20个小粒种咖啡种质氮吸收效率差异分析

为明确不同基因型小粒种咖啡的氮素吸收特性,进一步为遗传改良咖啡氮营养性状提供参考,本研究对同一氮素供应水平下20个小粒种咖啡氮素吸收效率的生理、形态机制进行研究。结果表明：大部分小粒种咖啡种质间叶绿素含量、硝酸还原酶活性（NRA）、根氮、茎氮、叶氮含量差异不显著,且叶绿素含量及NRA与叶氮、总氮累积量和氮吸收效率间相关性不显著;根长、根体积、根表面积均与根氮累积量、总氮累积量、氮吸收效率呈显著正相关;氮素在植株各器官的分配比例依次为：根氮>叶氮>茎氮;聚类分析表明,‘M13’氮吸收效率最高,为84.43%,最低为‘CATUAI’,仅为32.12%,其余种质为58.36%~43.08%。     

杨梅硝酸还原酶活性与根瘤固氮活性的研究

离体根瘤的固氮活性的测定采用乙炔还原法,硝酸还原酶的测定采用改进活体法,测试杨梅各器官硝酸还原酶活性的差异和温度、化合态氮对硝酸还原酶活性和固氮活性的影响,研究结果表明:①确定1%的正丙醇为活体法测定杨梅硝酸还原酶时所使用的渗透剂的最佳浓度。②杨梅NO3- 还原的主要部位在叶片,根瘤的硝酸还原酶活性受到宿主植物和内生菌的影响。③温度对植物体内硝酸还原酶和根瘤固氮活性水平影响很大,温度太高抑制酶活性,20℃时杨梅各器官的硝酸还原酶活性均达最高点,根瘤的固氮活性也达最高点。④用含10mmol/LNO3-的Hogland营养液培养的植株各部位的硝酸还原酶活性均高于对照,10mmol/L的NH4+ 对植株的硝酸还原酶活性未见明显影响,但能抑制根瘤的固氮活性,其抑制程度高于NO3-。⑤硝酸还原酶活性和根瘤固氮活性之间没有直接关系。      

Effect of nitrogen supply on the comparative productivity of maize and sorghum in a semi-arid tropical environment III. Grain yield and nitrogen accumulation

Differences in grain yield and grain nitrogen content due to variable N supply in maize and sorghum, grown under irrigation in the semi-arid tropics, were associated with differences in their rates of accumulation and in the extent of mobilization of pre-anthesis dry matter and N. Increases in harvest index, nitrogen harvest index, and grain size during grain-filling were essentially linear, and the rates were constant under variable N supply. Differences in harvest index at maturity at different levels of applied N were small relative to differences in biomass and grain yield, and differences in grain size were small relative to differences in grain number. In effect, variation in harvest index and grain size at maturity was associated with variation in the length of the effective grain-filling period. Nitrogen supply had a greater effect on the effective duration of grain-filling in maize than in sorghum.Maximum grain yields at high levels of N uptake were greater in maize (10.0 t ha⁻¹ at 15.5% moisture) than in sorghum (7.2 t ha⁻¹ at 14% moisture). These differences were related to differences in biomass production, rate of increase in harvest index and the effective duration of grain-filling. The rate of increase in harvest index was greater, but biomass production was less and the duration of grain-filling was shorter, in sorghum than in maize.     

甜菜硝酸还原酶活性研究

试验表明,甜菜幼苗期至叶丛快速生长期,叶片中的NR活性迅速上升至最高水平,以后缓慢下降,到糖分积累期迅速下降到最低水平。外源基质条件下NR活性较内源基质条件下高出10倍至几10倍,在高氮条件下NR活性下降.甜菜具有极高的NO_3~-还原潜力。叶片中还原糖含量和NR活性在整个营养生长期均表现为负相关,蔗糖含量与NR活性在糖分积累期呈显著负相关,含氮率与NR活性在各生育时期均呈正相关。外源基质对NR活性的影响随施氮量提高而下降。     

