Nitrogen nutrition index, chlorophyll leaf concentration Essay
Barley ( Hordeum vulgare L. ) is one of the most of import cereals worldwide and is being progressively grown in many countries of the universe. However, there is limited comparative research of the different works based methods for N measuring N position of the harvest such Nitrogen Nutrition Index ( NNI ) and chlorophyll metre ( CM ) readings and its relationship with Nitrogen Use Efficiency ( NUE ) on barley. A biennial field survey was hence conducted with the aim to find the consequence of N fertilisation ( 0, 60, and 120 kilograms ha-1 ) on CM readings, NNI and NUE and its constituents of four barley cultivars. CM readings and RCM readings were affected by the N intervention and were higher at both N degrees compared with the control. N nutrition index varied from 0.75 to 1.03 across old ages, growing phase and cultivar and was affected by the fertilisation degree. NUE was higher at the control compared with the two N degrees and was correlated with grain output and negatively correlated with N shoot concentration, NNI, and CM readings. This survey provides new information about the consequence of N application on chlorophyll metre readings, comparative chlorophyll metre readings, NNI, and NUE of barley that can be used for obtaining higher grain output.
Barley ( Hordeum vulgare L. ) is one of the chief cereals that is grown in many countries of the universe making 54 million hectares and entire production of 150 million Mg ( FAO 2011 ) . However, there is a deficiency of information about the usage of diagnostic tools for alimentary demands for barley and particularly on N which is one of the most of import foods required for higher grain output. Efficient usage of applied N is besides of import in barley for higher production and in order to maximise manufacturer ‘s economic returns and keep dirt and H2O quality. Several diagnostic tools have been developed in order to find N lack which is used to better N direction and diminish the hazard of N loss to land and surface Waterss ( Lemaire et al. 2008 ; Fageria and Baligar 2005 ) .
The plant-based diagnostic methods that were developed such as chlorophyll metres ( CM ) are rather utile since they provide a valuable appraisal of the N position of the harvest ( Lemaire et al. 2008 ; Lemaire and Gastal 2009 ) . However, CM readings remain one of the most popular attacks and have been proven to be effectual as a rapid diagnostic method to find the N position of many harvests, including spring wheat ( Triticum aestivum L. ) ( Follett et al. 1992 ; Vidal et al. 1999 ; Arregui et Al. 2006A ; Ziadi et Al. 2010 ) , rice ( Oryza sativa L. ) ( Turner and Jund 1991 ; Peng et Al. 1993 ; Ladha et Al. 1998 ) , safflower ( Carthamus tinctorius L. ) ( Dordas and Sioulas 2008 ) , and maize ( Zea mays L. ) ( Piekielek and Fox 1992 ; Dordas et Al. 2008 ; Ziadi et Al. 2008 ) . The consequences were based on the relationship between CM readings and comparative grain output ( RY ) ( Piekielek and Fox, 1992 ; Blackmer and Schepers, 1994 ; Fox et al. , 2001 ) . However, this relationship can change with works development and is lower at the vegetive phase ( Blackmer and Schepers 1995 ; Waskom et Al. 1996 ; Bullock and Anderson 1998 ) and higher at the ulterior developmental phases ( Blackmer and Schepers 1995 ; Smeal and Zhang 1994 ; Piekielek et Al. 1995 ; Waskom et Al. 1996 ; Bullock and Anderson 1998 ) . Besides CM readings have the disadvantages that they depend on cultivar, direction techniques, site features, disease or insect harm, works denseness, and other alimentary lacks ( Blackmer and Schepers 1995 ; Piekielek et Al. 1995 ; Waskom et al. , 1996 ) and this created the demand to happen a more stable diagnostic tool. Therefore, the comparative CM readings ( RCM ) have been proposed and was found to account for the influence of these factors ( Ziadi et al. 2008 ; Debaeke et Al. 2006 ; Prost and Jeuffrey 2007 ) . The RCM readings are calculated by spliting the readings from the trial country by the readings from a saturated secret plan that has received a high N rate.
Another attack has been proposed which is used to find the degree of works N nutrition is the N nutrition index ( NNI ) ( Prost and Jeuffroy 2007 ; Debaeke et Al. 2006 ; Dordas, 2011 ) . NNI can be calculated by spliting the existent N concentration by the critical N concentration ( Nc ) . The critical N concentration is defined as the minimal N concentration in the shoot biomass required for maximal growing rate, has been established for barley Justes et Al. ( 1994 ; Nc = 5.35 A- Wa?’0.442 where W is the entire shoot biomass expressed in Mg DM haa?’1 ) . The NNI is considered a mention tool for measuring works N position. However, NNI has a major restriction at the farm degree there is a demand to find the existent harvest biomass and its N concentration at different growing phases which rather hard in some instances and there is a demand to simplify the rating of harvest N position with a quicker method of gauging NNI is needed. That ‘s why chlorophyll measurings have been proposed as an alternate tool for gauging the harvest N position. There are surveies which showed that although CM and RCM readings were related to NNI, but they did non supply a valid and robust appraisal of the works N position because the relationships of CM and RCM readings with NNI varied with sites and old ages ( Ziadi et al. 2008 ) . In add-on, CM, RCM, and NNI were non used in barley to find the N position of the harvest and besides their relationship to NUE.
