Growth responses of cultivars of subterranean clover to temperature, plant density and nitrate supply

1990 ◽  
Vol 41 (1) ◽  
pp. 101 ◽  
Author(s):  
JH Silsbury ◽  
TW Hancock
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Plant Density ◽  
Subterranean Clover ◽  
Growth Conditions ◽  
High Density ◽  
Growth Responses ◽  
Mineral N ◽  
Nitrate Supply ◽  
Temperature Interaction

Six cultivars of subterranean clover were compared for growth as swards under controlled conditions in six separate experiments. Conditions common to all experiments were: 400 8mol quanta m-2 s-1 and 12 h day: 12 h night. The variable regimens were: 2 000 or 12 000 plants m-2 ('low' and 'high' density), 10 to 20�C; and no mineral N (0 mM) or N supplied as a 7.5 mM NO3- solution. Growth responses to these conditions were tested by sequential harvesting for dry matter and the fitting of linear and quadratic regression models. Special attention was given to testing for differential responses by cultivars to temperature. All cultivars except 'Woogenellup' grew about 20% faster when NO3- was supplied in the nutrient solution than when the N was derived entirely from N2 fixation under the 0mM treatment. Crop growth rate at 20�C was about double that at 10�C at low density, but at high density the rate at 20�C was 90-95% of that at 10�C. Cultivars differed significantly in growth rate but over all conditions, there was a hierarchical order from the highest to the lowest of: 'Clare', 'Woogenellup', 'Yarloop', 'Mt. Barker', 'Daliak' and 'Geraldton'. There was very little evidence of any cultivar by temperature interaction except for 'Woogenellup, which responded to a low temperature of 10�C compared with a 'high' of 20�C better than the other cultivars. The importance of seed size as a factor influencing the early growth of a subterranean clover sward was emphasized where swards established from large seeds of 'Mt. Barker' grew faster than where small seeds were used. 'Clare' was a highly productive cultivar under all growth conditions. It is concluded that the growth rates of swards of subterranean clover established at seedling densities in excess of 5000 plants m-2 are less sensitive to a low temperature of 10�C than are those established at more conventional densities.

scholarly journals Marginal superiority of maize: an indicator for density tolerance under high plant density

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Guangzhou Liu ◽  
Wanmao Liu ◽  
Yunshan Yang ◽  
Xiaoxia Guo ◽  
Guoqiang Zhang ◽  
...  
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Plant Density ◽  
Significant Negative Correlation ◽  
Growth Conditions ◽  
High Density ◽  
Leaf Angle ◽  
Individual Plant ◽  
High Plant Density ◽  
Tolerance Field

Abstract Marginal superiority is a common phenomenon in crops, and is caused by the competitiveness of individual plant for resources and crop adaptability to crowded growth conditions. In this study, in order to clarify the response of marginal superiority to maize morphology and plant-density tolerance, field experiments without water and nutrition stress were conducted at Qitai Farm in Xinjiang, China, in 2013–2014 and 2016–2019. The results showed that no more than three border rows of all the cultivars had marginal superiority under high density, about 90% of all the cultivars had no more than two border row that had marginal superiority and a significant negative correlation was observed between marginal superiority and population grain yield (first border row: y = − 2.193x + 213.9, p < 0.05; second border row: y = − 2.076x + 159.2, p < 0.01). Additionally, marginal superiority was found to have a significant positive relationship with plant density (first border row: y = 6.049x + 73.76, p < 0.01; second border row: y = 1.88x + 95.41, p < 0.05) and the average leaf angle above the ear (first border row: y = 2.306x + 103.1, p < 0.01). These results indicated that the smaller the leaf angle above the ear, the weaker the marginal superiority and the higher the grain yield. It suggests that the magnitude of marginal superiority in the border rows can be an indicator for plant-density tolerance under high density. What’s more, cultivars with small leaf angle above the ear can be selected to weaken the marginal superiority and improve grain yield under high plant density. Conversely, cultivars with a large leaf angle above the ear can be selected to achieve higher individual yield in intercropping systems with no more than four rows alternated with other crops.

Are some strains of subterranean clover (T. subterraneum) highly susceptible to low temperature stress?

