Plant Nutrient Demand Research Articles

SELECTION OF SUITABLE PLANT SPECIES FOR WASTEWATER TREATMENT BY CONSTRUCTED WETLAND AT THE FORMOSA HA TINH STEEL COMPANY

The study aimed to select suitable plant species in constructed wetland at Formosa Ha Tinh steel company and identify proper nutrient supplements for these plants growth. The tolerance of different aquatic plant species was tested with treated wastewater. Phragmites australis (Cav.), Typha angustifolia L. and Cyperus tegetiformis were selected for vegetation. In this experiment, removal efficiencies for monitored chemical parameters were in the range of 26.5 – 91.7 %, while elimination rates of total coliform were about 50 %. In the beginning, the plant nutrient demand for the first 3 months estimated based on theoretical mean annual nutrient uptake was 495 kg N, 153 kg P and 36 kg K per ha. When the wastewater entered CWs, the available nutrients in the influent could be enough for the plants growth. In fact, observations of the health status of the plants would serve as a basis for the fertilizer feeding decision, the concentration of mineral nutrients available in the wastewater are very important.

Nutrient demand and fungal access to resources control the carbon allocation to the symbiotic partners in tripartite interactions of Medicago truncatula.

Legumes form tripartite interactions with arbuscular mycorrhizal fungi and rhizobia, and both root symbionts exchange nutrients against carbon from their host. The carbon costs of these interactions are substantial, but our current understanding of how the host controls its carbon allocation to individual root symbionts is limited. We examined nutrient uptake and carbon allocation in tripartite interactions of Medicago truncatula under different nutrient supply conditions, and when the fungal partner had access to nitrogen, and followed the gene expression of several plant transporters of the Sucrose Uptake Transporter (SUT) and Sugars Will Eventually be Exported Transporter (SWEET) family. Tripartite interactions led to synergistic growth responses and stimulated the phosphate and nitrogen uptake of the plant. Plant nutrient demand but also fungal access to nutrients played an important role for the carbon transport to different root symbionts, and the plant allocated more carbon to rhizobia under nitrogen demand, but more carbon to the fungal partner when nitrogen was available. These changes in carbon allocation were consistent with changes in the SUT and SWEET expression. Our study provides important insights into how the host plant controls its carbon allocation under different nutrient supply conditions and changes its carbon allocation to different root symbionts to maximize its symbiotic benefits.

Unravelling the age of fine roots of temperate and boreal forests

Fine roots support the water and nutrient demands of plants and supply carbon to soils. Quantifying turnover times of fine roots is crucial for modeling soil organic matter dynamics and constraining carbon cycle–climate feedbacks. Here we challenge widely used isotope-based estimates suggesting the turnover of fine roots of trees to be as slow as a decade. By recording annual growth rings of roots from woody plant species, we show that mean chronological ages of fine roots vary from <1 to 12 years in temperate, boreal and sub-arctic forests. Radiocarbon dating reveals the same roots to be constructed from 10 ± 1 year (mean ± 1 SE) older carbon. This dramatic difference provides evidence for a time lag between plant carbon assimilation and production of fine roots, most likely due to internal carbon storage. The high root turnover documented here implies greater carbon inputs into soils than previously thought which has wide-ranging implications for quantifying ecosystem carbon allocation.

Nutrient demand and elemental stoichiometry of plants in wetland ecosystems in the Biebrza Valley, Poland

Nutrient demand and elemental stoichiometry of plants in wetland ecosystems in the Biebrza Valley, Poland

Yield and nutritional requirements of cassava in response to potassium fertilizer in the second cycle

ABSTRACTPotassium (K) is one of the most absorbed nutrients by cassava because it acts on the synthesis and starch accumulation in the storage roots. Here, we show that K application at the beginning of the second vegetative cycle of cassava submitted to shoot pruning increased the yield of roots and starch, and the nutrient demand of plants. Application of 45–89 kg ha−1 dipotassium oxide (K2O) in the second cycle increased the yield of storage roots and starch from 36–49% and K applied at this time had a greater effect on the synthesis and allocation of starch in the storage roots. K supply increased the accumulation of N and S by 2.0- to 3.0-fold and the accumulation of other nutrients by 1.4- to 1.7-fold. The removal of phosphorus (P), manganese (Mn), and zinc (Zn) by storage roots was not affected by K application, whereas the removal of other nutrients increased by 1.3- to 4.3-fold.

