Response of grain-filling rate and grain quality of mid-season indica rice to nitrogen application

Nitrogen is one of the important factors for high yield of rice. Apart from high yield, high quality has become the current urgent demand for rice production. Grain-filling stage is crucial for rice yield and quality formation. However, the effect of nitrogen on grain-filling characteristics and the relationship of grain-filling characteristics and rice quality of mid-season indica rice were still unclear. A field experiment was carried out to ascertain the critical grain-filling characteristics that contribute to rice milling quality, appearance quality and cooking and eating quality under nitrogen applications. The results showed that nitrogen applications prolonged the duration of superior and inferior grain filling. The mean grainfilling rate(G_(mean)) and the maximum grain-filling rate(G_(max)) of the inferior grains were positively correlated with chalky kernel rate, chalkiness, and amylose content. The time reaching the maximum grain-filling rate(T_(max) G) of the inferior grains was positively correlated with brown rice rate, milled rice rate, and head milled rice rate. Chalky kernel rate and chalkiness were negatively correlated with peak paste viscosity and breakdown viscosity. Less amylose content and more crude protein content were detected in nitrogen application of Liangyoupei 9 and Y Liangyou 2 both in 2016 and 2017. According to the correlation analysis, better cooking and eating quality of Y Liangyou 2 which had less amylose content might result from its higher G_(max) and G_(mean) of inferior grain than that of Liangyoupei 9 in the treatments of nitrogen application. These results indicated that the prolonging grain-filling duration and increasing grain weight at the maximum grain-filling rate of inferior grains contributed to the improvement of milling quality, appearance quality, and cooking and eating quality of mid-season indica rice under appropriate nitrogen applications.     

Modulation of plant root traits by nitrogen and phosphate: transporters,long-distance signaling proteins and peptides,and potential artificial traps

As sessile organisms, plants rely on their roots for anchorage and uptake of water and nutrients. Plant root is an organ showing extensive morphological and metabolic plasticity in response to diverse environmental stimuli including nitrogen (N) and phosphorus (P) nutrition/stresses. N and P are two essential macronutrients serving as not only cell structural components but also local and systemic signals triggering root acclimatory responses. Here, we mainly focused on the current advances on root responses to N and P nutrition/stresses regarding transporters as well as long-distance mobile proteins and peptides, which largely represent local and systemic regulators, respectively. Moreover, we exemplified some of the potential pitfalls in experimental design, which has been routinely adopted for decades. These commonly accepted methods may help researchers gain fundamental mechanistic insights into plant intrinsic responses, yet the output might lack strong relevance to the real situation in the context of natural and agricultural ecosystems. On this basis, we further discuss the established—and yet to be validated—improvements in experimental design, aiming at interpreting the data obtained under laboratory conditions in a more practical view.     

Assessment of the ideal ratios of digestible essential amino acids for pacu,Piaractus mesopotamicus,juveniles by the amino acid deletion method

The present study aimed to determine the ideal ratios of digestible essential amino acids (EAAs) for pacu (Piaractus mesopotamicus) juveniles by the amino acid (AA) deletion method. A completely randomized design which consisted of 11 treatments and three replicates each was used. The treatments included a control diet (CD) containing 55% of nonpurified natural ingredients and 45% of purified synthetic amino acids and ingredients, and other ten isonitrogenous and isoenergetic EAA limiting diets (LDs), each being deficient in 44.4 ± 0.02% of the respective EAA. Pacu juveniles with initial average body weight of 6.22 ± 0.09 g were distributed among 33 fiber glass tanks. Fish were fed with semipurified and extruded diets for 113 days two times a day until apparent satiation. The ideal ratio of each dietary EAA was calculated on the basis of the relationship between body N retention and amount of EAA deleted from the respective EAA LD. Based on the AA deletion method, the ideal ratios of digestible EAAs for pacu juveniles, relative to lysine requirement of 100% were estimated as: methionine 14.6%, threonine 35.0%, tryptophan 6.6%, arginine 62.8%, histidine 13.6%, isoleucine 26.3%, leucine 43.7%, phenylalanine 27.2%, and valine 35.8%.     

