Phosphorus Use Efficiency Research Articles

Enhancing photosynthetic phosphorus-use efficiency through coordination of leaf phosphorus fractions, allocation and anatomy during soybean domestication.

Soybean domestication has significantly changed key agronomic traits, yet its impact on leaf photosynthetic phosphorus-use efficiency (PPUE) and its underlying traits remain poorly known. Further information on this would be important to increase soybean P-use efficiency. To address this gap, 48 soybean accessions (16 wild relatives, 16 landraces and 16 cultivars) were used to compare leaf anatomical traits, foliar chemical P fractions, P allocation and PPUE under two P levels. The results showed that the cultivars had higher area-based and mass-based photosynthesis rates, PPUE, metabolite P concentration, and its percentage of leaf total P, as well as a greater percentage of lipid P, nucleic acid P and residual P. Conversely, wild relatives tended to have higher leaf P concentration, palisade:spongy thickness ratio, and concentrations of inorganic P, nucleic acid P, lipid P and residual P. PPUE was negatively correlated with leaf inorganic P concentration and its percentage relative to leaf total P, while it was positively correlated with the concentration and percentage of metabolite P. We concluded that soybean domestication increased PPUE, as a result of both increased photosynthesis rate and decreased leaf P concentration; domestication reduced the palisade:spongy thickness ratio coupled with increased allocation of P to P-containing metabolites, thereby contributing to faster photosynthesis and higher PPUE. This study shed light on the significance of leaf P allocation and anatomical traits affecting PPUE during soybean domestication, offering a mechanistic understanding to further enhance soybean P-use efficiency.

Higher phosphorus and water use efficiencies and leaf stoichiometry contribute to legume success in drylands

Abstract Legumes are essential plants in dryland ecosystems worldwide because they increase nitrogen availability, so their understanding is vital for improving knowledge and modelling in the face of climate change. This work studies the differences in resource use efficiency and their relationship with photosynthetic, photochemical, bioelemental, and stoichiometric traits of coexistent legumes and non‐legumes in a Sonoran Desert ecosystem. We found that legumes had higher photosynthetic rates, intrinsic and seasonal water use efficiency (WUE), phosphorus use efficiency (PPUE), and higher light utilisation mediated by chlorophyll content and active reaction centers, which may increase their photoprotection. Legumes can increase their WUE and PPUE with no changes in nitrogen use efficiency (PNUE). Consequently, observed trait relationships between studied traits in these legumes have significant differences with the non‐legume species in the study. Stoichiometry is helpful, in some cases, as an indicator of nutrient use efficiency and enables functional group differentiation. Our results strongly relate legumes' higher resource use efficiency with their success in dryland ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Phosphorus recovery potential revealed by substance flow analysis of the Indian food, agricultural and sanitation system

Phosphorus is a finite resource that is in high demand due to its essential role as a fertiliser. We undertook a substance flow analysis of phosphorus for India's agri-food system to identify where the biggest losses of phosphorus occur and which flows could be targeted to move phosphorus from a linear use and waste approach to a circular approach encompassing recovery and re-use. A novel aspect of the analysis was the inclusion of sanitation systems in India. National phosphorus flows were calculated annually for the five years 2015–2019, and the mean was then used to provide a representative annual flow. The analysis showed that India is dependent on imports for 95% of applied mineral phosphorus fertiliser and has a low phosphorus-use efficiency of 32%. The largest recoverable flow is human excreta (urine and faeces), equivalent to 21% of the current phosphorus applied in mineral fertiliser in India. Phosphorus recovery from septic tanks, the most prevalent sanitation system in India, could alone replace 8% of phosphorus applied in mineral fertiliser in India. Alongside the ongoing development of sanitation systems in India this provides an opportunity to ensure that nutrient recovery is included in sanitation developments.

