Different Levels Of Nitrogen Application Research Articles

Macrogenomics-Based Analysis of the Effects of Intercropped Soybean Photosynthetic Characteristics and Nitrogen-Assimilating Enzyme Activities on Yield at Different Nitrogen Levels.

Currently, China's soybean self-sufficiency rate is only 15%, highlighting the soybean crisis and the supply chain risks that pose a major threat to China's food security. Thus, it has become imperative to step up efforts to boost soybean production capacity while promoting the green and sustainable development of regional farmland ecosystems. In this context, the present study comprehensively investigated the effects of intercropping and nitrogen application rate on soybean yield, as well as the changes in gradients generated by different levels of nitrogen application. Based on six consecutive years of maize-soybean intercropping planting patterns, the inter-root soils of soybeans were collected at the flowering stage and evaluated for soil nitrogen content, nitrogen-assimilating enzyme activities, and microbial community composition of soybean, which were correlated with yield, to clarify the main pathways and modes of intercropping effects. The N2 level (80 kg·ha-1) was favourable for higher yield. In comparison to monocropping, the intercropping reduced yield by 9.65-13.01%, photosynthetic characteristics by 1.33-7.31%, and plant nitrogen-assimilating enzyme activities by 8.08-32.01% at the same level of N application. Likewise, soil urease and catalase activities were reduced by 9.22 and 1.80%, while soil nitrogen content declined by an average of 6.38%. Gemmatimonas and Bradyrhizobium enrichment significantly increased soil nitrogen content, photosynthetic characteristics, and soybean yield, while it was reduced by Candidatus_Udaeobacter and Candidatus_Solibacte enrichment. The results of this study provide a theoretical basis for further optimising maize-soybean intercropping, which is crucial for enhancing the agricultural production structure and improving the overall soybean production capacity.

Simultaneous Quantification and Visualization of Photosynthetic Pigments in Lycopersicon esculentum Mill. under Different Levels of Nitrogen Application with Visible-Near Infrared Hyperspectral Imaging Technology.

Leaf photosynthetic pigments play a crucial role in evaluating nutritional elements and physiological states. In facility agriculture, it is vital to rapidly and accurately obtain the pigment content and distribution of leaves to ensure precise water and fertilizer management. In our research, we utilized chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophylls (Chls) and total carotenoids (Cars) as indicators to study the variations in the leaf positions of Lycopersicon esculentum Mill. Under 10 nitrogen concentration applications, a total of 2610 leaves (435 samples) were collected using visible-near infrared hyperspectral imaging (VNIR-HSI). In this study, a "coarse-fine" screening strategy was proposed using competitive adaptive reweighted sampling (CARS) and the iteratively retained informative variable (IRIV) algorithm to extract the characteristic wavelengths. Finally, simultaneous and quantitative models were established using partial least squares regression (PLSR). The CARS-IRIV-PLSR was used to create models to achieve a better prediction effect. The coefficient determination (R2), root mean square error (RMSE) and ratio performance deviation (RPD) were predicted to be 0.8240, 1.43 and 2.38 for Chla; 0.8391, 0.53 and 2.49 for Chlb; 0.7899, 2.24 and 2.18 for Chls; and 0.7577, 0.27 and 2.03 for Cars, respectively. The combination of these models with the pseudo-color image allowed for a visual inversion of the content and distribution of the pigment. These findings have important implications for guiding pigment distribution, nutrient diagnosis and fertilization decisions in plant growth management.

Performance of Three Boro Rice Varieties Under Different Levels of Nitrogen Application

