两个氮素利用率不同的水稻品种根系形态及生理特性的差异

The variation in nitrogen (N) uptake by rice has been widely studied but differences in rice root morphology that may contribute to this variation are not completely understood. Field and greenhouse experiments were carried out to study N accumulation, root dry weights, total root lengths, root surface areas, and root bleeding rates of two rice cultivars, Elio with low N-use efficiency and Nanguang with high N-use efficiency. Low (1 mmol N L^-1) and high (5 mmol N L^-1) N applications were established in the greenhouse experiment, and the N rates were 0, 120, and 240 kg ha^-1 in the field experiments at Jiangning and Jiangpu farms, Nanjing, China. The results showed that the N accumulation, root dry weight, total root length, and root surface area increased with an increase in N application. At the heading stage, N accumulation in the shoots and roots of Nanguang was greater than that of Elio in the field experiments and that of Elio at 5 mmol N L^-1 in the greenhouse experiment. After the heading stage, N accumulation was higher for Nanguang at both 1 and 5 mmol N L^-1 in the greenhouse experiment. The total root length and root surface area were significantly different between the two cultivars. Over the range of the fertilizer application rates, the root lengths of Nanguang at Jiangning Farm were 49%-61% greater at booting and 26%-39% greater at heading than those of Elio, and at Jiangpu Farm they were 22%-42% and 26%-38% greater, respectively. Nanguang had a greater root bleeding rate than Elio. It was concluded that the N-use efficiency of the two rice cultivars studied depended to a great extent on the root morphological parameters and root physiological characteristics at different growth stages.     

不同氮水平下粳稻的氮素累积和转运特征

Developing high-yielding rice （Oryza sativa L.） cultivars depends on having a better understanding of nitrogen （N） accumulation and translocation to the ear during the reproductive stage. Field experiments were carried out to evaluate the genetic variation for N accumulation and translocation in different Japonica rice cultivars at different N rates and to identify any relationship to grain yield in southeast China. Four Japonica cultivars with similar agronomic characteristics were grown at two experimental sites in 2004 with three N rates of 0, 60, and 180 kg N ha^-1. Dry weights and N contents of rice plants were measured at tillering, initiation, anthesis, and maturity. Grain yields exhibited significant differences （P 〈 0.05） among the cultivars and N application rates. Increasing N rates improved N uptake at anthesis and maturity in all four cultivars （P 〈 0.05）. N translocation from vegetative organs to the grains increased with enhanced N rates （P 〈 0.05）. N translocation to the grains ranged from 9 to 64 kg N ha^-1 and N-translocation efficiency from 33% to 68%. Grain yield was linear to N uptake at anthesis （r^2 = 0.78^＊＊） and N translocation （r^2 = 0.67^＊＊）. Thus, cultivars with a high N uptake at anthesis, low residual N in the straw at maturity, and appropriate low N fertilizer supply in southeast China should efficiently increase N-recovery rate while maintaining grain yield and soil fertility.     