The Use Efficiency of Phosphorus in Organomineral Fertilization Systems

ABSTRACT Aim The aim of this study was to determine the agronomic, physiological and recovery efficiency of phosphorus in the transition from conventional agriculture to organic agriculture of organomineral fertilizers, which are formed by combining different levels of phosphorus fertilizers and dairy manures at different rates. Materials and Methods The study was carried out between 2019 and 2021 during the two wheat growing season in Söke county of Aydın province in the Southwest of Türkiye. In the study, excluding the control (P0), 4 different levels of phosphorus (P1:10, P2:20, P3:30, and P4:40 kg P ha−1) and 4 different doses of dairy manure (DM1:10, DM2:20, DM3:30, and DM4:40 t ha−1) and 16 different organomineral fertilizer combinations were composed. The fertilizer combinations composed were divided into four sub-organomineral fertilization systems (OMF1, OMF2, OMF3, and OMF4). The study was carried out in three replications according to the randomized block design. Results In the study, according to the averages of both years, the highest agronomic, physiological and recovery efficiency (AE, PE, and RE) was determined as 29.5 kg kg−1, 175.0 kg kg−1 and 16.9% in DM1P1 application (OMF1 system), respectively. The lowest agronomic, physiological and recovery efficiency were recorded as 21.2 kg kg−1, 163.4 kg kg−1 and 13.0% in DM4P4 application (OMF4 system), respectively. As a result, organomineral fertilizers reduced the agronomic, physiological and recovery efficiency of phosphorus by 28.1%, 8.2% and 23.1%, respectively. Conclusions Finally, it was concluded that the fertilizer use efficiency increased as the amount of phosphorus applied to compose with organomineral fertilizers decreased.

Crop domestication increased photosynthetic phosphorus-use efficiency associated with changes in leaf phosphorus fractions under low soil phosphorus conditions

Crop domestication increased photosynthetic phosphorus-use efficiency associated with changes in leaf phosphorus fractions under low soil phosphorus conditions

Phosphorus use efficiency in common bean genotypes

Phosphorus absorption in plants can vary depending on the genotypes, mineral levels, and environmental conditions. Thus, this study aimed to evaluate phosphorus use efficiency and the response capacity of five common bean genotypes in two cultivation cycles. A 2x5 factorial scheme was used with three replicates. Factor A consisted of using and not phosphorus fertilization, and factor B consisted of five common bean genotypes (BRS Expedito, Iraí, Pérola, Maronze, and Vermelho). The evaluated yield components were the number of pods per plant (NPP), the number of grains per plant (NGP), and the mass of 1000 grains (M1000G). The yield was calculated and extrapolated to kg ha-1. We also evaluated the phosphorus levels accumulated in the leaves and grains (mg and %) and estimated the use efficiency of using phosphorus in the grains. The data obtained were subjected to analysis of variance and compared using the Scott-Knott test at a 5% significance level. There was a significant interaction for all studied variables, indicating the interference of phosphorus fertilization in the behavior of the genotypes. The growing season influenced the genotypes' responses regarding phosphorus use. Yields increased with phosphorus fertilization and changed according to genotype. The phosphorus accumulated in the leaves and grains showed little divergence. The Iraí, Pérola, and Maronze genotypes stand out for their efficient use of phosphorus, presenting an increase above 50% when grown in soil with phosphorus fertilization. When fertilized, the Vermelho variety most accumulated phosphorus in the grains in the first season. In the second season, it showed a significant change in its response when using the phosphate fertilizer, indicating a change in behavior due to the environmental component.

Seasonal variations of leaf ecophysiological traits and strategies of co-occurring evergreen and deciduous trees in white oak forest in the central Himalaya.