SITE-SPECIFIC NUTRIENT MANAGEMENT FOR MAIZE HYBRIDS IN ANINCEPTISOLOF WEST BENGAL, INDIA

SUMMARYThe area under hybrid maize cultivation is increasing rapidly across South Asia. However, information regarding the proper nutrient management for modern stay-green maize hybrids in India is not adequate resulting in low productivity. Existing nutrient management practices are not able to capture the momentum change in the scenario of soil nutrient supply capacity and plant nutrient demand for achieving higher yield target. The present study aims at establishing the site-specific nutrient management (SSNM) package for aninceptisol(West Bengal, India). Soil indigenous nutrient supply capacity and nutrient use efficiency was also evaluated by using the nutrient omission plot technique. The experiment was laid out in strip-plot design, assigning three maize hybrids (P 3522, P 3396 and Rajkumar) in the vertical strip and nine fertilizer treatments [50% RDF/Recommended dose of fertilizer, 75% RDF, 100% RDF (200-60-60 kg N-P2O5-K2O ha−1), 125% RDF, 150% RDF, 100% PK, 100% NK, 100% NP and control (zero-NPK)] in the horizontal strip, with three replications. Results of the experiment revealed that the differences among cultivars were generally non-significant. The maize hybrids showed greater yield response to fertilization with N (4.14 Mg ha−1) during winter, followed by K (2.54 Mg ha−1) and P (1.58 Mg ha−1). Indigenous nutrient supply was estimated 107.2, 37.6 and 107.7 kg ha−1for N, P and K, respectively. Both average agronomic efficiency (AE) and recovery efficiency (RE) were increased with 50% RDF and it decreased with further increase in NPK levels up to 150% RDF. The average internal efficiency (IE) was higher with 50% RDF closely followed by the treatment with absence of N. As grain yields and gross return over fertilizer (GRF) under 75 to 150% NPK treatments were similar, nutrient doses of 150 kg N, 45 kg P2O5and 45 kg K2O ha−1were recommended as optimum for maize hybrids.

Seasonality of nutrients vis-à-vis fruit quality of pomegranate cv. Bhagwa on vertisol

ABSTRACTThe temporal changes of nutrient concentration in leaves and their accumulation in fruit are good indicators of plant nutrient demand for each developmental stage. Seasonality of nutrients in leaves and fruits of pomegranate and their relation with fruit quality was evaluated in commercial orchards using cv. “Bhagwa.” The concentration of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), iron (Fe), zinc (Zn) and boron (B) in leaves decreased while calcium (Ca), magnesium (Mg), manganese (Mn) and copper (Cu) concentration increased during fruit growth and development. Total nutrient accumulation increased gradually in fruit and translated into growth of arils, and increase in juice content and total soluble solids, however as the biomass accumulation in fruit was much faster than nutrient accumulation, concentration of majority nutrients except Mg decreased rapidly, followed by slow and continuous decrease till maturity. During fruit enlargement, demand for N, P, K, Fe, Cu and Zn was high while requirement for Ca, Mg and S was high during fruit development.

