Assessing resource use in gerbera genotypes for precision nutrient use in protected condition

Abstract

The present study was conducted in the existing germplasm block of gerbera under protected condition at ICAR-IIHR, Bengaluru, India during 2017–2019 to obtain comprehensive information on biomass partitioning, nutrient uptake pattern and flower yields in different genotypes for precision use of critical inputs. The number of leaves (187.6–353.2 m^?2?yr^?1) and flower stalks (166.9–274.5 m^?2?yr^?1) varied significantly among genotypes. Specific leaf area (SLA) was similar among Balance, Stanza, Arka Aswha and Terra Kalina cultivars (0.150–0.156?cm² mg^?1). Strong positive influence of SLA on number of flower stalks was evident from the significant correlation (r = –0.774). Significant positive correlations among number of flower stalks and leaves, leaf area and SLA substantiate the flower yield pattern in gerbera. Optimum leaf number per plant was estimated at 18.6, while optimum range was quantified at 14.1 to 22.4. In gerbera genotypes, the partitioning of total aboveground dry biomass to leaves and flower stalks was 46–61% and 39–54%, respectively. The average nutrient removal was quantified at 32.8?g N, 7.3?g P, 78.7?g K, 24.7?g Ca and 4.1?g Mg m^?2?yr^?1 and the uptake of macronutrients was in the order of K?>?N > Ca > P?>?Mg. The order of micronutrient removal (g m^?2?yr^?1) was Fe (0.2), Zn (0.08), Mn (0.06) and Cu (0.03). The soil fertility status at uniform management was above optimum. It is clear that leaf number, biomass partitioning and nutrient removal pattern had direct impact on flower stalk yields of gerbera.     

Influence of sulfur deficiency on chlorophyll‐meter readings of corn leaves

Sulfur (S)‐diagnostic tools are essential for rational use of S fertilizers. There is little information about the suitability of leaf greenness intensity to detect S deficiency in corn (Zea mays L.). This work evaluates, under controlled S‐stressed conditions, (1) the performance of leaf greenness intensity as an indicator of the degree of S deficiency in corn, and (2) the advantage of the upper leaves in relation to the middle leaves for S‐deficiency determination. A pot experiment using sand as growth medium was conducted in greenhouse with corn at S rates of 0, 5, 10, 20, and 40 mg kg^–1 and sufficiency of other nutrients. Measurements of aboveground biomass (AB), total nitrogen (N), and S concentrations, and chlorophyll‐meter readings (CMR) in upper and middle leaves, were performed at the growth stages of 6–7, 11–12, and 14–15 fully expanded leaves (V6‐V7, V11‐V12, and V14‐V15, respectively). Sulfur application significantly increased AB, leaf S concentration, and CMR. Significantly positive relationships were obtained between leaf S concentration and CMR. A sulfur‐sufficiency index (SSI) based on CMR measured in upper and middle leaves was significantly associated with AB (R² = 0.58 and 0.62 for the middle and upper leaves, respectively). It is concluded that under sufficiency of other nutrients and high‐S‐stressed conditions, leaf greenness intensity could be a good indicator of corn S status, although little or no advantage was found for taking CMR from the upper leaves.     

Influence of catalyst,sample weight,and digestion conditions on Kjeldahl nitrogen

Abstract

The influence of catalyst (containing K₂SO₄/Cu/Ti, K₂SO₄/Se or Se alone), sample weight (0.2 or 0.4 g), and digestion blocks (Tecator DS 1015–20 or Tecator DS 1016‐ 40) on the Kjeldahl‐nitrogen (N) determination in pecan, corn, and turnip leaves was evaluated. Mean Kjeldahl‐N values were 1.84, 2.43, and 3.72 % for the pecan, corn, and turnip samples, respectively, which were significantly higher ( = 0.05) using K₂SO₄/Se as a catalyst, a 0.4 g aliquot of the sample, and a DS 1015–20 digestion block. The magnitude of the differences due to catalyst, sample weight, or digestion conditions did not affect the N diagnosis status when applying interpretative data for the selected crops. The higher standard deviation (SD) for the turnip leaves compared to the pecan or corn leaves may be due to a higher nitrate (NO₃) level in the turnip leaves. Selected catalyst, sample weight, and digestion conditions did not affect the SD, and therefore any combination of these factors could be used to determine Kjeldahl N. A protocol using K₂SO₄/Cu/Ti, a 0.4 g sample‐aliquot, and a digestion block equipped with condensers as the fume control system tended to give the lowest variance, and to be the most accurate and practical method.     