The I? diagnostic tools that were developed chiefly to optimize grain output. However, the jobs of the sustainability of agribusiness both from the environmental and the economic points of position require a reconsideration of these factors when ciphering fertilizer demands and particularly N fertilisers as they are responsible for an of import portion of agribusiness related pollution through leaching or denitrification ( Fageria and Baligar 2005 ) . This involves modifying these diagnostic tools and the determination regulations, which are decided on the footing of empirical databases. Therefore, limited pollution hazards could be achieved either with low fertilizer rates or cultivars that better absorb and utilize N ( Marino et al. 2004 ) . Refering N, high gross should be obtained with a maximal output and quality per unit of N applied. Plant engendering programmes must bring forth assortments that absorb N more expeditiously and utilize it more expeditiously to bring forth grain ( Moll et al. 1982 ; Dhugga and Waines 1989 ) . Field experiments have shown that familial variableness for N uptake exists in little grains ( Loffler et al. 1985 ; Van Sanford and MacKown 1986 ; Moll et Al. 1982 ; Dhugga and Waines 1989 ) . This information can be used by the agriculturists for following the appropriate cultural patterns and besides by the breeders for taking the most efficient choice standards in order to better N development. However, such information is limited for barley.
The chief aims of this survey were: ( I ) to set up the relationship between CM and RCM readings and NNI for barley and ( two ) to compare both methods as diagnostic tools for foretelling output response to N fertilisation, ( three ) to find NUE and its constituents N use efficiency and N uptake efficiency utilizing different barley cultivars.
2. Materials and methods
2.1 Experimental site, cropping history and apparatus
Field experiments were conducted at the experimental farm of the Aristotle University of Thessaloniki in northern Greece ( 22o59’6.17 ” Tocopherol, 40o32’9.32 ” N ) during the 2003-2004 and 2004-2005 turning seasons ( referred afterlife as 2004 and 2005 severally ) . The different cultivars that were used to compare the different diagnostic tools for barley and NUE were as follows: Carina ( a late-flowering cultivar used for malting ) , Thessaloniki ( an early-flowering cultivar ) , Konstantinos ( a late-flowering cultivar ) , and Mucho ( an early-flowering cultivar and the lone 1 that was six-rowed ) . The pick of the different rhythm cultivars was selected to find how the blossoming day of the month and other features can impact chlorophyll metre and comparative chlorophyll metre readings, NNI, and NUE. The different cultivars were chosen in order to hold cultivars with different blooming day of the month, different use and besides to hold a two row and six row cultivars. The dirt type where the experiment took topographic point was a chalky sandy loam ( Typic Xerorthent ) , and the dirt was sampled pre-planting at a deepness of 30 centimeters and before the application of the fertilisers. The dirt contained 7.2 g kg-1 organic affair, 60 kg ha-1 of N-NO3, 26 kg ha-1 of P, and 198 kg ha-1 of exchangeable K and had a pH of 7.96 ( 1:2 H2O ) . The dirt features were determined harmonizing to methods detailed by Sparks et Al. ( 1996 ) . The predating harvest was durum wheat ( Triticum turgidum subsp. durum L. ) . Weather informations ( i.e. , rainfall, upper limit, lower limit, and mean temperatures ) were recorded daily in the experimental country ( 20 m off from the experimental site ) and are given in Table 1 ( reported as average monthly informations for the two old ages of the survey ) together with the thirty-year norms for temperature and rainfall. During 2004, the spring was rather mild and there was more rainfall during the summer. In contrast, 2005 was warm during the spring and there was less rainfall during the spring ( Table 1 ) .
2.2 Crop direction and experimental design
The experimental design was split-split secret plan with the cultivars as the chief secret plans, the fertiliser interventions as the split secret plan and the source-sink interventions as the split-split secret plans with five reproductions. The experimental secret plans were 3 by 5 metres. The interventions were as follows: 0, 60, and 120 kilograms N ha-1 were applied ( pre-planting ) in the signifier of ( NH4 ) 2SO4 ( N-P-K, 20.5-0-0 ) . In add-on, P and K were applied at a rate of 60 kg ha-1 and 100 kilograms ha-1 ( pre-planting ) in the signifier of superphosphate and K2SO4, severally and were incorporated in the dirt before sowing.