The present study investigates the seasonal variations in leaf ecophysiological traits and strategies employed by co-occurring evergreen and deciduous tree species within a white oak forest (Quercus leucotrichophora A. Camus) ecosystem in the central Himalaya. Seasonal variations in physiological, morphological, and chemical traits were observed from leaf initiation until senescence in co-occurring deciduous and evergreen tree species. We compared various parameters, including net photosynthetic capacity (Aarea and Amass), leaf stomatal conductance (gswarea and gswmass), transpiration rate (Earea and Emass), specific leaf area (SLA), mid-day water potential (Ψmd), leaf nitrogen (N) and phosphorus (P) concentration, leaf total chlorophyll concentration, photosynthetic nitrogen- and phosphorus-use efficiency (PNUE and PPUE), and water use efficiency (WUE) across four evergreen and four deciduous tree species. Our findings reveal that evergreen and deciduous trees exhibit divergent strategies in coping with seasonal changes, which are crucial for their survival and growth. Deciduous trees consistently exhibited significantly higher photosynthetic rates, transpiration rates, mass-based N and P concentrations (Nmass and Pmass), mass-based chlorophyll concentration (Chlmass), SLA, and leaf Ψmd, while maintaining lower leaf structural investments throughout the year compared to evergreen trees. These findings indicate that deciduous trees achieve greater assimilation rates per unit mass and higher nutrient-use efficiency. Physiological, morphological, and leaf N and P concentrations were higher in the summer (fully expanded leaf) than in the fall (senesced leaf). These insights provide valuable contributions to our understanding of tree species coexistence and their ecological roles in temperate forest ecosystems, with implications for forest management and conservation in the Himalayan region.

Phosphorus solubilizing Bacillus sp. strain MN-54 increased the yield and economic returns of pearl millet due to improved phosphorus use efficiency

Phosphorus (P) deficiency is a frequent problem in calcareous soils of Pakistan because of P-fixation, which poses significant threats to pearl millet productivity. The use of P-solubilizing bacteria (PSB) is regarded as a promising approach for improving P-availability in soil-plant systems. However, it needs optimization of P application into the soil. Therefore, this 2-year field study was conducted to optimize P doses in combination with PSB (Bacillus sp. MN54) inoculation to improve phosphorus use efficiency (PUE), yield, economic returns, and grain quality of pearl millet. Five P doses, i.e. 0 (native soil P only - control), 30, 60, 90, and 120 kg P2O5 ha−1 combined with and without PSB inoculated seeds were used in the study. The application of 90 kg P2O5 ha−1 + seed inoculation with PSB improved the grain yield by 36.8% and 36.0% during 1st and 2nd year, respectively. The same treatment significantly improved the PUE, grain protein, zinc (Zn), and total grain P contents compared to the control treatment. Furthermore, the highest economic returns (1053.3 and 1050.5 $ ha−1) and benefit:cost ratio were observed under 90 kg P2O5 ha−1 + seed inoculation with PSB during both years. In conclusion, application of 90 kg P2O5 ha−1 combined with PSB seed inoculation is a pragmatic option to improve P uptake, grain yield, PUE, grain quality and economic returns of pearl millet grown on calcareous soils.

Identifying phosphorus use efficient genotypes by evaluating a chickpea reference set across different phosphorus regimes

AbstractLow phosphorus use efficiency (PUE) is one of the abiotic factors that hamper yield and production potential in chickpea (Cicer arietinum L.). Higher yield coupled with improved PUE can make this crop more adaptive and competitive to wide cropland area, especially on marginal soils having low-level phosphorus (P). To identify chickpea germplasm lines that assimilate phosphorus more efficiently under P-deficient soils, 288 diverse genotypes of chickpea belonging to reference set were evaluated for yield component traits and PUE under field conditions for two consecutive years at two phosphorus levels (low P – no phosphorus application and high P – phosphorus application at 40 kg/ha). Based on 2-year evaluation of data under high and low P soil conditions, we identified strong correlations for traits like number of primary and secondary branches, number of pods, biological yield and seed yield indicating that these traits can be used as proxy traits for PUE. ICC 6571 was the best performing genotype under low P conditions while ICC 6579 yielded maximum under high P regime. We report 16 genotypes namely ICC 1052, ICC 1083, ICC 1098, ICC 1161, ICC 2072, ICC 4418, ICC 4567, ICC 4991, ICC 5504, ICC 5639, ICC 7413, ICC 8350, ICC 9590, ICC 9702, ICC 11584 and ICC 13357 as phosphorus use efficient genotypes based on their better performance for yield and yield-contributing traits under low P compared to high P conditions. These genotypes can be exploited in future as potential donors for development of phosphorus use efficient chickpea cultivars.