Growth, nutrient accumulation and export by heliconia ‘Red Opal’

Synchronizing the timing of fertilizer applications with plant nutrient demand increases the nutritional efficiency and decrease the cost of production. The objective of this study was to determine the growth and the nutrient uptake and export by heliconia ‘Red Opal’. The experiment was carried out in a shade house and Heliconia psittacorum ‘Red Opal’ rhizomes were planted in soil classified as Arenic Kandinstults. The experimental design was completely randomized with nine plant sampling (zero; 30; 90; 150; 210; 270; 330; 390 and 450 days after planting) and five replicates. Leaves, sheathing leaf bases, flower stem, rhizomes and roots were collected every sampling and dry mass and nutrients accumulation were determined. Heliconia plants showed slow initial development but from the 210 days of planting, which corresponds with the beginning of the flower stem harvest there is a marked increase in dry mass accumulation. Nutrient accumulation followed the decreasing order: K &gt; N = Ca &gt; P = Mg &gt; S &gt; Fe = Mn &gt; Zn &gt; Cu = B. Potassium and calcium were the most exported macronutrients by heliconia flower stem and among the micronutrients, manganese was the most exported.

Age-related morphological and physiological responses of irrigated rice to declined soil phosphorus and potassium availability

Inorganic fertilisers need to be applied only when the inherent soil fertility alone cannot supply the plant nutrient demand for rice. When managing such systems, identification of the most sensitive morphological and/or physiological characteristics of a rice plant and the growth stage at which those responses appear when soil phosphorus (P) and potassium (K) availabilities have declined are important. Such a practice will increase fertiliser-use efficiency and enhance environmental sustenance. Experiment was conducted in a field differing in initial soil P and K availabilities due to the application of four fertiliser treatments for three consecutive seasons. Observations in this experiment were made in the fourth season. Four fertiliser treatments were the application of (i) both P and K (P1K1), (ii) only P (P1K0), (iii) only K (P0K1), and (iv) no P and K (P0K0). Rice variety Bg300 was grown. Shoot samples were obtained at two-week intervals, while root and soil samples were collected using a soil core up to 80 cm depth at physiological maturity. At physiological maturity, root length, diameter, and root length density were not responsive to the declined soil P and K availability, whereas the total above-ground dry weight (DW) reduced in P- and K-deficient plots. Shoot physiological responses [i.e. reduced green leaf P and K concentrations, and increased phosphorus-use efficiency (PUE) and potassium-use efficiency (KUE)] were more prominent than shoot morphological responses (i.e. plant height, number of tillers, and total above-ground DW), throughout the growth cycle. The intensity (i.e. statistical significance) and duration of the appearance of K deficiency symptoms were lower than those of P. The most sensitive growth stage of rice to slight deficiencies of P and K was the tillering stage. This knowledge on the morphological and physiological shoot and root responses that can be observed during the lifecycle of a rice plant, and the growth stage(s) at which those responses are prominent in response to declining soil P and K availability can be used when identifying the development of soil P and K limitations hindering the optimal growth of rice plant, and sustaining rice cropping systems.

Blueberry—Soil interactions from an organic perspective

Demand for organic blueberries has risen in response to consumers’ interest in healthy eating and greater awareness of the environment. Although organic production systems share many challenges with conventional systems, they have specific limitations and questions. Synchronisation of plant nutrient demand with the release of mineral nutrients from organic nutrient sources presents a particular challenge for the organic grower. In this paper we address belowground challenges in blueberry production from an organic perspective, such as soil properties and amendments as well as the choice of mulching material and organic fertilisers. We also address potential toxicity problems for blueberries associated with high concentrations of aluminium and manganese as well as salt stress. Symbiosis with ericoid mycorrhizal fungi is of potential interest in organic blueberry production as the fungi may improve plant access to nutrients from organic sources. The effects of management factors and limitations associated with the commercial utilisation of the symbiosis are also discussed.

