Presence Of Nitrogen Fertilizer Research Articles

Оценка ростостимулирующих свойств ризобактерий Bacillus sp. и их влияние на морфофизиологические характеристики рапса

Abstract. The use of biofertilizers based on plant growth promoting (PGP) bacteria is a promising direction in agri-biotechnology. The purpose was to evaluate the PGP-attributes of Bacillus sp. and to reveal the morphophysiological features of rapeseed (Brassica napus L.) when inoculated with these rhizobacteria. Methods. The ability of Bacillus sp. strain TO15c isolated from the rhizosphere of Taraxacum officinale on Zack's nitrogen-free medium to produce indol-3-acetic acid (IAA) and phosphates was studied. In pot-scale experiments, the assessment of changes in the morphophysiological characteristics of rapeseed upon inoculation with rhizobacteria both in the absence and in the presence of nitrogen fertilizer was performed. At the end of 100-day vegetation, shoot length, total leaf area, fresh biomass, content of macronutrients and photosynthetic pigments were determined. Results. The ability of TO15c to produce IAA (up to 26 mg/L) and solubilize phosphate (up to 60 mg/L) has been proven. Soil inoculation with rhizobacteria in the presence of ammonium nitrate led to the increase in shoot length by 24 % and total leaf area by 16 %. The aboveground fresh biomass increased by 1.5 times, the underground by 2.5 times, and the content of macronutrients improved. The rise in the photosynthetic pigment content (1.5 times on average) was also noted when inoculated with TO15c. The maximum effect was achieved with the rhizobacteria and nitrogen fertilizer combined application. Scientific novelty. The effectiveness of Bacillus sp. TO15c on rapeseed increased in the presence of nitrogen fertilizer, despite the fact that these PGPR were able to fix atmospheric nitrogen.

Differential responses of soil N2O to biochar depend on the predominant microbial pathway

Biochar amendment has been proposed as a potential strategy to reduce soil nitrous oxide (N2O) emissions, although experimental studies have generated inconsistent results on N2O emissions following biochar amendment. Differential responses of soil N2O to biochar amendment may depend on soil microbial functional genes abundance and abiotic properties. Here we sampled three types of soil from fields under long-term cultivation of green tea (TG), film greenhouse vegetable cabbage (GV) and Jerusalem artichoke (JA), respectively. We conducted a microcosm experiment to examine N2O emissions from the different soils following biochar amendment. Results showed that biochar amendment increased N2O emissions from the GV soil while decreasing N2O emissions from the TG and JA soils in the presence of nitrogen fertilizer. Biochar amendment increased soil pH and C/N ratio across the three soils. Quantitative PCR (qPCR) analysis showed that biochar amendment also consistently increased the abundances of AOB and nosZ genes but decreased the AOA abundances for all the soils, while the effects of biochar on the abundances of nirK and nirS genes differed between the soils. Our results suggest that biochar amendment can affect the processes of both ammonia oxidation and reduction of N2O to N2 for all the soils and the net effect of biochar on N2O emissions depended on the predominant process in a specific soil. Biochar-induced increase in N2O emissions in the GV soil was largely attributed to the stimulated nitrification rate, which was primarily driven by AOB. Biochar-induced decreases in N2O emissions in the TG and JA soils were linked to the increased nosZ gene abundances. Overall, the effectiveness of biochar for mitigating N2O emissions is linked to its dominant N2O production pathway in soils.

Burkholderia fungorum promotes common bean growth in a dystrophic oxisol

Burkolderia fungorum and Azospirillum brasilense are species commonly found in soils, and have been shown to be plant growth-promoting rhizobacteria (PGPR). This study examined the effect on the growth of the common bean plant of three strains belonging to B. fungorum and A. brasilense species inoculated alone or co-inoculated with Rhizobium tropici CIAT 899T (commercial inoculant strain). The ability of PGPR strains to improve bean growth in the presence of mineral nitrogen was also studied. CIAT 899T co-inoculated with B. fungorum UFLA 04-155 and UFLA 04-226 and A. brasilense BR 11001T did not show any benefits for bean growth. However, inoculation with B. fungorum UFLA 04-155 alone resulted in increased dry weight of the nodules and shoots, increased foliar contents of P, Mg, Cu, Fe, K, Ca, S, and Zn, and fostered nodulation by the indigenous rhizobia community. Plant growth promotion by B. fungorum UFLA 04-226 was stimulated in the presence of nitrogen fertilizer in experiments using potted plants. The results indicate the potential ability of B. fungorum to promote growth of the common bean plant under natural conditions.

