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This research was instigated by the fact that during the last decade annually repeated shallow disk tillage on the same field became frequent practice in Hungary. In order to study the changes of soil condition associated with disk tillage and to assess it is consequences, long-term tillage field experiments with different levels of nutrients were set up in 1991 (A) and in 1994 (B) on Chromic Luvisol at Gödöllö. The effects of disk tillage (D) and disk tillage combined with loosening (LD) on soil condition, on yield of maize and winter wheat, and on weed infestation were examined. The evaluation of soil condition measured by cone index and bulk density indicated that use of disking annually resulted in a dense soil layer below the disking depth (diskpan-compaction). It was found, that soil condition deteriorated by diskpan-compaction decreased the yield of maize significantly by 20 and 42% (w/w), and that of wheat by 13 and 15% (w/w) when compared to soils with no diskpan-compaction. Averaged over seven years, and three fertilizer levels, the cover % of the total, grass and perennial weeds on loosened soils were 73, 69 and 65% of soils contained diskpan-compaction.

Composting has been considerably recognized as a viable management method for solid organic wastes aimed at recycling of its end-product as a potting substrate for ornamental plants. Pelargonium and Salvia as salt-sensitive plants were grown in the mixture of compost (75, 50, 25% by volume) and additives (Hygromull, Cocofiber and SPS-standard soil type 73 with 70% peat and 30% clay). Since plants may suffer from a high salt content, thus in a further experiment compost was added as a partial substitute for peat. The results of the first pot experiment reveal that the large percentage of compost in the substrate had negative effects on plant growth and nutrient uptake (N, P, K and Na). Both yield formation and nutrient uptake significantly increased and almost gained levels of those in the control in the second pot experiment when plants were grown in peat-based substrates. Especially, the growth of Salvia was significantly improved. Consequently, the compost-based media (> 50% volume of compost) cannot be recommended for salt sensitive ornamental plants, while less than 25% of compost incorporated into peat creates peat-based substrates which reasonably enhanced growth of Pelargonium and Salvia.

The aim of this work is to evaluate the changes of Mehlich 3 - P, K, Ca and Mg contents in soil during a long-term field experiments with sewage sludge, farmyard manure (FYM) and mineral NPK (NPK) application, compared to the control non-fertilized treatment. The experiment was established at the Humpolec and Suchdol sites (Czech Republic). Potatoes, wheat and barley were grown in crop rotation. Fertilizing system was based on the same nitrogen dose of 330 kg N/ha per one crop rotation. Archive soil samples from the beginning of the experiment (1996) and from the end of each year's crop rotation (1999, 2002, 2005, 2008 and 2011) were analyzed. In spite of the different soil-climatic conditions of the studied sites, very similar tendencies of P, K, Ca and Mg contents changes after the fertilizing systems used were observed in the soil. In case of the same nitrogen dose (330 kg N/ha), sewage sludge appeared to be better source of bioavailable soil phosphorus compared to the farmyard manure and NPK. On the contrary, FYM was a better source of bioavailable potassium and magnesium, despite the lower total magnesium content in FYM. The NPK treatment was the best long-term source of bioavailable potassium.

We measured the long-term (28 years) sustainability of rice-wheat cropping system under integrated nutrient management practices emphasizing the trends in grain yields, sustainable yield index (SYI) and nutrient budgeting. The data of long-term experiment revealed that grain yield of both rice and wheat declined under control and sub-optimal fertilizer inputs (50% or 75% recommended fertilizer NPK). Negative yield trend (slope) was observed in control plots for rice (-0.0296) and wheat (-0.0070); whereas positive yield trend was observed under treatments receiving organic supplements. The SYI values indicate that rice yields are more sustainable than wheat. Data on apparent nutrient balance showed a deficit of N (-42.2 kg/ha/year), P (-9.1 kg/ha/year) and K (-52.2 kg/ha/year) under control plots. Surprisingly, there was net depletion of K under the organic supplemented plots. Correlation study revealed that apparent balance of K was negatively correlated with SYI (r = -0.921 for rice; r = -0.914 for wheat) and yield slope (r = -0.870 for rice; r = -0.896 for wheat). If the trend of K imbalance is not reversed, the potential to improve N and P fertilizer use efficiency and crop yields will be limited.