The fertiliser was incorporated with a tandem harrow phonograph record to a deepness of 12-15 centimeter after application. Barley cultivars were sown on 10th of December 2003 and 5th of December 2004 at a rate of 200 kilograms ha-1 which corresponds to a rate of 370 seeds m-2 with a commercial seeder. Plants were grown without auxiliary irrigation in both the turning seasons. The harvest was unbroken free of weeds by manus hoeing when necessary.
2.3 Dry affair, N and grain quality features
The undermentioned variables were determined: entire aboveground biomass and chlorophyll content at blossoming ( Zadoks growing phase 65 ) , and at harvest ( Zadoks growing phase 95 ) ( Zadoks et al. 1974 ) . At each sampling, 2 m rows were indiscriminately selected and dried at 80oC until they reached a changeless weight. The dry vegetative samples were first land in a cock factory and so reground finely utilizing a 1 millimeter screen. N content was determined by the Kjeldhal method ( Dordas and Sioulas 2009 ) .
One 1000 grain weight ( TGW ) was determined by mensurating the weight of 100 seeds from each secret plan and multiplying by 10 in order to show one thousand seed weight. Grain weight per unit volume ( kg m-3 ) was determined by mensurating the weight of 0.5 cubic decimeter of grains from each secret plan. Seed protein content was determined by multiplying by 6.25 the seed N concentration and protein output was determined by multiplying the seed output by the seed protein content. Seed output was determined by reaping the five cardinal rows with a research secret plan combine ( Wintersteiger AG, Austria ) in the last hebdomad of June in both old ages. Relative outputs at each secret plan were computed as the ratio of seed output at a given N rate by the highest seed output among all N interventions.
2.4 Chlorophyll measurings
Chlorophyll metre readings were taken with a handheld dual-wavelength metre ( SPAD 502, Chlorophyll metre, Minolta Camera Co. , Ltd. , Japan ) . For each secret plan the 20 youngest to the full expanded foliages per secret plan were used when the workss were at blossoming ( Zadoks growing phase 65 ) , at milk phase ( Zadoks growing phase 75 ) and at soft dough phase ( Zadoks growing phase 85 ) ( Zadoks et al. 1974 ) . The instrument stored and automatically averaged these readings to bring forth one reading per secret plan. Relative chlorophyll metre ( RCM ) readings were calculated by spliting any SPAD reading by the maximum value from the 120 kilogram N ha-1. This index, runing from 0.5 to 1, is besides called the sufficiency index ( Varvel et al. 1997 ) .
2.5 Nitrogen Nutrition Index
The Nitrogen Nutrition Index ( NNI ) of the harvest at each trying day of the month was determined by spliting the N concentration of the shoot biomass by the critical N concentration ( Nc ) ( Ziadi et al. 2008 ) . Critical N concentration, the minimal N concentration required to accomplish maximal shoot growing, was defined as a map of shoot biomass as proposed for barley by Justes et Al. ( 1994 ; Nc = 5.35 A- Wa?’0.442 where W is the entire shoot biomass expressed in Mg DM haa?’1 ) .
2.6 Nitrogen efficiency and its constituents
Nitrogen usage efficiency was defined as grain production per unit of N available in the dirt. Nitrogen usage efficiency is Gw/Ns ( kg kg-1 ) in which Gw is the grain weight and Ns is N supply expressed in the same units ( e.g. kg ha-1 ) . Ns was calculated from the dirt N concentration and N applied rate. There are two primary constituents of N usage efficiency ( 1 ) N uptake efficiency ( Nt/Ns ) ( kg kg-1 ) and ( 2 ) N use efficiency ( kg kg-1 ) which describes how the N that is absorbed is utilized to bring forth grains ( Gw/Nt ) , where Nt is the entire N in the works at adulthood. Therefore the N usage efficiency can follow the equation:
Gw/Ns= ( Nt/Ns ) ( Gw/Nt )
The look can be expanded to include extra factors. For illustration, N uptake during grain filling and translocation of N to grain.
Gw/Ns= ( Nt/Ns ) ( Gw/Ng ) ( Na/Nt ) ( Ng/Na )
where Gw/Ng=grain produced per unit of grain N
Ng/Nt=fraction of entire N that is translocated to grain
Na/Nt=fraction of entire N that is accumulated after blossoming
Ng/Na=ratio of N translocated to grain to N accumulated after blossoming.
where Ng is the N consumption by grains and Na is the N consumption after blossoming.
