Rate Of Dry Matter Accumulation Research Articles

RADIATION USE EFFICIENCY OF MAIZE UNDER INFLUENCE OF DIFFERENT LEVELS OF NITROGEN FERTILIZATION AND TWO DIFFERENT SEASONAL CONDITIONS

The objective of this study to estimate the Radiation Use Efficiency under effect of three levels of nitrogen (N1 = 80 Kg N ha-1, N2 =120 Kg N ha-1, and N3=160 Kg N ha-1) for a set of maize hybrids include (Gloria, Market, Cruze and Draxma) in two different seasons in spring and fall of 2017 in Qlyasn-Sulaimani. The experiment was conducted using split plot design with three replicates . The results revealed higher intensity of PAR in autumn season than that of spring (15.672 and 10.555)MJm-2d-1 respectively that led to higher RUE in autumn revealing (4.311,3.546, and 4.702)g MJ-1 m-2 under the effect of (N1,N2, and N3) respectively, while the results of the autumn were higher (5.237, 4.681, and 6.019) g MJ-1 m-2 under the same levels of nitrogen fertilization, the highest application of nitrogen was more effective in autumn. The RGR and the rate of total dry matter accumulation were higher in autumn season displaying positive performance of studied maize hybrids to the higher intercepted of solar energy as well higher temperature.

A developmental research on wild Dipsacus asper in Chongqing Wulong district

In order to study the distribution and dynamics growth of wild Dipsacus asper resources in the Wulong district of Chongqing, 9 sample plots were selected for 12 consecutive months in the natural distribution area of the D. asper in Wulong district by using the sample line + plot survey method to conduct a field survey. The results showed that D.asper was distributed in forest edge wasteland or shrub-grassland, and growbetter with loose yellow-brownsoil or red soil, and poor with lithologic soil or impounded surface water.The growth curve of the plant height from June to July and the ground fresh weight from July to August showed a turning point, it might consume large amounts of nutrients during its flowering period, resulting in the restriction of vegetative growth.The highest temperature in the distribution area of D.asperoides in Wulong district is less than 30 °C, the minimum temperature is about 0 °C, and the rainfall is 1 241-1 392 mm. Its growth environment is no severecold in winter, no heat in summer, and abundant rainfall.The main growth stage of D.asper is from July to October, and the range of root dry rate was 0.162 5-0.239 7 in Xiangkou, 0.154 9-0.223 6 in Baima Mountain, and 0.143 7-0.203 3 Xiannv Mountain. The vegetative growth and dry matter accumulation synchronized in the main growth stage, and the accumulation rate of dry matter was faster than that of vegetative growth. The correlation analysis between indicators and root fresh weight showed that the fresh weight of the aerial part and root fresh weight had the best correlation.

Multisplit Nitrogen Application via Drip Irrigation Improves Maize Grain Yield and Nitrogen Use Efficiency

Conventional fertilization with most N applied before or during early maize (Zea maysL.) growth stages can negatively affect production if soil N is insufficient after silking. Here, drip irrigation with a split application of N (drip fertigation) was evaluated to determine whether the effect on yield and N use efficiency (NUE) differs with cropping practice. Compared with conventional fertilization, drip fertigation increased yield by 13 and 14% at a low planting density under a low N rate (L) and by 15% at a high planting density under a high N rate (H) in 2012 and 2013, respectively. Yield increases under drip fertigation were attributed to 18 and 17% increases in postsilking dry matter (DM) accumulation under L, and 12 and 10% increases in presilking DM accumulation, and 17 and 16% increases in postsilking DM accumulation under H in 2012 and 2013, respectively. Increased postsilking N accumulation under drip fertigation, promoted by greater root length and soil mineral N after silking, maintained increased leaf area index (LAI) and DM accumulation rate to improve postsilking DM accumulation under L. Greater N accumulation under drip fertigation from the 12‐leaf stage to silking and after silking promoted greater LAI and DM accumulation rate to increase pre‐ and postsilking DM accumulation under H. Because of greater grain yield and N uptake and less water consumption, drip irrigation improved NUE and irrigation water use efficiency. Drip fertigation can effectively improving maize grain yield and NUE resulting from improved DM accumulation with increased early‐season N uptake.