不同施氮水平对柳枝稷光合特性及抗旱性的影响

为了探究宁夏银北盐碱地区柳枝稷高产优质高效栽培过程中最佳的施氮量及其对柳枝稷叶片光合特性及抗旱性的影响,本研究采用大田试验,以Cave-in-Rock品种柳枝稷为供试材料,设无氮添加(0 kg·hm-2,N0)、施低氮(60 kg·hm-2,N60)、中氮(120 kg·hm-2,N120)和高氮(240 kg·hm-2,N240)共4个施氮水平,分析比较了各生育时期内柳枝稷叶片光合特性、渗透调节物质及抗氧化酶活性的变化,同时采用隶属函数法综合评价了盐碱地柳枝稷的抗旱性.结果表明,随着不同施氮水平的增加,柳枝稷各生育时期内叶片叶绿素相对含量(SPAD)、净光合速率(Pn)、气孔导度(Gs)和细胞间隙CO2浓度(Ci)整体呈现先升后降的趋势,均在施中氮(N120)处理下达到峰值.与无氮添加(N0)处理相比,施低氮(N60)、中氮(N120)和高氮(N240)处理下柳枝稷叶片的SPAD值平均增加了4.73％、18.71％和8.86％,净光合速率(Pn)平均提高了5.55％、17.02％和12.41％,气孔导度(Gs)平均升高了7.87％、56.18％和39.33％,细胞间隙CO2浓度(Ci)平均增加了7.86％、30.71％和13.81％.柳枝稷叶片蒸腾速率(Tr)在高氮(N240)处理下达到最大值,叶片水分利用效率(WUE)随着不同施氮水平的增加而逐渐下降.隶属函数分析结果表明,施中氮(N120)处理下柳枝稷各抗旱指标隶属函数值的均值最大.因此,本试验条件下有利于提高柳枝稷叶片光合能力和抗旱性的适宜施氮水平为120 kg·hm-2.     

施氮量对农田土壤有机氮组分及酶活性的影响

【目的】探讨不同施氮量条件下土壤氮素转化酶活性和有机氮组分含量的变化规律,并分析氮素转化酶活性与各有机氮组分之间的关系,为陇中黄土高原旱作农业区合理制定施肥量和施肥方案提供参考依据。【方法】基于设置在陇中黄土高原定西市李家堡镇麻子川村的不同施氮量（0（CK）、52.5（N1）、105（N2）、157.5（N3）、210（N4）kg N·hm^-2）春小麦长期定位试验,收获后使用Bremner法测定0—40 cm土层中有机氮组分含量,以及4种氮素转化相关酶的活性。【结果】土壤有机氮组分分配比例顺序为氨基酸态氮>酸解铵态氮>酸解未知态氮>氨基糖态氮,同一土层随着施氮量的增加土壤有机碳、全氮、酸解总氮、氨基酸态氮、酸解铵态氮和脲酶活性、蛋白酶活性均呈先增大后降低的趋势,除全氮外其余都在N2处理时最大,全氮含量在N3处理时达到最大;同一处理不同土层间均随土层加深而降低。冗余分析结果表明,全氮含量和蛋白酶活性是影响陇中黄土高原农田有机氮组分分布与转化的关键因子;碳氮比与所有有机氮组分均呈负相关,蛋白酶、有机碳和脲酶与氨基酸态氮呈极显著正相关。【结论】综合而言,N2处理土壤供氮潜力最高,全氮和蛋白酶是影响该区春小麦土壤有机氮组分转化的关键因子。氮肥合理施用能明显提高土壤有机氮含量,不同施氮量条件下土壤有机氮组分变化差异明显,改变了氮素相关转化酶的活性。     

