Aboveground Biomass Content Research Articles

Effect of Zinc Foliar Fertilization Alone and Combined with Trehalose on Maize (Zea mays L.) Growth under the Drought.

Maize (Zea mays L.) is one of the most widely grown cereals in the world. Its cultivation is affected by abiotic stress caused by climate change, in particular, drought. Zinc (Zn) supplied by foliar nutrition can increase plant resistance to water stress by enhancing physiological and enzymatic antioxidant defence mechanisms. One of the possibilities to reduce the effect of drought on plant production is also the utilization of trehalose. In order to confirm the effect of the foliar application of selected forms of Zn (0.1% w/v solution)-zinc oxide micro- (ZnO) and nanoparticles (ZnONP), zinc sulphate (ZnSO4) and zinc chelate (ZnEDTA)-a pot experiment in controlled conditions was conducted in combination with trehalose (1% w/v solution) on selected growth parameters of maize exposed to the drought stress. A significant effect of coapplication of Zn and trehalose on chlorophyll content, chlorophyll fluorescence parameters, root electrical capacity, weight of maize aboveground biomass (AGB) and Zn content in AGB was found. At the same time, the hypothesis of a positive effect of carbohydrates on increasing the uptake of foliar-applied Zn was confirmed, especially for the ZnEDTA and ZnSO4. This paper presents the first empirical evidence of the trehalose addition to sprays for zinc foliar fertilization of maize proving to be an effective way of increasing the resistance of maize grown under drought stress conditions.

Phytoremediation of nickel and zinc using Jatropha curcas and Pongamia pinnata from the soils contaminated by municipal solid wastes and paper mill wastes

The primary source of soil pollution is a complex mixture of numerous inorganic and organic compounds (including chlorinated compounds, nutrients, and heavy metals, etc.). The presence of all of these compounds makes remediation and cleanup difficult. In this study, the phytoremediation ability of Jatropha curcas and Pongamia pinnata was tested to remove nickel (Ni) and Zinc (Zn) from paper mill and municipal landfill contaminated soils, to understand the uptake potential and to estimate the accumulation pattern of Ni and Zn in the vegetative parts of the plant. The experiments were carried out in pots (3 kg capacity) and the different combinations of soil were made by mixing the contaminated soil with a reference soil (forest soil) as T0, T25, T50, T75 and T100. The plant biomass, chlorophyll content, proline, nitrate reductase activity and metal removal efficiency (%)were determined after 120 DAS (i.e., the days after sowing). The results of the study showed that with increasing metal stress, there is a reduction in the above-ground biomass content in both the plant species with a slightly less impact on the root biomass. Over a period of 4 months, J. curcas and P. pinnata removed 82–86% and 93-90% Ni, respectively. The removal of Zn was significantly less as compared to Ni as most of the Zn remained in the belowground part (roots) and in the soil. Besides, the phytostabilization capacities of the plants were calculated on the basis of their tolerance index (TI), bioaccumulation factor (BAF) and translocation factor (TF). The low BAF and TF values with increasing heavy metals (HMs) content indicates its higher phytostabilization capacity in the root and rhizospheric region as compared to phytoaccumulation.

Effects of Nitrogen Addition on Plant Properties and Microbiomes Under High Phosphorus Addition Level in the Alpine Steppe.

Nitrogen (N) addition can increase the vegetative growth, improve the plant production, and restore the degraded terrestrial ecosystems. But, it simultaneously aggravates the soil phosphorus (P) limitation for plant growth, thus affecting its positive effects on ecosystems. However, how plants and soil microorganisms will change under conditions of high P content in soil is still unknown. In this study, we explored the effects of three levels of N addition (0, 7.5, and 15 g.N.m–2.year–1) on plants and microorganisms at the high P addition level (13.09 g.P.m–2.year–1) in the alpine steppe. We found that the soil microbial community composition had no significant difference between different N addition levels, and the soil AN and AP had a significant effect on the phospholipid fatty acid (PLFA) composition. The abundance of the core PLFAs (i.e., 16:1ω7c, 16:0, a17:1, i17:0, 18:1ω9c, and 18:1ω7c) also remained unchanged after N addition, and microbes at individual, population, and community levels were all correlated with SOM, AK, AN, and pH. Conversely, plant biomass and nutrient content showed linear trends with increasing N addition, especially the dominant functional groups. Specifically, the biomass and plant tissue N content of Gramineae, and the total N content of aboveground biomass were all improved by N addition. They were correlated with soil ammonium and AP. The structural equation modeling (SEM) demonstrated that N addition had a direct negative effect on soil microbial biomass, but an indirect positive effect on aboveground biomass via soil ammonium. These findings clarify the importance of N-amendment in regulating plants and microorganisms under high P conditions and provide a better understanding of the N-added effects in the alpine steppe.

