Total Dry Mass Production Research Articles

Biomass Accumulation, Photosynthetic Traits and Root Development of Cotton as Affected by Irrigation and Nitrogen-Fertilization.

Limitations of soil water and nitrogen (N) are factors which cause a substantial reduction in cotton (Gossypium hirsutum L.) yield, especially in an arid environment. Suitable management decisions like irrigation method and nitrogen fertilization are the key yield improvement technologies in cotton production systems. Therefore, we hypothesized that optimal water-N supply can increase cotton plant biomass accumulation by maintaining leaf photosynthetic capacity and improving root growth. An outdoor polyvinyl chloride (PVC) tube study was conducted to investigate the effects of two water-N application depths, i.e., 20 cm (H20) or 40 cm (H40) from soil surface and four water-N combinations [deficit irrigation (W55) and no N (N0) (W55N0), W55 and moderate N (N1) (W55N1), moderate irrigation (W75) and N0 (W75N0), W75N1] on the roots growth, leaf photosynthetic traits and dry mass accumulation of cotton crops. H20W55N1 combination increased total dry mass production by 29–82% and reproductive organs biomass by 47–101% compared with other counterparts. Root protective enzyme and nitrate reductase (NR) activity, potential quantum yield of photosystem (PS) II (Fv/Fm), PSII quantum yield in the light [Y(II)] and electron transport rate of PSII were significantly higher in H20W55N1 prior to 82 days after emergence. Root NR activity and protective enzyme were significantly correlated with chlorophyll, Fv/Fm, Y(II) and stomatal conductance. Hence, shallow irrigation (20 cm) with moderate irrigation and N-fertilization application could increase cotton root NR activity and protective enzyme leading to enhance light capture and photochemical energy conversion of PSII before the full flowering stage. This enhanced photoassimilate to reproductive organs.

Efeito da salinidade na germinação e crescimento inicial de plântulas de três espécies arbóreas florestais

O objetivo do presente trabalho foi avaliar o efeito do estresse salino na germinação e crescimento inicial de canafístula (Peltophorum dubium (Sprengel) Taubert), tamboril (Enterolobium contortisiliquum (Vell.) Morong.) e pau-formiga (Triplaris americana L.), além de determinar a máxima tolerância das três espécies arbóreas florestais à presença de NaCl na solução de embebição. Foi adotado delineamento experimental inteiramente casualizado, com quatro repetições de 50 sementes, no esquema fatorial 3 x 5, sendo estudada a resposta das três espécies a cinco níveis de potencial osmótico (0; -0,3; -0,6; -1,2 e -1,8 MPa), por simulação de estresse salino com NaCl. Aos 28 dias após semeadura foram avaliados: percentagem de germinação; índice de velocidade de germinação (IVG); tempo médio de germinação; comprimento da maior raiz; massa seca da parte aérea, raízes e total. A germinação e o crescimento inicial de plântulas de tamboril e canafístula foram afetados negativamente pelo aumento da concentração salina do meio. Pau-formiga mostrou-se mais tolerante ao estresse salino, apresentando elevação dos valores médios de percentagem de germinação, IVG, comprimento da maior raiz e produção de massa seca total em potenciais osmóticos variando de -0,81 a -1,15 Mpa. Os maiores valores médios de produção de massa seca da parte aérea, raízes e total foram observados em plântulas de tamboril.

Forage characters of different Paspalum species in Rio Grande do Sul: a meta-analysis

ABSTRACT: The objective of this study was to evaluate, through meta-analysis, the forage characteristics of various species of the genus Paspalum and to use them to select the best ecotypes that can be used in artificial hybridization as parents and hybrids for pasture production and natural pasture recovery systems. Data were obtained from studies conducted by the Department of Forage Plants and Agrometeorology of the Universidade Federal do Rio Grande do Sul. Database comprised tests conducted with ecotypes and/or hybrids of Paspalum spp. in plots for evaluating total dry mass production, leaf dry mass production, and stem dry mass production by means of cuts. Total dry mass production, which included leaves and stems, differed between the ecotypes and hybrids. Hybrid H12 was the most divergent of all evaluated accessions. The greatest genetic divergence occurred due to dry mass production. Hybrids showed high total dry mass production, comprised mainly of leaves. Hybrid H12 and the accession of Paspalum lepton 28E were identified as the most dissimilar based on the generalized Mahalanobis distance using Tocher’s method. Total dry mass production is the characteristic that most contributed to the detection of genetic variability.