Coffee mucilage impact on young coffee seedlings and soil microorganisms

A greenhouse pot experiment was carried out to assess the effects of fermented coffee mucilage applied as mulch together with maize leaves on the growth of young coffee plants of two different varieties and on soil microbial biomass indices. The coffee variety Catuai required 32% more water per g plant biomass than the variety Yellow Caturra, but had a 49% lower leaf area, 34% less shoot and 46% less root biomass. Maize and mucilage amendments did not affect leaf area, shoot and root yield, or the N concentration in shoot and root dry matter. The amendments always reduced the water use efficiency values, but this reduction was only significant in the maize+mucilage‐14 (= 14 g mucilage pot^?1) treatment. Soil pH significantly increased from 4.30 in the control to 4.63 in the maize+mucilage‐14 treatment. Microbial biomass C increased by 18.5 µg g^?1 soil, microbial biomass N by 3.1 µg g^?1 soil, and ergosterol by 0.21 µg g^?1 soil per g mucilage added pot^?1. The presence of mucilage significantly reduced the microbial biomass‐C/N ratio from a mean of 13.4 in the control and maize treatments to 9.3, without addition rate and coffee variety effects. The application of non‐composted mucilage is recommended in areas where drought leads to economic losses and in coffee plantations on low fertility soils like Oxisols, where Al toxicity is a major constraint.     

Composition and seasonal variation of the essential oil from leaves and peel of a Cretan lemon variety.

The essential oil of leaves and peel from the Cretan variety Zambetakis (Citrus limon) was obtained by steam distillation with a Clevenger apparatus. The essential oil was subjected to GC-MS analysis, and 35 substances were identified. The main component in both essential oils was limonene. beta-Pinene, myrcene, neral, geranial, neryl acetate, geranyl acetate, and beta-caryophyllene have been identified in the leaf oil. The peel oil contained gamma-terpinene, beta-pinene, myrcene, neral, and geranial. The quantification of volatile substances was based on the internal standard method, using octyl acetate as internal standard, and expressed in milligrams per kilogram of the essential oil. The high contents of neral and geranial were indicative of the high quality of both essential oils. The aroma profile and quantitative variations among the essential oil components were measured at six different time intervals over a period of greater than one year. Differences between the components of lemon leaves and peel were observed.     

Physiological responses of lupinus mutabilis to phosphorus nutrition and season of growth

The response to phosphorus (P) concentration in the nutrient solution (0–0.5 mol P m^‐3) was studied in Lupinus mutabilis Sweet cv. Potosi in two different seasons (winter and spring). Phosphorus deficiency was more severe on growth than on photosynthesis and the season of growth dramatically influenced the optimal concentration of P for plant growth; root biomass was proportionally less affected than shoot biomass. During winter, growth and photosynthesis of plants supplied with 0.02–0.5 mol P m^‐3 were not significantly different, whereas in spring, rates of growth and photosynthesis were faster at the 0.5 mol P m^‐3 level. Stomatal conductance decreased with deficient P independently of leaf water relations. Severe P deficiency limited carbon (C) assimilation rates due to reduction in stomatal conductance and mesophyll photosynthetic capacity. Decreased sucrose/starch in P‐deficient leaves was a consequence of the observed source/sink imbalance which was more marked in winter. Hydraulic conductance was not a limiting factor for leaf expansion under low P. In conclusion, growth and metabolic changes observed in lupins grown at low P supply can be ascribed to an adjustment at the whole plant level, preventing a large drop in leaf P, reducing shoot growth and facilitating P uptake through higher root biomass.     