Contribution of the Study of Physiological Disturbances of Wheat Triticum durum in the Presence of Nitrogen Fertilizer

Contribution of the Study of Physiological Disturbances of Wheat Triticum durum in the Presence of Nitrogen Fertilizer

Evaluating spatial arrangement for durum wheat (Triticum durum Desf.) and subclover (Trifolium subterraneum L.) intercropping systems

Cover crops and mulches can be used for increasing sustainability in winter cereal cropping systems. We performed a 2-year field experiment in Central Italy with the aim of finding a suitable spatial arrangement for durum wheat (Triticum durum Desf.) and subclover (Trifolium subterraneum L.) as a living mulch system in order to provide a high cereal grain yield and a sufficient subclover reseeding following the wheat harvest. Experimental treatments consisted of: (i) five cropping patterns [wheat and subclover mixed in the same row, with rows 15cm apart (same row); 2 rows of wheat and 1 row of subclover at a distance of 10cm between rows (narrow rows); 2 rows of wheat and 1 row of subclover with a distance of 10cm between the wheat rows and 17.5cm between the wheat and subclover rows (wide rows); durum wheat sole crop and subclover sole crop, both in rows 15cm apart]; (ii) two nitrogen fertilization levels (0 and 100kgha−1 of N); (iii) and two weed management levels (weed-free and weedy). The wheat grain yield was not reduced by the intercropped subclover in narrow rows, while it was around 14% lower in same row and wide rows compared to the one in the pure crop treatment. When intercropped with subclover, wheat was the competitively superior species and its competitive advantage was greater when it was closer to the legume and/or in presence of nitrogen fertilization. A strong negative relationship between wheat aggressivity and subclover seed production was observed. Following the wheat harvest, the legume reseeding was sufficient to regenerate a cover crop in the autumn of the second year regardless the spatial arrangement, even if the density of the subclover seedlings was almost twice in wide rows compared to the one in the same row. Although the intercropped systems were characterized by an increase in plant density compared to the sole crops (100% of wheat+50% of subclover), the competitive ability of the wheat-subclover system against the weeds was higher than the wheat sole crop only in narrow rows where a significant reduction of both weed density and weed biomass was observed. When the subclover is used as living mulch in durum wheat, a moderate separation between the two species could be a suitable spatial arrangement for obtaining an adequate wheat grain yield, ensuring satisfactory subclover reseeding, controlling the weeds more effectively.

Implications of selection in common bean lines in contrasting environments concerning nitrogen levels

Grain productivities of 100 bean lines were evaluated in the presence and absence of nitrogen fertilizer in order to identify those with high nitrogen use efficiency (NUE) and to determine the correlated response observed in a stressed environment following selection in a non-stressed environment. The genetic and phenotypic characteristics of the lines, as wellas the response index to applied nitrogen, were determined. The average grain productivities at both locations were 39.5% higher in the presence of nitrogen fertilizer, with 8.3 kg of grain being produced per kg of nitrogen applied. NUE varied greatly between lines. Lines BP-16, CVII-85-11, BP-24, Ouro Negro and MA-IV-15-203 were the most efficient and responsive. The results showed that it is possible to select bean lines in stressed and non-stressed environments. It was inferred that common bean lines for environments with low nitrogenav ailability should preferably be selected under nitrogen stress.

Arabidopsis has a cytosolic fumarase required for the massive allocation of photosynthate into fumaric acid and for rapid plant growth on high nitrogen

The Arabidopsis genome has two fumarase genes, one of which encodes a protein with mitochondrial targeting information (FUM1) while the other (FUM2) does not. We show that a FUM1-green fluorescent protein fusion is directed to mitochondria while FUM2-red fluorescent protein remains in the cytosol. While mitochondrial FUM1 is an essential gene, cytosolic FUM2 is not required for plant growth. However FUM2 is required for the massive accumulation of carbon into fumarate that occurs in Arabidopsis leaves during the day. In fum2 knock-out mutants, fumarate levels remain low while malate increases, and these changes can be reversed with a FUM2 transgene. The fum2 mutant has lower levels of many amino acids in leaves during the day compared with the wild type, but higher levels at night, consistent with a link between fumarate and amino acid metabolism. To further test this relationship we grew plants in the absence or presence of nitrogen fertilizer. The amount of fumarate in leaves increased several fold in response to nitrogen in wild-type plants, but not in fum2. Malate increased to a small extent in the wild type but to a greater extent in fum2. Growth of fum2 plants was similar to that of the wild type in low nitrogen but much slower in the presence of high nitrogen. Activities of key enzymes of nitrogen assimilation were similar in both genotypes. We conclude that FUM2 is required for the accumulation of fumarate in leaves, which is in turn required for rapid nitrogen assimilation and growth on high nitrogen.

Effect of Method of Inoculation and Nitrogen Fertilizer on Nodulation and Yield of Selected Tropical Legumes

AbstractMany factors affect nodulation of legumes of which, nitrogen fertilizer and method of inoculation play a vital role. Thus, a study evaluated the effects of the above factors on nodulation and yields of two common tropical food legumes, namely Mungbean and Bushbeans which are considered extensive and poor nodulatingo species respectively.Inoculation increased nodulation of bushbeans and to a lesser extent in mungbeans. This effect was more evident with time. Nodulation was reduced in the presence of nitrogen fertilizer, and the effect was more pronounced in the extensively nodulating species, mungbean. Nitrogen and nodulation increased yields of both species. The results indicate the inability of bushbeans and to a lesser extent mungbean, to meet all nitrogen requirements by nodulation and nitrogen fixation alone. This suggests the need for some fertilizer nitrogen for tropical legumes in addition to inoculation to obtain optimal yields.