The field experiment with different soil tillage treatments has been carried out in Prague-Ruzyně locality (Czech Republic) since 1995. Data of two growing cycles in the years 2007-2010 and 2011-2014 were evaluated. Tillage technique was decisive for changes in soil characteristics and crop yields. Bulk density, organic carbon (C_org) and microbial biomass C (C_mic) were more equilibrated throughout all tested soil layers (0-0.1; 0.1-0.2 and 0.2-0.3 m) in conventional tillage (CT). In reduced tillage (RT) and no-tillage (NT) treatments significant accumulation of C_org and increase of C_mic in the surface layer were found, compared to CT. No significant differences in C_org and C_mic between two growing cycles were determined; however, mostly higher values were obtained in the top layer of NT during the second growing period. Higher bulk density under conservation tillage techniques did not negatively affect soil characteristics and should be taken in consideration for data evaluation as it can alter interpretation of their changes in the soil profile. Crop yields were comparable in CT and RT. Yield decrease in NT was mostly observed for winter wheat and pea. Beneficial effects of RT and NT conserving soil moisture on crop yield were not observed in dry years.

We conducted field experiments since 2006 to determine the effect of tillage practices and rate of nitrogen fertilization on soil properties and crop yield. Four tillage practices and five N rates were used. The results showed that the year-round total yield of wheat and maize under harrow tillage (HT) and rotary tillage (RT) was not significantly different from that of conventional tillage (CT, moldboard tillage) but was higher than that of no-tillage (NT). Reduced tillage (HT and RT) with straw returned and rate of nitrogen (157.5 kg/ha for wheat and 202.5 kg/ha N for maize) were suitable to increase the yield and adjust the soil carbon and nitrogen situation for the winter wheat-summer maize cropping system.

Winter Orychophragmus violaceus (OV)/spring maize is a novel eco-agricultural system in North China Plain, but little is known about OV's nitrogen (N) effects on succeeding maize growth and its contribution to maize N uptake and utilization during the growth. A pot experiment using ¹⁵N was conducted, including five treatments: (1) Control - without OV incorporation and N fertilizer; (2) G - high ¹⁵N labelled-OV incorporation; (3) 50%G - lower ¹⁵N labelled-OV incorporation; (4) F - ¹⁵N labelled urea fertilizer merely; (5) G + F - high OV incorporation combined with urea fertilizer. Increasing OV incorporation rate increased maize dry matter, yield, and total N uptake. Approximately 84-97% of the released OV's nitrogen was absorbed before the V8 (the 8^th leaf fully expanded) stage in G and 50%G treatments. However, only 19% of the released OV's nitrogen was taken up at this period in G + F, and the rest was absorbed from V8 to maturity. G treated maize doubled the OV's nitrogen uptake than the 50%G at maturity, and also had higher percentage contribution of OV's N to total N accumulation. The G and 50%G maize obtained similar OV's nitrogen use efficiency of 30%; however, this efficiency was further improved to 43% in the G + F. And more, G + F treatment further improved the maize yield by 9% compared to F treatments.

A three-year field experiment was conducted in North-East Poland. Each year three sulfur fertilization rates in the form of sulphate (S-SO₄^2-) and pure (S-S⁰) sulfur were applied: 40, 80, and 120 kg/ha. After the third year of the study, the application of sulfate and elemental sulfur decreased the zinc content of 0-40 and 40-80 cm soil layers, as compared with soil sampled before the experiment. Over the entire experimental period, sulfur fertilization had no significant effect on changes in the natural copper content of soil at a depth of 0-40 and 40-80 cm. Manganese concentrations remained at a similar level at a soil depth of 0-40 cm. The manganese content of the 40-80 cm soil layer was substantially lower than in the 0-40 cm horizon. An insignificant increase in the lead content of soil was observed. The applied doses of sulfate and elemental sulfur led to an increase in the cadmium content of soil depth of 0-40 cm. Sulfur fertilization contributed to a decrease in the nickel content of soil. The applied doses of sulfate and elemental sulfur exerted a stronger effect in the 0-40 cm soil layer than in the 40-80 cm horizon.