Growth attributes,xylem sap composition,and photosynthesis in common bean as affected by nitrogen and phosphorus deficiency

The effects of nitrogen (N‐) and phosphorus (P‐) deficiency, isolatedly or in combination, on growth, nitrogenous fraction, and inorganic phosphate in xylem exudade, and photosynthesis of common bean (Phaseolus vulgaris L. cv. Negrito) were investigated. Plants were grown in nutrient solution adjusted daily to pH 5.5 and aerated continuously. Ten days after emergence mineral deficiency was imposed. Plants were then supplied with high N (7.5 mol m^‐3) or low N (0.5 mol m^‐3), and also with high P (0.5 mol m^‐3) or low P (0.005 mol m^‐3). All sampling and measurements were made 28 days after emergence. N‐ or P‐deprivation brought about large decreases in total leaf area by inhibiting the emergence of new leaves and primarily the expansion of the leaves. The specific leaf area did not change under N‐ but decreased under P‐limitation. The decreased shoot to root ratio in all deficiency treatments was a consequence of a lowering mass of above‐ground organs, especially of leaves.

The content of chlorophylls declined significantly only under N‐deficiency alone; carotenoids declined under both N‐ and combined N‐ and P‐limitation. No alteration in amino acid concentration in xylem exudate occurred in plants experiencing N‐starvation, while ureides increased by 79%, and nitrate and inorganic phosphate decreased greatly. Under P‐deprivation, amino acids and nitrate in xylem sap dropped by about half; ureides were held relatively constant, and phosphate was severely depressed. Total upward translocation of N through xylem was estimated to be about 16% higher in N‐deficient plants than in plants without mineral limitation, but leaf N levels in the former were lower as compared to control plants. The net carbon (C) assimilation decreased similarly regardless of the imposed deficiency treatment. Such a decrease was mainly determined by non‐stomatal factors. In general, no additive effect between N‐ and P‐limitation on any of measured parameters was observed.     

Soil Plus Foliar Nitrogen Application increases Cotton Growth and Salinity Tolerance

Soil or foliar application of nitrogen (N) can increase plant growth and salinity tolerance in cotton, but a combination of both methods is seldom studied under salinity stress. A pot experiment was conducted to study the effects of soil application (S), foliar application (F), and a combination of both (S+F) with labeled nitrogen (¹⁵N) on cotton growth, N uptake and translocation under salinity stress (ECe = 12.5 dS m^?1). Plant biomass, leaf area, leaf chlorophyll (Chl) content, leaf net photosynthetic (Pn) rate, levels of ¹⁵N and [Na⁺] and K⁺/ Na⁺ ratio in plant tissues were determined at 3, 7, 14 and 28 days after N application (DAN). Results showed that soil or foliar nitrogen fertilization improved plant biomass, leaf area per plant and leaf photosynthesis, and a combination of soil- plus foliar-applied N was superior to either S or F alone under salinity stress. Although foliar application favored a rapid accumulation of leaf N and soil application a rapid accumulation of root N, S+F enhanced N accumulation in both leaf and root under salinity stress. The combined N application also maintained significantly greater [K⁺] and K⁺/Na⁺ than either soil or foliar application alone. Therefore, the improved plant growth and salinity tolerance under S+F relative to soil or foliar N application alone was attributed to the increased total uptake of N, balanced N concentrations in different tissues through enhanced uptake and accumulation in both leaves and roots, and higher ratio of K⁺/Na⁺.     

Antitermitic activity of leaf essential oils and components from Cinnamomum osmophleum

The antitermitic activities of the essential oils from the leaves of two Cinnamomum osmophloeumclones (A and B) and their chemical ingredients against Coptotermes formosanus Shiraki were investigated according to direct contact application. Results from this experiment have demonstrated that the indigenous cinnamon B leaf essential oil has a more effective antitermitic activity than indigenous cinnamon A leaf essential oil. Furthermore, when cinnamaldehyde, eugenol, and alpha-terpineol are extracted from indigenous cinnamon leaf essential oil and used at the strength of 1 mg/g, their antitermitic effectiveness is much higher than that using indigenous cinnamon leaf essential oil. Among the congeners of cinnamaldehyde examined, cinnamaldehyde has exhibited the strongest termiticidal property.     