Effects of Cultivar, Nitrogen Rate and Harvest Time on the Content of Carbohydrates and Protein in the Biomass of Perennial Ryegrass

The aim of this study was to determine the effects of cultivar, nitrogen (N) rate and harvest time on the content of water-soluble carbohydrates (WSC), crude protein (CP) and the WSC:CP ratio in the aboveground biomass of perennial ryegrass (Lolium perenne L.). A small-area field experiment was conducted in the Agricultural Experiment Station in Tomaszkowo (53°42′40.8″ N 20°26′04.7″ E, north-eastern Poland). Data were presented for three years of full utilization (2013–2015). The experimental factors were as follows: (i) perennial ryegrass cultivar: Bajka and Baronka, (ii) N rate (kg ha−1): 0, 120, and 240, and (iii) harvest time: 8.00–10.00 a.m., 12.00–2.00 p.m., and 4.00–6.00 p.m. The tetraploid cultivar Baronka had higher WSC content and lower CP content on a dry matter (DM) basis than the diploid cultivar Bajka (by approx. 3% on average). An increase in N fertilizer rate to 240 kg ha−1 contributed to a decrease in WSC concentrations by 23% in cv. Bajka and by 19% in cv. Baronka, and to an increase in the CP content of aboveground biomass by 32% and 23%, respectively. Both cultivars accumulated significantly higher WSC amounts when biomass was harvested at noon and in the afternoon than in the morning. The CP content of biomass was also affected by harvest time, and it was higher in cv. Bajka when harvesting was carried out at 12.00–2.00 p.m. and 4.00–6.00 p.m., and in cv. Baronka when harvesting was carried out at 4.00–6.00 p.m. The WSC:CP ratio in the biomass of the analyzed cultivars was within the optimal range for ruminants, and it was higher in cv. Baronka (1:1.11). Nitrogen applied at 240 kg ha−1 had a negative influence on the WSC:CP ratio, decreasing its value by around 36% (relative to the rate of 120 kg N ha−1) and around 35% (relative to the unfertilized treatment). In both perennial ryegrass cultivars, biomass harvested in the morning was characterized by the lowest WSC:CP ratio.

Upscaling proximal sensor N-uptake predictions in winter wheat (Triticum aestivum L.) with Sentinel-2 satellite data for use in a decision support system

Total nitrogen (N) content in aboveground biomass (N-uptake) in winter wheat (Triticum aestivum L.) as measured in a national monitoring programme was scaled up to full spatial coverage using Sentinel-2 satellite data and implemented in a decision support system (DSS) for precision agriculture. Weekly field measurements of N-uptake had been carried out using a proximal canopy reflectance sensor (handheld Yara N-Sensor) during 2017 and 2018. Sentinel-2 satellite data from two processing levels (top-of-atmosphere reflectance, L1C, and bottom-of-atmosphere reflectance, L2A) were extracted and related to the proximal sensor data (n = 251). The utility of five vegetation indices for estimation of N-uptake was compared. A linear model based on the red-edge chlorophyll index (CI) provided the best N-uptake prediction (L1C data: r2 = 0.74, mean absolute error; MAE = 14 kg ha−1) when models were applied on independent sites and dates. Use of L2A data, rather than L1C, did not improve the prediction models. The CI-based prediction model was applied on all fields in an area with intensive winter wheat production. Statistics on N-uptake at the end of the stem elongation growth stage were calculated for 4169 winter wheat fields > 5 ha. Within-field variation in predicted N-uptake was > 30 kg N ha−1 in 62% of these fields. Predicted N-uptake was compared against N-uptake maps derived from tractor-borne Yara N-Sensor measurements in 13 fields (1.7–30 ha in size). The model based on satellite data generated similar information as the tractor-borne sensing data (r2 = 0.81; MAE = 7 kg ha−1), and can therefore be valuable in a DSS for variable-rate N application.