The study evaluates the effect of liming materials application in combination with NPK fertilizer and borax on macronutrient contents (nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg)), in an extremely acid soil and raspberry leaves and fruits during a two-year period. Liming increased soil pH, N mineral content, P, Ca and Mg soil content, while K content either increased (dolomite and borax application), or decreased (lime application). The N and P contents in raspberry leaves after liming increased significantly, but P content remained below the optimal values. Some treatments with lime caused a decrease in K content in leaves, while dolomite and borax application increased K content. Initially optimal Ca content in leaves increased significantly in the treatments with lime, but decreased after dolomite application. The Mg content in leaves increased after dolomite and borax application, but mainly remained below optimal values. Liming either did not alter or only slightly altered macronutrient contents in raspberry fruits.

This study aimed to separate the respective contributions of root and microbial respiration to soil respiration in a rape field in Southwest China. The soil respiration was measured with a closed chamber technique and a regression method was used to apportion root and microbial respiration. Microbial and root respiration ranged from 70.67 to 183.77 mg CO₂/m²/h and 21.99 to 193.09 mg CO₂/m²/h, averaged 127.16 and 116.66 mg CO₂/m²/h during the rape growing season, respectively. Root respiration coefficient ranged from 0.41 to 5.39 mg C-CO₂/g C/h and was negatively correlated with root/shoot ratio, aboveground and belowground biomass, but positively correlated with root N content. The contribution of root respiration to soil respiration averaged 44.2%, ranging from 14.5% to 62.62%.

A study was conducted to investigate the influence of sodicity induced changes in soil physical properties on paddy root growth in the normal agriculture, semi-reclaimed and sodic soils. The root growth (length, length density, biomass and distribution pattern) were unfavourably affected by the soil physical properties (bulk density, soil aggregate stability, available water content, hydraulic conductivity and soil water retention potential) in the case of sodic soil. The microbial biomass carbon, bacterial, fungal population and dehydrogenase activity showed the lower values in the case of sodosol compared to the normal soil. These soil biological properties tend to sustain paddy root growth in normal and semi-reclaimed soils. Principal component analysis revealed that soil physical properties accounted for 98.2% of total variance in root growth. The study revealed that salt stress induces changes in soil physical properties limiting paddy root growth in the salt affected soils. It is important to reclaim sodosols to alleviate salt induced physical stress for optimum paddy root growth.

The aim of the studies was to determine the effect of the used herbicides and their mixtures on the level of glycoalkaloids (TGA) in the leaves and tubers of three edible potato cultivars. The studied factors were: I - three cultivars: Cekin, Satina and Tajfun. II - five ways of care: 1. mechanical care - the control object and four objects using herbicides Command 480 EC, Afalon Dispersion 450 SC and Stomp 400 SC. The content of glycoalkaloids both in the leaves and in the tubers of the edible potato significantly depended on the genotype. The highest content of TGA characterised the cv. Cekin - 623.5 mg/kg and 67.21 mg/kg of fresh weight (FW), respectively, while the smallest was found in cv. Satina - 339.3 mg/kg and 33.60 mg/kg of FW, respectively. Herbicides used in the experiment caused the increase of the content of glycoalkaloids compared to the tubers from the control object. However, a significantly higher concentration of TGA was stated after using the mixture of herbicides Command 480 EC + Afalon Dispersion 450 SC and Stomp 400 SC + Afalon Dispersion 450 SC.

The complex interaction process of the abiotic factors (sunlight, air temperature and soil water) in regulating maize (Zea mays L.) photosynthesis has not been fully understood. Our field experiment explored the changed sensitivity (or role) of the abiotic factors in regulating maize photosynthesis under a drought development process. The experiment established a scenario with a long-term drought and an instantaneous cloud cover. The results revealed that long-term drought stress causes the sensitivity (or role) of sunlight and temperature exchanged in regulating maize photosynthesis. The maize photosynthesis was more sensitive to instantaneous sunlight rather than temperature in the absence of drought. However, a diminishing photosynthetic sensitivity to sunlight but an increasing photosynthetic sensitivity to temperature was observed with drought development process. The variable photosynthetic sensitivity indicated that the roles of temperature and sunlight in regulating maize photosynthesis were exchanged, so it is expected that higher photosynthetic rate could be achieved by adjusting temperature rather than sunlight after severe drought. Nevertheless, further studies are needed to provide more evidence and mechanism explanations.