Anatomical and physiological bases of sugarcane tolerance to manganese toxicity

Sugarcane is generally cultivated in low fertility acid soils that are prone to the occurrence of manganese (Mn) toxicity. However, the use of genotypes more tolerant to such limiting condition could enhance plant performance in poor soils. Therefore, the aims of this study were to add insights into the mechanisms driving sugarcane adaptation to Mn stress by testing the hypothesis that genotypes with higher tolerance maintain improved ultrastructure of leaf cell organelles (i.e., chloroplast and nucleus) and photosynthetic capacity under high Mn concentrations. Accordingly, six sugarcane varieties were grown in sand and fertigated with two Mn concentrations (control=10μM; and toxicity=500μM). After growing for 110days under both conditions, the plants were harvested to estimate dry mass production and tissue Mn concentrations. Leaf gas exchange and chlorophyll fluorescence were assessed in mature leaves that were further evaluated for antioxidant metabolism and cell organelle ultrastructure. Sugarcane varieties exhibited differential tolerance to Mn stress, and based on the relative total dry mass production of plants growing under Mn toxicity versus the control, tolerant (mean relative growth of 98%) and sensitive (mean relative growth of 71%) genotypes could be identified. Our results suggested that the different capabilities of these varieties in sustaining photoassimilate supply for biomass production under Mn stress were explained by leaf area formation rather than photosynthetic rate per unit of leaf area as tolerant varieties presented reduction in photosynthesis. Moreover, as revealed by the transmission electronic microscopy analysis, tolerant varieties were able to sustain greater integrity in the nucleus of the mesophyll cells under Mn stress than sensitive varieties, improving leaf growth and canopy development. Taken together, our results revealed the mechanisms underlying sugarcane tolerance to Mn toxicity, contributing to the identification of strategies aimed at developing genotypes better adapted to low fertility acid soils, with subsequent positive effects on crop yield stability.

Characterization of dhaincha accessions based on morphological descriptors and biomass production

Forty five accessions of dhaincha germplasms were collected from different parts of Bangladesh and characterized on the basis of morphological descriptors and biomass production ability. Thirty eight accessions were identified as Sesbania bispinosa, four as S. cannabina and two as unidentified Sesbania spp. One accession as S. rostrata was included for comparison. Both at seedling and maturity stages, wide and significant differences were observed among the accessions of different dhaincha germplasms for their biomass production capability and other morphological descriptors. At the seedling stage, total dry mass (TDM) production varied from 10.2 to 41.6g 30-plants–1. At the maturity stage, plant height, total number of branches and base diameter of dhaincha germplasms varied from 347.5–474.7cm, 10.4–23.7, and 1.9–4.9cm, respectively. The highest amount (4.10kg 10-plants–1) of above-ground TDM was produced in one accession of unidentified Sesbania sp. followed by S. rostrata and one accession of S. cannabina (3.85kg 10-plants–1), and the lowest TDM (0.9kg 10-plants–1) was measured in two accessions of S. bispinosa. It may be concluded that the biomass production capability of at least two accessions of local Sesbania germplasms were higher/comparable to that of exotic S. rostrata. It will be too early to make a conclusive remark based on only a few dhaincha germplasms. A detailed study with a large number of germplasms collected from whole Bangladesh is obviously needed to reach in a precise conclusion.J. Bangladesh Agril. Univ. 13(1): 55-60, June 2015

Intraspecific variation in leaf growth of wheat (Triticum aestivum) under Australian Grain Free Air CO2 Enrichment (AGFACE): is it regulated through carbon and/or nitrogen supply?

Underlying physiological mechanisms of intraspecific variation in growth response to elevated CO2 concentration [CO2] were investigated using two spring wheat (Triticum aestivum L.) cultivars: Yitpi and H45. Leaf blade elongation rate (LER), leaf carbon (C), nitrogen (N) in the expanding leaf blade (ELB, sink) and photosynthesis (A) and C and N status in the last fully expanded leaf blade (LFELB, source) were measured. Plants were grown at ambient [CO2] (~384µmolmol-1) and elevated [CO2] (~550µmolmol-1) in the Australian Grains Free Air CO2 Enrichment facility. Elevated [CO2] increased leaf area and total dry mass production, respectively, by 42 and 53% for Yitpi compared with 2 and 13% for H45. Elevated [CO2] also stimulated the LER by 36% for Yitpi compared with 5% for H45. Yitpi showed a 99% increase in A at elevated [CO2] but no A stimulation was found for H45. There was a strong correlation (r2=0.807) between LER of the ELB and soluble carbohydrate concentration in LFELB. In ELB, the highest spatial N concentration was observed in the cell division zone, where N concentrations were 67.3 and 60.6mg g-1 for Yitpi compared with 51.1 and 39.2mg g-1 for H45 at ambient and elevated [CO2]. In contrast, C concentration increased only in the cell division and cell expansion zone of the ELB of Yitpi. These findings suggest that C supply from the source (LFELB) is cultivar dependent and well correlated with LER, leaf area expansion and whole-plant growth response to elevated [CO2].