Effect of basal and foliar application of diammonium phosphate in cognizance with phosphate-solubilizing bacteria on growth, yield and quality of rainfed chickpea (Cicer arietinum)

A rainfed experiment was conducted during the winter (rabi) seasons of 2011–12 and 2012–13 at Kumarganj, Faizabad, Uttar Pradesh to study the effect of diammonium phosphate (DAP) applied through soil and foliage in conjunction with phosphate-solubilizing bacteria (PSB) on growth characters, yield attributes and yield, seed protein content, nutrient uptake and phosphorus-use efficiency (PUE) of chickpea (Cicer arietinum L.). The application of 50 kg DAP/ha as basal + 50 kg DAP/ha as foliar in 2 splits 45 and 60 days after sowing + PSB significantly increased the growth attributes (plant height, primary branches/plant, leaf area/plant, number and dry weight of nodules/plant, root and shoot dry weight/plant, root: shoot ratio), yield attributes and yield (pods/plant, 1,000-seed weight, seed yield, biological yield), seed protein content, N and P uptake and PUE of chickpea. However, seeds/ pod and harvest index were not affected significantly due to the application of DAP in cognizance with PSB. Thus, split application of 100 kg DAP/ha (½ through soil + ½ through foliage in 2 splits at 45 and 60 DAS) in conjunction with PSB proved effective in enhancing growth, yield (1,486 kg/ha; 102% increase over the control) and quality of chickpea grown under rainfed conditions.

Enhancing phosphorus use efficiency and soil quality indicators in lowland paddy ecosystem through Azolla, rice straw, and NPKS fertilizers

PurposeThis study investigates the influence of incorporating Azolla, rice straw, and NPKS fertilizers on phosphorus use efficiency (PUE) and rice productivity in lowland paddy fields. Despite Azolla’s well-known role as a nitrogen-fixing aquatic fern in rice production, its specific impact on PUE remains unclear. The primary objective is to explore diverse treatment combinations to identify synergies that enhance both PUE and overall rice productivity.MethodsThe study was conducted at Mkula Irrigation Scheme in the Kilombero Valley, Tanzania; the field experiment employed a randomized complete block design with 13 treatments and three replications. Treatments comprised various combinations of Azolla, rice straw, and chemical fertilizers, incorporating 50% and 100% rates of nitrogen (N) applied with phosphorus (P), potassium (K), and sulfur (S).ResultsThe study reveals the substantial impact of Azolla application on total nitrogen, available phosphorus, and exchangeable potassium levels in the soil. Particularly noteworthy were treatment combinations involving Azolla, rice straw, and reduced rates of synthetic nitrogen, along with specific P, K, and S applications, which exhibited the highest phosphorus uptake and PUE. Specifically, combining rice straw and Azolla with reduced N rates, alongside 30 kg P ha−1 + 30 kg K ha−1 + 20 kg S ha−1, resulted in the highest phosphorus uptake (73.57 kg/ha) and PUE (46.24%).ConclusionIntegrated nutrient management, incorporating rice straw and Azolla alongside synthetic fertilizers, demonstrates synergistic effects on phosphorus uptake and efficiency while maintaining soil quality. The study underscores the potential of such integrated strategies to optimize PUE and contribute to sustainable rice production in lowland paddy fields.

