scholarly journals Nitrate fertilization may delay autumn leaf senescence, while amino acid treatments do not

2021 ◽  
Author(s):  
Nazeer Fataftah ◽  
Erik Edlund ◽  
Jenna Lihavainen ◽  
Pushan Bag ◽  
Lars Björkén ◽  
...  

Fertilization with nitrogen (N)-rich compounds leads to increased growth, but may compromise phenology and winter survival of trees in boreal regions. During autumn, N is remobilized from senescing leaves and stored in other parts of the tree to be used in the next growing season. However, the mechanism behind the N fertilization effect on winter survival is not well understood and it is unclear how N levels or forms modulate autumn senescence. We performed fertilization experiments and showed that treating Populus saplings with high or low levels of inorganic nitrogen resulted in a delay in senescence. In addition, by using precise delivery of solutes into the xylem stream of Populus trees in their natural environment, we found that delay of autumn senescence was dependent on the form of N administered: inorganic N (NO3-1) delayed senescence but amino acids (Arg, Glu, Gln, and Leu) did not. Metabolite profiling of leaves showed that the levels of tricarboxylic acids (TCA), arginine catabolites (ammonium, ornithine), glycine, glycine-serine ratio and overall carbon-to-nitrogen (C/N) ratio were affected differently by the way of applying NO3-1 and Arg treatments. In addition, the onset of senescence did not coincide with soluble sugar accumulation in any of the treatments. Taken together, metabolomic rearrangement under different N forms or experimental setups could modulate senescence process, but not initiation and progression in Populus. We propose that the different regulation of C and N status through direct molecular signaling of NO3-1 could account for the contrasting effects of NO3-1 and Arg on senescence.

2021 ◽  
Vol 11 (13) ◽  
pp. 5788
Author(s):  
Dominic Kwadwo Anning ◽  
Zhilong Li ◽  
Huizhen Qiu ◽  
Delei Deng ◽  
Chunhong Zhang ◽  
...  

Amino sugars are key microbial biomarkers for determining the contribution of microbial residues in soil organic matter (SOM). However, it remains largely unclear as to what extent inorganic nitrogen (N) fertilization can lead to the significant degradation of SOM in alkaline agricultural soils. A six-year field experiment was conducted from 2013 to 2018 to evaluate the effects of chronic N enrichment on microbial residues, amino sugars, and soil biochemical properties under four nitrogen (urea, 46% N) fertilization scenarios: 0 (no-N, control), 75 (low-N), 225 (medium-N), and 375 (high-N) kg N ha−1. The results showed that chronic N enrichment stimulated microbial residues and amino sugar accumulation over time. The medium-N treatment increased the concentration of muramic acid (15.77%), glucosamine (13.55%), galactosamine (18.84%), bacterial residues (16.88%), fungal residues (11.31%), and total microbial residues (12.57%) compared to the control in 2018; however, these concentrations were comparable to the high-N treatment concentrations. The ratio of glucosamine to galactosamine and of glucosamine to muramic acid decreased over time due to a larger increase in bacterial residues as compared to fungal residues. Microbial biomass, soil organic carbon, and aboveground plant biomass positively correlated with microbial residues and amino sugar components. Chronic N enrichment improved the soil biochemical properties and aboveground plant biomass, which stimulated microbial residues and amino sugar accumulation over time.


2019 ◽  
Author(s):  
Xinzhuan YAO ◽  
Litang Lu ◽  
Degang ZHAO

Abstract Background: Brassinosteroids (BRs) are essential hormones that play crucial roles in plant growth, reproduction and response to abiotic and biotic stress. Results: In transgenic Petunia hybrida , resulting in short stature, dark green leaves, and slowed aging.We demonstrate that the exogenous expression of the SAG12-BAS1 gene results in delayed senescence of flowers. SAG12-BAS1 transgenic lines, grown in the vegetative state, exhibited a range of phenotypic changes, including dark green leaves, short stature, delayed senescence, increased flower bud counts, branching, reduced internode lengths, and delayed flowering. SAG12-BAS1 transgenic expression increased the activity of protective enzymes, reduced malondialdehyde content, and increased chlorophyll content and soluble sugar accumulation in plants. Expression of senescence genes was increased in the transgenic Petunia hybrida compared to wild-type plants. Conclusions: Our finding suggests that BAS1 could be used as a potential candidate gene regulate plant flower senescence and prolong flower longevity.


Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1328
Author(s):  
Danielle Le Lievre ◽  
Rachelle Anderson ◽  
Helen Boldingh ◽  
Janine Cooney ◽  
Richard Seelye ◽  
...  