Crescimento e tolerância à salinidade em três espécies medicinais do gênero Plectranthus expostas a diferentes níveis de radiação

No cultivo de plantas medicinais as condições de salinidade e de luz podem exercer influência no rendimento e na qualidade final da produção de biomassa. O objetivo deste trabalho foi avaliar o efeito de diferentes luminosidades e níveis de salinidade na água de irrigação sobre o crescimento e tolerância de três espécies de plantas do gênero Plectranthus. O ensaio foi conduzido em parcelas subsubdivididas com cinco repetições, sendo as parcelas referente ao fator ambiente (pleno sol e telado), as subparcelas aos níveis de salinidade na água de irrigação - CEa (0,7; 1,9; 3,1; 4,3 e 5,5 dS m-1), e as subsubparcelas às três espécies do gênero Plectranthus (P. amboinicus, P. barbatus e P. grandis). As variáveis de resposta foram: índice relativo de clorofila (IRC), área foliar (AF), razão de área foliar (RAF), área foliar específica (AFE), matéria seca da parte aérea (MSPA), matéria seca das raízes (MSR), matéria seca total (MST), relação MSR/MSPA, grau de tolerância à salinidade, e teor dos íons Na+ e K+. O estresse salino reduziu o crescimento das plantas, sendo as maiores reduções observadas nas plantas expostas a pleno sol. A salinidade influenciou a partição de matéria seca, sendo as raízes mais afetadas do que a parte aérea. Com o aumento da CEa houve aumento expressivo no teor foliar de Na+, enquanto o teor de K+ e o IRC foram reduzidos. Entretanto, o acúmulo de Na+ foi menor em P. grandis. Considerando-se a MST, verificou-se que as três espécies se mostraram moderadamente tolerantes à salinidade de até 3,1 dS m-1, exceto P. grandis cultivada em telado, classificada como tolerante. Em relação ao grau de redução na produção MSPA (parte de interesse comercial), poderia se recomendar o cultivo de P. grandis quando a água de irrigação contiver CEa de até 3,1 dS m-1.

Initial physic nut nutrition and potassium balance in the soil-plant system

The objectives of this study were to evaluate the mineral nutrition and the response of physic nut to potassium fertilization as well as to assess whether the species can absorb K from the non-exchangeable soil fraction. The study was conducted in a greenhouse, in randomized blocks, and with four repetitions. Physic nut plants were cultivated in plastic recipients filled with 50 dm³ of a Dark Red Latosol fertilized with rates of 0, 40, 80, 120 and 160 mg K dm-3 of soil. One hundred and fifty days after planting, the height, stem diameter and leaf area of the plants were measured, and the dry mass, concentration in leaf and total accumulation of macro and micronutrients were determined, as well as the soil contents of exchangeable and non-exchangeable K. The K balance in the soil-plant system was also calculated. The increase of potassium fertilization resulted in a greater uptake of K, Ca and Mn but did not alter the total dry mass production of physic nut. The species can release and absorb K from the non-exchangeable soil fraction.

Iron Tolerance in Calla Lilies (Zantedeschia aethiopica)

Excess iron in soils affects many agricultural areas worldwide, causing great losses in cultivated plants particularly in waterlogged environments. Plants, such as the calla lily (Zantedeschia aethiopica), which grows in such wetlands, have been widely used for the treatment of wastewater. White calla lily plants were grown hydroponically from seeds in a greenhouse in Tunja, Colombia, under either of three different levels of iron (0, 100 or 200 ppm Fe) to evaluate the plant’s tolerance to excess iron. The total dry mass production, water uptake, water use efficiency (WUE), dry matter partitioning and root to shoot ratio were recorded four months after transplanting. The dry mass production per plant decreased as the iron level increased. Although water uptake decreased inversely proportional to the iron level, the WUE was not affected by iron. On the other hand, iron affected dry matter partitioning to the plant organs, accumulating more dry matter in the roots than in the shoot with higher iron levels. Hence, we suggest that the calla plant is moderately tolerant to excess iron and would be appropriate for the phytoremediation of wetlands contaminated with this metal.