2.7 Component analysis
Assorted looks were constructed and analyzed harmonizing to the method suggested by Moll et Al. ( 1982 ) and Dhugga and Waines ( 1989 ) . The analysis involves linearising the multiplicative relationships by taking logs and so finding the part of each constituent trait to the amount of squares of the attendant trait. The amount of cross merchandises of each constituent trait by the attendant trait ( i?“xiyi ) divided by the amount of squares of the attendant trait ( i?“yi2 ) gives the comparative part of each constituent variable to resultant variable. This analysis describes the net part of each constituent variable both straight and indirectly through the other variable ( Moll et al. 1982 ) . The undermentioned looks were analyzed:
log ( N usage efficiency ( Grainw/Ns ) ) = log ( Uptake efficiency ( Nt/Ns ) ) + log ( Utilization efficiency ( Grainw/Nt ) )
log ( protein output ) = log ( grain output ) + log ( grain N concentration )
The informations were analyzed by the ANOVA method harmonizing to a 2A-3A-4 factorial design ( Turning season A- N degrees A- Cultivars ) with 5 reproductions per intervention combination. More specifically, the experiment was set up as a Randomized Complete Block Design for the Cultivars ( chief secret plans ) , and N degrees as split secret plans. A combined analysis over Turning season was carried out harmonizing to the aforementioned design Steel et Al. ( 1997 ) . Tukey ‘s station hoc process was used for proving the differences between intervention agencies. The significance degree of all hypotheses proving was preset at P & lt ; 0.05. All statistical analyses were performed utilizing the SPSS ver. 17 package bundle ( SPSS Inc. , USA, IL: Chicago ) .
Cultivars affected most of the features that were studied except from the N concentration at harvest, seed protein content and fraction of entire N that is accumulated after blossoming ( Table 2 ) . Besides N degrees affected most of the features that were studied except from the grain volume, the fraction of entire N that is translocated to grain, the fraction of entire N that is accumulated after blossoming, and the ratio of N translocated to grain N accumulated after blossoming. Turning season affected most of the features that were studied except from the TGW, CM readings at blossoming and at milk growing phase and the several RCM readings and the fraction of entire N that is accumulated after blossoming. The interaction between the cultivars and interventions were important in the grain volume, the CM readings at blossoming, milk growing phase, and soft dough growing phase and besides at the N usage efficiency, N uptake efficiency and ratio of N translocated to grain to N accumulated after blossoming. The interaction between the turning season and interventions were important in protein output, grain and comparative grain output, the CM and RCM readings at blossoming, at milk phase and at soft dough phase, the N usage efficiency and its constituents. The interaction between the cultivars and turning season were important in most features and except from N concentration at crop, the grain protein content, and grain produced per unit of grain N. The interaction among cultivars, interventions, and turning season were important at the CM and RCM readings at blossoming, at milk phase and at soft dough phase and besides grain volume ( Table 2 ) . Therefore, these features are presented in greater item, whereas the remainder of the features where there is no interaction among the interventions, old ages, and cultivars merely the chief effects are presented.
3.1 Nitrogen concentration and NNI
Nitrogen concentration at blossoming was affected by the cultivar at blossoming but it was non affected by the cultivar at crop ( Table 3 ) . N fertilisation affected N concentration at both growing phases and was higher by an norm of 8 % at both growing phases. Besides N concentration was higher during 2005 due to take down dry affair and growing. N concentration in barley workss was non different between the applied N rates but it was different between the control and 120 kilograms N ha-1.
Nitrogen nutrition indices varied from 0.75 to 1.03 across turning season, growing phase, interventions, and cultivar and was affected by the fertilisation degree ( Table 3 ) . Valuess of NNI a‰? 1.0 indicate that N supply to the harvest is nonlimiting or in extra, while values of NNI & lt ; 1.0 indicate N lack. NNI was higher at Thessaloniki and lower at Konstantinos at harvest and at blossoming it was higher at Much and lower at Konstantinos and Carina. NNI was by and large significantly affected by N fertilisation as at blossoming NNI were higher by an norm of 23 % at the fertilisation interventions compared with the control and besides NNI was higher during the 2005 than the 2004. However, this tendency was changed at crop as NNI was higher during 2004 compared with 2005.
3.2 Grain output, comparative grain output, and grain quality features
Grain output was higher at Thessaloniki and Mucho and followed by Carina and Konstantinos. Besides grain output was increased with N fertilisation in the three cultivars by an norm of 27 % ( Table 4 ) . Besides grain output was higher during the first twelvemonth due to the better conditions conditions. Relative grain output was lower at Carina and Konstantinos cultivars and higher at Thessaloniki cultivar and ranged between 0.74 to 1.0. Relative grain output was increased by 26 % with N fertilisation compared with the control. Besides at 2004 the comparative grain output was 0.90 and was lower during the 2nd twelvemonth which was 0.84.