Towards a zero-waste aquaponics-centered eco-industrial food park

The scarcity of natural resources, rising energy prices and strict environmental policies are incentives for the food industry to reform current production strategies. As part of this shift, the eco-industrial park concept is gaining momentum. Industrial aquaponics, integrating aquaculture and hydroponics, emerges as a pioneering food production system. Its focus on reusing and conserving resources aligns with eco-industrial parks. The novel concept of an aquaponics-centered eco-industrial food park fits into a biobased circular economy and supports large-scale exploitation to overcome current economic constraints that prevent commercial adoption. However, balancing aquaponics-centered eco-industrial food parks to minimize external inputs as well as waste is challenging. The present study aims to investigate how a quasi-dynamic optimization method can be used in the design of aquaponics-centered eco-industrial food parks under different seasonal weather conditions. The food park encompasses an aquaculture-hydroponic and anaerobic digestion system that mineralizes internal waste streams. The study prioritizes enhancing nitrogen and phosphorus use-efficiency and self-sufficiency. The results unveil specific optimal hydroponic system sizes for a standardized 100 m3 aquaculture volume. Cooler regions thrive around 0.6–1.0 ha hydroponic system, while warmer areas excel at 0.2–0.3 ha with corresponding nitrogen and phosphorus use-efficiencies of 90% and 67% and self-sufficiencies of 88% and 95%, respectively. A supernatant nitrification step with light supplementation improved the design with maximum self-sufficiency and high water use-efficiency of 88% for a hydroponic-aquaculture area-volume ratio of 0.22:100. Complete nitrogen and phosphorus self-sufficient, near zero-waste, food park was achieved by introducing mineralization of chicken manure for a hydroponic-aquaculture ratio of 1.1:100. Moreover, the food park yielded a 6.7-fold lower carbon footprint compared to an optimized traditional on-demand coupled aquaponics system with a hydroponic-aquaculture ratio of 0.15:100.

Why is nutrient cycling in food systems so limited? A case study from the North-Netherlands region

AbstractIdentifying pathways to circular agriculture requires a profound understanding of nutrient flows and losses throughout the food system, and of interactions between biophysical conditions, land use, food production and food consumption. We quantified nitrogen (N) and phosphorus (P) flows of the food system of the North-Netherlands (NN) region and of its 30 subregions varying in biophysical and socio-economic conditions. The food system included agriculture, food processing, consumption, and waste processing. Nitrogen use efficiency (NUE), phosphorus use efficiency (PUE) and the nutrient cycling counts were calculated. Results show a low NUE (25%) and PUE (59%) of the food system. External inputs were used to maintain high yields and production. Nutrient cycling was very limited with losses from agriculture ranging from 143 to 465 kg N ha−1 y−1 and 4 to 11 kg P ha−1 y−1. Food system losses ranged from 181 to 480 kg N ha−1 y−1 and from 7 to 31 kg P ha−1 y−1 and varied with biophysical conditions, population density and farming systems. Large losses were associated with livestock farming and farming on drained peat soils. Food system efficiency was strongly associated with the utilization of produce. We conclude that increasing circularity requires tailoring of agriculture to local biophysical conditions and food system redesign to facilitate nutrient recycling. Steps towards circularity in NN include: matching livestock production to feed supply from residual flows and lands unsuitable for food crops, diversifying crop production to better match local demand and increasing waste recovery.

Genotypic responses to phosphorus and water management in winter wheat: Strategies to increase resource use efficiency and productivity

The phosphorus (P) addition can be helpful in the mitigation of the adverse effects of water deficit stress. However, the efficiency of wheat in utilizing both components has not been assessed in field conditions. This research aims to assess the effects of P and water addition on phosphorus use efficiency (PUE) and water productivity (WP) in field conditions for select wheat cultivars co-adapted to climate-induced agronomic challenges. Three wheat cultivars were selected based on their PUE and water WP from a previous experiment. The trials were conducted in field conditions over two consecutive years, from 2020 to 2021 (Season 1) and 2021–2022 (Season 2). The plants were grown on an andisol with a soil P concentration of 10 mg P kg−1 and 30 mg P kg−1. Two irrigation treatments were imposed: Well-watered (+W) and dryland (-W). The plants were sampled at three stages: tillering (Z25), anthesis (Z65), and ripening (Z95). At the end of the phenological cycle, grain yield components, grain yield, grain quality, PUE, and WP were evaluated. Phosphorus addition promotes plant growth, especially in the early vegetative stages, by enhancing tiller development and nutrient and water uptake. These effects were critical during the anthesis and ripening stages, enhancing yield components and higher grain production. Differential responses were observed across cultivars, underscoring the genotype-specificity in PUE and WP. Seasonal water deficit stress modulated these effects, highlighting a more complex genotype-environment-nutrient interaction. The water addition promoted PUE and WP, suggesting a synergy between the two components. Among the cultivars, Chevignon outperformed in grain yield, PUE, and WP. However, while phosphorus, water, and environmental factors influenced grain quality, the genetic background of the cultivar was the primary determinant of these components. This study advocates for implementing individual nutrient management strategies tailored to the specific cultivar and adaptable to environmental conditions under climate change.