Effects of free-air CO2 enrichment (FACE) on the uptake and utilization of N, P and K in Vigna radiata

Elevated [CO2] stimulates plant growth, which in turn demands more nutrients to sustain it. The nutrient demand of N-fixing plants may differ from that of other plants under elevated [CO2]. We conducted an experiment to determine how elevated [CO2] affected N, P and K content, assimilation of nutrients and accumulation of metabolites in the legume mung bean [Vigna radiata L.]. We investigated the effect of 550±19μmolmol−1 [CO2] on N, P, K uptake and utilization by mung bean at the free-air carbon dioxide enrichment (FACE) experimental facility in north China. At maturity, N concentration in whole plants decreased by 4.4%, but P and K concentration was unchanged at elevated [CO2]. The weight of nodules per plant significantly increased at elevated [CO2] but N, P, K-use efficiency for seed and the ratio of seed yield to cumulative absorption of N, P and K was unaffected. These results indicate that under elevated [CO2] the mechanisms governing N absorption and metabolism in mung bean was different from that for P and K. The nutrient dynamics between different elements of overall plant biomass and the soil nutrients pool could, therefore, be changed in future by elevated [CO2].

Palygorskite-coated fertilizers with a timely release of nutrients increase potato productivity in a rain-fed cropland

In many semiarid areas of China, potato production is often limited by poor soil fertility and low fertilizer use efficiency, but topdressing to deeper soil layers in the late growing period is difficult. With the aim of improving fertilizer use efficiency and minimizing negative impacts on the environment, a new palygorskite-coated slow-release fertilizer was prepared. According to the nutrient requirements of potato in its three main growth stages, the product consisted of three parts of chemical fertilizers with each part coated by palygorskite. A two-year study was undertaken to investigate the controlled release behavior of the product, and its impact on potato yield and fertilizer uptake was also evaluated. Two coating ratios (20 and 30%) of palygorskite-coated vs. palygorskite-mixed chemical fertilizer and chemical fertilizers only were applied with three rates (allkgha−1): (1) low (94.5 N and 4.5 P), (2) medium (137.9 N, 16.5 P and 10.5 K), and (3) high (223.4 N, 24.0 P and 81.0 K). The results both from soil (mineral N and available P) and crop (leaf nitrate N) indicated a controlled release characteristic of palygorskite-coated fertilizer which synchronized better with nutrient demands of potato plants. The palygorskite-coated fertilizer treatment resulted in the highest total tuber yield, 14.6–20.3% higher than the control. Partial factor productivity of N, P and K fertilizer was also significantly increased by palygorskite-coated fertilizer. The palygorskite-coated fertilizer could be promising for potato production and be beneficial to agricultural sustainability in semiarid areas.

Fertilização de plantas ornamentais pelo método requerimento-suprimento: proposição de técnica experimental

A dose de fertilizantes a ser recomendada para uma cultura depende do balanço de perdas e dos ganhos dos nutrientes no sistema agrícola (Lei da Restituição). Na UFV, o balanço foi modelado para recomendação de corretivos e fertilizantes para eucalipto (NUTRICALC), abacaxizeiro, algodoeiro, arroz, bananeira, cafeeiro, cana de açúcar, coqueiro, laranjeira, meloeiro, milho, pastagens, soja e tomate (FERTICALC) e teca (FERTI-UFV). A fertilização e a nutrição de plantas ornamentais tropicais baseam-se apenas na experiência de produtores e fabricantes de fertilizantes. Os objetivos deste trabalho foram desenvolver e apresentar técnica experimental que permita determinar: as taxas de recuperação de macro e micronutrientes por extratores de formas disponíveis, a demanda e as taxas de recuperação de nutrientes por plantas ornamentais e determinar a dose e os teores de nutrientes em fertilizante que suplementem os requerimentos das plantas. Para a modelagem, consideraram-se dois módulos: o módulo planta, que obtém a demanda e o requerimento dos nutrientes para definida produtividade; e o módulo substrato, que permite calcular o suprimento de nutrientes do vaso ou do canteiro a ser utilizado para o cultivo. A modelagem vislumbrou um novo método de pesquisa para recomendação de corretivos e fertilizantes para culturas com carência de informação, como para cultivo de plantas ornamentais, especialmente as tropicais. Esse Método Requerimento-Suprimento determina a dose e os teores de nutrientes no fertilizante-suprimento (FS), que suplementam os requerimentos das plantas. O método é iterativo e foi desenvolvido por meio de três tentativas. Na primeira tentativa, considerou-se a produção de plântulas de orquídea; e, na segunda e terceira tentativas, determinaram-se as curvas de crescimento com FS no cultivo de violetas, em vasos com substrato, e definiram-se os critérios para determinar as taxas de recuperação de nutrientes pelos extratores em análises químicas do substrato e pelas plantas. Por último, apresentou-se a técnica experimental projetada.