1980 ◽  
Vol 20 (103) ◽  
pp. 197 ◽  
Author(s):  
RC Rossiter ◽  
WJ Collins
Keyword(s):  
Low Temperature ◽  
Temperature Stress ◽  
Growth Temperature ◽  
Temperature Effects ◽  
Subterranean Clover ◽  
The Other ◽  
Field Observations ◽  
Winter Dormancy ◽  
Plant Experiment ◽  
Temperature Interaction

Two experiments, one with spaced plants and the other with swards, were conducted in a controlled-temperature glasshouse at Perth, Western Australia. Three strains-Phillip Island, CPI 18293 and CPI 68043H-were selected on the basis of field observations of apparent very poor winter growth in rows, and tested against Tallarook as a control. The temperature treatments were 22/17� (day/night) and 12/7�C. In the spaced plant experiment (occupying the first 48 days of growth), temperature and strain effects were highly significant, but there was no indication of a strain x temperature interaction. In the sward experiment (from days 51 to 77) temperature effects were small; and in only one strain, Phillip Island, was the decline in tops growth due to low temperature greater (P< 0.05) than for Tallarook. The experiments failed to provide support for the so-called 'winter dormancy' phenomenon. Possible explanations for the discrepancy between the present findings and the field observations are given.

Role of Cl/Si Ratio in the Low-Temperature Chloro-Carbon Epitaxial Growth of SiC

2013 ◽  
Vol 740-742 ◽  
pp. 205-208
Author(s):  
Galyna Melnychuk ◽  
Siva Prasad Kotamraju ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Growth Process ◽  
Growth Conditions ◽  
The Other ◽  
Additional Increase ◽  
Other Hand

In order to understand the influence of the Cl/Si ratio on the morphology of the low-temperature chloro-carbon epitaxial growth, HCl was added during the SiCl4/CH3Cl growth at 1300°C. Use of higher Cl/Si ratio allowed only modest improvements of the growth rate without morphology degradation, which did not go far beyond what has been achieved previously by optimizing the value of the input C/Si ratio. On the other hand, when the epitaxial growth process operated at too low or too high values of the input C/Si ratio, i.e., outside of the window of good epilayer morphology, any additional increase of the Cl/Si ratio caused improvement of the epilayer morphology. It was established that this improvement was due to a change of the effective C/Si ratio towards its intermediate values, which corresponded to more favorable growth conditions.

Superphosphate on perennial pastures. I. Effects of a pasture response on sheep production

1977 ◽  
Vol 28 (6) ◽  
pp. 991 ◽  
Author(s):  
ML Curll
Keyword(s):  
Growth Rate ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Experimental Period ◽  
Stocking Rate ◽  
Growth Responses ◽  
South Wales ◽  
History Of ◽  
Sheep Production ◽  
Gross Margins

From 1973 to 1975 in the Mediterranean environment of southern New South Wales, superphosphate was applied annually at four rates (0, 62, 125 and 250 kg ha-1) to an established perennial pasture with a substantial history of superphosphate use. The pasture was continuously grazed by Border Leicester × Merino ewes (at 10 and 13.3 ha-1), so that plant growth responses to superphosphate could be assessed in sheep production terms and an estimate made of the monetary value of these responses. Growth rate of unfertilized pastures declined over the experimental period, and depending on the quantity of superphosphate applied and stocking rate, responses of fertilized pastures ranged from 20 to 36% in 1973, 28 to 157% in 1974 and 75 to 233% in 1975. From having similar proportions of perennial ryegrass (Lolium perenne) and subterranean clover (Trifolium subterraneum), pastures tended towards clover dominance with little (62 kg ha-1) or no superphosphate, particularly at high stocking rate, and to grass dominance at higher rates of superphosphate, particularly at low stocking rate. By increasing the level of available pasture, superphosphate increased wool production and ewe liveweight, lambs reared, their growth rate and the percentage that reached marketable weight (32 kg). These trends were similar at both stocking rates. Significant quadratic response relationships existed between these parameters and rate of superphosphate. Withholding superphosphate caused a progressive reduction in gross margins of about 37% over the 3 year trial period, while its application increased gross margins, relative to those from unfertilized pastures, by a maximum 10, 42, and 140% for the first, second and third year respectively. It is suggested that these pasture responses calibrated in animal production terms may be extended to other situations most effectively by using the data to test and improve tentative models used to predict fertilizer requirements.