Phenotypic and Nodule Microbial Diversity among Crimson Clover (Trifolium incarnatum L.) Accessions

Crimson clover (Trifolium incarnatum L.) is the most common legume cover crop in the United States. Previous research found limited genetic variation for crimson clover within the National Plant Germplasm System (NPGS) collection. The aim of this study was to assess the phenotypic and nodule microbial diversity within the NPGS crimson clover collection, focusing on traits important for cover crop performance. Experiments were conducted at the Beltsville Agricultural Research Center (Maryland, USA) across three growing seasons (2012–2013, 2013–2014, 2014–2015) to evaluate 37 crimson clover accessions for six phenotypic traits: fall emergence, winter survival, flowering time, biomass per plant, nitrogen (N) content in aboveground biomass, and proportion of plant N from biological nitrogen fixation (BNF). Accession effect was significant across all six traits. Fall emergence of plant introductions (PIs) ranged from 16.0% to 70.5%, winter survival ranged from 52.8% to 82.0%, and growing degree days (GDD) to 25% maturity ranged from 1470 GDD to 1910 GDD. Biomass per plant ranged from 1.52 to 6.51 g, N content ranged from 1.87% to 2.24%, and proportion of plant N from BNF ranged from 50.2% to 85.6%. Accessions showed particularly clear differences for fall emergence and flowering time, indicating greater diversity and potential for selection in cover crop breeding programs. Fall emergence and winter survival were positively correlated, and both were negatively correlated with biomass per plant and plant N from BNF. A few promising lines performed well across multiple key traits, and are of particular interest as parents in future breeding efforts, including PIs 369045, 418900, 561943, 561944, and 655006. In 2014–2015, accessions were also assessed for nodule microbiome diversity, and 11 genera were identified across the sampled nodules. There was large variation among accessions in terms of species diversity, but this diversity was not associated with observed plant traits, and the functional implications of nodule microbiome diversity remain unclear.

Available Nitrogen in Paddy Soils Depth: Influence on Rice Root Morphology and Plant Nutrition

Nitrogen (N) is a key nutrient for rice (Oryza sativa L.) and its availability in soil profile can influence the plant root morphology and total nutrient uptake. This study evaluated if N from deeper soil layers would increase rice root growth, N uptake and influence plant nutritional status. Flooded rice was grown in undisturbed soil samples from three locations with 15N-labeled ammonium sulfate application at different depths (0, 10, 20, 30, and 45 cm). At rice heading, chlorophyll content and photosynthesis rate were measured at flag leaves and rice biomass production, root morphology, and total N and 15N uptake were evaluated. Higher biomass and N uptake were observed with N application at near soil surface layers. The majority of rice N uptake was derived from soil, which was more evident when N fertilizer was injected at 45 cm deep (on average 74%). The highest root growth was observed at the near surface layers with constant decrease in depth, up to 60 cm. Roots from deeper layers exhibited smaller diameter, as they were mainly highly branched roots. The N application at 30 and 45 cm depths provided N later in the season, resulting in plants with lower total biomass but with higher N content in aboveground biomass, with higher chlorophyll content, photosynthesis rate, and carboxylation efficiency by Rubisco. The N available below 20 cm contributes to plant nutrition and root growth, hence soils with available N in depth likely cause plants to function more optimally in photosynthates supply.

Clipping strategy to assist phytoremediation by hyperaccumulator Dicranopteris dichotoma at rare earth mines

Little is known about the clipping strategy to assist phytoremediation by Dicranopteris dichotoma at rare earth mines. We evaluated the phytoremediation ability of D. dichotoma, designed an appropriate clipping strategy, and obtained the phytoextraction time for rare earth elements (REE) by field investigation, laboratory measurement, and statistical analysis etc. at four rare earth mines in south China. D. dichotoma growth and soil nutrients tended to increase across the ecological restoration chronosequence, the total REE content in aboveground biomass was ≥1,000 mg kg−1, the bioabsorption coefficient and translocation factor were ≥1, and the phytoextraction of light REE was greater than heavy REE. Overall, the REE accumulation did not vary significantly among seasons, the total REE accumulation in the underground biomass accounted for 26.55–64% and the vegetation covers were about 90% two years after clipping. It would take 57.88–168.57 years to reduce soil total REE content, and the soil nutrients and REE accumulations of D. dichotoma at Longjing were the highest. D. dichotoma has potential for REE phytoextraction and phytostabilization simultaneously. D. dichotoma should be clipped in winter once every two years with underground biomass retained. The REE phytoextraction time is long with soil nutrients being important influencing factors.