Shedding light onto nutrient responses of arbuscular mycorrhizal plants: Nutrient interactions may lead to unpredicted outcomes of the symbiosis

The role and importance of arbuscular mycorrhizae (AM) in plant nitrogen (N) nutrition is uncertain. We propose that this be clarified by using more integrative experimental designs, with the use of a gradient of N supply and the quantification of an extensive array of plant nutrient contents. Using such an experimental design, we investigated AM effects on plant N nutrition, whether the mycorrhizal N response (MNR) determines the mycorrhizal growth response (MGR), and how MNR influences plants’ C economy.Oryza sativa plants were inoculated with Rhizophagus irregularis or Funneliformis mossae. AM effects were studied along a gradient of N supplies. Biomass, photosynthesis, nutrient and starch contents, mycorrhizal colonization and OsPT11 gene expression were measured. C investment in fungal growth was estimated. Results showed that, in rice, MGR was dependent on AM nutrient uptake effects, namely on the synergy between N and Zn, and not on C expenditure. The supply of C to the fungus was dependent on the plant's nutrient demand, indicated by high shoot C/N or low %N. We conclude that one of the real reasons for the negative MGR of rice, Zn deficiency of AMF plants, would have remained hidden without an experimental design allowing the observation of plants’ response to AM along gradients of nutrient concentrations. Adopting more integrative and comprehensive experimental approaches in mycorrhizal studies seems therefore essential if we are to achieve a true understanding of AM function, namely of the mechanisms of C/N exchange regulation in AM.

English

Adsorbed or precipitated phosphorus can be susceptible to dissolution depending upon environmental conditions. This work evaluated both the partitioning and availability of the inorganic forms of P bound to Al, Fe and Ca in samples of a&nbsp;clayey Dystrophic Red Latosol (Oxisol) (DRL)&nbsp;with different land use history, fertilized with Arad reactive natural phosphate in Goias State, Brazil. The inorganic fractions of Al-P, Fe-P and Ca-P and the contents of Mehlich-1, ion-exchange resin, citric acid and Olsen extracted available P were determined in DRL. Plants grown in soil previously cultivated produce more beans than plants grown in soil not previously cultivated. The fractions Al-P and Fe-P represent the main inorganic forms in clayey DRL, being phosphorus availability closely related with the fraction Al-P. The distributions of the inorganic fractions of P in the soil fertilized with reactive phosphate were Fe-P = 45%, Al-P = 40% and Ca-P = 15%. The phosphorus content determined by alkaline extraction (Olsen Method) was closely related to levels of Al-P and Fe-P. On other hand, the concentrations determined by extracting acids (Mehlich-1 and citric acid) were more related to the Ca-P fraction. Fe-P and Al-P inorganic forms stocked over time with successive fertilizations in Oxisol with a history of cultivation in no-tillage may return to soil solution and provide the nutrient demand of plants. &nbsp; Key words:&nbsp;Cerrado soil, phosphorus fertilization, phosphorus fractionation, inorganic phosphorus.