Grain protein content was non affected by the cultivar but was affected by the N degree and turning season. In peculiar, grain protein content was higher by an norm of 6 % at the N degrees compared with the control and there was no difference between the two N rates. Besides it was higher during the 2004 turning season compared with the 2005. A somewhat different tendency was found at the protein output as it was lower in Konstantinos and Carina due possible to the lower grain output and higher at the other two cultivars ( Thessaloniki and Mucho ) ( Table 4 ) . Besides there was an addition at the protein output with N application and was higher during 2004 compared with the 2005 turning season. Grain volume was higher at Thessaloniki and Mucho two cultivars that were early blossoming and was followed by Konstantinos and the last 1 was Carina ( Figure 1 ) . However, the N degree did non impact the grain volume and besides the turning season ( Table 2 ) . TGW was lower at Carina and Konstantinos cultivars and higher at Thessaloniki and Mucho ( Table 4 ) . Besides TGW was higher at the N fertilisation degree and was non affected by the turning season ( Table 4 ) .
3.3 Chlorophyll and comparative chlorophyll metre readings
Chlorophyll metre ( CM ) readings were affected by the N interventions and were higher at both N degrees compared with the control ( Figure 2 ) . The same tendency was observed during the 2nd twelvemonth. At blossoming, CM readings were higher by an norm of 15 % in the fertilized interventions compared with the control. At milk growing phase, there were important differences between the control and the N interventions particularly during the first twelvemonth, where the chlorophyll degree was by 22 % higher compared with the control. RCM readings were higher at the fertilisation interventions compared with the control and were in the scope of 0.76 to 1.00. At blossoming, RCM readings were higher by an norm of 24 % in the fertilized interventions compared with the control. At soft dough phase, there were important differences between the control and the N interventions particularly during the first twelvemonth, where the RCM degree was by 22 % higher compared with the control ( Figure 3 ) .
3.4 Nitrogen efficiency and its constituents
Nitrogen usage efficiency and its constituents N uptake efficiency and N use efficiency were affected by N fertilisation, turning season, and cultivars. N usage efficiency, N uptake efficiency, and N use efficiency was higher at the control compared with the two fertilisation interventions ( Table 5 ) . Thessaloniki had higher N uptake efficiency at both N degrees, while Konstantinos had the lowest and it was in the scope from 0.67 to 1.14. Konstantinos had highest N use efficiency compared with Thessaloniki and Carina. N utilisation efficiency ranged from 26.87 to 41.14 kilograms kg-1 N. The fraction of entire N that was translocated to grain ( Ng/Nt ) was affected merely by the cultivar and turning season and was higher in Thessaloniki compared with the other cultivars and besides it was higher during 2005 compared with the 2004 ( Table 5 ) . The fraction of entire N that was accumulated after blossoming was higher at Carina ( a tardily blossoming cultivar ) compared with the Thessaloniki cultivar ( an early blossoming cultivar ) . Besides it was higher at the control compared with the 120 kilogram N ha-1 and was higher during 2005 than in 2004. The ratio of N translocated to grain to N accumulated after blossoming ( Ng/Na ) was higher at the Thessaloniki and lower at the Carina cultivar and it was higher during the 2005 turning season compared with the 2004. Grains produced per unit of grain N were higher at the Mucho and Carina compared with the other two cultivars. In add-on, grains produced per unit of grain N were higher at the control compared with the other two interventions and besides during the 2004 compared with the 2005.
3.5 Component analysis of the different traits.
The comparative parts of N usage efficiency constituents are presented in Table 6. N utilization efficiency accounted for more of the fluctuation of N usage efficiency than the N uptake efficiency and was higher at the 0 kilogram N ha-1 than two N degrees and particularly during the first twelvemonth. During the 2005 the tendency was different as the N uptake efficiency accounted for more of the fluctuation than the N use efficiency and besides there was at 120 kilograms ha-1 higher fluctuation in the N use efficiency than the N uptake efficiency. The fluctuation attributed to the N uptake efficiency was higher at the control which indicates that there was a important interaction in N usage efficiency among cultivars, interventions, and old ages.
The comparative parts of grain protein output constituents showed that protein concentration was accounted more of the fluctuation in grain protein concentration that grain output. The fluctuation attributed to the protein concentration was more at the control than at the other N degrees particularly during the 2004 turning season and there was no difference between the N degrees ( Table 6 ) .
Barley is a species that has been studied extensively nevertheless, there are many features such as CM and RCM readings, NNI and NUE that are used to depict responses to different interventions and their relationships are non known ( Table 7 ) . CM readings at blossoming were correlated with N concentration at blossoming and negatively correlated with NUE and N uptake efficiency ( Table 7 ) . Besides N concentration at blossoming was correlated with NNI at blossoming, TGW, and negative correlated with NUE, and N uptake efficiency. Grain output was correlated with NNI at harvest, grain protein content, TGW, NUE, N consumption, and utilization efficiency. NUE was correlated with grain protein content, N uptake efficiency and N use efficiency. Grain protein content was correlated with NNI at harvest and grain output. NNI was correlated with the N concentration at the same growing phase besides NNI at crop was correlated with grain output. NNI was negatively correlated with NUE and N use efficiency. This is the first study where the consequence of N supply on certain physiological features was determined for barley and besides their relationship with grain output.