Consumer acceptance of fruit is determined by size, flavour and ripeness. In this study we investigated how altering the carbohydrate supply to Actinidia chinensis var. chinensis ‘Zesy002′ kiwifruit altered the balance between growth and accumulation of metabolites. Canes were phloem girdled and fruit thinned to a leaf-to-fruit ratio (L:F) of either 2 (Low carbohydrate) or 6 (High carbohydrate) at either 38 (Early) or 86 (Late) days after anthesis (DAA) and compared with ungirdled control canes with a L:F of 3. Fruit growth, metabolite accumulation, cytokinin concentrations and maturation were monitored and the sensory attributes of ripe fruit were assessed. The final weight of Early-High and Late-High carbohydrate fruit was 38% and 16% greater compared with control fruit. High carbohydrate fruit had increased starch,soluble sugar and cytokinin concentrations and fruit began to mature earlier and those with a Low carbohydrate had decreased concentrations and matured later compared with control fruit. Control fruit were described by consumers as more acidic and under-ripe compared with those from Early-High carbohydrate canes, but as sweeter than those from Low carbohydrate canes. This study showed that carbohydrate supply can have a major impact on the growth, sugar accumulation and maturity of ‘Zesy002′ fruit sinks.


2021 ◽  
Author(s):  
Nakian Kim ◽  
Gevan D. Behnke ◽  
María B. Villamil

Abstract. Modern agricultural systems rely on inorganic nitrogen (N) fertilization to enhance crop yields, but its overuse may negatively affect soil properties. Our objective was to investigate the effect of long-term N fertilization on key soil properties under continuous corn [Zea mays L.] (CCC) and both the corn (Cs) and soybean [Glycine max L. Merr.] (Sc) phases of a corn-soybean rotation. Research plots were established in 1981 with treatments arranged as a split-plot design in a randomized complete block design with three replications. The main plot was crop rotation (CCC, Cs, and Sc), and the subplots were N fertilizer rates of 0 kg N ha−1 (N0, controls), and 202 kg N ha−1, and 269 kg N ha−1 (N202, and N269, respectively). After 36 years and within the CCC, the yearly addition of N269 compared to unfertilized controls significantly increased cation exchange capacity (CEC, 65 % higher under N269) and acidified the top 15 cm of the soil (pH 4.8 vs. pH 6.5). Soil organic matter (SOM) and total carbon stocks (TCs) were not affected by treatments, yet water aggregate stability (WAS) decreased by 6.7 % within the soybean phase of the CS rotation compared to CCC. Soil bulk density (BD) decreased with increased fertilization by 5 % from N0 to N269. Although ammonium (NH4+) did not differ by treatments, nitrate (NO3−) increased eight-fold with N269 compared to N0, implying increased nitrification. Soils of unfertilized controls under CCC have over twice the available phosphorus level (P) and 40 % more potassium (K) than the soils of fertilized plots (N202 and N269). On average, corn yields increased 60 % with N fertilization compared to N0. Likewise, under N0, rotated corn yielded 45 % more than CCC; the addition of N (N202 and N269) decreased the crop rotation benefit to 17 %. Our results indicated that due to the increased level of corn residues returned to the soil in fertilized systems, long-term N fertilization improved WAS and BD, yet not SOM, at the cost of significant soil acidification and greater risk of N leaching and increased nitrous oxide emissions.


1970 ◽  
Vol 16 ◽  
pp. 95-99 ◽  
Author(s):  
Md Rezaul Karim ◽  
MMH Khan ◽  
Md Salim Uddin ◽  
NK Sana ◽  
F Nikkon ◽  
...  

Significant differences were found in sugar content and carbohydrate splitting enzyme activities in tubers of ten indigenous potato varieties at harvesting and after keeping at cold storage. The activities of invertase, amylase, β-galactosidase and cellulase in all varieties were found to be increased by 2-12, 1.2-4, 1.9-4.5, and 1.1-3.7 folds, respectively from harvesting to cold stored potatoes. The amount of starch and sucrose were found to be decreased by 1.15-2.8 and 1.02-1.4 folds, respectively from harvesting to cold stored in all varieties. Total soluble sugar and reducing sugar contents in potatoes were increased by 1.02-1.4 and 4-11 folds, respectively from harvesting to cold stored in all varieties of potatoes. The amount of reducing sugar increased in cold stored potatoes due to the increased activities of carbohydrate splitting enzymes. Key words: Potatoes, Indigenous, Carbohydrate splitting enzymes, Sugars. DOI:10.3329/jbs.v16i0.3748 J. bio-sci. 16: 95-99, 2008


Agronomy ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 609 ◽  
Author(s):  
Qaswar ◽  
Jing ◽  
Ahmed ◽  
Shujun ◽  
Dongchu ◽  
...  

A long-term field experiment was carried out (since 2008) for evaluating the effects of different substitution rates of inorganic nitrogen (N) fertilizer by green manure (GM) on yield stability and N balance under double rice cropping system. Treatments included, (1) N0 (no N fertilizer and no green manure); (2) N100 (recommended rate of N fertilizer and no green manure); (3) N100-M (recommended rate of N fertilizer and green manure); (4) N80-M (80% of recommended N fertilizer and green manure); (5) N60-M (60% of recommended N fertilizer and green manure); and (6) M (green manure without N fertilization). Results showed that, among all treatments, annual crop yield under N80-M treatment was highest. Crop yield did not show significant differences between N100-M and N80-M treatments. Substitution of different N fertilizer rates by GM reduced the yield variability index. Compared to the N0 treatment, yield variability index of early rice under N100-M, N80-M, and N60-M treatments was decreased by 11%, 26%, and 36%, respectively. Compared to the N0 treatment, yield variability index of late rice was decreased by 12%, 38%, 49%, 47%, and 24% under the N100, N100-M, N80-M, N60-M, and M treatments, respectively. During period of 2009–2013 and 2014–2018, nitrogen recovery efficiency (NRE) was highest under N80-M treatment and N balance was highest under N100 treatment. NRE of all treatments with GM was increased over the time from 2009–2013 to 2014–2018. All treatments with GM showed increasing trend of SOC over the years. Substitution of N fertilizer by GM also increased C inputs and soil C:N ratio compared to the N100 and N0 treatments. Boosted regression model indicated that C input, N uptake and AN were most influencing factors of crop yield. Thus, we concluded that N fertilization rates should be reduced by 20% under GM rotation to attain high yield stability of double rice cropping system through increasing NRE and C inputs.