Vermicompost management: An alternative to meet the water and nutritive demands of tomato under greenhouse conditions

Different studies have suggested that the use of vermicompost as part of the plant growth media can provide nutrients and retain moisture while promoting the development of crops. To corroborate this assumption we tested the effects of vermicompost supplementation to tomato (saladette type) under greenhouse conditions. The evaluated treatments included four mixtures (T1, T2, T3, and T4) of vermicompost and river sand, with volume ratios 0:1, 1:1, 1:2 and 1:3, respectively. Physical and chemical tests were performed in each mixture to determine nutritional elements (N, P, K, Ca, Mg, Na, Fe, Cu, Zn, Mn, organic matter, pH, texture, cationexchange capacity, electric conductivity, and apparent density) and water holding capacity. Treatment with 0:1 volume ratio (T1) was used as control, and it was fertilized with a nutrient solution [KNO3, Ca(NO3)2, Mg(NO3)2, phosphoric acid concentrate, and multi Maxiquel (Bioagro ®)]. Seeds were sown in polystyrene trays with 200 cavities, padded with peat moss; seedlings were transplanted 37 days after sowing in 20 L black plastic bags. Harvest, including up to the fifth cluster, was performed manually, when the fruits reached a pink color. The treatment effects on tomato were evaluated considering the number of fruits, number of locules, equatorial and polar diameters, pulp thickness, soluble solids, fruit weight and fruit yield. The four treatments were repeated eight times in a completely randomized design. Data were statistically analyzed by analysis of variance and means were separated by the LSD0.05 test. Five of the variables studied - number of fruits, number of locules, soluble solids, pulp thickness, and yield- showed highly significant difference (P?0.01) among treatments; the polar diameter showed significant differences (P?0.05), and both equatorial diameter and weight of fruit were not significantly different among the substrates tested. The maximum yield (50.29 t?ha-1) was obtained in treatment T2 with a water volume of 40 L?pot-1, followed by T1 (49.93 t?ha-1), applying a water volume of 95.72 L?pot-1. Derived from the results of the best treatment (T2), and under conditions described, the productivity was estimated in 30.66 kg?m-3. Since no synthetic fertilizers were used during the crop production, the results indicate that the vermicompost was able to satisfy the nutrient demand of tomato plants and reduces the volume of water required by this crop.

Suprimento de potássio em função da adubação potássica residual em um Latossolo Vermelho do Cerrado

Em alguns solos com baixos teores de potássio trocável, formas não trocáveis participam do suprimento às plantas. Há evidências de que a disponibilização do K não trocável depende mais da demanda das plantas pelo nutriente do que das propriedades do solo. O objetivo deste trabalho foi avaliar o suprimento e a exaustão de formas de K em um Latossolo Vermelho do Cerrado em decorrência da adubação potássica residual e do cultivo de Brachiaria ruziziensis (Syn. Urochloa ruziziensis). Amostras de solos foram coletadas na camada de 0-20 cm, em parcelas de um experimento de campo em que a soja vinha sendo adubada anualmente, por 10 anos, com 0, 60, 120 e 180 kg ha-1 de K2O. Em casa de vegetação, as amostras de solo receberam a aplicação de 0, 150 e 300 mg dm-3 de K e foram cultivadas com B. ruziziensis, com cinco cortes sucessivos. O suprimento de K às plantas dependeu mais do fertilizante recém-adicionado do que do efeito residual de adubações anteriores. O K não trocável foi responsável, ao longo do tempo, pela manutenção dos teores de K trocáveis e, na ausência de adubação potássica, constituiu a principal fonte de K para as plantas de B. ruziziensis. As plantas de B. ruziziensis possuem capacidade de extrair quantidade considerável de K do solo, confirmando sua importância como cultura de cobertura, na ciclagem do nutriente no solo.