Controls on use efficiency of plant nutrients along subtropical to alpine gradients on the Tibetan Plateau

AbstractQuestionKnowledge of how nutrient use strategies differ between forest trees and alpine shrubs/grasses is important to understand the mechanisms of vegetation changes from montane forests to alpine shrubs/grasslands along altitudinal gradients. We tested the hypothesis that, to maximize the nitrogen use efficiency (NUE) of canopy production, forest trees tend to have a higher mean residence time (MRT) of nitrogen in the plants through increased leaf life span, whereas alpine shrublands and grasslands tend to have higher nitrogen productivity through increased below‐ground biomass fraction. We further tested whether similar patterns are found in phosphorus use efficiency (PUE).LocationTwenty‐one sampling sites along Tibetan Alpine Vegetation Transects (TAVT) at altitudes from 1900 m to 4900 m.MethodsWe measured the maximum biomass of new canopy leaves and twigs and the concentrations of their nutrients N and P and associated ecosystem variables along the TAVT. NUE (PUE) was calculated as the product of nutrient productivity (dry matter production per unit N or P in new canopy leaves and twigs) and MRT (the ratio of foliage nutrient pool to annual nutrient uptake).ResultsWith increasing altitude, leaf life span increased in forest trees but decreased in shrublands and grasslands, while below‐ground fraction increased when vegetation changed from montane forests to alpine shrubs/grasslands. In forest trees, higher N‐MRT and P‐MRT and lower P productivity were associated with longer leaf life span and lower below‐ground fraction, while N productivity varied little. In alpine shrublands and grasslands, N‐MRT, P‐MRT and P productivity varied little with leaf life span and below‐ground fraction, while N productivity was positively correlated with below‐ground fraction.ConclusionsOur data supported the hypothesis, suggesting that NUE of canopy production would be a measure of changes in ecosystem functioning from montane forests to alpine shrublands and grasslands along altitudinal gradients. The findings provide an insight into the linkage between biogeochemistry and phytogeographic processes across ecosystems.

The effect of phosphorus utilization efficiency on durum wheat cultivars under semi-arid environmental conditions

Faced with the high cost of phosphate fertilisers in several African countries, including Algeria, and in order to better select varieties according to their fertiliser use efficiency, this study was proposed. The goal of the study was to determine how “variety” impacts durum wheat's capacity to utilize phosphorus effectively and to try to pinpoint the agro-morphological factors that contribute to this efficiency so that they can be taken into consideration when choosing which varieties to sow in semi-arid environments. The experimental setup consisted of a split plot with two investigated factors and three repetitions, with the main plot receiving the phosphate treatment while the sub plot receives the variety. The trial set up consisted of 11 durum wheat varieties, which were cultivated over two years successively. The PUE of the fertiliser, provided in 46% triple superphosphate (TSP) granules, and agro-morphological parameters like aerial biomass, plant height, grain yield and yield components were determined. The findings demonstrated that triple superphosphate, a type of phosphorus fertilizer, increases grain yield by between 40 and 60% for all varieties examined as compared to the phosphorus-free control at the average dose employed in this field trial, or 20 kg P2O5.ha-1. This increase in yield is due to an increase: from 20 to 22% in the number of ears per m², 41.5% in the number of grains per ear, and 9% in the average weight of the grain. The PUE is strongly correlated to the yield components (Number of ears per square meter- NEM, Number of grains per ear- NGE, thousand grain weight- TGW and Yield) but also to the height at heading (r=0.86) and dry matter (r=0.85). Phosphorus use efficiency is also strongly correlated to flag leaf length and width as well as leaf area. Also, that genotypes with higher weight of thousand grains (WTG) showed better use of available phosphorus. The principal component analysis (PCA) confirms that the efficiency of phosphorus use by the varieties tested explains a large portion of the variation noted in these varieties. This genetic variation in PUE was associated with plant height and phosphorus content of the sown grains. These results could be of a significant impact in improving rainfed durum wheat productivity in semi-arid areas and preserving the environment as well. Key words: Durum wheat, Phosphorus use efficiency, Plant’s height, Genetic variation, Fertilizers’ reduction