尼日利亚两个农业生态区施用氮肥和杂草干扰对热带玉米基因型的影响

Low soil nitrogen (N) and weed infestations are some of the major constraints to maize production in Nigeria.A split-split plot experiment in a randomized complete block design with three replicates was established at two sites with different agroecological zones,Ikenne (Typic Paleudalf) and Shika (Typic Tropaquept),in Nigeria in 2002 and 2003 rainy seasons to investigate the responses of four maize genotypes (Oba super II,Low N pool C2,TZB-SR,and ACR 8328 BN C7) to N fertilizer applied at four rates,0,30,60,and 90 kg N ha^-1,and three weed pressure treatments,no weed pressure (weekly weeding),low weed pressure (inter-row weekly weeding),and high weed pressure (no weeding throughout the growing season).Growth and yield parameters of maize and weeds were taken at flwering and harvest.The results indicated that there was a significant reduction in maize leaf area,leaf area index,and photosynthetically active radiation due to weed interference at both sites.The application of nitrogen at 90 kg N ha^-1 significantly increased maize leaf area.Reductions in maize growth and yield at flowering and harvest were significant due to weed interference at both Ikenne and Shika,thus showing that the reductions in maize growth and yield due to weed interference were not ecological zone specific even though weed species and their seed banks may differ.Ameliorative management options could thus be the same in the two agroecological zones.Application of 90 kg N ha^-1 led to a significant increase in maize grain yield at Shika while there was no fertilizer effect at Ikenne on grain yield.There was no significant difference between 60 and 90 kg N ha^-1,suggesting that 60 kg N ha^-1 could be a possible replacement for the higher fertilizer rate at least for the identified maize genotypes.Low weed pressure treatment led to 26% and 35% reductions in maize grain yield at Ikenne and Shika,respectively,while 22% and 51 % reductions,respectively,were observed due to high weed pressure.Generally,maize grain yield was higher at Ikenne than Shika.The maize genotypes Low N pool C2 and ACR 8328 BN C7 performed better than the other genotypes at Ikenne while the maize genotype Oba super II had the best performance at harvest at Shika.Application of nitrogen increased weed biomass at flowering at Ikenne.The maize grain yield was highest in the N-efficient genotypes,Oba super II and Low N pool C2;the susceptible genotype TZB-SR had the least yield at Shika.There existed a negative and significant correlation between maize grain yield and weed biomass at both sites.     

在施钾条件下灌溉水稻的养分吸收和利用效率研究

Potassium is one of the most important nutrients for rice production in many areas of Asia, especially in southeast China where potassium deficiency in soil is a widespread problem. Field experiments were conducted for four consecutive years in Jinhua City, Zhejiang Province, to determine utilization of nutrients (N, P and K) by inbred and hybrid rice and rice grain yields as affected by application of potassium fertilizer under irrigated conditions. Grain yield and nutrient harvest index showed a significant response to the NPK treatment as compared to the NP treatment. This suggested that potassium improved transfer of nitrogen and phosphorus from stems and leaves to panicles in rice plants. N and P use efficiencies of rice were not strongly responsive to potassium, but K use efficiency decreased significantly despite the fact that the amount of total K uptake increased. A significant difference between varieties was also observed with respect to nutrient uptake and use efficiency. Hybrid rice exhibited physiological advantage in N and P uptake and use efficiency over inbred rice. Analysis of annual dynamic change of exchangeable K and non-exchangeable K in the test soil indicated that non-exchangeable K was an important K source for rice. Potassium application caused an annual decrease in the concentration of available K in the soil tested, whereas an increase was observed in non-exchangeable K. It could be concluded that K fertilizer application at the rate of 100 kg ha^-1 per season was not high enough to match K output, and efficient K management for rice must be based on the K input/output balance.     

Assessing Nitrogen Fertilization Strategies in Winter Wheat and Cotton Crops in Northern Greece

The management of fertilizer application is crucial for agricultural production and environmental safety.The objective of this study was to assess the effciency of different fertilization strategies,applying fertilizers with and without nitrification inhibitors(NIs) in split application,in Greece.The assessment criteria used were based on crop yield,soil nitrogen(N)concentrations and economic effciency.For this purpose two crops(winter wheat and cotton)were seffected in order to explore the optimum fertilization strategy for each crop.Three treatments combining fertilizers with NIs were tested compared with conventional fertilization(CF).Slight differences in the quantity and the combination of fertilizers with NIs applied resulted in variable effects on crop yield,soil N and economic return.Split N application of 102 kg ha^-1,with half of the total amount applied at seeding,resulted in higher grain yield of winter wheat,lower NO₃^--N in soil and higher economic return.This result reveals the importance of N application at seeding in wheat crop.Fertilization strategy with 109.5 kg N ha^-1 and split P application resulted in higher cotton yield and higher economic profit.Split P application seemed to increase yield,even though it is not a common practise in the area.     

