scholarly journals Evaluation of Plant Growth on Expanded Black Cotton Soil

2018 ◽  
Vol 7 (2) ◽  
pp. 41
Author(s):  
Samwel Nyakach ◽  
Seth F.O. Owido ◽  
Japheth O. Onyando
Keyword(s):  
Root Length Density ◽  
Stem Elongation ◽  
Growth Characteristics ◽  
Black Cotton Soil ◽  
Coarse Aggregates ◽  
Adequate Evaluation ◽  
Aeration Conditions ◽  
Clay Aggregates ◽  
Medium Preparation ◽  
Better Than

In aggregate hydroponics, the suitability of a particular medium is often guided by its physical properties. However these may not provide adequate evaluation. By growing a crop, the growth characteristics can also be used to guide medium preparation and selection. Tomatoes (Anna F1 variety) were grown in containers under a greenhouse and provided with equal amount of nutrient solution. The expanded black cotton soil was prepared by mixing with rice husk at a ratio of 90:10, fired at 750oC for 30 minutes and size reduced to various textures. The crops planted in the expanded clay aggregates performed better than the black cotton soil both in terms of stem elongation and enlargement due to improved drainage, nutrient flow and aeration conditions. The root length density was 25654 m m-3 in black cotton soil, being the highest and lowest in the coarse aggregates which had 9433 m m-3. 

SEASONAL GROWTH CHARACTERISTICS OF LONG AND SHORT SHOOTS OF TAMARACK

1967 ◽  
Vol 45 (9) ◽  
pp. 1643-1651 ◽  
Author(s):  
J. Johanna Clausen ◽  
T. T. Kozlowski
Keyword(s):  
Seasonal Changes ◽  
Stem Elongation ◽  
Growth Characteristics ◽  
Weight Increase ◽  
Stem Length ◽  
Larix Laricina ◽  
Seasonal Growth ◽  
Long Shoots ◽  
Short Shoots ◽  
Food Reserves

Tamarack (Larix laricina (DuRoi) K. Koch) produces long shoots which bear two kinds of needles. Early needles are present in the bud and elongate rapidly after budbreak. Late needles, few of which are present in the bud, elongate later than early needles. Short shoots bear early needles only, and stem length seldom exceeds 1 mm. Seasonal changes in length and weight of needles and stems of both shoot types were measured. In long shoots, 75% of stem elongation, more than 70% of stem weight increment, and 65–70% of late needle elongation occurred after early needles were full-sized. Stem and late needle elongation ceased simultaneously, after which time needle weight decreased and stem weight increased. Early needles probably drew on food reserves while developing, and then themselves contributed to stem and late needle elongation. Final stem weight increase probably used photosynthate from both late and early needles of the current year.Shading of current and last year's needles showed that shoots in which photosynthesis was interrupted in this way produced shorter, lighter-weight stems than did control shoots.

scholarly journals Acidic solution effects on no-fines concrete produced by using recycled concrete as coarse aggregate

2018 ◽  
Vol 162 ◽  
pp. 02002
Author(s):  
Ikbal Gorgis ◽  
Whab Faleh Abd ◽  
Shaker Al-Mishhadani
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Maximum Size ◽  
Recycled Concrete ◽  
Type I ◽  
Coarse Aggregates ◽  
Crushed Concrete ◽  
Compaction Factor ◽  
Single Size ◽  
Better Than

This paper investigates durability of no fine concrete containing demolished concrete as coarse aggregate after crushing to different sizes. Different no fine concrete mixes were considered using Portland cement type I with two types of coarse aggregates, crushed demolished concrete and crushed natural gravel were used with two ratios by weight (1:5 and 1:7) C/Agg. Graded aggregate and single size were used with a maximum size of 20 mm. W /C ratio was kept as 0.4 for all mixes and super-plasticizer was required to keep the same flow and compaction factor value for all mixes. Cube specimens with 150mm were cured and divided to two parts, the first part was exposed to 60 cycles of freezing- thawing; the second part of the sample was immersed in Nitric Acids solution with pH of 3.5 for (7, 28, 90 and 180 days) and then tested for compressive strength. The results indicated that it is possible to produce homogenous and workable mixes by using demolished crushed concrete as coarse aggregate. The compressive strength after cycles of freezing- thawing and immersing in Nitric acid (HNO3) at (7, 28, 90 and 180) days was decreased for samples made with crushed demolished concrete. Also it is found that the performance of concrete mixes containing graded coarse aggregate and 1:5 cement/aggregate ratios was better than other mixes.