The effect of 24-epibrassinolide and 28-homobrassinolide on seed germination and seedling growth of radish (Raphanus sativus L.) was studied under cadmium toxicity. The impact of brassinosteroids (BRs) on free proline levels and the activity of antioxidant enzymes catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1), ascorbic peroxidase (APOX; EC 1.11.1.11) and guaiacol peroxidase (GPX; EC 1.11.1.7) in radish seedlings under Cd toxicity was evaluated. The effect of BRs on the activity of ascorbic acid oxidase (AAO; EC 1.10.3.3) and lipid peroxidation in radish seedlings challenged with Cd stress was also investigated. BRs supplementation alleviated the toxic effect of the heavy metal and increased the percentage of seed germination and seedling growth. Out of the two substances, HBL was found to be more effective than EBL in stress alleviation. HBL (3µM) alleviated the toxic effect of the heavy metal and increased the percentage of seed germination by 57% over Cd and 20% over unstressed control. Similarly supplementation of HBL (3µM) caused an increase of 156%, 78% and 91% in length, fresh weight and dry weight of seedling, respectively, over Cd treatment alone. The amelioration of seedling growth by BRs under metal toxicity was associated with enhanced levels of free proline. The activities of antioxidant enzymes CAT, SOD, APOX and GPX were increased in the seedlings from treatments with Cd along with BRs. Brassinosteroid treatment reduced the activity of POD and AAO in heavy metal stressed seedlings. Lipid peroxidation induced by Cd was found reduced with the supplementation of BRs. The results obtained in the study clearly indicated the ameliorative influence of brassinosteroids on the inhibitory effect of Cd toxicity.

Our study focuses on the phosphorus (P) balance in two long-term fertilization experiments which were carried out in characteristic soils of Hungary with four fertilization treatments and four main crops. The objectives of this study are: (1) to quantify the P accumulation rate in the upper soil layers and (2) to calibrate and validate the P-balance module of the 4M crop model. The concentration of ammonium-lactate soluble P (AL-P) increased with time in both soils. The mean AL-P accumulation rates in the 0-20, 20-40 and 40-60 cm soil layers were 3.7, 0.7, 0.1 and 3.7, 4.3, 0.6 mg/kg/year in the chernozem and the sandy soil, respectively. The P accumulation rates in the top layers (0-20 cm) changed significantly in time as these gradually decreased from around 6.5 mg/kg/year to zero in about 26 years in both soils. The model results of the phosphorus content in different soil layers, as well as the plant phosphorus uptake were in good agreement with the observed values.

The study of soil enzyme activities under different land use is of importance for exploration of the soil quality evolution and its evaluation during the revegetation at karst area in Nanchuan, Chongqing, China. Seven kinds of land use were chosen as subject, aiming at revealing the changes in soil enzyme activities through experimental and statistical analysis. The results showed that different land use significantly influenced the enzyme activities. Soil urease, invertase, catalase and amylase behaved the different change. A descending order of urease activity was artificial forest, natural forest, shrubbery, grassland, slope field into terrace, rock desertification and farmland. As to invertase and amylase, they have no clear change orderliness with land use change. Moreover, no significant change was observed in catalase activity and the lower value was found in natural forest. The above results cannot reflect the land use effect on the enzyme activities. According to the soil enzyme index (SEI), it can be seen that the SEI changed with an order of natural forest > artificial forest > grassland > shrubbery > farmland > slope field into terrace > rock desertification, which can objectively and fully evaluate the land use change in soil enzyme.