苋菜对钾素吸收和利用上的基因型差异

The kinetics of K^ absorption and the utilization of both applied K and K in a calcareous alluvisol with low available K by different genotypes of grain amaranth(Amaranthus spp.),an ancient pseudo-cereal that produces a large biomass and a rich source of health nutrients and mineral elements,were studied by means of ion depletion technique and pot experiments.Grain amaranth had a high affinity for K^ absorption comparison with corn and cotton.However,there were differences among Amaranthus spp.in Kabsorption and utilization.Some cultivars such as R104,CX-4,Du001,Hy015 and Hr029 which had a higher rate of K absorption and stronger affinity for K^ were typical varieties with high K-use efficiency(KUE).The results showed that high KUE cultivars grew quickly,possessed stronger ability to take up soil slowly available K and Mineral K,and did not respond to K fertilization in the soil with low available K.Correspondingly,grain amaranth cultivars CX-77,Cr024,Vd001,Re003 and Sn003 were relatively low in KUE,Compared with high KUE cultivars,they took up more soil available K and both of their dry matter accumulation and K uptake responded to K applied significalty.     

Effect of Incorporation of Wheat Straw and Urea into Soil on Biomass Nitrogen and Nitrogen-Supplying Characteristics of Paddy Soil

Pot experiments were carried out to study the effect of incorporation of wheat straw and/ or urea into soil on biomass nitrogen and mineral nitrogen and its relation to the growth and yield of rice.The combined appliation of wheat straw and urea increased much more biomass nitrogen in soil than the application of wheat straw or urea alone and consequently increased the immobilization of urea nitrogen added and reduced the loss of urea nitrogen.An adequate nitrogen-supplying process to rice plant could be obtained if C/ N ratio of the material added was about 20.The three yield components of rice were affected significantly by the status of nitrogen supplying.More than 30mg N/ kg soil of mineral nitrogen at effective tillering stage,panicle initiation stage and filling stage should be maintained in order to get high rice yield,though the criteria varied with the different experimental conditions.     

磷和钾对巴基斯坦西北部向日葵生长、产量的交互效应

Potassium (K) and phosphorus (P) applications improve growth, increase yield and yield components of sunflower (Helianthus annuus L.) on K and P deficient soils in Northwest Pakistan. A field experiment was conducted using sunflower cv. Hysun-33 at the New Developmental Research Farm of KPK Agricultural University, Peshawar, Pakistan, during summer 2006. The experimental design was a randomized complete block in split plot arrangements, with six levels of K (0, 25, 50, 75, 100, and 125 kg K ha^-1) as main plots and four levels of P (0, 45, 90, and 135 kg P ha^-1) as sub-plots with three replications. Sunflower yield and yield components responded positively to K and P fertilization but the magnitude of response varied with the levels of K and P. Days to flowering and maturity, grains per head, 1000-grain weight, shelling percentage, and grain yield increased tremendously in the K and P-fertilized plots as compared to the control with no K and P applied. The combined application of 100 kg K and 45 kg P ha^-1 significantly increased yield components, grain yield, harvest index, and shelling percentage of sunflower, suggesting that 100 kg K ha^-1 in combination with 45 kg P ha^-1 could maximize productivity of sunflower planted after wheat on the K and P deficient soils in the study area.     

Nutrient Uptake and Use Efficiency of Irrigated Rice in Response to Potassium Application

Potassium is one of the most important nutrients for rice production in many areas of Asia, especially in southeast China where potassium deficiency in soil is a widespread problem. Field experiments were conducted for four consecutive years in Jinhua City, Zhejiang Province, to determine utilization of nutrients (N,P and K) by inbred and hybrid rice and rice grain yields as affected by application of potassium fertilizer under irrigated conditions. Grain yield and nutrient harvest index showed a significant response to the NPK treatment as compared to the NP treatment. This suggested that potassium improved transfer of nitrogen and phosphorus from stems and leaves to panicles in rice plants. N and P use efficiencies of rice were not strongly responsive to potassium, but K use efficiency decreased significantly despite the fact that the amount of total K uptake increased. A significant difference between varieties was also observed with respect to nutrient uptake and use efficiency. Hybrid rice exhibited physiological advantage in N and P uptake and use efficiency over inbred rice. Analysis of annual dynamic change of exchangeable K and non-exchangeable K in the test soil indicated that non-exchangeable K was an important K source for rice. Potassium application caused an annual decrease in the concentration of available K in the soil tested, whereas an increase was observed in non-exchangeable K. It could be concluded that K fertilizer application at the rate of 100 kg ha^-1 per season was not high enough to match K output, and efficient K management for rice must be based on the K input/output balance.     