冬小麦冠层氮素及硝酸还原酶活性的垂直分布

为了探讨冬小麦冠层不同层次氮素及NRA分布规律，解释冠层氮素垂直分布差异的内在原因，对两个籽粒蛋白质含量不同的冬小麦品种进行了研究。结果表明，冬小麦叶片含氮量沿冠层垂直分布呈明显的梯度，自冠层顶部向下逯层降低。不同品种间存在差异，籽粒蛋白含量高的中优9507上部层次梯度大于籽粒蛋白含量低的京冬8号，下部层次则反之，后期中优9507与京冬8号下部层次的差异更为明显。硝酸还原酶活性(NRA)也自冠层顶部逐层降低，但其梯度变化趋势与含氮量变化趋势并不完全一致。中优9507NRA高于京冬8号，其垂直梯度值也高于京冬8号相应梯度。京冬8号上部叶片NRA与叶片含氮量具有较高的相关性，能较好地反映植株的氮素状况，而中优9507上、中部叶片NRA均可以反映其植株氮素状况。二者下层叶片NRA都表现出与叶片氮素消长的不同步性。     

咖啡的硝酸还原酶活性及其对根外追肥的反应

用体内法测定小粒种咖啡植株硝酸还原酶活性及分析其对根外追肥反应的结果表明:①漂浮于低浓度NO_8~-诱导液中的咖啡叶片,NO_8~-积累量少,硝酸还原酶体内测定的活性是保温介质中NO_8~-浓度的函数,硝酸还原酶米氏方程模拟良好,双倒数作图在高底物浓度下近乎直线(r=0.9396)。②直接从田间采样的咖啡叶片,不需经硝态氮诱导就有可测定的酶活性。沙培的咖啡籽苗通过根部进行硝态氮诱导,其硝酸还原酶活性以根中为最强,叶和茎中次之,移栽了3个月的小苗,其根、茎、叶中酶活性的强弱相差不大;2—3年生成龄植株的酶活性以叶中的为最强,而且植株外围成熟阳叶的要比内层阴叶的强,枝梢幼叶的最弱。③施用钼酸铵和螯合稀土钼能增强田间咖啡叶片的硝酸还原酶活性,但对硝态氮诱导的最大酶活性没有增益效应;施用硝酸稀土也能增强田间咖啡叶片的硝酸还原酶活性,而且对硝态氮诱导的最大酶活性仍有增益效应;施用尿素对咖啡叶片的硝酸还原酶活性及其硝态氮诱导的最大酶活性都不具增效作用。     

Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in south-western Zimbabwe: Unravelling the effects of water and nitrogen using a simulation model

The APSIM model was used to assess the impact of legumes on sorghum grown in rotation in a nutrient-limited system under dry conditions in south-western Zimbabwe. An experiment was conducted at Lucydale, Matopos Research Station, between 2002 and 2005. The model was used to simulate soil and plant responses in the experiment. Sequences of cowpea (Vigna unguiculata), pigeonpea (Cajanus cajan), groundnut (Arachis hypogaea) and sorghum (Sorghum bicolor) were used in the rotations. Legumes accumulated up to 130 kg of N ha⁻¹ which was potentially available for uptake by sorghum in the following season. The APSIM model predicted total biomass, grain and N yields of the legume phase within the experimental error and performed well in predicting sorghum yield and N supplied in the rotation after cowpea and groundnut. The model generally under-predicted sorghum total biomass and grain yield after pigeonpea. Observed patterns of crop water use, evaporative losses during the dry season and re-charge of soil profile at the start of the rainy season were generally well predicted by the model. An assessment of output on sorghum N and water stresses in the rotation indicated that the legume–cereal rotation is more driven by soil nitrogen availability than water availability even under semi-arid conditions. Further legume–cereal rotation analysis using the model will assist in the understanding of other processes in the rotations in dry environments.     

Land Equivalent Ratio of Groundnut-Fingermillet Intercrops as Affected by Plant Combination Ratio,and Nitrogen and Water Availability