LOW-TEMPERATURE GROWTH RESPONSES OF THE TOMATO

1968 ◽  
Vol 48 (3) ◽  
pp. 281-286 ◽  
Author(s):  
G. A. Kemp
Keyword(s):  
Growth Rate ◽  
Seed Germination ◽  
Low Temperature ◽  
Seedling Growth ◽  
Low Temperatures ◽  
Fruit Set ◽  
Growth Responses ◽  
Growth Phases ◽  
Night Temperature ◽  
Temperature Growth

The effects of low temperatures on several growth phases of the tomato were studied. The tests, each conducted over a 2-week period, included seed germination at 8.5 °C, rate of seedling growth at a night temperature of 10 °C, root and top growth of plants in soil at 15 °C, and fruit set at a night temperature of 4.5 °C.Varietal response to growth rate at low temperatures differed in all phases studied, and varieties that performed well in some phases did not always perform well in others. Of the varieties studied, six grew well under most of the low-temperature conditions. These were: Earlinorth, Bonita, Azerbidzivisky, P.I. 205040, P.I. 280597, and Cold Set.

scholarly journals Testing a New Approach to Quantify Growth Responses to Pruning Among Three Temperate Tree Species

2016 ◽  
Vol 42 (3) ◽  
Author(s):  
Matt Follett ◽  
Charles Nock ◽  
Christian Buteau ◽  
Christian Messier
Keyword(s):  
Growth Rate ◽  
Growth Response ◽  
Abiotic Factors ◽  
Growth Conditions ◽  
Accurate Estimation ◽  
Cycle Duration ◽  
Growth Responses ◽  
Laser Measurements ◽  
Branch Growth ◽  
Highly Correlated

In settled areas, electrical line safety is maintained by pruning encroaching trees. Identifying key predictors of branch elongation growth rate following pruning would assist in developing predictive models and optimizing pruning cycles. However, measuring branches in trees near electrical lines is complex and challenging. This paper describes an innovative approach using a handheld laser rangefinder to safely and accurately estimate growth from the ground. In-tree and ground-based laser measurements were highly correlated. This was followed by testing for correlations between branch growth response over a number of years after pruning and many biotic and abiotic factors for Fraxinus pennsylvanica, Acer platanoides, and Acer saccharinum, in the city of Montreal, Canada. In a sample of 59 trees, A. saccharinum had the greatest branch growth, followed by F. pennsylvanica, and finally A. platanoides. Branch growth increased following pruning and subsequently strongly declined, with A. platanoides declining the fastest. Branch inclination angle was positively correlated with growth rate for two species, but not for A. saccharinum. Among the types of pruning used, directional pruning techniques resulted in the least branch regrowth rate. Tree diameter was weakly related to branch growth rates. These results suggest that while growth conditions for street trees may be perceived as homogenous, there is substantial variation in branch growth response. This variation may be related to pruning history, or unmeasured abiotic or biotic variables. Estimating pruning cycle duration is a complex task and further work is needed to develop a predictive model for more accurate estimation of return times.

scholarly journals Effects of MOVPE Growth Conditions on GaN Layers Doped with Germanium

2020 ◽  
Author(s):  
Dario Schiavon ◽  
Elżbieta Litwin-Staszewska ◽  
Rafał Jakieła ◽  
Szymon Grzanka ◽  
Piotr Perlin
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Low Temperature ◽  
Surface Morphology ◽  
Growth Temperature ◽  
High Growth ◽  
Growth Conditions ◽  
High Growth Rate ◽  
Pit Formation ◽  
Movpe Growth

The effect of growth temperature and precursor flows on the doping level and surface morphology of Ge-doped GaN layers was researched. The results show that germanium is more readily incorporated at low temperature, high growth rate and high V/III ratio, thus revealing a similar behavior to what was previously observed for indium. V-pit formation can be blocked at high temperature but also at low V/III ratio, the latter of which however causing step bunching.