Effects of different stocking density start-up conditions on water nitrogen and phosphorus use efficiency, production, and microbial composition in aquaponics systems

Controlling environmental parameters, including nitrogen and phosphorus use efficiency, is a crucial aspect of maintaining effective aquaponic systems. In this study, we evaluated the impact of start-ups under high (20 kg/m3) and low (5 kg/m3) stocking density conditions on water quality, productivity, nitrogen use efficiency (NUE), phosphorus use efficiency (PUE), microbial community compositions, and functional genes in the aquaponics system. Six experimental units (three replications per treatment) were categorized into two groups. The experimental process was divided into two phases: Phase I (Days 1–40) and Phase II (Days 41–145). During Phase I, the two system groups were initiated under high and low stocking densities. Phase II constituted the fish and vegetable production phase, with all aquaponics systems standardized at a stocking density of 10 kg/m3 and a planting density of 12 plants/m2. The results indicated superior water quality in the low aquaponics systems than that in the high aquaponics systems during Phase I, whereas the opposite was observed during Phase II. The final weight, specific growth rate, and fish weight gain of jade perch (Scortum barcoo), as well as the plant weight gain of tomato plants, were significantly higher in the high aquaponics system than those in the low aquaponics system. The NUE and PUE of the high aquaponics system were 49.55 ± 1.02% and 60.12 ± 1.28%, respectively, surpassing those of the low aquaponics system (43.41 ± 2.16% and 49.06 ± 1.59%). The microbial diversity in the moving bed biofilm reactor and roots of the high aquaponics system was lower than in the low aquaponics system. However, the relative abundances of nitrifying and denitrifying bacteria were higher than those in the low aquaponics system. The number of copies of functional genes for nitrification and denitrification, including amoA, nxrB, nirS, nirK, and nosZ, was higher in the high aquaponics systems. Overall, the results indicated that high aquaponics systems initiated with high stocking density yield more products, improved water quality, and higher NUE and PUE by altering the composition of microbial communities. This study presents a method for enhancing the functional microbial community of a system by optimizing conditions during the initiation period.

Influence of Drip Fertigation and Foliar Spray of Boron on Yield and Nutrient Uptake by Cucumber cv. Himangi