4.1 Nitrogen concentration and NNI
Nitrogen fertilisation affected N concentration of barley workss at blossoming and at harvest. When the N degree is fringy, as in the present survey, there was an addition in N concentration with N fertilisation ( Dordas et al. 2008 ) . However, even if the dirt N concentration is fringy there are surveies which showed no addition in N concentration and besides in grain output ( Prystupa et al. 2004 ; Le Gouis et Al. 1999 ) which can be because the response of barley to N fertilisation is affected by the dirt type, barley cultivar, clime, turning season wet conditions, N fertiliser signifier and arrangement, and seeding rate and seeding day of the month ( Prystupa et al. 2004 ; Le Gouis et Al. 1999 ) .
The chief aim of this survey was to find whether there is a relationship between NNI and N concentration and besides CM readings. NNI varied from 0.75 to 1.03 across turning season, cultivars, N interventions, and developmental phase. Similar scopes have been reported for a figure of different harvests such maize ( Ziadi et al. 2008 ; 0.29-1.3 ; Plenet and Cruz 1997 ; 0.55-1.45 ; and Justes et Al. 1997 ; 0.45-1.30 ) , one-year rye grass ( Marino et al. 2004 ; 0.4-1.6 ) , jumping wheat ( Ziadi et al. 2010 ; 0.34-1.43 ) , durum wheat ( Debaeue et al. 2006 ; 0.25-1.5 ) , cotton ( Xiaping et al. 2007 ; 0.75-1.16 ) , and flaxseed ( Dordas 2011 ; 0.65-1.16 ) . Valuess of NNI a‰? 1.0 indicate that N supply to the harvest is nonlimiting or in extra, while values of NNI & lt ; 1.0 indicate N lack. In understandings with old findings in other harvest species NNI for barley showed comparatively low fluctuation within N interventions through the growing period and showed higher values at higher N fertilisation degree ( Lemaire et al. 2008 ) . The addition in NNI values with increasing N fertilisation has been reported in maize, wheat, flaxseed, and other harvests but has non reported in barley ( Plenet and Cruz 1997 ; Justes et Al. 1997 ; Dordas 2011 ) . NNI is recognized as a mention method for observing N lack in wheat in Europe and from the present survey seems that can be used besides for barley ( Justes et al. 1997 ) . NNI can be used as a priori diagnosing of works position during harvest growing to find the necessity of using extra fertilisation. However, a major trouble in utilizing the NNI as a diagnostic tool is the demand to find the existent harvest biomass and its N concentration ( Lemaire and Gastal 2009 ) . Therefore, it was suggested for many harvests and seems that the same exists for barley that NNI can be used as a mention for simpler processs ( eg chlorophyll measurings or nitrate concentration in root base infusion ) to find harvest N position ( Justes et al. 1997 ; Debaeke et Al. 2006 ; Prost and Jeuffroy 2007 ; Dordas 2011 ) . The NNI was besides used in harvest theoretical accounts to account for the consequence of N on growing and output of winter wheat ( Devienne-Barter et al. 2000 ) .
4.2 Grain output, comparative grain output, protein content and protein output
Grain output was increased by an norm of 27 % , in understanding with other surveies in which the N was limited and the N application was shown to increase grain output ( Dordas and Sioulas 2008 ; Prystupa et Al. 2004 ; Dordas 2011 ; Papakosta and Ganianas 1991 ; Delogu et Al. 1998 ; Maidl et Al. 1998 ) . Relative grain output was besides increased by an norm of 26 % , nevertheless the comparative grain output was non studied before in barley and it was non used to find the response to N fertilisation. The response of grain output to N fertilisation can besides change with site, twelvemonth, dirt type, cultivar, clime, N signifier and arrangement, seeding rate, and day of the month ( Papakosta and Ganianas 1991 ; Maidl et Al. 1998 ) . During 2004, the higher grain output in the present survey was due to the better conditions conditions. Low rainfall and high temperatures during blossoming and grain filling phase can hold a important consequence on grain output ( Bloom et al. 1985 ) . In add-on, observed limited response of barley to N application where dirt NO3 degrees were high. However, when the N is applied in high rates grain output can be reduced because of housing ( Maidl et al. 1998 ; White 1995 ) .