Root characteristics of vigorous wheat improve early nitrogen uptake

2006 ◽  
Vol 57 (10) ◽  
pp. 1097 ◽  
Author(s):  
Mingtan Liao ◽  
Jairo A. Palta ◽  
Ian R. P. Fillery
Keyword(s):  
Root Growth ◽  
Soil Profile ◽  
Root Length ◽  
Root Length Density ◽  
Stem Elongation ◽  
N Uptake ◽  
Soil Layer ◽  
Mapping Technique ◽  
Genotypic Differences ◽  
Root Characteristics

Root growth is important for the acquisition of nitrogen (N) and water in deep sandy soil profiles with high leaching potential. Root growth characteristics and the N uptake of wheat genotypes differing in early vigour were investigated in 2 glasshouse experiments. In both experiments the vigorous breeding lines Vigor18 and B18 and the well-adapted commercial cultivar Janz were grown in glass-walled growth boxes in a controlled-temperature glasshouse up to the onset of stem elongation. In Expt 1, rooting parameters and detailed measurements of root growth and proliferation were made at 2-day intervals using a root mapping technique. In Expt 2 the glass-walled growth boxes were segmented into upper (0–0.2 m), middle (0.2–0.7 m), and bottom (0.7–1.0 m) soil layers, and the contribution of N fertiliser uptake by roots from each soil layer to the total plant N uptake was determined by applying 15N-urea to a single soil layer each time. The accumulated total root length across the soil profile from the 1-leaf stage to the onset of stem elongation was 33–83% higher in the vigorous lines Vigor18 and B18 than in Janz. The roots of the 3 genotypes grew vertically down the soil profile at a similar rate, but the roots of vigorous lines branched earlier and grew horizontally faster and more extensively than those of cv. Janz, resulting in a greater root-length density and root number in the top 0.7-m soil layer. Uptake of N fertiliser by roots in the upper 0–0.2 m of the soil profile was 60–68% higher in the vigorous lines than in Janz. Roots of the vigorous lines located in the segment 0.2–0.7 m of the soil profile captured twice as much N fertiliser than those of Janz. Uptake of N fertiliser by roots in the lower 0.7–1.0 m of the soil profile was similar in the vigorous lines and Janz. This indicates that the early and more extensive horizontal growth of the roots in the 0.2–0.7 m of the soil profile was responsible for the superior uptake of N by the vigorous lines. The implications of these genotypic differences in root growth and proliferation and their relationship with the early acquisition of N are discussed with emphasis on their role in improving the efficiency of N fertiliser uptake and reducing nitrate leaching, particularly in the sandy soils of the Mediterranean climatic region of Australia.

scholarly journals Application of Light Expanded Clay Aggregate as Replacement of Coarse Aggregate in Concrete Pavement

2018 ◽  
Vol 7 (4.2) ◽  
pp. 1
Author(s):  
Pavithra A ◽  
Jerosia De Rose D
Keyword(s):  
Coarse Aggregate ◽  
Mineral Admixture ◽  
Maintenance Cost ◽  
Light Weight ◽  
Conventional Concrete ◽  
Coarse Aggregates ◽  
Light Weight Concrete ◽  
Clay Aggregates ◽  
Light Weight Aggregate ◽  
Effect Of Light

The main aim of this project is to develop a light weight concrete (LWC) by replacing the coarse aggregate with light weight expanded clay aggregate. The damage caused in LWC is less significant than conventional concrete and therefore the maintenance cost is also reduced. In order to understand the effect of light weight aggregate in concrete, conventional concrete of strength 30MPa was designed with the density of 2400 kg/m3. Then the natural coarse aggregates were replaced by clay aggregates and light weight concrete mix of density 1800 kg/m3 was designed to meet the desired strength requirement. As the density of the concrete tends to be lowered, the strength of the concrete may also tend to decrease. Hence suitable chemical and mineral admixture is to be incorporated in addition to significant water reduction to meet the strength requirement. Cement content kept constant in both the cases. The details of mechanical properties and durability properties of conventional and light weight concrete are reported in this paper. 

Immersed membranes activated sludge process applied to the treatment of municipal wastewater

1998 ◽  
Vol 38 (4-5) ◽  
pp. 437-442 ◽  
Author(s):  
Pierre Côté ◽  
Hervé Buisson ◽  
Matthieu Praderie
Keyword(s):  
Activated Sludge ◽  
Membrane Filtration ◽  
Municipal Wastewater ◽  
Pilot Scale ◽  
Activated Sludge Process ◽  
Hybrid Techniques ◽  
Membrane Flux ◽  
Aeration Conditions ◽  
New Generation ◽  
Better Than

An immersed membrane activated sludge process has been evaluated at pilot scale by Anjou Recherche. This process represents a new generation of hybrid techniques, which aims at coupling biological treatment and membrane filtration functions, in a configuration adapted to the treatment of municipal wastewater. The process was evaluated under extended aeration conditions, but with concentrations of biomass of between 15 to 25 gMLSS/l, which corresponded to volumetric loadings of between 1.2 to 2.3 kg COD/m3/d. Under these conditions, COD and TKN removal were better than 96% and 95%, respectively. The membrane ensured total removal of suspended solids and produced treated water of excellent bacteriological quality. The sludge production stabilized at 0.20 gDS/kg COD removed. The membrane flux was stable for all conditions tested.