Metabolism and efficiency in nitrogen utilization during senescence in pepper plants: Response to nitrogenous fertilization

The effect that application of nitrogen (N) rates exerts on some parameters of N metabolism in pepper plants (Capsicum annuum L. cv. Lamuyo) during senescence was studied. All plants were grown under controlled conditions in an experimental greenhouse. The treatments consisted of the application of 4 rates of N at the onset of flowering in the form of KNO₃ (N1: 6 g m^‐2, N2:12 g m^‐2, N3:18 g m^‐2, N4:24 g m^‐2). The results obtained show a optimal effect ofN2 fertilization on uptake, translocation, and assimilation of NO₃ ^‐ in the leaves. The N2 treatment registered maximums in the concentration of chlorophyll a and b, and in commercial yield. In conclusion, for improved pepper cultivation during senescence, treatment N2 gave the maximum yield, and increased metabolism and efficient utilization of N.     

Nutritional characteristics of sago palm and oil palm in tropical peat soil

To make clear the nutritional characteristics of sago palm (Metroxylon sagu Rottb.) and oil palm (Elaeis guineensin Jacq.) grown in tropical peat soil, minerals concentration, organic compounds concentration, and photo‐synthetic rate were estimated, and the obtained results were as follows. Since, the nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and sodium (Na) concentration in mature leaves and trunk were higher in the oil palm than in the sago palm, but potassium (K) concentration was higher in the sago palm than in the oil palm, the minerals (especially N, P, Ca, and Mg) requirement for the oil palm were higher than in the sago palm. This indicates that the sago palm will adapt better than the oil palm to soils with poor nutrients. The manganese (Mn) and zinc (Zn) concentration in leaves of the sago palm and Ca and aluminum (Al) concentration in leaves of the oil palm increased with the increase of aging, indicating that those elements are eliminated from plants through leaf senescence. In the sago palm, the N and P distribution ratio to leaves remained almost constant during growth, indicating that N and P were predominantly distributed to leaves for maintaining leaf function. The photosynthetic rate [μmole carbon dioxide (CO₂) m² LA sec^‐1] at light saturation was lower in the sago palm (5.8) and oil palm (10.0) than in wheat (25.4). As leaf longevity of sago and oil palms was longer (about 12 times) than that of wheat (Triticum aevstium L.), and the minerals concentration and photosynthetic rate remained constant for a long duration of growth, the cumulative carbon (C) accumulation per unit dry weight (photosynthetic rate x leaf longevity) in the individual leaf is assumed to be equal or greater than that of wheat. The photosynthetic ability of sago and oil palms leaves is very important for understanding why sago and oil palms have high productivity in spite of a low nutrient environment.     

Agrochemical characterization,net N mineralization,and potential N leaching of composted olive‐mill pomace currently produced in southern Spain

In S Spain, the Andalusian olive oil industry generates annually 2.5–3.0 million tons of olive mill pomace, a by‐product which is comprised of the residues from the two‐phase oil‐extraction process. The agricultural policies of the EU have led to widespread interest in recycling these agricultural by‐products. Olive mill pomace might be evaluated as an organic fertilizer after composting, however, before wider use of composted olive mill pomace is advocated, characterization of the final product is needed. In this study, the physico‐chemical characteristics, net N mineralization, and the potential for N leaching of 7 out of the 11 olive‐mill‐pomace composts currently produced in the Andalusian olive mills were investigated. Compost of olive mill pomace differed in the proportions of raw materials co‐composted with the olive mill pomace, such as olive leaf material, manure, and straw. In all the composts tested, organic matter, total C and K were high with 60.5%, 30.7%, and 1.7% on average, respectively, whereas total P was low (0.4%) and with intermediate levels of N (1.5%). Compost pH (8.03), electrical conductivity (2.85 dS m^–1), and germination index (65% on average) were adequate for agricultural use. Furthermore, principal component analyses revealed a clear relationship between the quality of the composts and the proportion of manure mixed with the raw materials. Net N mineralization was negative on average (–20 μg IN g^–1) after 1 y, but positive after 2 y of incubation with up to 94% of available N from the total N added and the short‐term potential N leaching after compost application was negligible (less than 3.9% of added N) and much lower than the other N fertilizer with up to 80% added N leached. Overall, results of this study clearly show that these currently produced composts of olive mill pomace are suitable as soil improvers for agricultural purposes, but may not contribute significantly as a N fertilizer for up to 2 y after application.     

