Growth,yield and nutrient uptake of taro grown under upland conditions

There is a scarcity of basic information on dry matter accumulation by various plant organs, nutrient uptake, and yield of taro [Colocasia esculenta (L.) Schott] grown under upland conditions. These data are essential for the development of technological packages, growth simulation models, and decision support systems designed to promote agrotechnology transfer of the crop in the tropics. Two taro cultivars were planted and harvested for biomass about every six weeks during the growing season. At each harvest, plants were separated into various plant parts and their dry matter and nutrient content were determined. There were no significant differences (P<0.05) in total and edible dry matter content between cultivars. However, cultivar ‘Lila’ absorbed significantly smaller amounts of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and zinc (Zn) than cultivar ‘Blanca’, suggesting that it had a higher nutrient‐use efficiency. Fresh corm yields were not significantly different and averaged 20,221 kg/ha for both cultivars.     

Growth response and nutrient uptake by forage crops under effluent irrigation

Abstract

The forage crops corn (Zea Mays), sorghum‐sudangrass (Sorghum Vulgare Pers. x Sorghum sundanese stapf.), and kenaf (Hybiscus cannabinus L.) were irrigated with municipal effluent at rates of 5, 10, 15, and 20 cm/week on Lakeland fine sand. Plant samples were collected weekly from each plot to measure green weight, dry matter, and nitrogen content. From these data crop nitrogen (kg/ha) was calculated for each week. Finally, uptake of nitrogen was calculated to determine efficiency of nitrogen recovery from the effluent as the crops matured. In all cases efficiency of uptake decreased with increasing application rates, as expected from fertility studies. For corn, efficiency of uptake continued to increase up to harvest. For sorghum‐sudangrass and kenaf a peak was reached at about 50 days after planting, after which efficiency of uptake declined rapidly.     

Uptake of sulfur by four cotton cultivars grown under field conditions

There has never been an intensive study of the sulfur (S) nutrition of cotton (Gossypium hirsutum L.) when grown under field conditions. Field studies were conducted on two non‐irrigated soils to evaluate the S‐uptake characteristics of four selected cotton cultivars that are representative of those produced in the Southern United States. Four cultivars with diverse genetic backgrounds, Deltapine 90, Coker 315, Paymaster 145, and Stoneville 825 were grown on a Norfolk fine sandy loam (fine loamy, siliceous, thermic, Typic Kandiudults) and a Decatur silt loam (clayey, kaolinitic, thermic, Rhodic Paleudults). Whole plants were collected at two‐week intervals over the growing season starting at 15 days after planting. The plants were partitioned into leaves, stems, burs, seed, and lint, and analyzed (except for lint) for S. Total S uptake when averaged over both soils and all four cultivars was 20.4 (±9.4) kg/ha [or 2.7 (±0.7) kg S per 100 kg lint produced]. Sulfur uptake on the Norfolk soil (15.6 (±8.5) kg/ha) was lower compared to the Decatur soil [25.1 (±7.9) kg/ha]. There were no cultivar differences in total S uptake on the Norfolk soil, but total S uptake on the Decatur soil was affected by the interaction between sampling date and cultivar. The concentration of S and S uptake by some plant parts were affected by the interaction between sampling date and cultivar, however, cultivar differences were not consistent among soils or over the growing season. Maximum daily accumulation of S occurred during the final two week sampling period at the end of the growing season (cumulative heat unit 1193–1444) during which an average of 29.5% of the total S was accumulated.     

Growth and nutrient uptake in grain sorghum grown under mulch

Mulches can alter plant growth by changing the soil environment, but their effects on mineral uptake in grain sorghum are unknown. A 3‐year study was conducted to measure nutrient uptake in plants grown under 0, 2200, 4400, and 8800 kg/ha mulch. Plants were irrigated to insure that moisture was not limiting. Dry‐matter production, total mineral uptake and concentrations were determined at 7‐ to 9‐leaf, late boot, soft dough, and physiological maturity growth stages. Mulches altered sorghum growth by delaying plant maturity and by increasing dry‐matter yields. Nutrient uptake increased with increased dry‐matter production although elemental concentrations declined. Hybrid reaction to mineral uptake was dependent on the specific environment created by the mulch. Hybrids did not respond the same to given mulch rates each year. Management considerations for soil fertility under mulch conditions should be made on the basis of expected dry‐matter yields for the specific environment.     