Evidence of a strong coupling between root exudation, C and N availability, and stimulated SOM decomposition caused by rhizosphere priming effects

Increased temperatures and concomitant changes in vegetation patterns are expected to dramatically alter the functioning of northern ecosystems over the next few decades. Predicting the ecosystem response to such a shift in climate and vegetation is complicated by the lack of knowledge about the links between aboveground biota and belowground process rates. Current models suggest that increasing temperatures and rising concentrations of atmospheric CO2 will be partly mitigated by elevated C sequestration in plant biomass and soil. However, empirical evidence does not always support this assumption, as elevated temperature and CO2 concentrations also accelerate the belowground C flux, in many cases extending to increased decomposition of soil organic matter (SOM) and ultimately resulting in decreased soil C stocks. The mechanism behind the increase has remained largely unknown, but it has been suggested that priming might be the causative agent. Here, we provide quantitative evidence of a strong coupling between root exudation, SOM decomposition, and release of plant available N caused by rhizosphere priming effects. As plants tend to increase belowground C allocation with increased temperatures and CO2 concentrations, priming effects need to be considered in our long-term analysis of soil C budgets in a changing environment. The extent of priming seems to be intimately linked to resource availability, as shifts in the stoichiometric nutrient demands of plants and microorganisms will lead to either cooperation (resulting in priming) or competition (no priming will occur). The findings lead us on the way to resolve the varying response of primary production, SOM decomposition, and release of plant available N to elevated temperatures, CO2 concentrations, and N availability.

Accumulation and distribution characteristics for nitrogen, phosphorus and potassium in different cultivars of Petunia hybrida Vlim.

The management of mineral nutrition through fertilization is a key factor determining the ornamental value and marketability of potted plants. In this study, three cultivars of potted petunia (representing the double florabunda (DF), single milliflora (SM), and single florabunda (SF) types) were compared. Their dry matter accumulation characteristics, as well as NPK accumulation and distribution at different developmental stages were investigated in a soil–sand substrate. The different cultivars of petunia exhibited similar uptake ratios of N>K>P with mean NPK ratios of 1:0.11:0.71, but with differing levels of NPK accumulation in the total plant biomass. SF showed the highest accumulation of N, P and K nutrients and dry matter. There was a significant positive correlation between the accumulation of dry matter and nutrients, indicating that the nutrient demands of petunia plants may be estimated indirectly by dry matter accumulation. The maximum dry matter accumulation reached 0.24gd−1 for stems, 0.30gd−1 for leaves, 0.09gd−1 for roots, 0.18gd−1 for capsules and 0.02gd−1 for flowers. During the vegetative growth period, the mineral nutrients mostly accumulated in the leaves and stems. However, some of the mineral nutrients were translocated into the capsules and flowers at the flowering stage. N, P and K accumulation were 170.91mgplant−1, 15.34mgplant−1 and 136.71mgplant−1 respectively, before flowering stage, which possessed the highest accumulation of 441.6mgplant−1 (N), 76.48mgplant−1 (P) and 214.47mgplant−1 (K) during the senescence stage. Based on the experimental results, a recommended fertilization regime is 40% N, 80% P and 60% K as a base fertilizer, 30% N at bud stage, and 30% N, 20% P and 40% K after flowering.

Evidence, Regulation, and Consequences of Nitrogen-Driven Nutrient Demand by Turfgrass

Nutrient uptake is strongly influenced by plant growth rate. Accelerated growth leads to nutrient levels incapable of sustaining the optimal growth rate, resulting in shoot to root signaling for increased nutrient absorption. The factors controlling nutrient demand in turfgrass and its consequences have not been investigated. The objectives of this research were to verify that turfgrass exhibits the principal characteristics of demand-driven nutrient uptake and to identify the primary factor controlling nutrient demand via regulation of growth rates. Kentucky bluegrass clipping production increased linearly up to annual fertilizer N rates of 600 kg ha−1 and to 1000 kg N ha−1 for creeping bentgrass. At the typical annual N fertilization rates of 150 to 300 kg ha−1 for the two grasses, N supply was the primary determinant of turfgrass growth rate, plant nutrient demand, and nutrient uptake. Nitrogen uptake accounted for over 88% of uptake of all other nutrients. Uptake of P and K were strongly related to tissue N content irrespective of soil test levels. Variations in turfgrass species and cultivar nutrient requirements and nutrient use efficiencies were found to be directly related to differences in growth rates and, by inference, to differences in nutrient demand.