Morpho-physiological and reproductive characters and their relationships with seed yield of mungbean mutants

Experiment was conducted under sub-tropical condition to investigate the variations in some morphological features, growth, reproductive characters and its impact on seed yield using correlation coefficient in 15 promising mungbean mutants and cultivars. Correlation study revealed that among the traits investigated, leaf area was the most important source that determined total dry mass (TDM) yield, and reproductive characters like number of racemes, flowers and pods/plant were the most important sinks that determined seed yield. Contrarily, reproductive efficiency (RE, % pod set to opened flowers) did not show significant relationship with pod number, pod size and seed yield, indicating that selection of high yield based on RE may be misleading. Generally, high yielding genotypes had capacity to produce higher branches, total dry mass production, leaf area, crop growth rate and number of flowers per plant than the low yielding ones. This information may be used in future plant breeding programme.

고압나트륨등 조사가 파프리카의 동적 생장과 건물분배율에 미치는 영향

본 연구의 목적은 고압나트륨등 광원(HPS)을 조사하여 파프리카의 동적생장과 기관별 건물분배율 및 광이용효율에 미치는 효과를 구명하고자 수행하였다. 파프리카 육묘는 2010년 9월 29일에 <TEX>$m^2$</TEX>당 3.75주를 정식하여 2010년 12월 14일부터 HPS 광원을 실험종료일까지 하루 16시간 조사하였다. HPS 처리는 엽수를 증가시켰으나, 절간수와 엽면적에는 미비한 영향을 미쳤다. HPS 처리구의 초장은 대조구에 비해 짧았으나, 줄기당 착과수의 증가를 나타냈다. 줄기와 과실 및 총건물중은 HPS 처리구가 대조구보다 각각 28.5%, 97.1%, 67.8%를 증가시켰다. 총 건물중의 증가율 대비 엽과 줄기 생장율을 비율로 나타낸 각 기관의 건물분배율은 생육초기에 45-47%로 동일하다가 과실의 생장이 시작되는 시점에서 급격히 감소하였다. 영양생장기관으로의 건물분배율은 대조구에서 HPS 처리구보다 4% 높았다. 과실로의 평균 건물 분배율을 HPS 처리구에서 대조구에 비해 14.2% 증가하였다. 동적생장량은 지수선형함수의 최대상대생장율, 최대 절대생장율 및 손실일수로 잘 묘사할 수 있었다. 대조구에 비해 처리구의 엽의 최대절대생장율은 18.6%, 줄기는 74.7%, 과실은 143.5%가 증가하는 것으로 추정되었다. 총 건물중에 대한 광이용효율(LUE)은 HPS 처리구에서 <TEX>$4.90g{\cdot}MJ^{-1}$</TEX>로 대조구의 <TEX>$3.84g{\cdot}MJ^{-1}$</TEX> 높았으며, 영양생장기관의 LUE는 HPS 처리구가 <TEX>$1.56g{\cdot}MJ^{-1}$</TEX>로 대조구의 <TEX>$1.61g{\cdot}MJ^{-1}$</TEX>보다 약간 낮았으며, 과실 생산에 대한 LUE는 처리구가 <TEX>$3.34g{\cdot}MJ^{-1}$</TEX>로 대조구 <TEX>$2.23g{\cdot}MJ^{-1}$</TEX>보다 49.8% 증가하였다. 처리간 총 건물중의 LUE의 차이는 HPS 처리구의 과실생산에 대한 LUE가 높았기 때문에 발생되었다. The objective of this study was to describe and analyze the effect of high pressure sodium lamp lighting (HPS) on dynamics of growth and dry matter partitioning, and light use efficiency of sweet pepper crop grown over winter season. Young sweet pepper seedlings were planted at 3.75 plants per <TEX>$m^2$</TEX> on September 29, 2010 and treated with HPS for 16 hours from December 14, 2010 until March 18, 2011. The number of leaves per plant were significantly increased with HPS, whereas the number of internodes and leaf area were less affected. HPS reduced the plant height with higher number of fruits per stem compared to those of without HPS lighting (CON). There were large differences in total dry mass production, stem and fruit dry mass between HPS and CON and those with HPS increased by 67.8%, 28.5%, and 97.1% compared to CON, respectively. Each organs of dry mass partitioning was calculated by leaf, stem or fruit growth rate divided by total plant growth rate. Dynamics of dry mass partitioning to leaf and stem between HPC and CON was measured in range of 45-47% at beginning of growth phase and drastically decreased after starting fruit growth in both treatments. Dry matter partitioning to vegetative organs was 4% higher compared to the plant grown under HPS lighting. Averaged dry matter partitioning to fruit with HPS, however, was largely increased by 14.2% compared to CON. Dynamics of the plant growth were well described by expolinear growth equation with three parameters of maximum relative growth rate, absolute growth rate and lost time to reach linear phase. The maximum growth rate of leaf, stem and fruit with HPS was increased by 18.6%, 74.7%, and 143.5% compared to CON. There was a linear relationship between intercepted light integral and vegetative organs (leaf and stem), fruit or total dry mass production. Light use efficiency (LUE, <TEX>$g{\cdot}MJ^{-1}$</TEX>) of total dry mass was <TEX>$4.90g{\cdot}MJ^{-1}$</TEX> for HPS and <TEX>$3.84g{\cdot}MJ^{-1}$</TEX> for CON, LUE of vegetative organs was <TEX>$1.56g{\cdot}MJ^{-1}$</TEX> for HPS and <TEX>$1.61g{\cdot}MJ^{-1}$</TEX> for CON and LUE of fruit dry mass was <TEX>$3.34g{\cdot}MJ^{-1}$</TEX> for HPS and <TEX>$2.23g{\cdot}MJ^{-1}$</TEX> for CON. The difference in LUE of total dry mass between treatments, therefore, occurred mainly from the different in LUE of fruit dry mass.