Grain protein content was increased with N application by an norm of 6 % in all cultivars over the two old ages and grain protein output was increased by an norm of 28 % compared with the control. The highest addition in grain protein output compared with the grain protein content was because N fertilisation affected more the grain output than the grain protein content. Grain protein content was found to increase with N fertilisation ( Maidl et al. 1998 ; Gauer et Al. 1992 ; Ehdaie and Waines 2001 ) when the conditions conditions are favourable. But when there was low rainfall and with high temperatures there was no response to N fertilisation ( ) . However, the TGW was affected by N fertilisation. Several other writers have besides reported that N fertilisation can impact TGW ( ) . However, others found that N fertilisation did non increase the TGW ( Arduini et al. 2006 ; Ferrise et Al. 2010 ; Gonzales et Al. 2003 ) . Grain volume was affected by the N interventions and showed a important interaction among the turning season ten interventions ten cultivars.
4.3 Chlorophyll metre and comparative chlorophyll metre readings
Chlorophyll metre readings ranged from 29 to 55 which is rather typical since there is variableness in chlorophyll content ( Ziadi et al. 2008 ; Dordas et Al. 2008 ) . Chlorophyll metre readings were affected by the N intervention and were higher at blossoming and milk phase than at dough phase. CM readings by and large show addition during the turning season up to a upper limit and so bit by bit diminish when the foliage aging start and there is debasement of the chlorophyll content ( Ziadi et al. 2008 ; Dordas et Al. 2008 ) . However, this fluctuation over the turning period is of import as there is a demand to stipulate the developmental phase at which CM readings are taken. At the earlier turning phases the CM readings are non significantly affected by N interventions which can be because of the residuary N in the dirt and the low demands of N for the works ( Ziadi et al. 2008 ; Dordas et Al. 2008 ) . As the works grows and particularly at blossoming is by and large a clip where the differences in the response to N fertilisation are more marked. Furthermore as the workss reach adulthood there is loss of chlorophyll due to senescence and there is a gradual lessening of the CM readings. There was much higher diminution in CM readings at the control than at the N interventions which indicates that the lower sum of N available to the control was possibly remobilized for grain growing, doing the foliages to age quicker and take downing the sum of chlorophyll ( Shukla et al. 2004 ) . This clearly indicates that when there is equal N supply in the dirt foliage aging is slower and the works supplies the grain with N and photoassimilates for longer clip which consequences in higher outputs ( Eghball and Power 1999 ) . The CM readings can be affected by cultivar, site features, developmental phase, disease or insect harm, works denseness and other alimentary lacks ( Masoni et al. 1996 ) . That ‘s why RCM readings have been proposed which are recommended to account for the influence of the above mentioned factors on CM readings ( Blackmer and Schepers 1995 ; Piekielek et Al. 1995 ; Waskom et Al. 1996 ) . RCM readings ranged from 0.76 to 1.00 and the fluctuations that was noted was lower at the RCM readings compared with the CM readings which agrees with others ( Ziadi et al. 2008 ) .
4.4 Nitrogen efficiency and its constituents
Nitrogen usage efficiency and its constituents were by and large higher in 2004 than in 2005. NUE was decreased with increasing N fertilisation rate ( Marino et al. 2004 ) . Genotype differences were observed in NUEs with Thessaloniki to hold the highest value and the lowest was found at Carina. NUE was non correlated with seed output but it was negatively correlated with the comparative grain output, bespeaking that high output was non associated with more efficient development of N. These relationships suggest that high output is the consequence of better development of N or high seed N concentration, and accordingly, may be accompanied by low NUEs ( Le Gouis et Al. 1999 ; Sinebo et Al. 2004 ) . Therefore, barley breeders should choose for both high output and NUEs in order to guarantee an betterment in both traits ( Le Gouis et Al. 1999 ) .
Nitrogen uptake efficiency was higher for 2005 than for 2004. Under field conditions, dirt N handiness shows high spacial and temporal heterogeneousness that affects workss ‘ N consumption. During the winter and early spring of 2005 lower rainfall during grain filling period and comparatively high average temperature ( particularly in April and early May, which is blossoming and the grain filling starts ) could hold determined short periods of dirt H2O lack and, accordingly, a decreased in N consumption of the applied fertiliser ( Bloom et al. 1985 ) . In contrast, the higher H2O handiness during the experimental period of 2004 in relation to the same period of 2005 might hold favored a greater N consumption from the fertiliser applied. The uptake rate of a given component depends on its external concentration and on the workss soaking up capacity ( Lee 1993 ) . It was found that the maximum alimentary soaking up capacity of workss is higher than that needed to obtain the maximal output ( Jarvis and Macduff 1989 ; Jeuffroy and Meynard 1997 ) . Justes et Al. ( 1994 ) observed that, for a certain sums of aerial biomass, the N concentration could be up to 160 % of the N concentration considered critical. Foods such as N can be accumulated ( stored ) in workss during periods of external copiousness and consumed in subsequent growing when they are externally limited ( Bloom et al. 1985 ) .