Density management diagrams for sweet chestnut high-forest stands in Portugal

Abstract: This study aims to develop stand density management diagrams (SDMDs) for pure even-aged high-forest stands of sweet chestnut in Portugal, defining the appropriate upper and lower limits of growing stock while considering the biological, technological and economic objectives that are expected for these stands. The SDMDs were developed with data collected from high-forest stands in northern Portugal, which is the main representative area of these stands in the country. Data were collected from 23 pure even-aged permanent plots with re-measurement intervals of 4-10 years, 43 semi-permanent plots and 18 even-aged temporary plots; all plots were established in chestnut high-forest stands with a broad range of ages. SDMDs were constructed by simultaneously fitting four nonlinear equations relating stand variables using the full information likelihood technique. SDMDs for the estimation of stand total volume, stand stem biomass, stand total aboveground biomass, and carbon content in aboveground biomass are presented as bivariate graphs with dominant height on the x-axis and the number of trees per hectare on the y-axis (using logarithmic scale). A tool is made available to define an optimal range of stand density for a silviculture oriented to single-stem selection on a tree-by-tree basis, focusing management on the most valuable trees. This tool is aimed to support forest managers in the decision-making process, enabling them to schedule thinnings on the basis of the dominant height growth of the trees with the greatest potential (frame trees), maintaining an adequate growing stock and assessing the corresponding aboveground wood volume, biomass, carbon, and mean diameter breast height.

Distinguishing the vegetation dynamics induced by anthropogenic factors using vegetation optical depth and AVHRR NDVI: A cross-border study on the Mongolian Plateau

Distinguishing the vegetation dynamics induced by anthropogenic factors and identifying the major drivers can provide crucial information for designing actionable and practical countermeasures to restore degraded grassland ecosystems. Based on the residual trend (RESTREND) method, this study distinguished the vegetation dynamics induced by anthropogenic factors from the effects of climate variability on the Mongolian Plateau during 1993–2012 using vegetation optical depth (VOD) and normalized difference vegetation index (NDVI), which measure vegetation water content in aboveground biomass and chlorophyll abundance in canopy cover respectively; afterwards, the major drivers within different agricultural zones and socio-institutional periods were identified by integrating agricultural statistics with statistical analysis techniques. The results showed that grasslands in Mongolia and the grazing zone of Inner Mongolia Autonomous Region (IMAR), China underwent a significant human-induced decrease in aboveground biomass during 1993–2012 and 1993–2000 respectively, which was attributable to the rapid growth of livestock densities stimulated by livestock privatization and market factors; by contrast, grasslands in these two regions did not experience a concurrent human-induced reduction in canopy greenness. Besides, the results indicated that grasslands in the grazing zone of IMAR underwent a significant human-induced increase in aboveground biomass since 2000, which was attributable to the reduced grazing pressure induced by China's ecological restoration programs; concurrently, grasslands in this region also experienced a remarkable increase in canopy greenness, however, this increase was found not directly caused by the decreased stocking densities. Furthermore, the results revealed that the farming and semi-grazing/farming zone of IMAR underwent a significant human-induced increase in both aboveground biomass and canopy greenness since 2000, which was attributable to the intensified grain production stimulated by market factors, open grazing regulation and confined feeding popularization. These findings suggest that China's grassland restoration practice has important implications for Mongolia to reverse the severe and continuous grassland degradation in the future.