Observations on tillering in cultivars of phalaris under rotational grazing in a year with a summer - autumn drought

1997 ◽  
Vol 48 (4) ◽  
pp. 467 ◽  
Author(s):  
R. A. Culvenor
Keyword(s):  
Stem Elongation ◽  
Reproductive Development ◽  
Moisture Stress ◽  
Grazing Pressure ◽  
Early Spring ◽  
Late Winter ◽  
Grazing Tolerance ◽  
Summer Dormancy ◽  
Stem Development ◽  
Better Than

Changes in tiller numbers, timing of stem elongation, and tiller survival under summer moisture stress were measured in phalaris (Phalaris aquatica L.) pastures rotationally grazed at 15 wethers/ha during a study of the survival and productivity of a semi-winter-dormant cultivar (Australian) compared with 3 winter-active cultivars (Sirosa, Holdfast, Perla Retainer). The semi-winter-dormant cultivar maintained higher tiller numbers per plant and per area than the 3 winter-active cultivars, was later in its reproductive stem development, and was capable of more new tillering early in spring, but could display higher rates of tiller death late in spring. Although stem elongation in Australian started later in 1990, it was no less synchronous than in the winter-active cultivars. However, Sirosa had a higher proportion of elongating tillers than Australian under very infrequent grazing in a supplementary experiment during 1991. Cultivars did not differ in the proportion of tillers that were decapitated during spring 1990. Perla Retainer displayed higher summer dormancy after rainfall in January 1991 and new tillers of Perla Retainer and Holdfast survived subsequent drought better than tillers of Australian. However, regeneration of the tiller population of Australian after drought ended was enhanced by a slightly higher propensity for tillering during July–September 1991. The results suggested that maintaining grazing pressure and frequency in late winter and early spring should enhance tiller survival and improve the resilience of phalaris to episodes of heavy spring grazing. Later reproductive development probably benefits grazing tolerance in semi-winter-dormant cultivars, but the value of selecting for this in winter-active phalaris is uncertain. In areas with harsh summers, higher summer dormancy is required for survival combined with a capacity for tiller survival should growth occur. However, unnecessarily high summer dormancy will reduce the growth of green herbage and, consequently, animal production.

scholarly journals Design and Performance of Anticracking Asphalt-Treated Base

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaoge Tian ◽  
Haifeng Han ◽  
Qisen Zhang ◽  
Xinwei Li ◽  
Ye Li
Keyword(s):  
Crack Resistance ◽  
Design Method ◽  
Temperature Stability ◽  
Performance Tests ◽  
High Temperature Stability ◽  
Coarse Aggregates ◽  
Superpave Gyratory Compactor ◽  
Different Types ◽  
And Performance ◽  
Better Than

To enhance the crack resistance of asphalt-treated base (ATB), a type of gapped and semiopened gradation ATB mixture, GSOG, was designed. Its design method was proposed based on the volume design method and performance tests. Firstly, several gradations were designed preliminarily in which middle particle sizes of coarse aggregates were partially or completely gapped according to the gradation specification. Secondly, their voids in coarse aggregates (VCA) were determined through dry rod compaction test on coarse aggregates, and then their theoretical voids were calculated. Gradations whose theoretical voids met the requirements were selected to fabricate specimens with Superpave Gyratory Compactor, and their voids were determined using vacuum sealing method and submerged weight in water method. Finally, gradations whose voids meet requirements were selected to fabricate different types of specimens for various performance tests, and the optimal gradation can be selected comprehensively considering their performances, especially focusing on their crack resistance. According to this gradation design method, the gradation of GSOG-25 was designed, and its performances, including high-temperature stability, water stability, fatigue, and antireflection crack resistance, were measured and compared to ordinary ATB-25. The results demonstrate that the performance of GSOG-25 is much better than that of ordinary ATB-25, especially in anticracking capacity.