栽培方法对穗直立型稻株养分含量的影响

Field experiments were carried out with rice variety of Shennong 91 of short culms and erect panicles to study nutrient contents in high-yielding rice plants and to increase rice yield by appropriate fertilization. Nitrogen, phosphorus, potassium, magnesium, zinc, manganese, iron and copper contents in rice plants varied with different treatment factors. The relationship between the nutrient contents and treatment factors could be simulated using a multiple quadratic equation. The nutrient contents in plants should be appropriate for high-yielding rice. If the mean nutrient content in rice plants producing 11 t ha^-1 or more of grain (μ_j) was set as the standard value and the standard deviation (σ_j) was set as the range of variation, the nutrient content in high-yielding rice plants should be μ_j ± 1.99σ_j. Rice leaves were sensitive to the nutrient elements. Heavy nitrogen dressing increased the content of nitrogen in rice plants. Sparse transplanting also increased nitrogen content. Improper application of nitrogen, phosphorus and potassium could affect the nutrient contents and decrease the grain yield.     

不同氮效率水稻生育后期氮素积累转运特征

以不同氮效率水稻基因型为供试材料,通过15N标记的氮肥盆栽试验精确定量不同氮效率的水稻齐穗后氮素积累和转运量。结果表明,无论在何种施氮水平下,氮高效水稻(南光和武运粳)的籽粒产量均显著高于氮低效水稻Elio;不同氮效率水稻在齐穗期和齐穗后15天时干物质积累量差异不显著,但在成熟期时氮高效水稻的干物质积累量显著高于氮低效水稻,增幅约为16·4%;与干物质积累相对应的是,不同氮效率水稻的氮素积累量在齐穗期和齐穗后15天也没有差异,但在成熟期时氮高效基因型水稻武运粳和南光的氮素积累量较氮低效基因型水稻Elio高约31%和21%,差异显著。15N标记试验结果可以看出,氮低效水稻Elio齐穗时吸收的一部分15N移出了植株体,其占15N转运量的11%。从齐穗至成熟,氮低效水稻Elio从茎叶转移出的15N量(2·75mg穴-1)远远低于氮高效水稻武运粳(3·54mg穴-1)和南光(3·22mg穴-1),差异显著。氮高效水稻武运粳和南光从茎叶转移出的15N量约占籽粒所需N量的91%和85%,而从土壤中吸收的15N量约占9%和15%。综上所述,氮高效、低效水稻氮素积累和转运特征的差异主要表现在齐穗期以后,氮高效水稻具有强的氮素吸收或者转运能力,以满足籽粒形成期植株对氮素的利用。     

不同氮效率水稻品种增硝营养下根系生长的响应特征

试验采用两室分根盒和溶液培养方法,研究了在增硝营养下不同氮效率水稻品种根系生长的响应特征。结果表明,在本试验条件下,与全铵培养下的根系相比,氮高效水稻品种南光在铵硝混合培养下的根系干重和氮积累量显著增加,增幅达33%和41%;同时其根系表面积、根系体积和侧根数增幅均达到显著水平,但根系长度却无明显增加。氮低效水稻品种Elio在铵硝混合培养下的根系生长差异均不显著。这表明氮高效水稻品种南光的根系生长对增硝营养的响应度强,进而促进了根系对氮素的吸收利用。从本试验的结果可推论,水稻对增硝营养的强响应度可能是水稻氮素高效吸收利用的生理机制之一。     

Response of Wheat Cultivars to Nitrogen and Sulfur for Crop Yield,Nitrogen Use Efficiency,and Protein Quality in the Semiarid Region