EFEKTIVITAS VERMIKOMPOS EISENIA FOETIDA SAVIGNY DALAM MEMPERBAIKI TINGKAT PRODUKSI DAN KUALITAS NUTRISI Sorghum bicolor (L.) Moench DAN Centrosema pubescens Benth

Vermicomspost is an organic product resulted from metabolism process of soil worm like Eisenia foetida Savigny. The experiment was conducted to evaluate the effectivity of vermicompost derived from E. Foetida Savigny in improvement of growth, biomass production and quality of Sorghum bicolor (L.) Moench and Centrosema pubescencs. The results showed that application of vermicompost effectively improved growth, biomass production and N, P, K content of above ground biomass of those experimental plants.Keywords : vermicompost, productivity, quality.

Providing optimum models for predicting the water loss after harvesting and extracting trees aboveground biomass from the Hyrcanian mixed-beech forests

The ecological and biological attributes of trees stand as well as the water cycle in forests are substantially related to variations of water storage capacity in forest ecosystems. This study aimed to figure out a protocol for monitoring the water storage capacity variations in the Hyrcanian mixed-beech stands after harvesting and extracting trees form the forest. A total of 174 trees were felled and weighed, and destructive sampling following lines of exploitation was carried out for measuring the water content in aboveground biomass of trees. Curve estimation regression analyses including the tree biophysical variables (breast height diameter DBH, total height H, basic wood density $$\rho$$ ) were used for examining the prediction accuracy. Nonlinear models were log-transformed, and systematic bias was corrected by correction factor depending on standard error of estimate when back-transforming to the originally dependent value. The findings showed that the power-law models were the best functional form for predicting the dependent variables. Using only DBH in the simple power model explained 76% of total variance (Adj.R 2 = 0.76) with a low Akaike information criterion (AIC) and normalized root-mean-square error RMSE%, indicating a high accuracy of prediction ( $${\text{AIC}} \approx - 238$$ ; RMSE% = 11.7). Adding H and $$\rho$$ in the linear log-transformed power models with different interaction terms increased the certainty of prediction with the highest accuracy ( $${\text{Adj}}.R^{2} = 0.86,\;{\text{AIC}} = - 329,\;{\text{RMSE}}\% = 9$$ ). Considering diverse conditions for natural forest sites, the optimum models including the biophysical variables may have associated parameters in the other forests having different stand types and compositions.

Interactions of Nitrogen Source and Rate and Weed Removal Timing Relative to Nitrogen Content in Corn and Weeds and Corn Grain Yield.

Adequate fertility combined with effective weed management is important in maximizing corn (Zea mays L.) grain yield. Corn uptake of nitrogen (N) is dependent upon many factors including weed species and density and the rate and formulation of applied N fertilizer. Understanding interactions among corn, applied N, and weeds is important in developing management strategies. Field studies were conducted in North Carolina to compare corn and weed responses to urea ammonium nitrate (UAN), sulfur-coated urea (SCU), and composted poultry litter (CPL) when a mixture of Palmer amaranth (Amaranthus palmeri S. Wats.) and large crabgrass (Digitaria sanguinalis L.) was removed with herbicides at heights of 8 or 16 cm. These respective removal timings corresponded with 22 and 28 days after corn planting or V2 and V3 stages of growth, respectively. Differences in N content in above-ground biomass of corn were noted early in the season due to weed interference but did not translate into differences in corn grain yield. Interactions of N source and N rate were noted for corn grain yield but these factors did not interact with timing of weed control. These results underscore that timely implementation of control tactics regardless of N fertility management is important to protect corn grain yield.

Growth Efficacy of Sorghum and Rice Amended with Dried Versus Composted Aquatic Vegetation

Aquatic vegetation is a potential source of organic matter and nutrients for crop production and soil sustainability. However, its high water content and presence of toxic compounds have been major deterrents for commercial application. This split-pot study evaluated the application of <em>Pistia stratiotes</em> (PS) (water lettuce) and <em>Lyngbya wollei</em> (LW) (filamentous cyanobacteria) to grow rice and sorghum. The aquatic vegetation was applied as dried and composted amendments on sandy (<3% organic matter) and muck (>80% organic matter) soils. A completely randomized split-pot design evaluated the effect of the amendments on root dry weight (RDW), shoot dry weight (SDW), and nutrient content of above ground biomass. The application of dried PS and LW on sandy soil produced larger and heavier sorghum shoots than those grown under composted treatments. Soil type was not a determinant factor of plant nutrient content: total Kjeldahl nitrogen, phosphorus, potassium and silicon. Shoot dry weight of rice grown on sandy soils was significantly greater than grown on muck soils using dried LW and composted LW treatments. The allelopathic effects of PS and LW were more pronounced on sandy soil compared to muck soil, indicating the potential application for using aquatic vegetation as a soil amendment on sandy soil in the future.