2017 ◽  
Vol 9 (8) ◽  
pp. 155
Author(s):  
Ying-zhi Li ◽  
Xiao-qiang Duan ◽  
Sheng-hui Liu ◽  
Ying Li ◽  
Xing-hai Zhang ◽  
...  

Jackfruit (Artocarpus heterophyllus Lam.) is an important food crop widely grown in the tropical region. However, little is known about sugar metabolism during fruit ripening of jackfruit. Here we examined sugar profiles (sucrose, glucose and fructose) and corresponding enzyme activities (SPS, E.C.2.4.1.14; SuSy, EC 2.4.1.13; IV, EC 3.2.1.26) of four soft type and four firm type varieties of jackfruit during four stages of fruit ripening. We found that during fruit ripening, there was a rapid increase in contents of total soluble sugar and sucrose, whereas increases in glucose and fructose contents were much slower. Ratios of glucose versus fructose varied among different varieties and ripening stages but within the range of 0.9 to 1.2 in the ripe fruits. Five of these varieties exhibited markedly high levels of SuSy activity for sucrose synthesis at early ripening stage, and then decreased towards fully ripe stage. All soft type varieties exhibited a conspicuous peak of AIV activity and had overall higher AIV activities than NIV during ripening. The changing patterns for other enzymes varied among varieties. Our studies support the notion that sucrose was the major sugar species contributing to the fruit sweetness, followed by fructose and glucose. We also demonstrated that AIV and NIV were probably the primary enzymes responsible for sucrose hydrolysis during ripening, while SPS and SuSy were responsible for sucrose synthesis. We propose that during fruit ripening of jackfruit, glucose is released from starch hydrolysis, followed by sucrose hydrolysis leading to increase in both glucose and fructose contents.


2001 ◽  
Vol 31 (5) ◽  
pp. 899-909 ◽  
Author(s):  
Staffan Jacobson ◽  
Folke Pettersson

To study growth responses to refertilization, 12 Scots pine (Pinus sylvestris L.) and 6 Norway spruce (Picea abies (L.) Karst.) stands used in long-term nitrogen (N) fertilization experiments were refertilized with N, either alone or with various combinations and doses of phosphorus (P), potassium (K), and magnesium (Mg). Many of the experimental plots had previously been subjected to heavy N fertilization regimes over a period of 20–30 years. On average, for all the experiments, the latest N addition resulted in a significant growth increase, corresponding to 57% of the mean annual volume increment and comparable with the response to the initial fertilization. Differences in growth response between fertilization with N alone or in combination with P–K–Mg were in most cases insignificant for both tree species. Overall, the joint addition of P–K–Mg resulted in a nonsignificant additional growth increase of 0.2 m3·ha–1·year–1, corresponding to 6% of the N fertilization effect. Repeated additions of N alone had no effect on the P, K, and Mg concentrations in current-year needles. It was concluded that the repeated N fertilizations did not cause any serious nutrient deficiencies.


2021 ◽  
Author(s):  
Haicui Xie ◽  
Fengyu Shi ◽  
Jingshi Li ◽  
miaomai Yu ◽  
Jia Fan ◽  
...  

Abstract Due to rising concentration of atmospheric CO2, climate change is predicted to intensify episodes of drought, however, our understanding of how combined environmental conditions will influence crop-insect interactions is limited. The direct effects of elevated CO2 and drought stress on wheat (Triticum aestivum L.) nutritional quality, insect resistance and their indirect effects on the grain aphid (Sitobion avenae) performance are reported here. Elevated CO2 was able to alleviate low water content in wheat caused by drought stress. Both elevated CO2 and drought promoted soluble sugar accumulation in wheat. However, elevated CO2 decreased and drought increased the amino acid content in wheat. Elevated CO2 induced the down-regulation of jasmonic acid (JA) -dependent defense, but up-regulated the salicylic acid-dependent defense. Drought enhanced abscisic acid accumulation that promoted the JA-dependent defense in wheat. Aphid-induced phytohormone resistance in wheat was not influenced by elevated CO2 and drought. The negative effects of drought on the performance of the aphid population was offset by positive effect of elevated CO2. In conclusion, elevated CO2 can alleviate the effects of drought stress on wheat nutritional quality and resistance, which results in unchanged damage to wheat from aphid populations under future elevated CO2 and drier conditions.


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