Effect of plant regulators on growth and flowering of 'Meyer' zoysiagrass

This trial aimed to evaluate the effect of sequential applications of different plant regulators over growth and flower rachis emission of 'Meyer' zoysiagrass (Zoysia japonica). The study was conducted on 15-month old green turfgrass under a randomized complete block design with four replications. The following plant regulator and doses were tested: trinexapac-ethyl (113+113, 226+113, 226+226, 452+113, 452+226, 452+452, 678+339 e 904+452 g a.i./ha-1), prohexadione-calcium (100+100 e 200+200 g a.i. ha-1) and bispyribac-sodium (40+40 e 60+60 g a.i. ha-1), as well as an untreated control. The turfgrass was mowed again at 3.0 cm aboveground and the second plant regulator was applied when 'Meyer' zoysiagrass was between 5.0 and 6.0 cm high. The effect of the treatments was visually rated for visual injury, plant height, height and number of flower rachis, and total dry mass production of clippings. Only bispyribac-sodium had visual symptoms of injury on 'Meyer' zoysiagrass, and no intoxication was observed at 28 days after the second application (DAAB). The sequential applications of trinexapac-ethyl, prohexadione-calcium and bispyribac-sodium reduced by more than 80% the total clipping dry mass produced by 'Meyer' zoysiagrass. All the plant regulators tested also showed promising results in reducing the height and emission of rachis, especially when trinexapac-ethyl was applied at the doses 452+452, 678+339 and 904+452 g a.i. ha-1. 'Meyer' zoysiagrass turfgrass can be handled with the sequential application of a plant regulator, which reduces the need for mowing over a period up to 110 days after the application of the second plant regulator, and it also avoids deleterious visual effects over turfgrass.

Pea crop (Pisum sativum L.) responseto the nickel application

El niquel (Ni), se considera el ultimo de los micronutrientes esenciales para las plantas superiores, debido a su participacion en la enzima ureasa; sin embargo, a la fecha son pocas las investigaciones orientadas a conocer su influencia en el crecimiento y en la produccion de los cultivos. Con el fin de determinar la respuesta de la arveja a la aplicacion de Ni, se realizo el montaje de un experimento en la Universidad de Ciencias Ambientales y Aplicadas U.D.C.A, donde se evaluaron, como tratamientos, cuatro dosis de Ni: 0,0; 2,0; 4,0 y 6,0 mg L-1 de Ni. La investigacion, se adelanto en el marco de un diseno en bloques completos al azar. Las plantas fueron sembradas en materas con arena lavada de rio, como sustrato. Los resultados demuestran que la aplicacion de 2,0 mg L-1 Ni promueve una mayor produccion de masa seca total, asi como un mayor numero de vainas por planta y un mayor numero de granos por vaina; no obstante, estos resultados no son estadisticamente significativos. Las concentraciones foliares de Ni variaron cercana a 0,0, en el testigo y 13,73 mg kg-1, en el tratamiento 6,0 mg L-1 Ni. Las concentraciones cercanas a 5,0 mg kg-1 estuvieron asociadas al mayor crecimiento en las plantas de arveja.