Carbon and nitrogen storage in California sage scrub and non-native grassland habitats

Human activity has altered global carbon and nitrogen cycles, leading to changes in global temperatures and plant communities. Because atmospheric carbon (C) and nitrogen (N) concentrations are affected by storage in terrestrial vegetation and soil, it is critical to understand how conversions from native to non-native vegetation may alter the C and N storage potential of terrestrial landscapes. In this study, we compared C and N storage in native California sage scrub, non-native grassland, and recovering California sage scrub habitats in the spring and fall by determining the C and N content in aboveground biomass, litter, and surface soil. Significantly more C and N were stored in intact and recovering California sage scrub than in grassland habitats. Intact and recovering sage scrub did not differ significantly in C or N storage. Our results highlight that preserving and restoring California sage scrub habitat not only provides habitat for native biodiversity, but also increases carbon and nitrogen storage potential even without restoration to intact sage scrub.

Early-maturing annual legumes: an option for cover cropping in rainfed olive orchards

Cover cropping is a major challenge in the sustainable management of rainfed olive orchards. From a 5 year study (2009–2014), the effect of a mixture of early-maturing and self-reseeding annual legumes (Legs) grown as a cover crop in a rainfed olive orchard was compared with a cover of natural vegetation fertilized with 60 kg nitrogen (N) ha−1 year−1 (NV +N), and a cover of natural vegetation not fertilized (NV −N). The study took place in NE Portugal. The following were assessed: (1) the performance of the covers by measuring ground cover percentages, dry matter yields and N content in aboveground biomass; (2) the soil fertility through chemical and microbiological assays and by growing plants in pot experiments; and (3) the nutritional status of olive trees and olive yields. Legumes gave higher ground-cover percentages, produced more biomass and accumulated more N in shoots in comparison to natural vegetation, whether fertilized or not. The results showed intense biological activity [microbial carbon (C) and N, CO2–C evolved in a laboratory incubation, metabolic quotient, total culturable fungi and bacteria, and acid phosphatase activity] in the 0–10 cm soil layer of the treatments producing more biomass (Legs and NV +N). However, soil available N was greater in soil samples from the Legs plot. N recoveries by turnip (Brassica rapa var. rapa L.) and rye (Secale cereale L.) grown in pot experiments were 84.4 and 60.2 mg pot−1 in soil samples from the Legs treatment and 29.4 and 27.1 mg pot−1 and 14.2 and 13.6 mg pot−1, respectively in NV +N and NV −N plots. Sown legumes appeared less effective in increasing organic C than natural vegetation. Nevertheless, in the Legs plot the increase of easily mineralizable C was proportionally higher than the increase of total organic C, which may mean that a more reactive pool of organic C is created, which may reduce the turnover of organic C and N in the soil. In the 10–20 cm soil layer, total organic C was significantly lower in Legs (14.0 g kg−1) than in NV −N (22.1 g kg−1) and N +NV (25.2 g kg−1) treatments, likely due to a priming effect caused by mineral N coming from the surface layer. Two years after the trial started, the N nutritional status of the olive trees was significantly higher in Legs than in natural vegetation plots even when 60 kg N ha−1 year−1 was applied. The cumulative olive yields in NV −N and NV +N plots were only 58.6 and 77.7 % in comparison to those found in the Legs plot, if only the last four harvests were considered, which were those influenced by the ground-cover treatments (2010–2013).