Nitrogen Doping in Low-Temperature Halo-Carbon Homoepitaxial Growth of SiC

2008 ◽  
Vol 600-603 ◽  
pp. 159-162 ◽  
Author(s):  
Krista Chindanon ◽  
Huang De Lin ◽  
Galyna Melnychuk ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Nitrogen Doping ◽  
Critical Role ◽  
Growth Conditions ◽  
Vapor Condensation ◽  
Nitrogen Incorporation ◽  
Wide Range ◽  
Complex Temperature ◽  
Site Competition

In this work, nitrogen doping was investigated during the low-temperature halo-carbon epitaxial growth of 4H-SiC on Si- and C-faces. The dependencies of nitrogen incorporation on nitrogen flow rate, Si/C ratio, growth rate, and temperature were investigated. It was established that the efficiency of nitrogen incorporation for the C-face growth at 1300 °C is higher than that for the Si-face for a wide range of the growth conditions. Seeming deviation of the Si/C ratio dependence from the “site-competition” trend confirmed the critical role of the silicon vapor condensation during the low-temperature epitaxy. Opposite trends for the nitrogen doping dependence on the growth rate were observed on the Si- and C-faces. Finally, a complex temperature dependence of the nitrogen doping in the temperature range from 1300 to 1450 0C was observed.

scholarly journals Threshold and adaptation in Phycomyces. Their interrelation and regulation by light.

1984 ◽  
Vol 84 (1) ◽  
pp. 119-132 ◽  
Author(s):  
P Galland ◽  
V E Russo
Keyword(s):  
Growth Rate ◽  
Dark Adaptation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Light Sensitivity ◽  
Growth Conditions ◽  
Continuous Illumination ◽  
Growth Responses ◽  
Wild Type

The absolute light sensitivity of Phycomyces sporangiophores was determined by analyzing the intensity dependence of the phototropic bending rate and of the light growth and dark growth responses to step changes of the intensity. We found that the different methods give approximately the same results for the wild-type strain, as well as for several behavioral mutants with defects in the genes madA, madB, and madC. A crucial factor in the determination of thresholds is the light intensity at which the strains grow during the 4 d after inoculation and prior to the experiment. When the wild-type strain grows in the dark, its threshold for the bending rate is 10(-9) W X m-2, compared with 2 X 10(-7) W X m-2 when it is grown under continuous illumination. Further, the maximal bending rate is twice as high in dark-grown strains. This phenomenon is further complicated by the fact that the diameter and growth rate of the sporangiophores also depend on the illumination conditions prior to the experiment: light-grown sporangiophores have an increased diameter and an increased growth rate compared with dark-grown ones. Some of the behavioral mutants, however, are indifferent to this form of light control. Another factor that is controlled by the growth conditions is adaptation: the kinetics of dark adaptation are slower in light-grown sporangiophores than in dark-grown ones. We found empirically a positive correlation between the slower dark adaptation constant and the threshold of the bending rate, which shows that the two underlying phenomena are functionally related.

A physiological analysis of the effect of sowing density on the growth rate of subterranean clover

1982 ◽  
Vol 33 (2) ◽  
pp. 213 ◽  
Author(s):  
J-L Prioul ◽  
JH Silsbury
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Growth Curves ◽  
Subterranean Clover ◽  
Crop Growth ◽  
High Density ◽  
Planting Density ◽  
Low Density ◽  
Response Curves ◽  
Crop Growth Rate

The initial planting density of subterranean clover swards is known to affect the subsequent crop growth rate in such a way that a low density crop reaches the same final yield as does one sown at high density. To explain this phenomenon, daily carbon influxes and effluxes were measured during the growth of 'low' and 'high' density swards in a constant environment. The growth characteristics of individual plants in the sward and the photosynthetic responses of individual leaves to light were measured during ontogeny. Good agreement was found between the growth curves reconstructed from daily carbon increment and growth curves previously derived from dry matter sampling. The crop growth rate of a low density sward was found to be higher than that of a high density sward, and this is shown to be due to a lower respiratory loss. The high respiration rate of a high density crop can be attributed to plant mortality when dry matter density is higher than 400 g m-2. The photosynthetic light response curves of individual leaves at the top of the canopy were not found to be affected by the initial planting density, which suggests that subterranean clover plants are extremely well adapted to growth under sward conditions.

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