Mulberry nutrient management for silk production in Hubei Province of China

The silk industry is important for south China's rural economy. Leaves of mulberry (Morus spp.) are used for silkworm production. Hubei province is one of the main silk‐producing provinces in China. The objectives of this research were to survey the fertilization practices in the mulberry‐producing regions in the province and to determine the best nutrition‐management practice for mulberry plantations. A survey and a series of field experiments with N, P, K, and micronutrients were conducted from 2001 to 2002. In addition, a silkworm‐growth experiment was also conducted by feeding leaves harvested from various fertilization treatments. The results indicate that poor soil fertility and unbalanced fertilization were the main factors limiting mulberry‐leaf yield and quality in Hubei province. Nitrogen fertilization of mulberry has reached a high level (454 kg ha^–1 y^–1) in Hubei province, but P‐ and K‐fertilization rates have not been matched with N‐fertilization rates as farmers are not aware of the significance of P and K. Balanced fertilization showed positive nutrient interactions with respect to mulberry yield and quality. Potassium application increased yield and quality (protein and sugar concentration) of mulberry leaves. Silkworm growth and cocoon quality were improved when silkworms were fed with the leaves derived from K‐fertilized plants in comparison with those taken from control plots. Application of Mg, S, and B also significantly improved leaf sugar, essential and total amino acid concentrations, but did not increase leaf yield significantly. It is concluded that a fertilizer dose of 375 kg N ha^–1, 66 kg P ha^–1, and 125 kg K ha^–1 is suitable for the cultivation of mulberry in the Hubei province along with Mg, S, and B, wherever necessary, for the improvement of yield and quality of mulberry leaves.     

Methods for evaluating human impact on soil microorganisms based on their activity,biomass, and diversity in agricultural soils

The present review is focused on microbiological methods used in agricultural soils accustomed to human disturbance. Recent developments in soil biology are analyzed with the aim of highlighting gaps in knowledge, unsolved research questions, and controversial results. Activity rates (basal respiration, N mineralization) and biomass are used as overall indices for assessing microbial functions in soil and can be supplemented by biomass ratios (C : N, C : P, and C : S) and eco‐physiological ratios (soil organic C : microbial‐biomass C, qCO₂, qN_min). The community structure can be characterized by functional groups of the soil microbial biomass such as fungi and bacteria, Gram‐negative and Gram‐positive bacteria, or by biotic diversity. Methodological aspects of soil microbial indices are assessed, such as sampling, pretreatment of samples, and conversion factors of data into biomass values. Microbial‐biomass C (µg (g soil)^–1) can be estimated by multiplying total PLFA (nmol (g soil)^–1) by the F_PLFA‐factor of 5.8 and DNA (µg (g soil)^–1) by the F_DNA‐factor of 6.0. In addition, the turnover of the soil microbial biomass is appreciated as a key process for maintaining nutrient cycles in soil. Examples are briefly presented that show the direction of human impact on soil microorganisms by the methods evaluated. These examples are taken from research on organic farming, reduced tillage, de‐intensification of land‐use management, degradation of peatland, slurry application, salinization, heavy‐metal contamination, lignite deposition, pesticide application, antibiotics, TNT, and genetically modified plants.     

Quantification of N2 fixation and annual N benefit from N2 fixation in soybean accrued to the soil under soybean‐wheat continuous rotation

A computational exercise was undertaken to quantify the percent N derived from atmosphere %Ndfa) in soybean and consequent N benefit from biological N₂‐fixation process annually accrued to the soil by the soybean crop using average annual N‐input/‐output balance sheet from a 7 yr old soybean‐wheat continuous rotational experiment on a Typic Haplustert. The experiment was conducted with 16 treatments comprised of combinations of four annual rates of farmyard manure (FYM ? 0, 4, 8, and 16 t ha^–1) and four annual rates of fertilizer N (? 0, 72.5, 145, and 230 kg N ha^–1) applications. The estimated N contributed through residual biomass of soybean (RBN_S) consisting of leaf fall, root, nodules, and rhizodeposition varied in the ranges of 7.02–16.94, 11.65–28.83, 3.31–8.91, and 11.3–23.8 kg N ha^–1 yr^–1, respectively. A linear relationship was observed between RBN_S and harvested biomass N (HBN_S) of soybean in the form of RBN_S = 0.461 × HBN_S – 20.67 (r = 0.989, P < 0.01), indicating that for each 100 kg N assimilated by the harvested biomass of soybean, 25.4 kg N was added to the soil through residual biomass. The Ndfa values ranged between 13% and 81% depending upon the annual rates of application of fertilizer N and FYM. As per the main effects, the %Ndfa declined from 76.4 to 26.0 with the increase in annual fertilizer‐N application from 0 to 230 kg N ha^–1, whereas %Ndfa increased from 40.8 to 65.8 with the increase in FYM rates from 0 to 16 t ha^–1, respectively. The N benefit from biological N₂ fixation accrued to the soil through residual biomass of soybean ranged from 7.6 to 53.7 kg N ha^–1 yr^–1. The treatments having %Ndfa values higher than 78 showed considerable annual contribution of N from N₂ fixation to the soil which were sufficient enough to offset the quantity of N removed from the soil (i.e., native soil N / FYM‐N / fertilizer‐N) with harvested biomass of soybean.     