Forage accumulation, tillering and bromatological characteristics of Brachiaria grass under nitrogen fertilization

The objective of this study was to evaluate the influence of different nitrogen doses on the forage accumulation, tillering and chemical characteristics of Braquiaria grass ( Urochloa decumbens (Stapf) Webster cv. Basilisk). A randomized block design with four replications was used, and each plot (50 m²) was an experi­mental unit. The treatments consisted of four doses of N (100, 200, 300 and 400 kg ha -1 year -1 of N) and the con­trol treatment. There was an increase in whole-plant crude protein (CP) and in leaf crude protein (LCP) and a decrease in whole-plant neutral detergent fiber (NDF) and leaf neutral detergent fiber (LNDF). Total dry matter accumulation (TDMA) and dry matter accumulation rate (DMAR) increased linearly in response to the N doses applied. Nitrogen fertilization promotes benefits such as increased biomass accumulation and improved forage chemical composition and tillering in Brachiaria grass.

Productive characteristics of the grass Digitaria umfolozi subjected to defoliation frequencies

An experiment was carried out to evaluate the dry matter production, total dry matter availability, daily dry matter accumulation rate, light interception, leaf area index, daily accumulation rate, dry matter availability of the morphological components (leaf blades, stems + sheaths and dead material), leaf/stem ratio, crude protein, neutral detergent fibre and acid detergent fibre of Faixa-Brancagrass under seven defoliation frequencies (14, 21, 28, 35, 42, 49, and 56 days). Longer defoliation frequencies reduced the percentage of leaf blades and increased the percentage of stems + sheaths. The defoliation frequency positively influenced the availability of leaf blades, stems + sheaths, dead material and total dry matter. In the range of 42 days of defoliation, light interception reached 95%. At frequencies of 14 and 21 days of defoliation, the crude protein content of the leaves was above 20%. The highest utilization efficiency of D. umfolozi grass is achieved when the forage is managed with cutting intervals of 40 to 46 days. Higher defoliation frequencies positively contribute to the increase in the number of total white band grass leaves and higher crude protein content of the leaf blades and stems + sheaths.

Phenophases and cutting time of forage cactus under irrigation and cropping systems

ABSTRACT Management practices can affect the phenology and, consequently, the harvest time and crop production level of forage cactus. This study aimed at evaluating the effect of irrigation depths and cropping systems on the phenophases and cutting time of the forage cactus Opuntia stricta (Haw.) Haw. The experimental design was a randomized block with split plots and four replications. Irrigation depths based on reference evapotranspiration (8.75 %, 17.5 %, 26.25 % and 35 % ETo) and a control (0 % ETo) made up the plots, while cropping systems (exclusive cropping, exclusive cropping on mulch and forage cactus-sorghum intercropping) were distributed in the subplots. Cladode emission morphogenesis was used to define the phenological phases, while the extrapolation of the monthly dry matter accumulation rate was applied to obtain the cutting time. The use of irrigation depths significantly increased the phenophase II (higher emission of second-order daughter cladodes), decreasing the phenophase III, associated with third-order daughter cladodes. The phenophase III was lower in the exclusive cropping on mulch and forage cactus-sorghum intercropping systems, when compared to the exclusive cropping system. The ideal cutting time for irrigated forage cactus is 19 months, regardless of the cropping system. The exclusive cropping on mulch and forage cactus-sorghum intercropping systems significantly increased the monthly forage dry matter accumulation rate, with an earlier cutting time for the forage cactus-sorghum intercropping system (17 months).

