied with soil nutrient richness under long-term balanced and organic/inorganic combined fertilization promoted abundance and diversity of AOB and DNB in the rice paddy.

Long range migration of rice planthoppers and associated meteorological conditions in Yulin,Ganzhou,and Huangyan

In recent years,it has been demonstrated that thelow-level jet streams(LLJs)developed in thesouth of the Meiyu(Baiu)front play a critical role inthe overseas migrations of the planthoppers intoJapan and Korea. However, the involement of theLLJs during the process of sequential displacements

Determination of the Drying Kinetics Modeling and Activation Energy of Medium-Grain and Long-Grain Rough Rice under Isothermal Conditions

The available literature revealed a gap in reporting the rough rice drying kinetics parameters under isothermal conditions, particularly for Arkansas medium- and long-grain varieties. Therefore, medium-grain (RO170112 and Titan) and the long-grain (Diamond and Wells) rough rice varieties were dried under isothermal conditions. The drying process occurred under 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C in a system emulating the thermogravimetric analyzer. Drying kinetics models were studied for four well-known models: Page, Newton, Logarithmic, and Henderson & Pabis. The drying kinetics constants were determined for the four studied models. The initial moisture content of rough rice was 28.2% db. Profound moisture reduction was observed during the first three hours of drying, followed by less moisture content reduction. The results showed that at the drying temperature of 100°C and after 6 hours of the drying process, the lowest moisture content reached 13.9% (db) for Titan rough rice. The drying rate of rough rice ranged between 7.41 and 2.01%/h during the first hour of drying under the studied temperature range of 40°C to 100°C. The drying rate was higher with the higher temperature levels during the first three hours. Among all the studied models, the Page, Newton, and Logarithmic models best fit 25%, 25%, and 50% of the twenty-eight studied cases. The challenge that arose from these results led to evolving a mathematical solution by joining the three models in one equation. The combined model showed the best fit for all the studied cases, with R2 ranging between 0.9999 and 0.9954 for the medium- and long-grain rice varieties. Increasing the drying temperature increased the effective moisture diffusivity values. The highest effective moisture diffusivity of 18.104 × 10-9 m2/s was obtained at the drying temperature of 100°C for medium-grain rice, Titan. The activation energy values ranged between 17.77 and 24.48 kJ/mol for the four rough rice varieties.

Development of a Novel Extrusion Process for Preparing Rice Straw/LLDPE Composites

Straw utilization is a key issue related to agricultural production and air pollution control.In this study,a novel extrusion process was proposed to improve the physical and mechanical properties of the straw-reinforced linear low-density polyethylene(LLDPE)composite.Instead of crushing the straw and mixing it with plastic matrix,the new method mixes straw with plastic matrix in its original form.The intact long rice straws were parallelly spread on the LLDPE film and then rolled up together into a prefabricated roll.The rolls experienced three extrusion processes as follows:(1)twin-screw melting,cooling and crushing,single-screw extruding;(2)twin-screw melting and single-screw extruding;(3)directly single-screw extruding.The testing results showed that the straw/LLDPE composite(with a ratio of 6:4)prepared by Method(2)exhibited optimized properties.Characterization by scanning electron microscopy indicated that the damage to rice straw fibers was relatively minor,the orientation of long fibers was good,and the binding of fibers with the LLDPE matrix was excellent in this case.The results of dynamic mechanical testing(DMA),differential scanning calorimetry(DSC)and thermogravimetric(TG)analysis demonstrated that composites prepared by the new process exhibited significantly improved thermal stability and energy storage modulus,compared with those prepared by conventional processes(e.g.,extruded straw particles/LLDPE composite).The new proposed method yielded significantly enhanced mechanical properties while reducing dust pollution.