A field exper iment was carr ied out to study the effect of levels of nitrogen on the performance of three Boro rice varieties e.g. cv. BRRI dhan28, cv BRRI dhan29 and cv. Surjomoni. The experiment comprised four levels of nitrogen viz. 0 kg N ha-1, 60 kg N ha-1, 120 kg N ha-1 and 180 kg N ha- 1 . The experiment was laid out in a randomized complete block design with three replications. The highest grain yield (4.23 t ha-1) was obtained from cv. BRRI dhan29 because of production of the highest number of both total tillers m-2 and effective tillers m-2. BRRI dhan28 produced higher grain yield (3.39 t ha-1) compared to that of Surjomoni (3.07 t ha-1). Application of 120 kg N ha-1 produced the highest grain yield (4.23 t ha-1) because of the production of the highest number of both total tillers m- ' and effective tillers m-2 in the t reatment . Appl icat ion of 180 kg N ha-1 produced the second-highest grain yield (3.70 t ha-1) and 0 kg N ha-1 produced the lowest grain yield (2.76 t ha-1). Interaction between variety and levels of nitrogen significantly influenced all parameters studied except plant height, total tillers hill -1, effective tillers hill-1, non-effective tillers hill-1, length of panicle, number of sterile spikelets panicle-1 and 1000-grain weight. The highest grain yield (4.60 t ha-1) was obtained from BRRI dhan29 with the application of 120 kg N ha-1 and the lowest grain yield (2.40 t ha- 1 ) was obtained f rom the treatment combination of Surjomoni and 0 kg N ha-1. Rice variety BRRI dhan29 can be provided with 120 kg N ha-1 to get the highest and economic production of the crop.
 Vol. 9, No. 3, December 2022: 267-278

Effect of Post-Drought Rehydration on Winter Wheat Fluorescence and Photosynthetic Indices under Different Levels of Nitrogen Application

Studying the response of winter wheat to post-drought rehydration is conducive to understanding the efficient utilization of water-saving technology, such as regulating deficit irrigation and increasing water use efficiency. The controlled condition experiment in the rain shelter was conducted in 2020. The two water stress treatments, including post-drought rehydration at the jointing and heading stages, were combined with high nitrogen (N) (250 kg/hm2), low N (125 kg/hm2), and no N (0 kg/hm2, control). The effects of post-drought rehydration on the relative chlorophyll content (SPAD), major fluorescence parameters, and photosynthetic indexes of winter wheat were determined. The results showed that post-drought rehydration increased the SPAD value, the efficiency of light energy conversion, maximum potential photo-electron transport, and the photosynthetic indices and decreased the photochemical quenching coefficient. Among them, the compensatory effect of rehydration at the heading stage on SPAD, fluorescence parameters, and photosynthetic indexes was more significant (p < 0.05), and the winter wheat needed a recovery process after rehydration. Increased application of N fertilizer can alleviate the effects of water stress on the fluorescence parameters and photosynthetic properties of flag leaf and promote the degree of the response of fluorescence parameters and photosynthetic properties to rehydration. The specific effects were as follows: high N > low N > no N application. As a result, winter wheat had a certain compensatory effect of rehydration after timely drought stress; the compensatory effect of rehydration could be enhanced under the condition of increasing N application.

Nitrogen application and differences in leaf number retained after topping affect the tobacco (Nicotiana tabacum) transcriptome and metabolome

BackgroundAgronomic treatments such as the application of nitrogen fertilizer and topping (removal of the inflorescence and top leaves) cause substantial changes in plant metabolism. To explore these changes, we conducted comparative transcriptomic and metabolomic analyses of leaves collected from four positions along the stem on plants exposed to two nitrogen doses and with different numbers of leaves retained after topping in tobacco (Nicotiana tabacum).ResultsWe identified 13,330 unique differentially expressed genes and 32 differentially abundant metabolites. Through RNA-seq and WGCNA analyze, we constructed 2 co-expression networks (green and blue) highly correlation to N application and leaf number retained, predicted a hub gene NtGER3 may play an important role in N metabolism related to amino acid (cysteine) through CK pathway in tobacco leaves, NtARFs may participated in modulating the auxin signal and N in bottom leaves and NtRAP2.12 as key gene involved in N regulation by ethylene pathway. What’s more, our data prove C/N transformation and balance affect the “source – flow - sink” redistribution and remobilization in tobacco during growth and development process.ConclusionsOverall, this comparative transcriptomics study provides novel insight into the complex molecular mechanisms underlying plant responses to different levels of nitrogen application and the number of leaves remaining after topping in plants.