Corn uptake of bromide under greenhouse and field conditions

Abstract

Bromide (Br) has been used frequently to trace the movement of fertilizer derived nitrate (NO₃) through the soil profile. Although not required for plant growth, Br is readily absorbed by plants. Consequently, the pulse of an anion tracer moving through the soil can be attenuated by actively growing plants. Greenhouse and field experiments were conducted to determine the amount of Br absorbed by corn, and to better understand potential competitive interactions between nitrogen (N) and Br in plant uptake. Under greenhouse conditions, over 85 percent of applied Brwas recovered by corn tops. Results from both greenhouse and field experiments demonstrated that the addition of Br or Cl neither reduced yield nor inhibited N uptake. Therefore, either Br or Cl could be used in N trials without concern for competitive inhibition of N uptake. However, both experiments demonstrated that N treatments affected Br concentration in the tissue, but this difference may have been due to increased yield of N treated plants causing Br dilution. Nitrogen treatments significantly affected plant Br uptake, but only in the greenhouse study. In the field experiment, corn recovery of 100 kg Br/ha applied in the spring of 1988 was as high as 38 percent in 1988, and 11 percent in 1989. This high rate of recovery demonstrates that the pulse of Br can be significantly reduced in the presence of developing plants, and should be taken into account when it is used as a tracer in leaching studies.     

Growth response of cabbage plants to arsenic and antimony under water culture conditions

Recently some attention has been paid to arsenic and antimony because these elements are polluting our environment (1, 2). The responses of crops to arsenic have been studied mainly from the view point of reduced growth due to arsenic toxicity (3). However little information on plant-antimony relations is available, although the chemical properties of arsenic are analogous to those of antimony. Thus, the present experiment was conducted to investigate the effect of widely graded-levels of arsenic an antimony in a culture solution on the growth of cabbage plants, which were selected as the experimental plant because their inner leaves are eaten by human beings.     

长期膜下滴灌棉田土壤盐分变化特征

为阐明膜下滴灌技术对土壤化学性质的影响,选择典型绿洲区(新疆石河子市下野地灌区)进行膜下滴灌1~6 a的棉田,于2009—2013年对其土壤盐分离子变化进行定点监测分析。结果表明,绿洲盐碱区棉田土壤中盐分、Na+、Ca2+、Mg2+、SO2-4以及Cl-随滴灌应用年限延长呈负指数幂函数曲线降低,在膜下滴灌技术使用初期,棉田盐分、离子下降较快,随后降幅减小;滴灌第1年土壤为盐土,滴灌第5年转为轻度盐化土;滴灌第6年后棉花成活率为76.39%,产量为4 515.48 kg/hm2。同时随着滴灌年限延长钠吸附比和Cl-/SO2-4当量比降低,土壤中阴阳离子组成亦在逐年发生变化,长期应用膜下滴灌技术后盐碱土类型将可能由氯化物-硫酸盐盐土转化为硫酸盐盐土。结果表明,绿洲盐碱灌区现行灌溉制度下膜下滴灌棉田土壤盐分向着有利于棉花生长的方向发展。研究可为规模化推广膜下滴灌技术提供一定的理论支持。     

Heavy metals mobility,sources, and risk assessment in soils and uptake by apple (Malus domestica Borkh.) leaves in urban apple orchards

The aim of the study was determine potential mobility, sources, and environmental impacts of heavy metals in soil of urban apple orchards using a sequential extraction procedure and multivariate analysis. The soil and apple (Malus domestica Borkh.) leaf samples were collected from apple orchards of urban areas in Çanakkale, Turkey. A sequential extraction procedure was employed to determine the binding forms of Cd, Cr, Cu, Ni, Pb, and Zn in soil samples. Sequential extraction procedure revealed that mobile fractions (acid soluble, reducible, and oxidizable) of Cd (60.2%) and Pb (56.8%) were higher than their immobile fractions. Such higher mobile fractions indicate the anthropogenic sources, and multivariate analysis results also supported the existence of such sources. The relationship between pH and mobile fractions of the metals (sum of acid soluble, reducible, and oxidizable) indicates that Cd and Pb become more mobile under decreasing pH conditions. Considering all metals, except for Cd, a strong relationship was observed between metal concentrations of apple leaves and mobile fractions, and plants were primarily able to uptake the metals in these fractions. Contamination factor and risk assessment code results together also revealed that Cd was highly mobile; retained less and had high risk for the environment.     