In the long-term field trial on an arable dystric Stagnosols, winter wheat (Triticum aestivum L.) grain yield, nitrogen use efficiency (NUE) and nitrate nitrogen (NO₃^--N) in lysimeter water were compared under treatments of 0, 100, 150, 200, 250 and 300 kg/ha of mineral nitrogen (N) during the growth years 1996/97, 1999/00, 2002/03 and 2005/06. Year properties significantly influenced N availability resulting in different responses of grain yield and NUE under variable treatments. Grain yield showed strong significant correlation with the rainfall accumulated from March to May (r = 0.77). In the case of a dry year 2003, winter wheat yield and NUE were adversely influenced by unfavourable climatic conditions. The optimal response of yield and NUE to increasing mineral N rates was found at the amount of 150-200 kg N/ha. Very strong significant correlation between the total amount of leached NO₃^--N and NUE was found for periods 1999/00 and 2005/06 where, in terms of increasing N levels, lower NUE conditioned higher NO₃^--N leaching (r = 0.91 and r = 0.94, respectively). According to the shallow depth of groundwater and installation of drainage systems, there is still a risk of freshwater contamination by nitrates if the N rates higher than 200 kg/ha were applied.

Changes in root anatomical structures at successive cycles of selection (cycle 1 to cycle 18, alternating) were observed in the study of maize (Zea mays L. cv. Saracura-BRS 4154) capable to survive and produce in temporarily flooded soils; this cultivars was developed by the Maize and Sorghum National Research Center through stratified phenotypic recurrent selection for cultivation wetland soils. Field trial was carried out and flooding of the soil was initiated at the six-leaf stage; the soil was flooded with water (20-cm deep) three times per week. Root sample was collected, fixed, and selected for observation in photon microscope. A gradual increase in the number of aerenchyma, the proportion of vascular cylinder, smaller metaxylem, and phloem and epidermis width, and a decrease in exodermis and cortex were observed in successive selection cycles. Such phenotypic changes impart the flood tolerance ability to this maize cultivar.

It is postulated that stabilized ammonium fertilizers improve fertilizer-N utilization by crops, leading thus to higher yields with the same fertilizer rate, especially on sandy soils. However, it must be taken into consideration that in clayey soil at least a part of the NH₄⁺ ions may be fixed by 2:1 clay minerals, thus delaying the effect of the N fertilizer. Because NH₄⁺ and K⁺ have similar size and valence properties and therefore compete for the same non-exchangeable sites of 2:1 clay minerals, we investigated the influence of time and K⁺ application rate on both fixation and release of NH₄⁺. Fixation of NH₄⁺ ions was higher when K⁺ was applied after NH₄⁺, while the influence of the K⁺ application rate was less pronounced. Mobilization of non-exchangeable NH₄⁺ was retarded when K⁺ was applied at the high rate after NH₄⁺. At the first harvest yield formation of ryegrass was neither influenced by the amount as well as the application time of K⁺, because plant available N was not growth limiting, while yield of the second harvest was significantly higher with the low K⁺ application rate after NH₄⁺. After the second harvest the blocking effect of K⁺ on the release of non-exchangeable NH₄⁺ was attenuated and the highest yields of the third cut were reached in the treatments with the high K⁺ application rate after NH₄⁺. Total dry matter yield was highest when K⁺ was applied at the low rate after NH₄⁺. Our results show that K⁺ governs fixation and release of non-exchangeable NH₄⁺, which should be taken into consideration when applying ammonium containing N fertilizers like ammonium sulfate, ammonium sulfate nitrate and ENTEC. Thus K⁺ can affect N availability when N is applied as NH₄⁺ in both the short and long term.