Response of soil biological properties and bacterial diversity to different levels of nitrogen application in sugarcane fields

To select an eco-friendly nitrogen (N) application level for sugarcane production, soil fertility and soil bacterial diversity under different nitrogen application levels were analyzed. Four levels of urea applications were high Nitrogen (H, 964 kg ha−1), medium Nitrogen (M, 482 kg ha−1), low Nitrogen (L, 96 kg ha−1) and no Nitrogen (CK, 0 kg ha−1) treatments, respectively. The results showed that the soil microbial biomass carbon and phosphorus were altered significantly by CK and L treatments. Moreover, the indexes of soil bacterial richness and diversity in the sugarcane field could be significantly improved by L. At the genus level, SC-I-84, Mycobacterium, Micropepsaceae, Saccharimonadales, Subgroup_2 and Acetobacteraceae were the unique dominant bacteria in the soil with the H treatment. JG30-KF-CM45 and Jatrophihabitans were the unique dominant genera in the M treatment. Subgroup_6, HSB_OF53-F07, Streptomyces, 67–14, SBR1031 and KD4-96 were the unique dominant genera in the L treatment. In contrast, FCPS473, Actinospica, 1921–2, Sinomonas, and Ktedonobacteraceae were the unique dominant genera in the CK treatment. The findings suggest that soil fertility all could be changed by different N application levels, but the most increasing integral effect only could be found in L. Moreover, even though soil bacterial richness could be significantly promoted by the M and H treatments, but soil bacterial diversity could not be significantly improved. On the contrary, soil bacterial diversity and richness all could be improved by L treatment. In addition, higher abundance of unique soil dominant bacteria could be only found in L treatment which compared to the CK, M and H treatments. These findings suggest that the rate of 96 kg ha−1 N application is ecofriendly for sugarcane production in Guangxi.

Effects of nitrogen regulation and strip intercropping on faba bean biomass, nitrogen accumulation and distribution, and interspecific interactions

AbstractEffects of nitrogen fertilization on the accumulation and distribution of biomass and plant nitrogen content in intercropped faba beans, together with its impact on the interspecific interactions between faba bean and wheat has not been well studied. Here, we have used a logistic model to analyze the cropping systems (i.e., monocropped faba bean, monocropped wheat, and faba bean intercropped with wheat) by evaluating the effects of different levels of nitrogen application on the dynamic changes in biomass and nitrogen accumulation, along with the interspecific interaction. Using monocropped and intercropped faba beans in field experiments spanning two years, we found that nitrogen application increased both monocropped and intercropped faba bean yields. The yield of intercropped faba beans was greatest at the lower nitrogen input for two consecutive years. Nitrogen application increased the biomass and nitrogen accumulation in both monocropped and intercropped faba beans. The simulation parameters that increased were maximum nitrogen accumulation (A') and maximum accumulation rate (R'max) while the initial cumulative rate (r') decreased. Compared with monocropping, intercropped faba bean–wheat showed increased yield and biomass accumulation, along with a significantly increased initial growth rate (r) and a maximum instantaneous growth rate (Rmax). Intercropping reduced stem and leaf biomass and the nitrogen distribution ratio while increasing the pod content. In the early intercropped faba bean growth stage, there was no competition for nutrients or any kind of yield advantage, while in the later stages, the nutrient competitiveness of intercropping was stronger than the intraspecific competition, showing the advantages of intercropping on biomass and yield (i.e., relative crowding coefficient [K] >1, relative interspecific competitiveness [RC] >0, and relative competition intensity [RCI] <0). In summary, nitrogen application of 45 kg ha–1 could be the desired amount that maximizes the nutrient competition and interspecific advantages in the middle and late stages of faba bean growth when intercropped, thus contributing to the yield.

Comparative response of some tropical maize hybrid and their parental varieties to low and high nitrogen regime