长期不同施肥模式对大麦–双季稻田根际土壤有机氮组分的影响

根际土壤有机氮组分在土壤养分和作物氮素营养中具有重要作用。本研究依托长期(37年)定位施肥试验田,设置4个施肥处理:不施肥对照(CK)、单独施用化肥(CF)、秸秆还田+化肥(RF)和30%有机肥+70%化肥(OM),于晚稻成熟期测定大麦–双季稻田根际土壤基础理化性质、微生物生物量氮和有机氮组分(氨基酸态氮、氨基糖态氮、酸解氨态氮、酸解未知态氮、非酸解性氮)含量。研究表明:相对CK处理,RF和OM处理显著增加了稻田根际土壤有机碳、全氮、铵态氮和硝态氮的含量。RF和OM处理土壤微生物生物量氮含量分别比CK处理增加了19.8%和30.7%。酸解性氮作为根际土壤全氮的主体部分,占全氮的59.61%~72.06%;各处理根际土壤酸解性氮含量大小顺序表现为OM>RF>CF>CK。各施肥处理中,酸解有机氮中的氨基糖态氮、氨基酸态氮和酸解未知态氮含量均以OM处理最大,分别比CK处理增加139.3%、47.9%和110.0%;酸解氨态氮以RF处理最大,比CK处理增加69.9%。土壤有机碳、全氮、铵态氮、硝态氮与土壤氨基酸态氮、氨基糖态氮、酸解未知态氮以及微生物生物量氮均呈极显著(P<0.01)正相关。因此,秸秆、有机肥配施化肥均能有效提高大麦–双季稻田根际土壤的供氮能力,是改善稻田土壤肥力的有效手段。

5G海域超远覆盖技术研究与实践

主要研究了5G网络海域超远覆盖的关键技术,分析了海域超远覆盖中存在的主要问题、5G频段的传播差异性以及站址高度对覆盖距离的影响,着重研究了TDD时隙结构调整、T+F时频双聚合对基站覆盖能力、上行链路健壮性的提升等,提出并使用Longley-Rice模型对2.1 GHz和3.5 GHz进行了覆盖仿真,最后通过工程实践验证了方案的有效性,为海域覆盖场景提供了参考和借鉴。

太湖地区稻麦轮作系统有机氮肥替代率的演变特征及其影响因素

有机肥替代化肥是化肥减量的关键措施。本研究的主要目标是明确太湖地区稻麦轮作体系中有机氮肥替代率的主要限制因素,为提高有机氮肥替代率提供理论基础。依托40 a长期定位观测试验,分别选择不施肥(CK)、单施化肥(NPK)和单施有机肥(OM)3个处理,研究有机氮肥替代率与土壤碳氮关系。其中,化肥采用尿素、过磷酸钙和氯化钾,年均施氮225~300 kg/hm^(2),年均施磷(P2O5)119.4 kg/hm^(2),年均施钾(K2O)179.1 kg/hm^(2);有机肥采用猪粪和菜籽饼,年均折合施氮103.1 kg/hm^(2),折合施磷(P2O5)82.7 kg/hm^(2),折合施钾(K2O)70.1 kg/hm^(2)。测定指标包括土壤有机碳、总氮,计算有机氮肥替代率和土壤碳氮比。结果表明,长期施肥提高了土壤有机碳水平,OM、NPK和CK处理土壤有机碳含量可用米氏方程拟合,且前10 a内快速累积、后30 a趋近平衡,平均含量分别为16.8、15.8、15.1 g/kg。长期施肥处理线性提高了土壤总氮含量,OM、NPK和CK处理土壤平均总氮含量分别为1.71、1.64、1.47 g/kg。有机氮肥替代率的时序演变可用分段线性模型拟合,有机氮肥替代率前期略降低后期增加,稻麦两季有机氮肥替代率的时间拐点分别出现在第11年和第15.5年。线性回归分析表明,有机氮肥替代率与土壤总有机碳无显著关系,但与土壤总氮和碳氮比显著线性相关。在太湖地区稻麦轮作系统中,长期施用有机肥可有效提高土壤碳氮库容,具有较高水平土壤有机碳(>17.0 g/kg)是提升有机氮肥替代率的前提,但在有机碳趋近饱和后,土壤总氮和碳氮比是限制有机氮肥替代率提升的主要因素。