ABSTRACT

The effects of nitrogen (N at 0, 100 and 180 kg N ha-1) and sulfur (S at 0, 20, 40 and 60 kg S ha-1) on crop yield, nutrient uptake, nitrogen use efficiency (NUE), and amino acid composition of two bread wheat cultivars, ‘Shehan’ and ‘Enkoy,’ grown in Andisols and Cambisols in randomized blocks with three replications were evaluated. Both cultivars responded significantly (P < 0.05) to N and S applications and S application with N improved the NUE by 28%. The yield increase for the two cultivars by N and S application ranged between 0.8 to 2.4 Mg ha^?1. The N concentration increased significantly from N0 to N2 in both cultivars. Sulfur fertilization increased the concentration of cysteine and methionine by 27% and 14%, respectively, as compared to N alone. The grain yield, NUE, N, and S uptake, and the S-amino acid concentration of ‘Enkoy’ were significantly higher than ‘Shehan’ cultivar.     

Nitrogen Use Efficiency of Rice Under Cadmium Contamination:Influence of Rice Cultivar Versus Soil Type

There is a need for rice cultivars with high yields and nitrogen (N) use efficiency (NUE), but with low cadmium (Cd) accumulation in Cd-contaminated paddy soils. To determine the relative effects of rice genotype, soil type, and Cd addition on rice grain yield and NUE, a pot experiment consisting of nine rice cultivars was conducted in two types of paddy soils, red soil (RS) and yellow soil (YS), without or with Cd spiked at 0.6 mg kg^-1. The N supply was from both soil organic N pools and N fertilizers; thus, NUE was defined as the grain yield per unit of total crop-available N in the soil. Cd addition decreased grain yield and NUE in most rice cultivars, which was mainly related to reduced N uptake efficiency (NpUE, defined as the percentage of N taken up by the crop per unit of soil available N). However, Cd addition enhanced N assimilation efficiency (NtUE, defined as the grain yield per unit of N taken up by the crop) by 21.9% on average in all rice cultivars. The NpUE was mainly affected by soil type, whereas NtUE was affected by rice cultivar. Hybrid cultivars had higher NUEs than the japonica and indica cultivars because of their greater biomass and higher tolerance to Cd contamination. Reduction of NUE after Cd addition was stronger in RS than in YS, which was related to the lower absorption capacity for Cd in RS. Canonical correspondence analysis-based variation partitioning showed that cultivar type had the largest effect (34.4%) on NUE, followed by Cd addition (15.2%) and soil type (10.0%).     

不同氮肥水平下水稻产量以及氮素吸收、利用的基因型差异比较

采用田间试验在施氮量为06、0、120、1802、40、3003、60.kg/hm27个水平下研究了不同水稻子粒产量、产量构成因子以及氮素吸收和利用的差异。结果表明,水稻品种4007的子粒产量在各个施氮水平下显著高于品种ELIO对氮肥的响应度高。施氮水平显著影响子粒产量构成因子。有效穗数与子粒产量存在显著正相关:ELIO和4007的相关系数(r)分别为0.839**和0.933**,表明有效穗数对水稻子粒产量起着非常重要的作用。本试验条件下,ELIO和4007获得最高产量所需的有效穗数分别为332、561个/m2;两者的氮素吸收效率在各施氮素水平下差异很小,均随着施氮量的增加而增加,而氮素利用效率均随着施氮量的增加而下降。4007的氮素利用效率在各个施氮水平下显著高于ELIO,较高的氮素收获指数(NHI)是主要原因之一。水稻氮素利用效率与成熟期茎秆、叶片的氮含量显著负相关,说明开花期后植物将吸收的氮素从营养器官有效地转运到子粒中是氮素利用效率高的重要原因之一。     