The study was carried to investigate the differential response of some maize hybrids and their open pollinated parents to low and high nitrogen soil condition. Ten open-pollinated varieties were crossed in a partial diallel fashion to generate 45 F1 hybrids during the 2011 cropping season at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. The 45 F1 hybrids and the ten parents were evaluated in four environments at Mokwa and Zaria in August, 2012 under high and low N conditions with two different levels of nitrogen application (30kgha-1 and 90kgha-1) respectively.Hybrids recorded shorter plant height under the two different nitrogen fertilizer conditions compare with open pollinated parents. Thus the hybrids are better for mechanical harvesting. Taller ear height was observed among the hybrids compare with the open pollinated parents; rate of stem and root lodging were consequently higher among the hybrids. Hybrid had better husk cover under both nitrogen fertilizer regime; that's they will be less susceptible to insect and animal attack.Mean difference of ear per plant between the maize hybrids and open pollinated parents was not significant. Significant difference was observed between maize hybrids and their parents for grain yield under low and high fertilizer regimes. That the hybrids had higher grain yield under both nitrogen fertilizer regime; indicates the tolerance of maize hybrid to low-N condition than the parental varieties. Low-N environment seemed to favor shorter day to silk for maize hybrid, however, high nitrogen soil condition appeared to increase day to silk. It is an evidence that flowering and consequently maturity time is delayed under favorable nitrogen soil environments.Days to 50% pollen shed are significantly different among the maize hybrids and their parents. The maize hybrids attained day to pollen earlier than the parents under both fertilizer regime. It is an indication that setting of maize grain occur earlier among hybrids than their open pollinated parents.

Influence of different rice establishment methods and nutrient levels on soil enzyme activity, nutrient status and grain yield of rice in North Coastal Zone of Andhra Pradesh

To enhance productivity, alleviate environmental and management constraints and enhance farmers' income in the rice, new approaches that are labour-saving, more productive and sustainable need to be developed. Experiment was formulated to know the impact/influence of different rice establishment methods and different levels of nitrogen application on soil and crop productivity of rice. Results revealed that, among different rice establishment systems, machine transplanting recorded significantly higher yields followed by SRI method. Lowest yields were recorded in dry seed broadcasting method. With increasing nitrogen levels, yields were increased in all the systems and further enhancement of rice yields were observed with potassium nitrate foliar spray along with chemical fertilizers. Soil enzyme activity particularly urease and dehydrogenase was significantly high under normal planting and SRI method of planting, respectively and lowest enzyme activities were recorded in broadcasting of dry seed. Soil organic carbon content also followed the same trend as like enzyme activity. With regard to soil nutrient status, significant differences were not observed in phosphorus and potassium, however available nitrogen status was increased with increasing fertilizer levels and among different methods, drum seeding recorded highest status (286 kg ha-1).

Chemical Composition of Essential Oil from Flower Heads of Arnica Chamissonis Less. under a Nitrogen Impact.

Chamisso arnica (Arnica chamissonis Less.) is a valuable plant species used in the pharmaceutical industry due to the content of many pharmacologically active substances and the similarity of its chemical composition to that of Arnica montana—a medicinal plant commonly used in pharmacy and cosmetics. The similarity of the two plant species implies that chamisso arnica can be a pharmaceutical substitute for the mountain arnica, i.e., an endangered and endemic plant species in Europe. Chamisso arnica extracts exhibit anti-inflammatory and antiradical activity and possesses high antioxidant properties that might be helpful in preventing or delaying the progress of free radical dependent diseases. The attributes of A. chamissonis are mainly related to the content and chemical composition of essential oil. Therefore, the objective of this study was to characterize the chemical composition of essential oil derived from A. chamissonis flower heads under a nitrogen impact. The experiment was performed on experimental fields in mid-eastern Poland on two soil types (sandy and loamy soils). The nitrogen fertilizer was applied as ammonium sulfate (control, 30, 60, 90, and 120 kg N ha−1). Collection of flower heads was carried out in the full flowering phase, which was characterized by the highest content of essential oil. The chemical composition of essential oil was examined using GC-MS. Among the 75 ingredients of the volatile oil of chamisso arnica flower heads, alpha-pinene, cumene, p-cymene, germacrene D, spathulenol, decanal, caryophyllene oxide, beta-pinene, and benzene acetaldehyde were present at relatively high levels. Both the nitrogen application and the soil type had an effect on the oil concentration and the yield of the main constituents (alpha-pinene and germacrene D) with pharmacological value. Different levels of nitrogen application could be considered as a relevant way to modify the chemical composition and to increase the essential oil production.

Effects of nitrogen level on the physicochemical properties of Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) starch.