Biology of Sourgrass and Its Competition with Buffelgrass and Guineagrass

Weed Science ◽  
1977 ◽  
Vol 25 (2) ◽  
pp. 171-174 ◽  
Author(s):  
J.Y. Pyon ◽  
A.S. Whitney ◽  
R.K. Nishimoto
Keyword(s):  
Early Growth ◽  
Growth Characteristics ◽  
Maximum Depth ◽  
Panicum Maximum ◽  
Cenchrus Ciliaris ◽  
Complete Darkness ◽  
Flowering Response ◽  
Better Than

Establishment and early growth characteristics were defined for sourgrass [Trichachne insularis(L.) Nees], one of the most serious pasture weeds in Hawaii. Optimum germination of sourgrass seeds was obtained in the light at 30 C or with alternating temperatures of 20 and 30 C or 25 and 35 C. Germination in complete darkness was poor except at alternating 25 and 35 C. Sourgrass germinated better than buffelgrass (Cenchrus ciliarisL.) and guineagrass (Panicum maximumJacq.) at low moisture tension. Sourgrass was capable of emerging from a maximum depth of 5 cm but percent emergence was greatly reduced at planting depths greater than 3 cm. Sourgrass flowering response to photoperiod was day-neutral. Under conditions of adequate moisture, the growth of sourgrass was severely suppressed when grown with buffelgrass, or/or guineagrass. If grazing is restricted, either of these grasses would be useful for controlling sourgrass.

scholarly journals Effect of Different Combinations of Red and Blue LED Light on Growth Characteristics and Pigment Content of In Vitro Tomato Plantlets

Agriculture ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 196 ◽  
Author(s):  
Most Tahera Naznin ◽  
Mark Lefsrud ◽  
Md Obyedul Kalam Azad ◽  
Cheol Ho Park
Keyword(s):  
Stem Elongation ◽  
Growth Characteristics ◽  
Photosynthesis Rate ◽  
Pigment Content ◽  
Growth Chamber ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Led Light ◽  
Shoot Number

The aim of this study was to evaluate the growth characteristics and pigment content of tomato plantlets grown under various ratios of red (R) (661 nm) and blue (B) (449 nm) LED light. In this study, three different ratios of R and B (RB) light such as 5:01, 10:01, and 19:01 along with R (100%) were used. The photosynthetic photon flux density (PPFD), and photoperiod of the growth chamber was 120 ± 5 μmol m−2s−1 and 16/8 h (day/night), respectively. Tomato plantlets were cultured for six weeks in the growth chamber. It was shown that tomato plantlets had higher photosynthesis rate, higher pigments content, higher growth characteristics (e.g., number of leaves, leaf area, shoot number, root number, root length, dry, and fresh mass), and greater surviving rate under the R:B = 10:01 ratio among the treatments. The plantlets showed at least a threefold decrease in photosynthesis rate, as well as a significant abnormal stem elongation when grown under 100% R light. It is concluded that the RB ratio of 10:01 showed excellent performance in all growth parameters. This result has shown that the optimum lighting environment improves tomato plantlet cultures in vitro.

scholarly journals A COMPREHENSIVE ASSESSMENT OF CANDIDATES TO SYNTHETIC VARIETY-POPULATIONS IN THE SCOTS PINE VARIETY TESTS IN GUTYANSKE FOREST ENTERPRISE

2018 ◽  
pp. 57-65
Author(s):  
V. A. Dyshko ◽  
L. O. Torosova
Keyword(s):  
Scots Pine ◽  
Local Control ◽  
Root Rot ◽  
Growth Characteristics ◽  
Synthetic Variety ◽  
Regional Control ◽  
Central Regions ◽  
Seed Stand ◽  
Scots Pine Stands ◽  
Better Than

The article presents the results of the examination of Scots pine progenies from nine clonal seed orchards (CSO) and one permanent forest seed stand (PFSS), which were potential synthetic variety-populations, as well as of their regional control variants (Kharkiv, Kyiv, Rivne and Volyn regions). All the progenies were tested in the Gutyanske Forest Enterprise in Kharkiv region. Mensuration and breeding indicators and state and level of resin productivity were estimated. At the age of 20, three out of ten potential variety-populations exceeded local control by the heights and diameters. The variants from the eastern and central regions were better than western ones by the breeding structure and state category. Only one candidate to the variety-population exceeded local control by the level of resin productivity, the rest ones were somewhat lower. In seven variants, the proportion of trees with higher resistance to phytopathology, in particular, to the annosum root rot, were higher (Pst = 45…50 %) than in the control (Pst = 40 %). The correlation between the resin productivity and the growth characteristics were weak (for diameter, r = 0,32 ± 0,055; for height, r = 0,17 ± 0,057). The results of integrated point assessment of candidates to variety-populations indicated the feasibility of using seeds from CSO and PFSS to create Scots pine stands to be potentially resistant to phytopathogenic diseases.

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