Abstract

Field experiments were conducted to characterize intercropping advantages in groundnut-fingermillet intercrop in relation to crop combination ratios, soil moisture and nitrogen (N) availability. Three intercrops in 1 : 2, 1 : 1 and 2 : 1 alternating rows of groundnut and fingermillet were examined for their growth and yield in comparison with their respective sole crops in 1996. The effect of well watered (W) and water stressed (D) conditions on the intercropping advantage was also examined for 1 : 1 intercrops in 1995 and 1996. Fertilizer N was applied at the rate of 20 kg ha^?1 in 1995 and 50 kg ha^?1 in 1996. The total above-ground biomass (DM) and its land equivalent ratio (LER) were highest in the 1 : 1 combination ratio. The DM production of intercropped fingermillet was higher in 1996 with higher N than in 1995 with low N application, while those of groundnut were similar in both years. The intercropped groundnut exhibited significantly higher DM production after the fingermillet harvest. The LERs in grain yield were higher in 1996 (1.43 under W and 1.45 under D), than in 1995 (0.87 under W and 1.22 under D). Also, LERs were consistently higher under D than W conditions. Water stress severely reduced the leaf area index (LAI) of fingermillet at a low N, especially in the later stages, whereas higher N alleviated the water stress effect. A close linear relationship was observed between LAI and leaf area (LA) per unit leaf N both for groundnut and fingermillet, with intercrops producing larger LA per unit leaf N than sole crops. Intercropping maintained higher ability in leaf net photosynthesis and transpiration of groundnut up to later stages, and significantly reduced water evaporation from the soil surface under the canopy than sole cropping of fingermillet. These results suggest that three processes associated with the intercropping yield advantages in the groundnut-fingermillet intercrop; 1) higher leaf photosynthesis and vigorous growth of groundnut after the fingermillet harvest, 2) higher LA production per unit N and 3) efficient water use. In conclusion, interspecific shading was considered to be the key mechanism associated with these processes, leading to the intercropping advantages. The degree of the interspecific shade and its effect on growth and yield depended on the available soil N and water.     

玉米杂交种氮效率遗传相关与通径分析

玉米过量施用氮肥可导致经济效益下降和硝酸盐向地下水淋失,因而受到人们越来越多的重视.选育氮高效杂交种可以降低生产成本和减少环境污染.本试验选用8个玉米杂交种,在高氮(纯N 200 kg/hm²)、低氮(不施氮)条件下分析了农艺性状决定氮效率高低的作用.结果表明:在氮高效杂交种选育中,高氮条件下选育高产品种,应注意对穗行数、行粒数、百粒重、吐丝期生物量、穗三叶面积的选择,而对其它性状的要求放宽;低氮条件下选育耐低氮的高效品种,更应注重选择大穗型、穗行数多,且有较大成熟期生物量、大的穗三叶叶面积的品种。     

施氮量对玉米产量和氮素利用效率及土壤硝态氮累积的影响

采用田间试验研究不同施氮量对两个玉米品种子粒产量、土壤硝态氮累积量及氮素利用率的影响。结果表明,玉米产量随施氮量增加显著提高,当施氮量高于200kg/hm2时玉米产量不再增加,高氮处理地上部分秸秆生物量出现下降趋势。0～100cm土层硝态氮累积量随氮素输入量的增加显著增加。不同玉米品种对氮素的吸收利用影响硝态氮在土壤中的累积,植株氮积累量存在差异。密植型玉米先玉335总吸氮量高于平展型玉米辽单28,土壤硝态氮的累积量也显著低于后者。不同氮肥水平的氮肥利用率为28.38%～35.33%,高氮处理氮肥利用率最低。本试验条件下,中氮处理水平基本能够满足作物生长的需求。综合产量、氮肥利用效率和土壤硝态氮累积情况,确定合理施氮量应控制在200kg/hm2左右。     

Physiological and Molecular Analysis of Applied Nitrogen in Rice Genotypes

Ten genotypes of rice (Oryza sativa L.) were grown for 30 d in complete nutrient solution with 1 mmol/L (N-insufficient),4 mmol/L (N-moderate) and 10 mmol/L (N-high) nitrogen levels,and nitrogen efficiency (NE) was analyzed.Growth performance,measured in terms of fresh weight,dry weight and lengths of root and shoot,was higher in N-efficient than in N-inefficient rice genotypes at low N level.Of these 10 genotypes,Suraksha was identified as the most N-efficient,while Vivek Dhan the most N-inefficient.To find out the physiological basis of this difference,the nitrate uptake rate of root and the activities of nitrate assimilatory enzymes in leaves of N-efficient and N-inefficient rice genotypes were studied.Uptake experiments revealed the presence of two separate nitrate transporter systems mediating high-and low-affinity nitrate uptake.Interestingly,the nitrate uptake by the roots of Suraksha is mediated by both high-and low-affinity nitrate transporter systems,while that of Vivek Dhan by only low-affinity nitrate transporter system.Study of the activities and expression levels of nitrate assimilatory enzymes in N-efficient and N-inefficient rice genotypes showed that nitrate reductase (NR) and glutamine synthetase (GS) play important roles in N assimilation under low-nitrogen conditions.     