Nitrogen is an essential nutrient for Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) because this substance affects the yield and quality of Tartary buckwheat. The physicochemical characteristics of starch represent the important parameters of Tartary buckwheat quality. The effects of different levels of nitrogen application at different levels (0, 45, 135 and 225kg/ha in 2015 and 0, 90, 180 and 270kg/ha in 2017) on the physicochemical characteristics of Tartary buckwheat starch were studied. The amylose content, particle size and retrogradation of Tartary buckwheat starch with nitrogen were lower than those of without nitrogen. The structure complexity, pasting temperature, gelatinization enthalpy, relative crystallinity, light transmittance and solubility of the former were higher than those of the latter. Nitrogen application did not change the 'A'-type crystalline pattern of Tartary buckwheat starch. This study indicated that nitrogen level and years and the interactions among nitrogen fertilizer levels and years significantly affected the physicochemical properties of Tartary buckwheat starch. These integrated results also provided information about the management of fertilization conditions to obtain starches with special properties for applications in food or nonfood industries.

Influence of different nitrogen application on flour properties, gluten properties by HPLC and end-use quality of Korean wheat

This study was performed to identify how the different levels of nitrogen application affected the variances of gluten properties and end-use qualities and the differences of variances among Korean wheat cultivars. Protein and dry gluten content, SDS sedimentation volume and water absorption of Mixolab increased as nitrogen application increased. This ratio of the increase was higher in Korean wheat cultivars for bread than in Korean wheat cultivars for noodles and cookies. The proportion of (α+β)-gliadin measured by reversed-phase high-performance liquid chromatography (RP-HPLC) increased, but the proportion of ω- and γ-gliadin decreased as the protein content increased. The Korean wheat cultivars for bread showed a high proportion of (α+β)-gliadin increase, the Korean cultivars for noodles had a high proportion of γ-gliadin decrease and the Korean wheat cultivars for cookies had a high proportion of ω-gliadin decrease. However, there was no variation of the component in the proportion of glutenin component measured by RP-HPLC, even though the protein content was increased, but all of the protein fractions measured by size exclusion (SE)-HPLC were increased. The soluble monomeric protein showed a high proportion of Korean wheat cultivars for bread by the increase of protein content. Bread loaf volume increased by the increase of protein content but there were no variances in the ratio of increase among Korean wheat cultivars. The cookie diameter decreased with the increase of protein content, and this ratio of decrease was the highest in Korean wheat cultivars for cookies. The hardness of cooked noodles also increased by the increase of protein content but there were no variations in springiness and cohesiveness. The decrease proportion of ω-gliadin affected the increase of bread loaf volume, the hardness of cooked noodles, and the decrease of cookie diameter.

Non-invasive spectral detection of the beneficial effects of Bradyrhizobium spp. and plant growth-promoting rhizobacteria under different levels of nitrogen application on the biomass, nitrogen status, and yield of peanut cultivars

ABSTRACT High-throughput phenotyping using spectral reflectance measurements offers the potential to provide more information for making better-informed management decisions at the crop canopy level in real time. The aim of this study was to investigate the suitability of hyperspectral reflectance measurements of the crop canopy for the assessment of biomass, nitrogen concentration, nitrogen uptake, relative chlorophyll contents, and yield in 2 peanut cultivars, Giza 5 and Giza 6. Peanuts were grown under field conditions and subjected to 3 doses of nitrogen fertilizer with or without the application of 2 bio-fertilizers, Bradyrhizobium spp. or plant growth-promoting rhizobacteria. Simple linear regression of normalized difference spectral indices and partial least square regression (PLSR) were employed to develop predictive models to estimate the measured parameters. The tested spectral reflectance indices were significantly related to all measured parameters with R2 of up to 0.89. The spectral reflectance index values differed at the same level of nitrogen fertilizer, as well as among the 3 levels of nitrogen fertilizer application for inoculation with Bradyrhizobium and co-inoculation with Bradyrhizobium and plant growth-promoting rhizobacteria. The calibration models of PLSR data analysis further improved the results, with R2 values reaching 0.95. The overall results of this study indicate that hyperspectral reflectance measurements monitoring peanut plants enable rapid and non-destructive assessment of biomass, nitrogen status, and yield parameters of peanut cultivars subjected to various agronomic treatments.