Morphological and physiological characteristics of rice leaves in response to PASP-urea and optimized nitrogen management

ABSTRACTPolyaspartic acid (PASP)-urea is known to increase crop yield. Field experiments were conducted to compare the morphological and physiological characteristics of the leaves between plots treated with urea (conventional urea or PASP-urea) and subject to different nitrogen (N) management methods [farmers’ standard fertilization practice (FFP, two splits) or optimized N management (ONM, four splits)] in Sichuan, China, in 2014 and 2015. A no-added-N plot served as the control. Grain yield was significantly associated with increased number of green leaves, total leaf area, chlorophyll concentration of rice leaves after the heading stage, photosynthetic rate per leaf lamina and accumulated temperature of senescence rate acceleration and deceleration. PASP-urea significantly enhanced the photosynthetic capacity of leaves to improve dry matter accumulation rate of the panicle after the heading stage over conventional urea, mainly by increasing the number of green lamina, leaf lamina area, chlorophyll concentration and photosynthetic rate per leaf lamina, as well as delaying senescence of the flag leaf. Compared with FFP, the ONM substantially improved the photosynthetic capacity of leaves to enhance dry matter accumulation rate of the panicle. Therefore, the ONM is a rational approach to applying PASP-urea that can improve grain yield by improving photosynthetic capacity.

Responses pastures of Cynodon mixed with forage peanut in Southwestern of Paraná

The objective of this study was to evaluate the development, the botanical and structural components of Coastcross-1 and Tifton 85 pastures mixed with increasing inclusion of forage peanut (0, 25, 50, 75% occupancy area), submitted to cuts, from August 2011 (planting of pastures) to April 2013 (last period of cut), totaling two years of study. The experimental design was factorial (three factors) distributed in randomized blocks, the factors were cultivars (two), the opportunities area for planting of forage peanut (four) and seasons that showed cuts, with three replications. It was evaluated the forage mass, dry matter accumulation rate, leaf:stem ratio, dead material, other species and forage peanut mass. The percentages of different implanted area with forage peanut did not affect the production parameters of pasture and structural composition of cultivars. The use of 75% of the area planted with forage peanut promoted share of close to 30% of the total mass of legumes. The leaf:stem ratio was higher for cv. Tifton 85 in daily average temperatures milder, in this situation, both cultivars decreased the forage rate accumulation. The increasing percentage of implanted area with forage peanut increased participation of legumes, decreasing the presence of dead material in the pasture, in the second year of evaluation.

Effects of N application reduction and fertilizing distance on saving fertilizer and improving yield in maize/soybean intercropping system

To study the effect of N supplied levels and fertilization distances on saving fertilizer and improving yield in maize/soybean intercropping system, a field experiment was carried out with three N supplying levels ( RN1: 210 kg N·hm-2, RN2: 270 kg N·hm-2 and CN: 330 kg N·hm-2) and four fertilizing distances (D1: 0 cm, D2: 15 cm, D3: 30 cm and D4: 45 cm, indicating the distance between fertilizing site and maize in narrow row). Compared with CN, the results showed that dry matter accumulation and translocation, and their contribution to grain of post-anthesis maize under RN2 were increased by 1.4%, 23.0% and 16.0%, respectively. Meanwhile, kernel number per ear and grain yield per plant of maize were increased by 1.6% and 4.9%. For soybean, dry matter accumulation and translocation, and their contribution to grain at pre-anthesis under RN2 were increased by 2.1%, 37.9% and 26.9%, respectively. Both of soybean grain number and yield per plant were increased by 7.3%. For the maize-soybean intercropping system, N uptake and use efficiency of RN2 were 5.0% and 44.4% higher than those of CN. The soil N content of maize was raised by 4.1% under RN2, but decreased by 0.8% for soybean. The saving fertilizer and improving yield effect of D2 were the best among all the fertilizing distances. Under RN2, contribution rate of dry matter accumulation to grain after anthesis and kernel number per ear of maize in D2 were 57.2% and 9.4% higher than those of D1. Compared with D4, the contribution rate of dry matter accumulation to grain before anthesis and grain number per plant of soybean in D2 were increased by 335.2% and 2.4%, respectively. For the maize/soybean intercropping system, N uptake and use efficiency of D2 were 15.1% and 112.4% greater than those of D1, and 21.4% and 66.3% higher than those of D4. The total soil N content of maize in D2 was 6.6% higher than that of D1, and the index for soybean was 16.0% higher than that of D4. Appropriate N application reduction and fertilizing distance would be beneficial to transfer dry matter to grain, improve grain number per plant, 100-grain mass and yield, promote N uptake and increase fertilizer use efficiency in the intercropping system, which could achieve the purpose of saving fertilizer and improving yield.