亏缺灌溉对南疆棉花生长和水分利用的影响

针对南疆地区水资源短缺、作物水分利用效率低等问题,以棉花为试验材料进行田间小区试验,在棉花现蕾期、开花期以及结铃期分别设置3个亏缺灌溉水平(W₁:50%ET_c,W₂:65%ET_c,W₃:80%ET_c,ET_c为作物蒸发蒸腾量),以全生育期100%ET_c灌溉处理为对照(CK),研究膜下滴灌条件下,不同生育期亏缺灌溉对棉花生长、产量、氮素吸收和水分利用效率的影响.结果表明:现蕾期亏水对棉花株高、叶面积指数、地上干物质生长、氮素吸收和产量有不同程度的抑制效应,但复水后补偿效应显著,其中轻度亏水(W₃)在籽棉产量减少3.48%的条件下,WUE高达1.57 kg/m³,显著高于CK的1.48 kg/m³;开花期亏水,棉花的各项生长指标均有显著降低,复水后补偿效应不显著,不利于棉花生长发育;结铃期亏水对棉花地上干物质累积、氮素吸收和产量均有显著的抑制效应,但在W₂和W₃水平下,WUE均达1.51 kg/m³.综合考虑在保证棉花产量的同时达到节水增产的目的,可在棉花蕾期进行80%ET_c灌水,其他生育阶段实施充分灌溉,来控制营养生长,促进生殖生长,获得更高的水分利用效率.     

Nitrogen fertilization affects yields and storage compound contents in seeds of field-grown soybeans cv Enrei (Glycine max. L) and its super-nodulating mutant En-b0-1 through changing N2 fixation activity of the plants

ABSTRACT

We compared the protein and oil contents, seed yields, and natural abundance of ¹⁵N (σ¹⁵N) of seeds from the plants of the cultivar Enrei, which has moderate nodulating ability (Enrei) with those of its two near-isogenic lines (NILs), a super-nodulating genotype of Enrei, i.e., En-b0-1, and a non-nodulating genotype of Enrei, i.e., En1282. Plants of these three genotypes were grown on four types of field plots with different types of urea coated slow-release nitrogen (N) fertilizers (CUSLNFs) which delivered N in different manners during plant growth . The seed yield of the En1282 plants was similar to that of the Enrei plants but much greater than that of the En-b0-1 plants when the plants were grown on the field to which a CUSLNF with a long lifespan was applied. The amounts of protein per seed were positively correlated with those of oil per seed in the case of En1282 plants irrespective of the field N conditions. The seed protein contents were proportional to the seed weight in both En1282 and Enrei plants. Such a relationship was not observed in the En-b0-1 plants, and the protein and oil contents in the seeds of En-b0-1 plants were negatively correlated with each other. These observations suggested that the N supply to maturing seeds was a key to the protein contents in the En1282 and Enrei plants and that the C supply to maturing seeds was a key to the protein contents in the En-b0-1 plants. The comparison of the σ¹⁵N values, protein contents, and seed yields of seeds from En1282 plants suggested that the Enrei plants assimilated considerable amounts of N from the soil during the late plant growth. We concluded that high N₂ fixation activity depressed the amounts of oil per seed and changed the protein and oil contents in soybean seeds.     

滴灌下生物质改良材料对盐渍土水盐氮运移的调控效应

为探究生物质改良材料对滴灌盐渍土水、盐、肥运移过程的调控效应，采用土箱模拟试验，研究了水肥一体化滴灌条件下，生物炭和腐殖酸两种改良材料对盐渍土水、盐、氮运移和再分布过程及其时空分布特征的影响规律。结果表明：在滴灌条件下，盐渍土壤水盐的时空动态变化表现出明显的水分入渗驱动的盐分运移过程和蒸发扩散驱动的水盐再分布过程；铵态氮含量在时间上表现出先增大、后减小的变化趋势，在空间上的运移再分布特征较弱；硝态氮含量初始时空分布表现出与水盐相似的运移特征，受铵态氮硝化作用的多重影响，后期空间分布与铵态氮空间分布相似；生物炭通过提高土壤饱和导水率，增大了入渗阶段土壤水、盐、氮的运移速率和分布范围；腐殖酸通过提高土壤田间持水率增大了再分布过程土壤水、盐、氮的分布范围和强度，同时其对尿素的水解和硝化过程表现出更强的抑制效果。应用生物质改良材料在改变土壤物理性状进而调控滴灌土壤水盐运移的同时，还影响土壤氮素转化运移过程及其分布，这为水肥一体化滴灌盐渍农田的节水、控盐、减肥治理提供了理论基础。     