Phosphorus behavior on an Oxisol fertilized by phosphate alkaline biosolid and cultivated with common bean

This study aimed to evaluate the extractable phosphorus Mehlich-1 in a distrophic Red-Yellow Latosol (Oxisol) which received alkaline sewage sludge (alkaline biosolid) along with 0, 0.436, 0.872 and 1.745 dag kg-1 of P from three different sources and cultivated with common bean (Phaseolus vulgaris cv. IPR Uirapuru) in greenhouse. It also aimed to quantify the phosphorus uptake by the plant, plant production and the relative agronomic effectiveness index. For the establishment of the treatment the recommended dose was 45.85 kg ha-1 of P from the treatments, except the control (0 dag kg-1 of P). This dose was calculated for 2.5 kg of this Oxisol from Contenda, Paraná State, Brazil, contained in recepients of 3 dm3 with 6 cultivated bean plants (cv. IPR Uirapuru). Phosphorus added in alkaline biosolid increased the extractable phosphorus (Mehlich-1) in soil and phosphorus accumulated in plants as well as the grain and total dry mass production of bean plants. The best level of phosphorus added to alkaline biosolid was 0.436 dag kg-1 of P from the partially acidulated phosphate rock Alvorada and single superphosphate.

Optimization of Sulphur Requirement to Sesame (Sesamum indicum L.) Genotypes Using Tracer Techniques

Four sesame genotypes viz., T6, SM4, SM7 and SM8 were verified with three levels of sulphur 10, 20 and 40 kg/ha including control. Factorial experiment was laid out in a completely randomized design with four replications. Biochemical parameters such as chlorophyll, nitrate reductase, amino acid and total sugar in leaves, total dry mass production, total nitrogen accumulation in seeds and seed yield increased with sulphur application up to 20 kg S/ha. Application of 40 kg S/ha had no significant benefit on biochemical parameters, dry matter and seed yield of sesame though 35S uptake in seeds increased with increasing sulphur levels till 40 kg/ha. The biochemical traits and nutrients uptake were superior in SM4 than other genotypes which resulted in the highest seed yield of SM4. Among the sulphur levels, 20 kg S/ha showed the maximum seed yield in all the genotypes. Therefore, sulphur @ 20 kg/ha can be recommended for getting maximum productivity of sesame genotypes. DOI: http://dx.doi.org/10.3329/bjb.v41i1.11076 Bangladesh J. Bot. 41(1): 7-13, 2012 (June)

Seed Yield of Mungbean (Vigna radiata(L.) Wilczek) in relation to Growth and Developmental Aspects

Growth parameters such as leaf area (LA), total dry mass (TDM) production, crop growth rate (CGR), relative growth rate (RGR), and net assimilation rate (NAR) were compared in six varieties of mungbean under subtropical condition (24°8′ N 90°0′ E) to identify limiting growth characters for the efficient application of physiology breeding for higher yields. Results revealed that a relatively smaller portion of TDM was produced before flower initiation and the bulk of it after anthesis. The maximum CGR was observed during pod filling stage in all the varieties due to maximum leaf area (LA) development at this stage. Two plant characters such as LA and CGR contributed to the higher TDM production. Results indicated that high yielding mungbean varieties should possess larger LA, higher TDM production ability, superior CGR at all growth stages, and high relative growth rate and net assimilation rate at vegetative stage which would result in superior yield components.

Fungos micorrízicos arbusculares nativos e doses de fósforo no desenvolvimento do amendoim RUNNER IAC 886

The objective was to evaluate the interaction between native arbuscular mycorrhizal fungi (AMF) with peanut plants (Arachis hypogea) RUNNER cultivar IAC 886, at different levels of phosphorus (P). The experiment was conducted in a greenhouse in a randomized design in factorial (2 x 5), with and without inoculation of AMF and five P levels (0; 20; 40; 60 and 180 mg kg-1 in the form of KH2PO4) in four replications. Shoot, root and total dry mass, root colonization, mycorrhizal dependency and mycorrhizal efficiency were evaluated. It was concluded that increasing levels of phosphorus caused an increase in the development of peanut plants. The AMF promoted maximum production of total dry mass of the peanut in estimated dose of 114.0 mg kg-1 of P. The highest root colonization and mycorrhizal efficiency were observed at 60 mg kg-1 of P.