Preanthesis biomass accumulation of plant and plant organs defines yield components in wheat

The preanthesis period in wheat is critical for growth of plant organs including leaves, stems, spikes and roots. However, the roles of the preanthesis biomass accumulation of plant and plant organs in yield determination are only partially elucidated, and the underlying genetic basis remains largely unknown. This study aimed to understand the physiological and genetic relationships between preanthesis biomass accumulation and yield determination. In a mapping population of bread wheat (Triticum aestivum ‘Forno’) and its relative spelt (Triticum spelta ‘Oberkulmer’) contrasting for biomass, the dry weight of above-ground whole shoots and different organs, and leaf area, were analysed at GS39 (full flag leaf emergence) and anthesis. Yield components (thousand grain weight, grains per spike, final shoot biomass and grain weight per spike) and plant height were measured at maturity, followed by identification of quantitative trait loci (QTL) for all above traits. Field experiments were carried out in UK in 2011–2012 and 2012–2013 seasons, each using a randomised complete block design with three replicates. The results showed that there was a significant variation in biomass and its partitioning to organs at different stages. Consistent with the previous findings, stem water soluble carbohydrates and spike dry weight at anthesis contributed to thousand grain weight and grains per spike, respectively. In addition, this study revealed many other traits positively associated with one or more yield components, including biomass and leaf area at GS39, leaf and structural stem growth as well as whole shoot biomass at anthesis, and higher dry matter accumulation and crop (and spike) growth rates between the two stages. Increasing shoot biomass by removing other tillers at GS39 led to higher grain number and grain weight per spike. These results indicate the importance of the preanthesis growth of plant and plant organs for yield determination. Plant height was only weakly correlated with final biomass at maturity so it is possible to produce high-biomass genotypes without increasing plant height. Genetic analysis revealed 193 QTL associated with biomass and biomass-related traits. Frequent QTL coincidences between biomass and yield traits were observed, mainly on chromosomes 2B, 3A, 4A, 4B, 5A, 6A and 7B, indicating pleiotropy or tight gene linkages, consistent with their phenotypic associations. The preanthesis biomass traits associated with yield components and the underlying QTL, would facilitate the trait-based physiological and molecular breeding in wheat.

<b>Forage mass and nutritive value of bermuda grass mixed to forage peanut or common vetch

Three pasture-based systems (PS) with bermuda grass (BG) + forage peanut + 75 kg of N ha-1; BG + common vetch + 75 kg of N ha-1 and BG + 150 kg of N ha-1 were evaluated. Lactating Holstein cows were used for evaluation and the experimental design was completely randomized. Forage mass, botanical and structural composition, daily dry matter accumulation rate and stocking rate were evaluated. Samples were collected by hand-plucking method to analyze crude protein (CP), neutral detergent fiber (NDF), (ISDMD), in situ organic matter digestibility (ISOMD) and total digestible nutrients (TDN). Average forage production and stocking rate were 13.8; 15.3 and 16.1 t ha-1 and 5.6; 6.4 and 5.5 UA ha-1 day-1 for PS respectively. Average CP and NDF were 16.4; 22.2 and 15.3%; 68.3; 65.7 and 66.3%; for ISDMD, ISOMD and TDN were 68.5; 70.3 and 66.4%; 64.3; 63.2 and 65.3%; 57.3; 58.3 and 57.5%, for PS respectively. Best results were reported on bermuda grass mixed with common vetch.