Self-reseeding annual legumes for cover cropping in rainfed managed olive orchards

Given the environmental impact of nitrogen (N)-fertilizer manufacture and use, the sustainable management of agro-systems should be sought by growing N-fixing legumes. In this work, eleven self-reseeding annual legumes were grown in pure stands as mulching cover crops in a rainfed olive orchard managed without grazing animals. Dry matter yield, N content in above-ground biomass, groundcover percentage and persistence of the sown species were assessed during four growing seasons. All covers provided enough soil protection over the year, with living plants during the autumn/winter period and a mulch of dead residues during the summer. The legumes overcame a false break observed in the third year recovering the dominance of the covers in the fourth growing season. This means that the seed bank established in previous seasons ensured the persistence of the sown legume even when a gap in seed production occurred. The early-maturing cultivars produced less biomass and fixed less N (approx. 50 kg N/ha/yr present in the above-ground biomass) than the late-maturing ones, but would compete less for water since the growing cycle finished earlier in the spring. They seem best suited to being grown in dry farmed olive orchards with low N demand in drought prone regions.

Multisite Yield Gap Analysis of Miscanthus × giganteus Using the STICS Model

Development and use of models to predict and study the production and the environmental impacts of biomass cropping systems are of great interest for their sustainable development. Improvements were made to the research version of the STICS crop–soil model in order to simulate biomass production and environmental impacts of Miscanthus × giganteus cropping systems in the long term. This research version was then validated on a large database and in various pedoclimatic environments in France and UK. The model accurately simulated biomass production and nitrogen (N) content in aboveground biomass, from planting until 4 to 20 years of cultivation. The model efficiency (EF) was 0.80 and 0.64 for biomass and N content, respectively, and the values of relative RMSE were 23 and 31 %. Soil water and mineral N contents were also satisfactorily predicted (EF = 0.96 and 0.42; relative RMSE = 10 and 72 %). The model accurately reproduced the effect of management practices on the harvested biomass and N export. Yield gap analysis using simulations with and without active stresses revealed that Miscanthus × giganteus biomass production was limited by both water and N availability during the establishment phase but mainly limited by water availability during the post-establishment phase. The STICS crop–soil model can accurately predict Miscanthus × giganteus biomass production and environmental impacts such as water drainage and nitrate leaching and compare strategies with varying N fertilization, irrigation and harvest date.

Content and Uptake of Nutrients with Plant Biomass of Potatoes Depending on Potassium Fertilization

Abstract The influence of potassium fertilizer source and the increasing potassium fertilization levels (0, 200, 400 and 600 mg К2О/kg soil) supplied either as K2SO4 or KCl at equal nitrogen and phosphorus fertilizer background (200 mg N/kg and 150 mg P2O5/kg soil) on the content and the uptake of nutrient elements from the soil in potato plant parts was studied. Pot experiment was carried out. The fertilization with K2SO4 decreased N content in roots from 2.91% at level К200 tо 2.52% at level К600 and increased N content in aboveground biomass compared to the control and variants fertilized with KCl. The increasing KCl rates led to decreasing of N content in aboveground biomass from 4.03% at К200 to 2.34% at potassium level К400. Nitrogen content in tubers at variants fertilized with K decreased compared to the control. Potassium fertilization did not influence considerably P content in the plant parts. The К content in plant parts at variants fertilized with KCl was higher than the plants fertilized with K2SO4. Approximately 74% of absorbed nitrogen from the soil was allocated in the above ground biomass. The rest of the nitrogen was distributed between roots (17%) and tubers (9%). The highest P uptake was determined in control plants. The quantity of the uptaken K allocated in aboveground biomass was the highest (83%). The rest of K was distributed between roots (11%) and tubers (6%).

Effect of Biochar on Relieving Cadmium Stress and Reducing Accumulation in Super japonica Rice

It is of great importance to solve the threats induced by cadmium pollution on crops. This paper examined the effect of biochar on cadmium accumulation in japonica rice and revealed the mechanism underlying the response of protective enzyme system to cadmium stress. Biochar derived from rice straw was applied at two application rates under three cadmium concentrations. Shennong 265, super japonica rice variety, was selected as the test crop. The results indicated that cadmium content in above-ground biomass of rice increased with increasing soil cadmium concentrations but the biochar application could suppress the accumulation of cadmium to some extent. Under high concentrations of cadmium, content of free proline and MDA (malondialdehyde) were high, so did the SOD (superoxide dismutase), POD (peroxidase) and CAT (catalase) activity in the flag leaf of rice. However, the protective enzyme activities remained at low level when biochar was added.