Role of nitrogen-responsive plant-type phosphoenolpyruvate carboxylase in the accumulation of seed storage protein in ancient wheat (spelt and kamut)

ABSTRACTAncient wheat such as Triticum spelta L. and T. turanicum is a possible genetic material for improving wheat seed quality due to its grain characteristics, which differ from those of common wheat. Ancient wheat grains accumulate proteins with fewer allergens and higher levels of essential amino acids, antioxidants, minerals and vitamins. The identification of a genetic factor that controls seed protein content would be useful for breeding wheat varieties in accordance with various purposes. Previous studies implied that phosphoenolpyruvate carboxylase (PEPC) is involved in nitrogen accumulation in crop seeds. However, multiple types of PEPC genes are present in plant genomes, and it has still not been clarified yet which type of PEPC is relevant to seed nitrogen metabolism. In this study, to determine which PEPC is involved in seed protein accumulation in ancient wheat, we examined the effects of different levels of nitrogen application at the flowering stage on PEPC activity on developing seeds and on the protein content in mature seeds of three ancient wheat varieties. The responses of the PEPC activity and seed protein content were observed, but their patterns differed among the varieties. Among the experimental plots, PEPC activity and seed protein content showed a high correlation (r = 0.757, p value = 1.09E−3). Immunoblot analysis revealed that plant-type PEPC seemed to underlie the response of PEPC activity to nitrogen application, while no bacterial-type PEPC was detected by a peptide-antigen antibody. These results indicate that plant-type PEPC plays an important role in storage protein accumulation in ancient wheat seeds under nitrogen application at the flowering stage.Abbreviations: PEPC, phosphoenolpyruvate carboxylase; 2-ME, 2-mercapto ethanol; EDTA, ethylenediaminetetraacetic acid; DAF, days after flowering; SDS-PAGE, sodium dodecylsulfate-polyacrylamide gel electrophoresis.

Expressed sequence tags related to nitrogen metabolism in maize inoculated with Azospirillum brasilense.

The relative quantitative real-time expression of two expressed sequence tags (ESTs) codifying for key enzymes in nitrogen metabolism in maize, nitrate reductase (ZmNR), and glutamine synthetase (ZmGln1-3) was performed for genotypes inoculated with Azospirillum brasilense. Two commercial single-cross hybrids (AG7098 and 2B707) and two experimental synthetic varieties (V2 and V4) were raised under controlled greenhouse conditions, in six treatment groups corresponding to different forms of inoculation and different levels of nitrogen application by top-dressing. The genotypes presented distinct responses to inoculation with A. brasilense. Increases in the expression of ZmNR were observed for the hybrids, while V4 only displayed a greater level of expression when the plants received nitrogenous fertilization by top-dressing and there was no inoculation. The expression of the ZmGln1-3EST was induced by A. brasilense in the hybrids and the variety V4. In contrast, the variety V2 did not respond to inoculation.

Nitrogen fixating ability of mungbean genotypes under different levels of nitrogen application

A pot culture experiment was conducted at the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur during kharif II, 2012 to evaluate the nodulation, biological nitrogen fixation and yield potential of genotypes of mungbean under varying levels of N application. There were 10 mungbean genotypes viz. IPSA 12, GK 27, IPSA 3, IPSA 5, ACC12890055, GK 63, ACC12890053, BU mug 4, BARI Mung 6 and Binamoog 5, each genotype treated with six levels of N (0, 20, 40, 60, 80 and 100 kg N ha-1) . Among the genotypes, the IPSA 12 at 40 kg N ha-1 produced the maximum number of nodules (14.54 plant-1) as well as the highest nitrogen fixation (2.684 mmol C2H4). This resulted in the highest seed yield (14.22 g plant-1). The genotype ACC12890053 recorded the lowest nodulation (6 plant-1), nitrogen fixation (1.134) and seed yield (7.33 g plant-1).Bangladesh J. Agril. Res. 41(1): 163-171, March 2016