基于基因芯片的嘉禾系列长粒优质食味粳稻综合评价与比较

【目的】嘉禾系列长粒粳稻粒型(细)长,外观品质突出,食味优良,丰产性与主栽品种相近,抗病性较好。本研究旨在明确嘉禾系列长粒粳稻品种的特点与存在问题,解析嘉禾系列长粒粳稻品种优质性状形成的遗传基础,为长粒粳稻品种创新利用提供依据。【方法】以5份嘉禾系列长粒粳稻品种(系)为材料,利用GSR40K水稻高密度芯片分析品种籼粳属性、相似度,鉴定育种相关功能基因,同时比较嘉禾系列长粒粳稻品种(系)与东北长粒粳稻稻花香2号遗传基础差异。【结果】嘉禾系列长粒粳稻品种(系)和稻花香2号基因组中,粳稻区段数占比84.20%~88.38%,均为典型粳稻类型;嘉禾系列长粒粳稻品种(系)间遗传相似度超过92%,基因组相似度为77.59%~91.73%,与稻花香2号遗传相似度为84.55%,基因组相似度为49.52%~53.68%;嘉禾系列长粒粳稻含有长粒优势功能基因gs3和GW7,嘉禾香1号还含有大粒型基因qSW5/GW5和多穗粒数基因LAX1;嘉禾系列品种的品质性状形成主要是ALK^(c)/Wx^(b)/OsAAP6等优势功能基因组合所致,嘉禾香1号香味是由Badh2第2外显子突变所致;嘉禾系列长粒粳稻品种(系)含有较多的抗稻瘟病基因,如抗病基因组合Pizt+Pii/HIT7/pi5-1、Pizt+Pi-ta、Pizt+Pii/HIT7/pi5-1+Pi-d2/Pid2+Pid3+Pi-ta,抗白叶枯基因只有Xa26/Xa3。【结论】嘉禾系列长粒粳稻食味优、丰产稳产、抗病抗逆的突出优点,是品种含有较多的产量、品质、抗性、株型、生育期等优势等位基因变异综合影响的结果,但也存在品种相似度较高、白叶枯抗性基因单一的不足。本研究结果也为后续嘉禾系列长粒粳稻品种遗传改良提供了依据。

长粒香型优质常规稻新品种松雅77的选育与应用

松雅77是湖南省水稻研究所以玉针香辐射后代M37为母本、象牙香占为父本杂交,经多代系统选育而成的长粒型香稻品种。该品种具有生育期适宜、株型紧凑、株高适中、米质优良、丰产稳产的特征特性,于2024年通过湖南省农作物品种审定委员会审定。本文介绍了松雅77的选育经过、特征特性、重要等位基因及栽培技术要点。

壳聚糖添加量对大米淀粉老化的影响

为探究壳聚糖添加量对大米淀粉老化性质的影响,采用差示扫描量热仪、红外光谱(FTIR)和X射线衍射仪对添加不同添加量壳聚糖的老化大米淀粉进行测试,以老化大米淀粉的回生焓值、R值以及相对结晶度等3项指标来评价壳聚糖添加量对大米淀粉老化的影响。结果表明:添加壳聚糖使老化大米淀粉回生焓值增大;FTIR分析结果证实了添加壳聚糖使老化大米淀粉的短程有序性降低;壳聚糖添加量为0.5g(占淀粉干重3.3%)时,淀粉短期回生阶段的短程有序性最低,添加量为0.4g(占淀粉干重2.7%)时,淀粉长期回生阶段的短程有序性最低;老化大米淀粉结构的长程有序性同壳聚糖添加量有关:壳聚糖添加量为0.1g(占淀粉干重0.7%)时,壳聚糖能降低淀粉的相对结晶度,添加量增加到0.5g(占淀粉干重3.3%)后,壳聚糖增大淀粉的相对结晶度,且老化时间越长,使淀粉相对结晶度增大所需的壳聚糖添加量越大。研究结果有助于拓宽壳聚糖的应用范围,也为淀粉老化的调控提供了新思路。