Higher values of N use efficiency were found in 2004 than in 2005. This means that a higher sum of biomass and grain output per unit of N consumption was produced in 2004. Harmonizing to the old treatment, the lower N utilization efficiency during 2005 in relation to 2004 reflects a luxury ingestion. In other words, in 2004, workss acquired N in surplus for its current growing.
4.6 Component analysis of the different traits
Analysis of the different constituents ( N uptake efficiency and N utilization efficiency ) that affect NUE showed important differences in the magnitude of the part of each constituent to the fluctuation in NUE among genotypes and besides among the N interventions. Nitrogen utilization efficiency was the most of import constituents of NUE and accounted for more of the fluctuation of N usage efficiency than the N uptake efficiency and was higher at the 0 kilogram N ha-1 than the 120 kilogram N ha-1 in both old ages. Like Moll et Al. ( 1982 ) , Dhugga and Waines ( 1989 ) , Ortiz-Monasterio et Al. ( 1997 ) , and the present survey showed that the part of N uptake efficiency and seed N use efficiency were dependent on N degree. Ortiz-Monasterio et Al. ( 1997 ) , found that N uptake efficiency accounted more for the fluctuation in N usage efficiency at the control than at the N fertilisation interventions which disagrees with the present survey where the N use efficiency accounted more for the fluctuation of the N usage efficiency. When N is rare, the ability to absorb N is surely of paramount importance and would so be related to root features. It may be hypothesised that differences for the ability to research the dirt or to absorb N existed in the stuff that were tested. When N is non the modification factor, N use efficiency have to be more deciding as N will be available for each genotype independent of the efficiency of their root system. Ortiz-Monasterio et Al. ( 1997 ) proposed choosing in medium-high birthrate environments to better for both low and high birthrate conditions. NUE was negatively correlated with N concentration at blossoming, proposing that low N concentration may be indicant of higher NUE.
Barley is a species that has been studied extensively but there are many features that relate to NUE and NNI that were non determined and are of import for higher productiveness of the barley cultivars and besides for the choice of new cultivars. Therefore, it is of import to cognize whether the selected features that it was chosen in this survey can be used to depict the response of other cultivars to N lack, or whether we can utilize them to better choice of new cultivars and hence addition productiveness. It was found a additive relationship between CM readings at blossoming, N concentration at blossoming, and negative correlativity with NUE and N uptake efficiency. NUE was correlated with grain output, bespeaking a demand for more research for a better apprehension of those features and a demand to seek to increase both features in new cultivars besides this indicated that high output was associated with more efficient development of N. Positive correlativity was found in other surveies ( Sinebo et al. 2004 ) . However, other reported an negative correlativity between NUE and seed output in flaxseed ( Dordas 2011 ) . Extra correlativity analysis indicated a negative correlativity between NUE and NNI at blossoming and at harvest. These relationships suggest that high output is the consequence of better development of N and as NNI increases this is accompanied by lower NUEs. In this survey the consequence of N supply on certain physiological features was determined for barley and besides their relationship with grain output. It is obvious that CM can be used as a tool for choice of new cultivars with high output. There are many tradeoffs between the different constituents of the NUE and many factors that can impact them, so correlativity analysis shows the general tendencies of these features. However, more research is needed to research these tools for barley genteelness and besides for better barley direction particularly under rainfed conditions.
Nitrogen is one of the most of import foods needed for works growing and development. Nitrogen fertilisation affected N concentration of the barley workss at blossoming and at crop and besides grain protein content and grain protein output. CM readings were affected by the N intervention and it was higher at both N degrees compared with the control. NNI varied from 0.75 to 1.03 across old ages, growing phase and cultivar and was affected by the N degree. In add-on, N usage efficiency, N uptake efficiency and N use efficiency was higher at the control compared with the two fertilisation interventions. N utilization efficiency accounted for more of the fluctuation of N usage efficiency than the N uptake efficiency and was higher at the 0 kilogram N ha-1 than the 120 kilogram N ha-1 in both old ages. CM readings at blossoming were correlated with NNI at blossoming, and grain output. NUE and its constituents were negatively correlated with CM readings. In decision, the interrelatednesss found among the assorted NUE-related traits suggest that utilizing simple choice standards to better NUE of barley might hold negative deductions on grain output and quality. Therefore, rating and choice of different genotypes for NUE should be based on multiple standards instead than merely one standard and besides should be accompanied by rating for grain output.
The writer is thankful to Professors N. Fotiadis and A. Gagianas, Faculty of Agriculture, Aristotle University of Thessaloniki, for their critical reappraisal of the manuscript.