Integrated Nutrient Management in Rainfed Upland Rice in the Northeastern Region of India

A field experiment on integrated nutrient management in rainfed upland rice was conducted during kharif season (July to October) of 2007 and 2008 in the farm of Krishi Vigyan Kendra, Tirap (27°26′N latitude, 95°27′E longitude and at 185 m a.s.l.), Arunachal Pradesh, India. The experimental soil is sandy loam in texture (55 % sand, 26 % silt and 17 % clay), acidic in reaction (pH 5.4), medium in available N (290 kg ha−1), but low in available P (7.7 kg ha−1) and K (125 kg ha−1). The results showed that integrated use of 75 % recommended dose of nitrogen (RDN) through farm yard manure (FYM)/vermicompost (VC) and 25 % recommended dose of fertilizer (RDF) produced taller plants, higher number of tillers m−2, higher leaf area index, dry matter accumulation and crop growth rate than those of other treatments. It recorded markedly greater number of panicles m−2 and grains panicle−1 that led to higher grain yield by 89.6 % over control and by 29.9–35.6 % over other treatments. The growth parameters showed strong and positive correlations with grain yield. Use of 75 % RDN through FYM/VC and 25 % RDF through chemical fertilizer seems to be conducive for improving growth and productivity of rainfed upland rice in the hill region of northeastern India.

Effect of site specific nutrient management on production and productivity of maize (Zea mays L.) under mid hill condition of Chhatisgarh

A field experiment was conducted in two consecutive Kharif seasons of 2012 and 2013 at Ambikapur to work out the effect of nutrient management on growth and development behavior of maize ( Zea mays L.) hybrids. Plant height, leafarea, dry matter accumulation, and crop growth rate (CGR) were significantly higher with site-specific nutrient management (SSNM) over the recommended dose of fertilizer (RDF) under conservation agriculture. On the maize hybrids, 'PMH 3' recorded significantly highest plant height, dry-matter accumulation and crop growth rate at various stages which was at par with 'PMH 1' but significantly superior to other hybrids. Significantly lowest leaf- area, dry matter accumulation and crop growth rate was recorded with 'HQPM 1'. SSNM recorded highest yield attributes, viz ., cob length (cm), cob girth (cm), grain rows/cob, grains/row, shelling per cent and 1000 grain weight (g) significantly higher over 50 per cent RDF but at par with 100 per cent RDF. SSNM recorded significantly highest cob yield and grain yield (kg/ha) over 100 and 50 per cent RDF. With regards to maize hybrids 'PMH 3' recorded yield attributes, viz ., cob length (cm), cob girth (cm), grain rows/cob, grains/row, shelling per cent and 1000 grain weight (g) which was at par with 'PMH 1' but significantly superior to other hybrids. Significantly lowest yield was recorded by 'HQPM 1'.

Investigations on the photosynthetic productivity of some newly selected grapevine varieties

Investigations were carried out on the photosynthetic productivity of 5 wine varieties which had been selected at the Institute of Viticulture and Enology: Storgoziya, Nikopolski mavrud, Pomoriiski biser, Dunavska gamza and Dunavski lazur. The first of them was grafted on Chasselas x Berlandieri 41 B rootstock, each of the others was on three rootstocks: Chasselas x Berlandieri 41 B, Berlandieri x Riparia SO 4, and. (Berlandieri x Riparia Kober 5 BB) x (Rupestris Martin) III-102 D. For all varieties, the leaf dry matter per unit leaf area was greatest when they were grafted on 111-102 rootstock. During the vegetation period, the specific leaf weight increased, but the rate of dry matter accumulation in leaves was not constant and gradually decreased with time. The content of pigments and the leaf area per vine were greatest on SO 4 rootstock On this rootstock, the highest yield was obtained for all cultivars mainly at the expense of the grape cluster weight. The thickness of the trunk under the graft-union, though, was smallest and an irregular increase of the diameters of the two components, rootstock and scion, occurred.

The effects of plastic film mulching on maize growth and water use in dry and rainy years in Northeast China.