废水污泥对土壤和植物酶活性及花生品质的影响

研究了沼气化废水（BSW）、酒糟水（RSW）及污水塘泥（LS）与一定量的NPK＋厩肥（FYM）对花生营养品质及土壤和植物酶活性影响。结果表明．废水污泥能增加种子产量，蛋氨酸和半胱胺酸含量比对照分别增加44％和24％，BSW处理种子产量最高，为6190kg／hm^2，其次是RSW和LS，分别为5570kg／hm^2和4720kg／hm^2，LS处理花生叶片中叶绿素含量最高为2．94mg／g FW。BSW和RSW能显著增加植物过氧化酶活性，使用废水污泥对硝化还原酶活性无影响。但其明显增加根际土壤硝酸盐的含量。三种废水污泥比化肥NPK＋厩肥（FYM）明显增加脱氢酶和碱性磷酸酶的活性。     

Influence of applied nitrogen on potato part I: Yield,quality, and Nitrogen uptake

Fertilizer nitrogen (N) may be managed to increase crop production and profitability while reducing nitrate contamination of groundwater. A two-year field investigation was conducted to evaluate the effects of applied N on tuber yield and quality, dry matter production and N uptake of potato (Solanum tuberosum L. var. Russet Burbank) grown on irrigated sandy soils in Michigan. Nitrogen was applied as ammonium sulfate [(NH₄)₂SO₄] at rates of 0, 56 and 112, kg N ha^?1 in a single application at planting or 112 and 168 kg N ha^?1 in split applications during the growing season. Total tuber yield generally increased with N applications up to 112 kg N ha^?1. Only one of the three experimental sites showed an increase in marketable tuber yield when 112 kg N ha^?1 was split evenly between planting and tuber initiation. Tuber specific gravity was not affected by N rate. Nitrogen rates of 112–168 kg N ha^?1 maximized dry matter production and plant tissue N concentration at onset of maturity and harvest. Tuber N concentration at harvest ranged from 13–17 g kg^?1 at two of the three locations. Values for the third experiment were 10–13 g N kg^?1. Whole crop N uptake at onset of senescence ranged from 45 to 225 kg N ha^?1 across all locations and treatments. An average of 67 percent of this N was found in tubers at harvest. Nitrogen fertilization exceeded N removal in harvested tubers by more than 50 kg N ha^?1 only for the 168 kg N ha^?1 treatment. These results indicate that acceptable tuber yield can be obtained with lower N rates than those currently used by most producers, with the potential for reducing net loss of N from the soil.     

施氮量对不同氮效率冬小麦品种苗期生长的影响

为了研究施氮量对不同氮效率冬小麦品种苗期生长及其生理特性的影响,通过水培试验,选用小偃128(氮低效低响应型)、陕农78(氮低效高响应型)、西农2208(氮高效低响应型)和小偃503(氮高效高响应型)等4个不同氮效率的冬小麦品种,以氮水平和品种基因型分别为主、副处理,测定了苗期生长过程中叶片叶绿素含量(SPAD值)、光合特性和硝酸还原酶活性(NRA)等生理指标及地上、地下干物质量和含氮量。结果表明,苗期不同氮效率基因型小麦叶片SPAD值、NRA和光合速率及植株含氮量在一定施氮范围内随着施氮量的增加而增加,且施氮处理较不施氮处理均有显著增加,而同一施氮处理不同基因型品种间差异不大。     

硫肥对玉米氮、磷、钾吸收利用影响的基因型差异

以我国夏玉米主产区的34个玉米基因型(6个自交系,4个特用玉米和24个杂交种)为试验材料,通过不同硫肥供应水平的大田试验,分析了硫肥对玉米氮、磷、钾吸收利用的影响.结果表明,施用硫肥促进了玉米对营养元素的吸收,植株氮、磷、钾的积累总量平均比未施用硫肥的对照分别增加6.07%、11.89%和19.31%,肥料利用效率提高.硫肥对氮、磷、钾吸收利用的影响不完全相同,并且存在明显的基因型差异施用硫肥后,自交系氮、磷、钾的收获指数和利用效率均有大幅度提高;杂交种的氮素收获指数和利用效率均有所提高,磷素利用效率下降,但是不同基因型的变化程度差异较大;另有17个杂交种的磷素收获指数降低,10个杂交种的钾素收获指数和14个杂交种的钾素利用效率降低.     