长粒优质三系杂交晚籼稻华盛优21丝苗的选育与应用

华盛优21丝苗是湖北华占种业科技有限公司和江西先农种业有限公司以华盛A为母本、21丝苗为父本杂交育成的长粒优质三系杂交晚籼稻新品种。该品种生育期适宜、株型好、株高适中、米质优良(1级优质米)、丰产稳产和制种产量高。2021年和2022年分别通过湖北省和国家农作物品种审定委员会审定。文章介绍了其选育经过、特征特性、栽培技术要点和制种关键技术。

基于CNN-BiLSTM和残差注意力的县域水稻产量预测模型

提出一种融合卷积神经网络(CNN)、双向长短期记忆网络(BiLSTM)和残差注意力(RA)机制的县域水稻产量预测模型(CNN-BiLSTM-RA),通过CNN层有效提取县域水稻气象数据中的关键空间特征,利用BiLSTM层深入分析时间序列数据的动态变化,引入RA机制强化对气象数据中关键特征的识别与捕捉,以2015—2017年广西81个县早稻历史产量和气象数据为样本,与CNN、TRANSFORMER、BiLSTM、CNN-BiLSTM、BiLSTM-RA模型进行对比,评价CNN-BiLSTM-RA模型的预测精度和有效性。结果表明,CNN-BiLSTM-RA模型的R~2、MAE、RMSE和MAPE分别为0.9861、0.1219、0.2248、0.8648,模型的预测值与实际值拟合程度较高。CNN-BiLSTM-RA模型充分发挥了CNN的空间特征提取能力、BiLSTM的时间序列数据分析优势和RA机制在增强关键特征捕捉方面的特性,是一种适用于县域水稻产量高精度预测的新方法。

稻谷储存过程中品质变化研究

通过对3个籼稻和3个粳稻在两种不同温度条件下储存的品质变化研究,探索稻谷储存品质产生的内在原因。结果表明:不同类型的稻谷在储存过程中的品质变化不同,与籼稻相比,粳稻部分指标对高温更加敏感;高温储藏比低温储藏导致稻谷品质劣变的速率大;稻谷糊化特性发生明显的变化,主要表现为峰值黏度,最低黏度,最终黏度和回生值都增大,而衰减值下降;利用物性仪对大米蒸煮后的质构特性测定表明,蒸煮米饭黏度减小、硬度增大、黏/硬减小;蒸煮品尝值与最低黏度、最终黏度极显著负相关,初步认为其可以作为初始判定稻谷陈化指标,但是对稻谷劣变程度的量化还需要进一步深入研究;利用SEM研究稻谷籽粒断面结构,显示:新鲜稻谷的胚乳细胞呈现非裸露状态,比较平滑,复粒淀粉被较厚的造体膜掩盖着,高温储藏下,稻谷横断面越来越粗糙,配入细胞内的淀粉粒裸露清晰可见,复粒淀粉的淀粉粒表面膜翘起并爆开。

长期稻-稻-绿肥轮作对水稻产量的影响

为探讨湘南红壤稻田多熟制的增产潜力,不断提高经济效益和土壤肥力,促进农业可持续发展,从1982年开始,对红壤稻田布置了紫云英(T1)、油菜(T2)、黑麦草(T3)绿肥翻压还田对水稻产量及生长发育影响的长期轮作制度定位试验。27年的研究结果表明:1)与冬闲(CK)处理相比,种植绿肥处理能促进水稻增产,增产幅度依次为T1>T2>T3;2)与CK相比,绿肥处理下水稻年产量与CK处理间差异随年份增加而增大;T1处理与T2、T3处理间及T2处理与T3处理间差异也是如此。