宽窄行配置一穴多株种植对膜下滴灌玉米产量和群体质量的影响

【目的】在保持种植密度和行距一定的条件下,选择适宜机械化运行的宽行距,研究1穴多株种植对膜下滴灌春玉米产量和群体质量的影响,进而实现增产、提高水肥利用效率和实现农业整体机械化的目标。【方法】试验在同一种植密度(9 900株/hm^2),等行距(30 cm)、等株距(30 cm)条件下,设置3种种植规格:1株/穴(H1,宽行37 cm)、2株/穴(H2,宽行104 cm)、3株/穴(H3,宽行172 cm)。【结果】不同种植株数下春玉米叶面积和叶面积指数(LAI)在大喇叭口期后差异显著,且H2处理叶面积显著大于H1、H3处理,分别高13.8%、7.6%;吐丝期以后H2处理干物质积累量显著高于H1和H3处理;吐丝期至成熟期H2处理的光合势、相对生长率显著高于H1、H3处理,光合势分别高4.60%~12.74%、8.97%~9.79%,相对生长率分别高21.15%、103.06%;H2处理的产量较H1、H3处理平均增产21.6%、24.6%,水分利用效率(WUE)分别提高25.0%、33.5%。【结论】春玉米膜下滴灌宽窄行配置1穴2株种植可以提高春玉米叶面积指数,延缓后期叶面积的衰老,增加光合势,有助于后期干物质的积累,提高粒重,最终提高玉米籽粒产量。与常规种植相比,玉米膜下滴灌采用1穴2株种植规格,产量提高约21.6%,WUE提高约25%。     

油菜-水稻轮作模式下油菜季氮肥投入与水稻季氮肥运筹对杂交籼稻光合生产力及产量的影响

【目的】探索油菜季氮肥投入与水稻季氮肥运筹对杂交籼稻光合生产力及产量的影响,为水旱轮作模式下水稻适宜的氮肥运筹方式提供理论和实践依据。【方法】以杂交籼稻‘F优498’为试验材料,研究油菜季2种氮肥投入量(常规施氮:180 kg·hm~(-2),减量施氮:150 kg·hm~(-2))、水稻季150 kg·hm~(-2)施氮量基础上3种氮肥运筹模式[M1—m(基肥)∶m(分蘖肥)∶m(穗肥)=2∶2∶6,M2—m(基肥)∶m(分蘖肥)∶m(穗肥)=3∶3∶4,M3—m(基肥)∶m(分蘖肥)∶m(穗肥)=4∶4∶2]对杂交稻光合特性、干物质积累与转运和产量的影响。【结果】相对于常规施氮,油菜季减量施氮影响了杂交稻齐穗期光合特性但没有达到显著水平;水稻季M1、M2、M3处理杂交稻齐穗期和齐穗后15 d的光合生产力均增加;油菜季减量施氮和水稻季M3运筹模式杂交稻的光合速率增幅最大。油菜季减量施氮处理杂交稻齐穗期和成熟期茎鞘干物质质量、转化率和产量均增加;水稻季M1、M2、M3处理杂交稻齐穗期茎鞘干物质质量和产量增加;油菜季减量施氮和水稻季M3运筹方式干物质积累增幅最大。【结论】油菜季减量施氮和水稻季M3运筹方式可增强杂交稻生育后期光合性能,提高杂交稻叶面积指数,增加杂交稻干物质积累与转运,从而提高杂交稻产量,为本研究最佳处理。