The paper compares the quality of Festulolium, Dactylis glomerata and Arrhenatherum elatius at the end of the growing season over three years with the contrasting weather in the Czech Republic. The effect of pre-utilisation dates in June or July on the quality of grass forage in October, November and December (harvest dates) was investigated. In the first two years, Arrhenatherum elatius exhibited higher yields (P < 0.05) than Festulolium and Dactylis glomerata. In all treatments, differences between the species and between the years were inconsistent for organic matter digestibility (OMD) and neutral detergent fibre (NDF) but Festulolium showed the lowest crude protein (CP) in all years and crude fibre (CF) in the first 2 years. The longer re-growth time due to earlier final cut in summer increased the yield and decreased the nutritive value in winter. Yields of DM, OMD and CP content generally declined and the CF content increased with the delay of winter harvest. Significant species harvest date interactions in some years were due to the steep increase of CF and NDF in Festulolium. Based on DM yields and nutritive value, all species have some merits as forage for use in possibly extended grazing season. Festulolium and Dactylis glomerata could be used to extend the grazing period in continental conditions. Arrhenatherum elatius had sufficient quality at both dry and warm end of the growing season due to the fact that Arrhenatherum elatius was a representative of drought-resistant species; however, intense grazing could suppress it.

The purpose of the studies was to establish the quantitative composition of bacteria Bacillus spp. and Pseudomonas spp. and their antagonistic effect towards soil-borne fungi after the cultivation of oats, spring vetch and tansy phacelia as intercrop cover plants. The total population of bacteria in 1 g dry weight of the soil from the experimental combination where mulch of oats was used was larger than in the combination with spring vetch or tansy phacelia. Totally, approximately three times as much Bacillus spp. was obtained from soil samples as compared to Pseudomonas spp. Tests showed that the most isolates of antagonistic bacteria out of the enumerated genera occurred in the soil after oats cultivation, and the least in the soil after the cultivation of tansy phacelia. Antagonistic Bacillus spp. and Pseudomonas spp. inhibited the growth and development of Fusarium oxysporum, Haematonectria haematococca and Thanatephorus cucumeris in the most effective way. The greatest total antagonistic effect of Bacillus spp. and Pseudomonas spp. towards Altenaria alternata, F. culmorum, F. oxysporum, H. haematococca, P. irregulare and T. cucumeris was found out after managing the mulch of oats. The smallest total antagonistic effect of bacteria was observed after managing the mulch of tansy phacelia.

The aim of this study was to compare the incidence of pathogens and pesticide residues in rapeseed samples depending on integrated and organic cultivation systems and cultivars. No pesticide residue was detected in seeds coming from the organic production system. However, trace amounts of pesticide residues admissible in rapeseed protection were detected for samples from integrated pest management. Seeds from both cultivation systems were most frequently infested by fungi Alternaria brassicicola and A. alternata. The greatest number of Leptosphaeria spp. cultures was obtained from seeds from organic cultivation.

Photosynthesis and transpiration rates in the interval of 30 min before and 30 min after copper fungicide application show an increase from the level of 5.0 to 7.0 µmol CO₂/m²/s and 0.75 to 1.00 mmol H₂0/m²/s. Long-term measurements show that the increase of photosynthesis rate after copper application is temporal and fades away after 10-14 days. No stress response was induced after the application of copper fungicides. Contents of copper in hop cones are up to 500 mg/kg if total amount of applied copper does not exceed 15 kg/ha. Contents of copper on leaves are 2-5 times higher at the same application dose. Application of 5 kg copper per one hectare of vigorous growth of Agnus variety increases content of copper on hop leaves by 1000 mg/kg at least. The same amount of copper increases its content in hop cones by 300 mg/kg at the ripening period. Tight correlation between the amount of copper applied and its content in hops does not exist. Elementary copper from leaves is brought into harvested hops in the form of biological admixtures. Copper content in hop cones shows a decreasing trend, which is given by gradual increase of cones size at the ripening period. Similar trend on hop leaves shows that washing off and dissolving of copper compounds by atmospheric water can participate in this process as well. Common content of copper in untreated hop cones and leaves is up to 20-25 mg/kg.

The experiments were conducted in four locations in Serbia: Valjevo, Kucevo, Nova Pazova and Surduk in 2012 and 2013. A working hypothesis that growing conditions would not affect the rutin content in buckwheat leaves was set up. The content of rutin in leaves of buckwheat was determined by the HPLC/DAD technique, using the external standard calibration method. Out of the basic biometric parameters, average value, variance, and the variation coefficient were estimated. Results were processed by the analysis of variance for the factorial experiment. The analysis of variance showed existence of significant differences in the rutin content, over locations, but only in the first year of testing. The average content of rutin in the first and the second year was 3.30% and 2.61%, respectively, and in both years of testing it amounted on average to 2.82%. The variation in the rutin content was larger in the second year of testing. On the other hand, this variation was lower in the first year (5.3-29.0%) in comparison to the second year (16.2-28.6%). Relatively lower rutin contents were recorded in samples collected at lower-altitude locations.