不同控制灌溉方式下稻田土壤盐分动态变化研究

对不同控制灌溉方式下稻田土壤盐分在水稻各生育期的动态变化规律进行了深入分析,并结合各生育期水稻冠层叶面积指数和稻田腾发量对土壤盐分动态成因进行了探讨。研究结果表明：控制灌溉或控制灌溉+淋洗条件下,各水稻生育期土壤含盐量均有不同程度降低,表现为随着淋洗水量的增加土壤含盐量逐渐降低的规律性,试验条件下不同处理间的差异不太显著;试验各灌溉方式并未引起土壤盐分显著积聚,并且具有重要的节水增产效益,其中水稻控制灌溉(即处理1)从节水增产角度而言是稻田较佳的灌溉管理方式。本项研究内容及其成果对于指导水稻灌溉管理实际具有重要的理论指导意义。     

Growth and nutrient uptake dynamics of Mytilaria laosensis seedlings under exponential and conventional fertilizations

The growth characteristics and nutrient uptake dynamics of Mytilaria laosensis Lec. seedlings treated weekly with conventional and exponential fertilizations were investigated at intervals of 3 weeks for 12 weeks in a greenhouse. Leaf area and pigment compositions were also examined at the final harvest. The fertility treatments (mg nitrogen seedling^–1) included two conventional (50C and 100C) and four exponential (50E, 100E, 200E and 400E) fertilizations, and no fertilization (0) as control. The biomass and nutrient contents of M. laosensis seedlings increased exponentially with time. Steady-state nutrition of nitrogen (N) and phosphorus (P) were achieved under exponential fertilization treatment of 50?mg?N?seedling^?1 (50E) and conventional fertilization treatment of 100?mg?N?seedling^–1 (100C), resulting from simultaneous increase of their biomass and nutrient contents. The nutrient uptake efficiency continuously increased over time in conventionally fertilized seedlings, but it increased initially and declined or remained stable from 11 weeks after transplanting in the exponentially fertilized seedlings. At the end of the experiment, the conventionally fertilized seedlings performed remarkably better than all exponentially fertilized seedlings except for seedlings in the exponential treatment of 200?mg?N?seedling^–1 (200E) in height, root collar diameter and biomass. The optimum N and P uptake occurred in 200E seedlings because their N and P contents were 71%/60% and 14%/9% higher than both conventionally fertilized seedlings (50C/100C) without significant differences in growth performance between them. The leaf areas and chlorophyll contents of seedlings increased significantly with the increase of fertilizer levels and nearly peaked at the range from 100 to 200?mg?N?seedling^–1, whereas the delivery schedule (conventional and exponential) had little effect on leaf areas and chlorophyll contents of seedlings at the same nutrient level (50 or 100?mg?N?seedling^–1). These findings will provide evidence to make guidelines on fertilization for nursery production of M. laosensis, and help understand the nutrient demands for this species and further benefit the development of its plantations.     

Mycorrhizae enhances horticultural plant yield and nutrient uptake under phosphorus deficient field soil condition

Mycorrhizae can enhance plant growth and phosphorus (P) use efficiency in horticultural plants. This research evaluated the effectiveness of mycorrhizae on increasing growth and yield of nine horticultural plants for two different rates of P fertilization under field conditions. The mycorrhizal inoculums increased the root colonization of mycorrhizal horticultural plants compared with the non-inoculated treatments. Mycorrhizal inoculation significantly increased onion, garlic, chickpea, broad bean, carrot, parsley and cress plants. Mycorrhizal effectiveness showed that without P addition the effect of mycorrhizae on plant yield is much higher than that with P fertilizer addition. Under low P fertilization inoculation effectiveness is much higher than P addition treatments. Mycorrhizal inoculums also increased tissue P and zinc (Zn) for horticultural plant. The improved growth, yield, Zn and P uptake in plants demonstrated the potential of mycorrhizal inoculation to reduce the effects P fertilization on horticultural plants grown under field conditions.     