Plastic film mulching (PM) has been widely used to improve maize (Zea mays L.) yields and water use efficiency (WUE) in Northeast China, but the effects of PM in a changing climate characterized by highly variable precipitation are not well understood. Six site-year field experiments were conducted in the dry and rainy years to investigate the effects of PM on maize growth, grain yield, and WUE in Northeast China. Compared to crops grown without PM treatment (control, CK), PM significantly increased the grain yield by 15-26% in the dry years, but no significant yield increase was observed in the rainy years. Yield increase in the dry years was mainly due to a large increase in dry matter accumulation pre-silking compared to the CK, which resulted from a greater dry matter accumulation rate due to the higher topsoil temperature and water content. As a result, the WUE of the crops that underwent PM (3.27 kg m-3) treatment was also increased by around 16% compared to the CK, although the overall evapotranspiration was similar between the two treatments. In the rainy years, due to frequent precipitation and scant sunshine, the topsoil temperature and water content in the field that received PM treatment was improved only at some stages and failed to cause higher dry matter accumulation, except at the 8th leaf stage. Consequently, the grain yield and WUE were not improved by PM in the rainy years. In addition, we found that PM caused leaf senescence at the late growth stage in both dry and rainy years. Therefore, in practice, PM should be applied cautiously, especially when in-season precipitation is taken into account.

MINERAL UPTAKE AND DRY MATTER ACCUMULATION OF BIOTIZED GF677/'ROYAL GLORY' NURSERY PLANTS

The aim of this work is to study the influence of different mycorrhizal fungi and their further treatment in the nursery on plant mineral uptake and dry matter accumulation. Additional biotizations were preliminary done in some of the experimental treatments. The analysis of dry matter accumulation was performed twice in vegetation period (in May and October). Each sample was analyzed also for plant mineral uptake at six basic macro and microelements (N, P, K, Ca, Mg, Fe). Generally, all additional mycorrhiza treatments have a positive effect on the dry matter accumulation. In Trichoderma experimental plots highest increase is observed in Trichoderma (BS)(TG) and Trichoderma (SL)(TG) treatments, which showed more than 55% dry matter accumulation rates. For comparison, Trichoderma non-treated increase rate is less than 10%. Similar results are obtained in Glomus and Glomus+Agrobacterium treatments where additional treated plots overrun non treated ones with 21.1% and 82.7% respectively. Concerning the mineral uptake, additional mycorrhiza application show advantages in all treatments.

Field evaluation of allelopathic plant extracts alongside herbicides on weed management indices and weed–crop regression analysis in maize

Synthetic herbicides are posing problems owing to the development of weed resistance and emerging debate on their associated health hazards and ecological threats. Allelopathic manipulations are evolving as applicable substitutes for weed management in agroecosystems. In order to assess the efficacy of potential allelopathic water extracts from different plant species, field experiments were conducted during 2010 and 2011. Sorghum bicolor L., Helianthus annuus L., Brassica napus L., Oryza sativa L., Zea mays L. and Morus alba L. aqueous extracts in different combinations alone or along with a reduced dose of herbicide were evaluated for weed suppression in a maize crop. A weedy check and two herbicidal treatments, S‐metolachlor + atrazine (pre‐emergence) and atrazine alone (early postemergence), were included for comparison. Sorghum, brassica or sunflower tank‐mixed with 25% of the recommended dose of atrazine significantly suppressed the total weed density and dry biomass, along with a concomitant decrease in the crop resistance indices and treatment efficacy indices over the control. The weed density and dry biomass that were recorded at 60 days after sowing showed a strong negative correlation, while the leaf area index, crop growth rate, dry matter accumulation and net assimilation rate predicted a strong positive correlation, with the stover and grain yield of maize.