Response of walnut aphid populations to increasing foliar nitrogen content

An understanding of how fertilizer input affects pest populations and, consequently, the need for pesticide use would allow for the development of more effective integrated management strategies. 2 The present study addressed the response of walnut aphid Chromaphis juglandicola (Kaltenbach) (Hemiptera: Aphididae) populations to different levels of nitrogen application to walnut seedlings and the relationship between aphid density and chlorophyll content index (CCI), a non-invasive measure of foliar nitrogen, for mature trees in commercial walnut orchards. 3 Although added nitrogen significantly increased soluble nitrogen content, CCI and soluble nitrogen : phosphorus ratios in the foliage of walnut seedlings, there was no effect on walnut aphid population growth. Similarly, there was no relationship between aphid density and CCI for mature trees in the field. 4 A neutral response suggests that walnut aphid population growth on potted seedlings is limited by factors other than soluble nitrogen, such as other nutrients, amino acid composition or defensive compounds. Consequently, fertilizer management appears unlikely to effectively contribute to the control of

Alleviation of drought stress effects on winter wheat production with nitrogen fertilization

In order to evaluation the effects of drought stress and nitrogen application on wheat yield and its components, a field experiment was organized in split split plot based on Randomized Complete Block Design with three replications at 2008-2010 in the research field of Karaj, Iran. Treatment included: two wheat cultivars (Gascogne and MV-17), three levels of nitrogen (0, 75 and 150 kg N ha -1 ), and three levels of withholding irrigation (I1: regular irrigation in total growth stages, I2: withholding irrigation at anthesis stage, and I3: withholding irrigation at seed filling period stage). Based on results, water deficit at anthesis time reduce seed number per spike and at seed filling period decrease seed weight. With nitrogen application, number of grain per spike increased 1.9% and 7.1% in 75 and 150 kg N ha-1 respectively. Withholding irrigation at anthesis caused that grain yield was declined from 8392.0 kg ha-1 to 7173.5 kg ha-1 compared with control treatment. Moreover, with 150 kg N ha -1 compared with check treatment, biological yield increased up to 28.0%. Also, harvest index was affected more by irrigation treatments than different levels of nitrogen application.

Effect of nitrogen application on growth, yield and oil contents of Fennel ( Foenoculum vulgare Mill.)

Fennel is used in pharmaceutical, preparation of various dishes, confectionaries and cosmetic products in Pakistan. Therefore, there is a dire need to know optimum nitrogen level for higher seed yield and oil contents of fennel. Field studies pertaining to the effects of different levels of nitrogen viz., 0, 30, 45, 60, 75, 90, 105 and 120 kg ha-1 on growth, seed yield and oil contents of fennel were carried out at the Agronomic Research Area, University of Agriculture, Faisalabad, during two consecutive years 2006 to 2007 and 2007 to 2008. Seed yield and yield components were influenced significantly by different levels of nitrogen application. The treatments of 90 kg N ha-1 produced higher seed yield but it was statistically similar to 105 and 120 kg N ha-1. The increase in yield was mainly due to greater plant height, umbels per plant, seeds per umbel and 1000-seed weight. The nitrogen application at the rate of 90 kg ha-1 seems to be the economical dose for fennel under agro-climatic conditions of Faisalabad.

Yield Response of Upland NERICAs under Rain-fed Upland Conditions with Different Levels of Nitrogen Application

NERICAs (New Rice for Africa), new genotypes produced from the interspecific hybridization of Oryza sativa and O. glaberrima, have been bred in an attempt to improve the yield potential of rice cultivars adapted to resource-limited conditions in Africa. Identification of physiological traits responsible for their high-yielding potential under such conditions should be useful for rice-breeding programs to be employed not only in Africa but in other regions where rice production is being undertaken under low input conditions. In a series of experiments, we evaluated the growth and yield performance of upland NERICAs under rain-fed upland conditions with two levels of nitrogen application in comparison with Japanese elite rice cultivars, and attempted to identify the physiological traits responsible for the superior yield, if any. The upland NERICAs (NERICA 1 and NERICA 5) exhibited greater biomass production and yield than Japanese cultivars. The NERICAs also showed a higher rate of transpiration and exudation during the ripening stage, compared with elite Japanese cultivars. These results suggested that the greater water uptake ability of NERICAs appeared to be associated with their high N uptake capability, leading to greater biomass production and yield under water- and N-limited ecosystems. Further studies are needed to identify the specific root morphology involved in the water uptake ability of NERICAs.