Soil microbial biomass and activity: the effect of site characteristics in humid temperate forest ecosystems

Microbial biomass, respiratory activity, and in‐situ substrate decomposition were studied in soils from humid temperate forest ecosystems in SW Germany. The sites cover a wide range of abiotic soil and climatic properties. Microbial biomass and respiration were related to both soil dry mass in individual horizons and to the soil volume in the top 25 cm. Soil microbial properties covered the following ranges: soil microbial biomass: 20 µg C g^–1–8.3 mg C g^–1 and 14–249 g C m^–2, respectively; microbial C–to–total organic C ratio: 0.1%–3.6%; soil respiration: 109–963 mg CO₂‐C m^–2 h^–1; metabolic quotient (qCO₂): 1.4–14.7 mg C (g C_mic)^–1 h^–1; daily in‐situ substrate decomposition rate: 0.17%–2.3%. The main abiotic properties affecting concentrations of microbial biomass differed between forest‐floor/organic horizons and mineral horizons. Whereas microbial biomass decreased with increasing soil moisture and altitude in the forest‐floor/organic horizons, it increased with increasing N_tot content and pH value in the mineral horizons. Quantities of microbial biomass in forest soils appear to be mainly controlled by the quality of the soil organic matter (SOM), i.e., by its C : N ratio, the quantity of N_tot, the soil pH, and also showed an optimum relationship with increasing soil moisture conditions. The ratio of C_mic to C_org was a good indicator of SOM quality. The quality of the SOM (C : N ratio) and soil pH appear to be crucial for the incorporation of C into microbial tissue. The data and functional relations between microbial and abiotic variables from this study provide the basis for a valuation scheme for the function of soils to serve as a habitat for microorganisms.     

Partitioning of carbon and nitrogen during decomposition of 13C15N‐labeled beech and ash leaf litter

The aim of this study was to determine the influence of leaf‐litter type (i.e., European beech—Fagus sylvatica L. and European ash—Fraxinus excelsior L.) and leaf‐litter mixture on the partitioning of leaf‐litter C and N between the O horizon, the topsoil, the soil microbial biomass, and the CO₂ emission during decomposition. In a mature beech stand of Hainich National Park, Thuringia, Germany, undisturbed soil cores (?? 24 cm) were transferred to plastic cylinders and the original leaf litter was either replaced by ¹³C¹⁵N‐labeled beech or ash leaf litter, or leaf‐litter‐mixture treatments in which only one of the two leaf‐litter types was labeled. Leaf‐litter‐derived CO₂‐C flux was measured every second week over a period of one year. Partitioning of leaf‐litter C and N to the soil and microbial biomass was measured 5 and 10 months after the start of the experiment. Ash leaf litter decomposed faster than beech leaf litter. The decomposition rate was negatively related to initial leaf‐litter lignin and positively to initial Ca concentrations. The mixture of both leaf‐litter types led to enhanced decomposition of ash leaf litter. However, it did not affect beech leaf‐litter decomposition. After 5 and 10 months of in situ incubation, recoveries of leaf‐litter‐derived C and N in the O horizon (7%–20% and 9%–35%, respectively) were higher than in the mineral soil (1%–5% and 3%–8%, respectively) showing no leaf‐litter‐type or leaf‐litter‐mixture effect. Partitioning of leaf‐litter‐derived C and N to microbial biomass in the upper mineral soil (< 1% of total leaf‐litter C and 2%–3% of total leaf‐litter N) did not differ between beech and ash. The results show that short‐term partitioning of leaf‐litter C and N to the soil after 10 months was similar for ash and beech leaf litter under standardized field conditions, even though mineralization was faster for ash leaf litter than for beech leaf litter.     