Biomass production and nitrogen accumulation and remobilisation by Miscanthus × giganteus as influenced by nitrogen stocks in belowground organs

The nitrogen (N) requirement of dedicated crops for bioenergy production is a particularly significant issue, since N fertilisers are energy-intensive to make and have environmental impacts on the local level (NO₃ leaching) and global level (N₂O gas emissions). Nitrogen nutrition of Miscanthus × giganteus aboveground organs is assumed to be dependent on N stocks in belowground organs, but the precise quantities involved are unknown. A kinetic study was carried out on the effect of harvest date (early harvest in October or late harvest in February) and nitrogen fertilisation (0 or 120 kg N ha⁻¹) on aboveground and belowground biomass production and N accumulation in established crops. Apparent N fluxes within the crop and their variability were also studied.Aboveground biomass varied between 24 and 28 t DM ha⁻¹ in early harvest treatments, and between 19 and 21 t DM ha⁻¹ in late harvest treatments. Nitrogen fertilisation had no effect on crop yield in late harvest treatments, but enhanced crop yield in early harvest treatments due to lower belowground biomass nitrogen content. Spring remobilisation, i.e. nitrogen flux from belowground to aboveground biomass, varied between 36 and 175 kg N ha⁻¹, due to the variability of initial belowground nitrogen stocks in the different treatments. Autumn remobilisation, i.e. nitrogen flux from aboveground to belowground organs, varied between 107 and 145 kg N ha⁻¹ in late harvest treatments, and between 39 and 93 kg N ha⁻¹ in early harvest treatments. Autumn remobilisation for a given harvest date was linked to aboveground nitrogen accumulation in the different treatments. Nitrogen accumulation in aboveground biomass was shown to be dependent firstly on initial belowground biomass nitrogen stocks and secondly on nitrogen uptake by the whole crop.The study demonstrated the key role of belowground nitrogen stocks on aboveground biomass nitrogen requirements. Early harvest depletes belowground nitrogen stocks and thus increases the need for nitrogen fertiliser.     

高浓度CO2条件下水稻叶片氮含量下降与氮代谢关键酶活性的关系

利用FACE（Free Air Carbon Dioxide Enrichment）平台技术,研究了低氮（125 kg/hm2,以纯N计）和常氮（250 kg/hm2）水平下,高浓度CO2（周围大气CO2浓度+200 μmol/mol）对水稻不同生育期功能叶N代谢关键酶活性的影响。结果表明,高浓度CO2提高了叶片硝酸还原酶和蛋白水解酶的活性,两者在常N下的响应程度大于在低N下的响应程度;高浓度CO2降低了低N下叶片谷氨酰胺合成酶和谷氨酸脱氢酶（NADH GDH）活性,常N水平下酶活性的下降趋势得到改变或缓解。由此可见,高浓度CO2条件下NO3-转化为NH4+加速,而NH4+进一步同化为有机N却受阻,而且,由于后期蛋白水解加速,将进一步加剧叶片N含量的下降。这是水稻叶片N含量下降的内在因素。而增施N肥,有利于同化酶的表达,降低叶片蛋白水解酶活力,从而缓解叶片N含量的下降。     

Nitrate-Induced Inhibition of Root Nodule Formation and Nitrogenase Activity in the Peanut (Arachis hypogaea L.)

Summary

The effect of nitrate in the culture solution (0.7, 3.5, 7.0, and 14.0 mM N) on the growth, root nodule formation and nitrogenase activity of the peanut (cv. chico) inoculated with Bradyrhizobium sp. was examined at early developmental stages. The amount of nitrogen derived from fixation and its percentage to total nitrogen in the nitrate-fed plant were evaluated using ¹⁵N labeled nitrate. The dry weight and total nitrogen content of the plant at 40 days after transplanting (day 40) varied with the concentration of nitrate in the culture solution. Both of them were higher in the plants grown in the presence of nitrate at the concentrations above 0.7 mM. On the other hand, the number and fresh weight of nodules, and acetylene reduction activity per plant were the lowest in the presence of nitrate at 14.0 mM, relatively high at 0.7 mM, and the highest at 3.5 mM. The proportion of N derived from atmosphere to total nitrogen in the plants examined at days 18 and 33 was 23–31% in the presence of nitrate at 3.5 and 14.0 mM. However, the proportion examined at day 48 was as high as 57–58% at 3.5 mM, and it was only 22–24% at 14.0 mM.     

~(15)N同位素标记筛选高固氮大豆种质的研究

田间自然条件下，利用15N稀释标记技术评价19价大豆种质的固氮能力。结果表明，固氮量和固氮比率的变幅分别为N67～140kg／hm2和35％～60％。筛选出3份固氮量超过N130kg／hm2和固氮率大于55％的高固氮种质材料。15N标记可真实地反映出品种的实际固氮水平。