不同基因型油菜氮素利用效率的差异及其与农艺性状和氮素营养性状的关系

通过田间试验对50个甘蓝型油菜基因型进行氮利用效率筛选,并将不同氮利用效率基因型在施氮（N 180 kg/hm2）和不施氮（N 0 kg/hm2）条件下的农艺性状和氮营养性状作了比较研究。结果表明,50个油菜基因型的氮利用效率具有显著差异,最大相差2.5倍（施氮）和1.7倍（不施氮）。油菜的农艺性状及氮素营养性状指标均表现出一定的基因型变异,其中第一个有效分枝高度变异系数最大,超过 50%,而籽粒含氮量的变异系数最小,只有 6% 左右。不论供氮水平高低,氮高效基因型的每角粒数,籽粒生物量,籽粒占地上部生物量的比例以及籽粒氮占地上部总氮的比例均高于氮低效基因型,第一个有效分枝高度则显著低于氮低效基因型。另外,油菜氮素利用效率与各器官含氮量、 茎叶氮素累积量、 果荚氮素累积量、 茎叶氮占地上部氮的比例和果荚氮占地上部氮的比例呈显著或极显著负相关,而不同氮效率基因型的地上部总生物量和地上部氮素累积总量则无显著差异。不同氮利用效率基因型的农艺性状和氮营养性状对氮肥的敏感性有显著差异。     

不同氮效率水稻生育后期氮代谢酶活性的变化特征

以不同氮效率水稻基因型为供试材料,研究了两个供氮水平下水稻生育后期功能叶和茎秆的氮、可溶性蛋白浓度和氮转运量以及氮代谢关键酶的变化。结果表明:与对照相比,施氮处理能显著增加不同氮效率水稻功能叶和茎秆的氮、可溶性蛋白的浓度和氮转运量。在不同的施氮水平下,水稻从齐穗至成熟顶三叶的氮浓度降低了60%～67%;而茎秆氮在生育后期对籽粒氮的贡献取决于环境供氮水平,与对照相比施氮处理水稻从茎秆转运出的氮大幅提高,在不同的供氮水平下南光的叶片和茎秆氮转运量显著高于Elio。与对照相比,施氮处理增加齐穗期时硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)和谷氨酸脱氢酶(GDH)的活性。随生育期的推进,四种氮代谢酶活性随之降低。南光的NR和GS酶活性显著高于Elio,但NR活性受水稻生育期和环境供氮水平的影响较大;南光的GOGAT和GDH的活性显著低于Elio。相关分析表明,NR和GS活性与功能叶和茎秆的氮转运量呈显著正相关。这就意味着水稻生育后期功能叶和茎秆的NR和GS活性高,尤其是GS活性高是筛选水稻氮高效的重要指标。     

Integrated rice management simultaneously improves rice yield and nitrogen use efficiency in various paddy fields

The hilly area of Southwest China is a typical rice production area which is limited by seasonal droughts and low temperature in the early rice growth period. A field experiment was conducted on three typical paddy fields (low-lying paddy field, medium-elevation paddy field, and upland paddy field) in this region. Nitrogen (N) treatment (180 kg N ha^-1 year^-1) was compared to a control treatment (0 kg N ha^-1 year^-1) to evaluate the effects of integrated rice management (IRM) on rice growth, grain yield, and N utilization. Integrated rice management integrated raised beds containing plastic mulch, furrow irrigation, and triangular transplanting. In comparison to traditional rice management (TRM), IRM promoted rice tiller development, with 7-13 more tillers per cluster at the maximum tillering stage and 1-6 more tillers per cluster at the end of tillering stage. Integrated rice management significantly increased the rice aboveground biomass by 34.4%-109.0% in different growth periods and the aboveground N uptake by 25.3%-159.0%. Number of productive tillers significantly increased by 33.0%, resulting in a 33.0% increase in grain yield and 8.0% improvement of N use efficiency (NUE). Grain yields were significantly increased in all three paddy fields assessed, with IRM being the most important factor for grain yield and productive tiller development. Effects of paddy field type and N level on N uptake by aboveground plants were reflected in the rice reproductive growth period, with the effects of IRM more striking due to the dry climate conditions. In conclusion, IRM simultaneously improved rice yield and NUE, presenting a valuable rice management technique in the paddy fields assessed.