Growth and chloride accumulation in soybean cultivars treated with excess KCl in solution culture

Abstract

Sensitivity to chloride was measured in soybean [Glycine max (L.) Merr.] cultivars Rinjani, Lokon, and Merbabu from Indonesia, and Lee from the United States. Plants were grown in solution culture to which KCl (0, 50, or 100 mol m^‐3) was added gradually during days 7–14 after emergence. Excess KCl reduced growth, measured as leaf area, shoot and root biomasses, total biomass, and root/shoot ratio in 24‐day‐old plants of all cultivars. The cultivar x KCl treatment interaction was significant for all growth parameters. The order of chloride tolerance at 50 mol m^‐3 Cl^‐, based on the mean of all growth parameters relative to the control, was Lee>Rinjani>Lokon=Merbabu. In the 50 mol m^‐3 Cl^‐ treatment Lee excluded Cl^‐ from the leaves, and accumulated Cl^‐ in the roots; Lokon, Rinjani, and Merbabu excluded less Cl^‐ from the leaves. At 100 mol m^‐3 KCl, cultivar Lee lost its capacity to exclude Cl^‐ from the leaves and its growth was poor. Chloride exclusion from the leaves at 100 mol m^‐3 KCl was most effective in Lokon, which corresponded to the relatively good growth of this cultivar in the high KCl treatment.     

Growth and essential oil composition responses of parsley cultivars to phosphorus fertilization and harvest date

Abstract

A field experiment was conducted on three cultivars (Italian Giant, Italian Plain, and Local) of parsley to compare plant growth, herb fresh weight, and essential oil (EO) content, yield and composition at three harvest times (Day 1, 47, and 91) in response to phosphorus (P) application rates (0, 12, 24, and 36?kg ha^?1). Repeated measures analysis revealed that the ideal P rate for the growth of parsley and its EO yield is 24?kg ha^?1; whereas the second harvest gives the highest height and weight; and the third harvest gives the highest EO content and yield. At all harvests, the highest EO content was obtained from Italian Giant fertilized with 36?kg ha^?1 P. β-myrcene, 1,3,8-p-menthatriene, β-phellandrene, and myristcin were the major compounds in all three cultivars, but their ideal P fertilization and harvest time varied with cultivar. This study showed biomass, EO content and yield, and the accumulation of EO constituents of parsley cultivars are influenced by P application and harvest date in different ways.     

Nitrogen mineralization from an organically managed soil and nitrogen accumulation in lettuce

The potential of an organically managed Cambic Arenosol to supply nitrogen (N) from either an applied commercial organic fertilizer (granulated hen manure), a compost produced on‐farm, or four different mixtures of both fertilizers was studied in a laboratory incubation and a pot experiment with lettuce. In the incubation experiment, a significant higher apparent N mineralization occurred after hen‐manure application (53.4% of the organic N applied) compared to compost (4.5%) or mixed‐fertilizer application (8.7% to 16.7%). The apparent N mineralization in a mixed treatment consisting of compost and half rate of hen manure (15.4% of the organic N applied) was significantly higher than that estimated based on the N mineralization for compost and hen‐manure treatments (7.6%), proving that a combined application of both fertilizers enhanced organic‐N mineralization when compared to separate fertilizer supply. In the pot experiment, a higher lettuce fresh‐matter yield was obtained with hen manure (1.9 kg m^–2) than with compost (1.7 kg m^–2) or unfertilized control treatment (1.3 kg m^–2). Combined application of compost with only a half rate of hen manure led to yields (2.0 kg m^–2) equal to those obtained with only hen manure. A good correlation was observed between the N‐mineralization incubation data and the N accumulated by lettuce plants in the pot experiment (r = 0.983). Hence, in the organic production of baby‐leaf lettuce, a mixture of compost and hen manure appears to be a good fertilization alternative, since it allows a reduction by half of the typical amount of commercial fertilizer usually applied (granulated hen manure), cutting fertilization costs, and providing an amount of available N that allows maintaining lettuce yields.