Crescimento e produtividade da abobrinha italiana: efeito da concentração iônica da solução nutritiva

With the objective of evaluating the effect of different ionic concentrations of the nutrient solution on growth of summer squash cultivated in raw rice husk substrate with leaching recirculation, two experiments were conducted in two crop-seasons: spring-summer of 2005 and summer-autumn of 2006, in Pelotas, RS. Four ionic concentrations of the nutrient solution (based on electrical conductivity - EC) were studied: 1.3; 1.7; 2.1 and 4.2 dS m-1. Crop growth was determinated by accumulated dry mass production and partitioning among the different above-ground plant organs (leafs, stem and fruits) at the end of the crop-seasons. Fruit yield was also evaluated. The obtained results indicate that ionic concentrations equal or lower than 1.7 dS m-1 were limiting for proper growth and yield of the crop. The effect of high ionic concentration of the nutrient solution (above 2.1 dS m-1) on dry mass production and partitioning varied according to the crop-season. The lower solar radiation availability of the summer-autumn crop season minimized the effects of the different concentrations of nutrient solution on dry mass production and partitioning to the fruits, as well as on the yield. The fruits comprised from 28 to 52% of the total above-ground dry mass production. Fruits represented the largest sink of assimilates of the plant only at 2.1 dS m-1 ionic concentration of the nutrient solution and in crescent solar radiation availability condition (spring-summer). According the mathematics models, the electrical conductivity that maximizes dry mass production and yield is approximately 3.0 dS m-1 for both crop-seasons.

Produção e composição bromatológica do capim-tifton 85 (Cynodon spp.) submetido a doses de nitrogênio

The experiment was carried out in Cáceres, Mato Grosso State, Brazil, aiming to evaluate the effect of nitrogen (N) on forage production and chemical composition of Tifton 85 bermudagrass (Cynodon spp.). A randomized complete block design was used, with five treatments (0, 60, 120, 180 and 240 kg ha-1) and four replications in 4.0 x 5.0 m plots. Four cuts were made at intervals of 30 days, at the height of 5 cm above ground level. N was applied after each cut, in the form of urea. For each kg ha-1 of N applied, we observed increases of 22.67 kg ha-1 in the production of total dry mass, 11.37 kg ha-1 in the production of green leaf blade, 0.052 cm in sward height, and 0.00955 dag kg-1 in crude protein content, and a reduction of 0.0142 dag kg-1 in NDF content. There was an increase in the extraction of N at a rate of 0.537 kg kg-1 of N, and sharp decline in the efficiency of N utilization from the estimated dose of 155 kg ha-1 of N.

Crescimento do morangueiro: influência da cultivar e da posição da planta no canteiro

O objetivo deste trabalho foi avaliar o crescimento de cultivares de morangueiro em sistema de cultivo orgânico, observando a influência da posição da planta no canteiro sobre a produção acumulada e a partição de massa seca entre os órgãos aéreos das plantas. O experimento foi realizado na Embrapa Clima Temperado, Estação Experimental Cascata, Pelotas, RS. Os tratamentos constaram da combinação de dois fatores experimentais: cultivar ('Albion', 'Aromas', 'Camarosa' e 'Camino Real') e a posição das plantas no canteiro (Central e Bordadura). O delineamento experimental adotado foi o de blocos completos casualizados com parcelas divididas e quatro repetições. A cultivar 'Camarosa' apresentou maior produção de massa seca dos órgãos aéreos das plantas (62,3; 27,5 e 88,0g planta-1 para folha, coroa e frutos, respectivamente) e, juntamente com a 'Aromas', maior produtividade (64,2 e 59,1Mg ha-1, respectivamente). A cultivar 'Aromas' apresentou a maior contribuição proporcional dos frutos para a composição do total de massa seca da planta (60,6%) e o maior índice de colheita (88%). A posição das plantas não influenciou o crescimento e a produtividade, indicando ausência de efeito de bordadura para as cultivares 'Albion', 'Aromas', 'Camarosa' e 'Camino Real'.