The effect of fertigation and foliar application of boron on yield, uptake of nutrients and nutrient use efficiency by cucumber Cv. Himangi was studied during two consecutive years 2018-19 and 2019-20. An experiment was carried out in open field conditions with five fertigation levels viz., 100 % RDF through soil, 120 %, 100 %, 80 % and 60 % RDF through fertigation in ten equal splits at 10 days interval along with three levels of foliar application of boron viz. 0.0, 0.1, and 0.2 per cent concentration at 30, 45 and 60 DAS to determine suitable fertigation and foliar spray of boron dose for cucumber cultivation. The experiment was consisting of fifteen treatment combinations of recommended doses of water soluble fertilizers, comprising of five levels of fertigation. The results indicated that, yield, nutrient uptake and nutrient use efficiency of nitrogen, phosphorus and potassium under study were significantly influenced by various fertigation and boron levels. On the basis of pooled data, it was observed that, among various treatment combinations, minimum male : female sex ratio (1:4), maximum average weight of fruit (239.88 g), yield per vine ( 2.44 kg), yield ( 228.37 q/ha), uptake of nitrogen by shoot, ( 13.03 kg/ha), ( 81.62 kg/ha) by fruit and (94.01 kg/ha) by whole cucumber vine, maximum uptake of phosphorus by shoot (3.62 kg/ha), (21.52 kg/ha) by fruit and ( 25.13 kg/ha) by whole cucumber vine and the maximum uptake of potassium by shoot ( 14.05 kg/ha), by fruit (101.45 kg/ha) and ( 115.20 kg/ha) by whole cucumber vine, B:C ratio (2.99) and minimum (27.73, 25.71 and 17.2, 16.85 and 55.28, 50.28 %, respectively) nutrient use efficiency of NPK were recorded with the application of 120 % RDF through fertigation due to nutrient losses through leaching, devolatilization. While, maximum (36.70, 34.70 and 25.38, 21.90 and 65.81, 63.43 respectively) nutrient use efficiency of NPK was recorded with the application of 60 % RDF through fertigation. The maximum (22.59, 20.61 and 6.99, 7.70 and 27.30, 30.47 %, respectively) nutrient use efficiency with foliar application of boron at concentration of 0.2 per cent and minimum (3.60, 3.44 and 0.56, 0.52 and 3.72, 4.05 %, respectively) nutrient use efficiency with foliar application of boron at concentration of 0.1 per cent.

More than colorful: phosphorus allocation to major chemical fractions shifts during leaf development in species exhibiting delayed greening

The colorful “delayed leaf greening” is a common but overlooked phenomenon in phosphorus (P)-limited environments in habitats in tropical, subtropical and temperate forests, but the physiological mechanism underpinning it remains unclear. It is important to understand how allocation of phosphorus to major leaf P fractions shifts during leaf development, as a strategy for utilizing P efficiently. We measured concentrations of leaf nitrogen and P and five chemical P fractions, and eight leaf chemical element concentrations (K, Ca, Mg, Mn, Fe, Cu, Zn and Se) in young and mature leaves of six woody plants exhibiting delayed greening in China. We also measured leaf mass per area, photosynthetic rate, photosynthetic phosphorus-use efficiency, and soil nutrient concentrations. The results indicate six species exhibiting delayed greening had different leaf P concentrations during leaf development, but the same nitrogen concentrations. We further show major leaf chemical P fractions like metabolite P, nucleic acid P and lipid P showed differences in young and mature leaves. The concentration of lipid P, nucleic acid P, Pi and residual P significantly decreased from young to mature leaves, while that of metabolite P was constant. There was a greater allocation of P to phospholipids and metabolite P in mature leaves. The concentration of Cu and K were significantly higher in young leaves. This study provides new insight to investigate the roles of different P fractions in young and mature leaves, and how the allocation shifts for plants to utilize phosphorus.

Evaluation and Selection of Bromegrass Genotypes under Phosphorus and Water Scarcity towards the Development of Resilient Agriculture Focusing on Efficient Resource Use

The relationship between phosphorus (P) availability and water restriction was explored in this study, focusing on its impact on phosphorus use efficiency (PUE) and water use efficiency (WUE) in various bromegrass (Bromus spp.) genotypes. Under controlled conditions, five bromegrass genotypes, as well as one ryegrass (Lolium perenne) cultivar, were compared by subjecting them to two P levels and two watering regimes. It was determined that combining water and phosphorus limitations led to reduced plant productivity. Initially, the ryegrass outperformed the bromegrass, but this result declined over time, while bromegrass exhibited consistent stability. Notably, under P and water stress, enhanced root development was observed in bromegrass compared to that in ryegrass. Distinct patterns of PUE and WUE allowed for the categorization of bromegrass genotypes into three groups. Genotype 3457 emerged as the most efficient, scoring 20 out of 24, while Pro 94-49 A achieved a score of only 10 out of 24. This study suggests that the drought resilience of bromegrass may be linked to increased root growth during the early vegetative stages, which potentially facilitates improved P acquisition. However, further validation through long-term field experiments is needed. The insights from this study are potentially valuable for use in shaping plant breeding programs by revealing the plant adaptation mechanisms for both P and water absorption.