Características produtivas da consorciação de trevo-persa e azevém submetidos a pastejo

Este estudo teve como objetivo avaliar o efeito de diferentes intervalos entre pastejos sobre as características produtivas de trevo-persa e azevém, consorciados e manejados sob lotação rotacionada, nos anos de 2009 e 2010. Os tratamentos consistiram em quatro intervalos entre pastejos (tempo para o surgimento de 2,5; 3,5; 4,5 e 5,5 folhas em plantas de trevo-persa), em delineamento de blocos completos ao acaso, com seis repetições. As variáveis analisadas foram: índice de área foliar, área foliar, altura do pasto e de plantas, comprimento de perfilhos/ramificações, taxa de acúmulo de matéria seca e produção de matéria seca. O índice de área foliar do dossel e do trevo-persa foi maior no intervalo de 5,5 folhas nos anos de 2009 e 2010. No ano de 2009, maiores valores de área foliar foram obtidos nos intervalos de 3,5 e 4,5 folhas e não se observou efeito dos intervalos entre pastejos sobre essa variável em 2010. Maiores intervalos entre pastejos proporcionaram maior altura do pasto e de plantas e também maior comprimento de perfilhos e ramificações. A produção de matéria seca do trevo-persa foi maior em 2010, ao passo que, para azevém, maior produção foi encontrada em 2009. A produção de matéria seca total foi maior no intervalo de 5,5 folhas. A taxa de acúmulo de matéria seca foi maior no intervalo de 5,5 folhas em 2009 e no intervalo de 2,5 folhas em 2010. As características produtivas da consorciação trevo-persa e azevém anual são modificadas pelos intervalos entre pastejos. Recomendam-se intervalos de até 3,5 folhas surgidas, em consorciação de trevo-persa e azevém anual, os quais proporcionam menor alongamento de caules associado à menor presença de material morto, o que, provavelmente, melhora a qualidade da forragem colhida.

Sewage sludge fertilization in larch seedlings: Effects on trace metal accumulation and growth performance

The spreading of sewage sludge (SS) among forest plantations may provide interesting results for firewood production. While sludges are good fertilizers, they may nevertheless contain trace metals, which can reduce productivity and lead to environmental risks. We investigated the effects of SS application on nutrient uptake and growth parameters in larch seedlings (Larix decidua) and determined trace metal and mineral distribution. Without incorporation into the soil, sludge was applied to the soil surface at three rates (0, 30 and 60t dry weight DW ha−1). The plants were harvested after 12 months. The results showed significantly increased nitrogen and phosphorus concentrations in the top soil layer in pots amended with sludge, whereas no changes appeared in the lower layers. Similar results were obtained for the Cu, Zn and Cd concentrations. However, no differences were observed for the other measured soil mineral elements. Nitrogen concentrations in needles increased with rising sewage sludge application rates, yet the sludge had no effect on the P, Mg, Zn, Pb and Cd concentrations. In addition, Cu accumulated only in the lateral roots of seedlings that received the highest sludge loading rate. Sludge application improved the net photosynthesis, which resulted in higher chlorophyll contents in the needles. Following application, the dry matter accumulation rate increased due to the excessive availability of N, whereas available mineral elements in the plant tissues were diluted. Furthermore, amending the soil with sewage sludge can promote a higher biomass yield which may result in an increased trace metal bioaccumulation capacity in plants. Though this investigation has established the benefits of municipal SS application, further studies are needed to assess the potential transfer of TM to groundwater and through the food chain.

Organic Reserves in ropical Grasses under Grazing

Inadequate management in recent times has been considered the main factor contributing to pasture degradation. A major reason for this is related to gross errors of grazing management as a consequence of the lack of knowledge of ecophysiological limits of forage. This review aimed to approach the importance of organic reserves for grasses under grazing. Therefore, the predominant effect of animal grazing is the reduction of leaf area which impacts on carbohydrate and nitrogen reserves and consequently the growth of tillers, leaves and roots. Grass growth after defoliation is related to organic reserves and rate of photosynthesis. The latter is affected by the level of canopy light interception of and by the reminiscent leaf area index. When grazing management is carried out with respect to the physiological limits of grass growth, the rate of dry matter accumulation will be quick and constant. In this aspect, grazing management consists of seeking an efficient balance between plant growth and consumption which will reflect on animal productivity. Therefore, a balance point among frequency and intensity of defoliation must be found to achieve greater animal production concerning the ecophysiological limits of the forage plants. So the challenge will be to find a balance between frequency and intensity of grazing to achieve greater production of animals respecting the eco-physiological limits of forage plants for each forage grass individually.