水稻-大麦长期轮作体系钾肥效率及土壤钾素平衡

【目的】研究水旱轮作系统中土壤自然供钾力、钾肥利用率和土壤钾素表观平衡,为农田钾素的可持续性管理提供理论依据。【方法】设置不施肥(CK)、施氮磷肥(NP)和施氮磷钾肥(NPK)3个处理,利用20年稻麦水旱轮作定位试验数据,研究大麦和水稻地上部生物量、产量及籽粒和秸秆中含钾量对不同施肥处理的响应。【结果】在一年两熟和三熟制稻麦轮作系统中,20年不施肥(CK)的作物平均每年可生产籽粒8.24和9.22 t·hm-2,其相当于相应轮作体系平衡施肥(NPK)的75.6%和71.9%,因此施肥对作物产量提高的贡献率分别为24.4%和28.1%,施钾肥对作物籽粒产量提高的贡献分别为11.8%和14.0%。钾肥对旱季作物的增产贡献率高于水季,其中钾肥对大麦产量提高的贡献率平均为17.9%,比水稻的高36.1%。在一年两熟和三熟轮作制中,不施肥的作物平均每年从土壤中吸收的钾量相当于相应平衡施肥的59.1%和58.3%。作物地上部吸钾量的绝大部分来源于秸秆。其中大麦地上部吸钾量的81.7%来源于秸秆,水稻为74.2%—87.6%。旱季土壤钾素自然供应能力低于水季。大麦生长期平均每年土壤钾素自然供应能力为69.8%,比早稻、连作晚稻和单季晚稻分别低15.5%、19.7%和19.4%。随着试验时间的延长,大麦生长期土壤钾素自然供应能力以每年1.6%的速率降低,但水稻生长期土壤供钾能力在时间上没有显著变化,20年定位试验后仍维持在80%以上。尽管施钾肥降低了作物钾素内部利用率,但是年度间各施肥处理作物钾素内部利用率没有显著变化。在平衡施肥条件下,每吸收1 kg钾素,大麦、早稻、连作晚稻和单季晚稻可生产籽粒平均为42.4、44.7、41.3和44.8 kg。每施入1 kg钾肥可生产籽粒分别为83.5、79.7、71.6和69.7 kg。旱季钾肥效率高于水季。在一年两熟轮作制中钾肥表观利用率平均为29.5%,而在一年三熟轮作制中,表观利用率可达41.5%。由于作物对钾素不断的吸收,造成在一年两熟和三熟水旱轮作系统中不施肥(CK)的土壤每年钾素亏缺148.2和182.7 kg·hm-2,而且施氮磷肥加速了土壤钾素的耗竭,每年多携带走钾素57.8和65.0 kg·hm-2。尽管施钾肥缓解了土壤钾素不足,但在一年两熟和三熟轮作制中施钾土壤平均每年仍亏钾分别为146.5和85.5kg·hm-2。【结论】在水旱轮作系统中,水稻生长期土壤供钾能力高于麦季,但旱季钾肥的利用效率高于水季,在年施钾量(K2O)187.5 kg·hm-2的条件下,土壤钾素仍表现亏缺,因此,应该重视土壤钾素平衡问题。

籼米为基质的脂肪替代品——糊化工艺研究

本文利用差示扫描量热仪 (DSC)法研究了籼米的蛋白质对淀粉糊化的影响 ,着重研究了籼米为了基质的脂肪替代品加工过程中的糊化工艺。研究结果表明 :在籼米淀粉中添加米蛋白其糊化温度基本不变 ,但糊化所需热量下降。籼米的最佳糊化条件为米粉粒度 10 0目 ,糊化温度 88℃ ,糊化时间