土壤状况及养分交互作用对棉花产量影响的数学分析

The influence of soil chemical properties and soil nutrition on cotton yields was studied by means of establishing mathematical models. The nultivariate quadratic regression equations developed by a stepwise regression method not only presented the single effect of soil factors but also displayed the interaction (synergistic or antagonistic) of soil nutrients. The effect of individual factor and the way of nutrient interaction were further analysed by the path analysis method. The results showed that among major factors affecting cotton yields, there existed the interactions between macronutrients(available P × available K), and between macronutrients and microelements (N × Zn, P × Mo, P × Cu, P × Zn, K × Mo) besides the single effect of soil pH, total P, available Cu and available Zn.     

不同滴灌施肥模式对棉花产量及养分吸收的影响

通过等养分和等成本施肥田间试验,研究不同滴灌施肥模式对棉花产量及养分吸收的影响。试验设4种滴灌施肥模式,分别为常规基施(CK)、常规追施(DCK)、普通滴灌专用肥(F1)和高磷钾滴灌专用肥(F2)。结果表明,在等养分施用条件下,高磷钾滴灌专用肥和普通滴灌专用肥处理的棉花干物质重、养分吸收量和产量均显著高于常规基施处理,但普通滴灌专用肥和常规追施处理差异不大;常规基施处理的氮肥和磷肥的利用率最低,普通滴灌专用肥和常规追施处理的氮肥和磷肥利用率差异不显著,高磷钾滴灌专用肥可显著提高磷肥利用率。在等成本施用条件下,常规追施处理的棉花干物质重、养分吸收量和产量最高,而高磷钾滴灌专用肥、普通滴灌专用肥和常规基施处理无显著差异。因此,滴灌专用肥尤其是高磷钾滴灌专用肥具有较好的应用效果,但是如何降低肥料成本是滴灌专用肥技术面临的重要问题。     

Nitrous oxide emission from an irrigated cotton field under semiarid subtropical conditions

In a 1-year study, quantification of nitrous oxide (N₂O) emission was made from a flood-irrigated cotton field fertilized with urea at 100kg N ha⁻¹ a⁻¹. Measurements were made during the cotton-growing season (May–November) and the fallow period (December–April). Of the total 95 sampling dates, 77 showed positive N₂O fluxes (range, 0.1 to 33.3g N ha⁻¹ d⁻¹), whereas negative fluxes (i.e., N₂O sink activity) were recorded on 18 occasions (range, −0.1 to −2.2g N ha⁻¹ d⁻¹). Nitrous oxide sink activity was more frequently observed during the growing season (15 out of 57 sampling dates) as compared to the fallow period (3 out of 38 sampling dates). During the growing season, contribution of N₂O to the denitrification gaseous N products was much less (average, 4%) as compared to that during the fallow period (average, 21%). Nitrous oxide emission integrated over the 6-month growing period amounted 324g N ha⁻¹, whereas the corresponding figure for the 6-month fallow period was 648g N ha⁻¹. Subtracting the N₂O sink activity (30.3g N ha⁻¹ and 3.8g N ha⁻¹ during the growing season and fallow period, respectively), the net N₂O emission amounted 938g N ha⁻¹ a⁻¹. Results suggested that high soil moisture and temperature prevailing under flood-irrigated cotton in the Central Punjab region of Pakistan though favor high denitrification rates, but are also conducive to N₂O reduction thus leading to relatively low N₂O emission.     