The effects of irrigation regimes (full irrigation and water-withholding at anthesis) and post-anthesis nitrogen supplies (LN: 0, MN: 20 and HN: 40 kg N/ha) on grain yield and its components in winter wheat were studied, with attention to biomass gain by assimilation and its loss by respiration. Fully-irrigated wheat responded to N fertilization with increased grain number (GN) and decreased grain weight (GW) and achieved similar grain yields (5.2 to 5.5 t/ha) at different N supplies. However, drought-stressed wheat responded to N with higher GN without significant changes in GW, and achieved higher grain yields (2.7 vs. 3.3 t/ha) with HN compared to LN. Net assimilation rates during grain filling (NARg) increased with increasing post-anthesis N fertilization for drought-stressed wheat (NARg: 3.8 and 4.5 g/m/day for LN and HN). Apparent whole-plant respiration (R_A) was not influenced by increased post-anthesis N fertilizer. Thus, in drought-stressed wheat, the total biomass and straw yield at maturity were increased by increasing N supply. These results suggest that high N supply at anthesis satisfied the grains' increased demand for N by increasing post-floral assimilation, and the surplus assimilates not only compensated for the low-N-induced biomass loss by respiration but may also have increased the

The use of switchgrass (Panicum virgatum L.) as an energy crop has gained great importance in past two decades due to its high biomass yields on marginal lands with low agricultural inputs and low maintenance requirements. Information on the allocation of photosynthetically fixed C in the switchgrass-soil system is important to understand the C flow and to quantify the sequestration of C in soils. The allocation of ¹³C labeled photosynthates in shoot, root, soil, and in microbial biomass carbon (MBC) of rhizosphere and bulk soil of 45 days old, greenhouse grown-switchgrass was examined during 20 days ¹³C-CO₂ pulse labeling period. The total ¹³C recovered in the plant-soil system varied from 79% after 1 day to 42% after 20 days of labeling. After labeling, 54%, 40%, and 6% excess ¹³C resided in shoot, root and soil, respectively on day 1; 27%, 61% and 11%, respectively on day 5 and 20%, 63% and 17%, respectively day 20 after labeling. The maximum incorporation of ¹³C from roots into the MB of rhizosphere soil occurred within the first 24 h of labeling. The excess ¹³C values of rhizosphere soil and rhizosphere MBC were significantly higher than excess ¹³C values of bulk soil and the bulk soil MBC, respectively. The proportion of excess ¹³C in soil as MBC declined from 92 to 15% in rhizosphere soil and from 79 to 18% in bulk soil, for 1 day and 20 days after labeling, respectively. The present study showed the effectiveness of ¹³C labeling to examine the fate of recently photosynthesized C in soil-plant (switchgrass) system and dynamics of MBC.

The effect of mineral nitrogen (N) nutrition on seed production and acquisition of ¹⁵N from fertilizers by components of cereal-pea mixtures was investigated. Yields of wheat-pea and oats-pea mixtures raised together with the increase of cereals percentage in the pot, and higher seed yields of mixture with barley was affected by a larger share of pea plants. The percentage of nitrogen derived from fertilizers was significantly higher in cereals as compared with pea. Pea accumulated the greatest quantity of nitrogen from fertilizers in straw and roots, and cereals translocated ¹⁵N mainly to ears - grain and glumes with rachis. The percentage of ¹⁵N in seeds of pea amounted to 15% on the average, and in grain of cereals - 54% to 60% of the total N taken up.