生物碳对土壤磷素和棉花养分吸收的影响

通过两年温室盆栽试验,研究了不同磷肥用量下生物碳对土壤磷素含量、 棉花生长和养分吸收的影响。试验以棉花秸秆为原料制备生物碳,制成三种热解温度（450℃、 600℃和750℃）的生物碳,分别以BC450、 BC600和BC750表示,同时以空白土壤为对照（CK）; 磷肥（P2O5）用量设3个水平0、 0.25、 0.5 g/kg（分别以P0、 P1、 P2表示）。研究结果表明,施用生物碳可显著提高土壤磷素含量及其有效性,随着生物碳热解温度的升高,土壤水溶性磷、 速效磷及全磷含量均显著增加,且对三种磷素含量的影响表现为水溶性磷 全磷 速效磷。施用生物碳处理两年棉花的干物质重均显著高于对照,但不同热解生物碳处理对两年棉花干物质重的影响各异。施用生物碳可显著增加棉花养分吸收量,总体表现为750℃ 600℃ 450℃。因此,施用生物碳可显著提高土壤磷素含量,促进棉花生长和养分吸收; 热解温度是影响生物碳质量的重要因素,生物碳的热解温度越高（450~750℃）,其促进作用越好。     

八达岭山地次生林土壤养分与磷酸酶活性研究

 为探讨北京八达岭山地土壤肥力状况,以黑桦、糠椴、核桃楸3种次生林为对象,对其土壤养分和磷酸酶活性进行研究。结果表明:土壤养分有明显的表聚效应;土壤全磷含量仅为0.39～0.66g.kg-1之间,有可能出现缺磷现象;土壤磷酸酶的活性以酸性磷酸酶为主,呈垂直递减分布规律;各种土壤养分和磷酸酶活性均有明显的根际效应,根系/本土比值在1.02～5.25之间。用SPSS软件进行分析表明,土壤磷酸酶活性与土壤pH、有机质、全氮、有效氮、有效磷和速效钾显著正相关,可以作为土壤肥力评价的一个指标。     

Metabolic response of Medicago sativa to severe nutrient imbalances and disturbances under field conditions

Our experiments were focused on the metabolic footprint of mineral‐nutrient availability under field conditions. While there are multiple factors potentially blurring such footprints, we hypothesized that physiological and metabolic adaptations of established plants are particularly important mechanisms under field conditions. To study respective differences between young and established plants and to study the impact of disturbances on the adaptive capacity of established plants, we analyzed Medicago sativa plants of different age from plots with marked differences in the levels of soil mineral nutrients established in a long‐term fertilization experiment. Gas chromatography–mass spectrometry was used to determine metabolite profiles of sink and source leaves of plants in an early state of development (“young plants”), just before the first harvest (“established plants”), and a short time after the second harvest (“regrowing plants”). Metabolite profiles from young plants were markedly responsive to soil mineral nutrients and resembled respective profiles from controlled conditions, demonstrating that overall variability of growth and sampling conditions had relatively little importance for the metabolite profiles recorded. In the case of established plants, however, we observed only little impact of availability of mineral nutrients on metabolite profiles. This low metabolic responsiveness of plants was partially lost after severe disturbances (removal of the plant shoot). Metabolite profiling, in summary, is able to detect a metabolic footprint of mineral‐nutrient availability in young plants under field conditions and may provide information about the ability of older plants to partially uncouple their metabolism from the environment. In addition, it is also possible to determine the impact of disturbances on this ability of the plant organism.     

Effects of plant-bacterial-amoebal interactions on plant uptake of nitrogen under field conditions

Summary Bacterial biomass and numbers of bacterivorous naked amoebae were estimated daily in soil associated with barley roots and, to avoid the influence of roots, in soil from a field in its fifth summer under bare fallow. The estimates were associated with two rainfall events and were started just before the first. Increases in bacteria were observed after each rainfall, and bacterial production was about the same size for both treatments. A peak in naked amoebae followed each burst of bacterial production in the root-associated soil, whereas in the fallowed soil protozoan production was low after the first rainfall and undetectable after the second. The bacterial populations in the fallowed soil had yet to decline by the end of the 12-day study, probably because grazing pressure by protozoa was low. Calculations based (1) on short-term decreases in bacterial biomass in soil close to roots or (2) on the amount of C added to the soil by plants over the growing season indicated that N released via bacterial-protozoan interactions contributed 10%–17% of the N taken up by the fertilized barley.