The effects of phosphate solubilizing bacterium (Bacillus FS-3) application on phosphorus contents of tomato (Lycopersicon esculentum L.) plant, growing performance and phosphorus forms in soil were evaluated under greenhouse condition. Five different phosphorus fertilizer treatments (normal superphosphate, triple superphosphate, di-ammonium phosphate, phosphoric acid, and rock phosphate) with and without bacterium (Bacillus FS-3) were applied in pots as 344 kg P/ha. Basal fertilizers were applied to all the pots as 180 kg N/ha (NH₄NO₃ 33% N), 100 kg K/ha (K₂SO₄ 50% K₂O). The results obtained showed that phosphorus availability from soil increased with phosphate solubilizing bacterium (PSB) application. The amount of plant available form of soil phosphorus fraction (resin-Pi + NaHCO₃-Pi + NaHCO₃-Po + NaOH-Pi + NaOH-Po) increased with PSB application. In all fertilizer types, bacteria application converted approximately 20% of less available phosphorus into labile forms. Statistically significant differences were obtained in shoot and root dry weight of tomato plants treated with PSB application. In all of the fertilizers, plant shoot and root weight and P uptake were greater with PSB applications than without PSB. The highest shoot-root dry weight and P uptake of plant were determined in triple superphosphate (TSP) with PSB application treatment. The data in the present study suggest that the application of PSB (FS-3) may increase the availability of soluble phosphate by dissolving the inorganic forms of phosphate and that bacterial strain tested in this study has a potential to be used as a bio-fertilizer in sustainable and organic agriculture.

Selenium (Se) contamination due to industrial activities has received increasing concerns. Phytoremediation has been suggested to be an efficient and feasible way to remove Se from Se-contaminated environment. Recently, an arsenic (As) hyperaccumulator Pteris vittata L. (Chinese Brake fern) was found to be a Se accumulator. This study was carried out to investigate Se accumulation mechanisms concentrating on antioxidant responses of this plant to six levels of selenite (0, 1, 2, 5, 10, and 20 mg/L). The results showed that Chinese Brake fern can accumulate a large amount of Se without any visible toxic symptoms and significant decreases in its biomass. However, the root took up more Se than the fronds. The highest concentration of Se in the roots and fronds was 1.536 mg/kg and 242 mg/kg, respectively, demonstrating a typical accumulation character to Se. Addition of 2 mg/L Se decreased, but ≥ 5 mg/L Se enhanced the production of malondialdehyde (MDA), suggesting an antioxidant role of low dosages of Se. The enzymes of catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) contributed their anti-oxidative functions only under low dosages of Se, as shown by their increased activities at Se levels ≤ 5 mg/L and lowered activities at Se levels > 5 mg/L. The concentration of glutathione (GSH) and enzyme activity of glutathione reductase (GR) were stimulated by ≥ 5 mg/L Se. Superoxide dismutase (SOD) activity was also enhanced by 20 mg/L Se. Our results suggest that SOD, GSH and GR were likely responsible for, but enzymes of POD, APX, and CAT have limited roles in Se accumulation in Chinese Brake fern.

Paddy rice is important for Chinese agriculture and crop production, which largely depends on the leaf nitrogen (N) levels. The purpose of this study is to discuss the relationship between the fluorescence parameters and leaf N content of paddy rice and to test their performance in inversing N content of crops through back-propagation (B-P) neural network. In the correlative analysis of the fluorescence parameters and the N content, we found that the correlation between fluorescence ratios (F740/F685 and F685/F525 (F740, F685, F525 - intensity of fluorescence at 740, 685 and 525 nm, respectively)) and the N content (R² are 0.735 and 0.4342, respectively) is weaker than that between the intensity of fluorescence peaks (F685 and F740) and N content (R² are 0.9743 and 0.9686, respectively). Our studies show that the accuracy and precision of N content inversion which is acquired from the intensity of fluorescence peaks through the B-P neural network model are significantly improved (root mean square error (MSRE) = 0.1702, the residual changes between -0.1-0.1 mg/g) compared with the fluorescence ratio (MSRE = 0.3655, the residual changes from -0.3-0.3 mg/g). Results demonstrate that the intensity of fluorescence peaks can be as a characteristic parameter to estimate N content of crops leaf. The B-P neural network model will be serviceable approach in inversing N content of paddy leaf.