Competitive interaction of grasses with contrasting temperature responses and water stress tolerances

1974 ◽  
Vol 25 (2) ◽  
pp. 227 ◽  
Author(s):  
W Harris ◽  
A Lazenby
Keyword(s):  
Water Stress ◽  
Festuca Arundinacea ◽  
Diallel Analysis ◽  
Short Rotation ◽  
Digestible Organic Matter ◽  
Different Seasons ◽  
Second Year ◽  
The Difference ◽  
Water Treatments ◽  
Temperature Responses

Lolium perenne (cv. Kangaroo Valley ryegrass), L. perenne x multiforum (cv. 'Grasslands Manawa' short rotation ryegrass), Phalaris tuberosa (cv. Australian Commercial),Festuca arundinacea (cv. Demeter) and Paspalum dilatatum were grown for 2 years in monoculture and two-species mixtures, under dryland and irrigated treatments at Armidale, N.S.W. Competition effects were described, with the use of diallel analysis. Early aggressivities were in the order L. perenne × multiflorum > L. perenne > F. arundinacea = P. tuberosa > P. dilatatum in both water treatments; subsequently, the aggressiveness of F. arundinacea, P. tuberosa and P. dilatatum increased relative to the ryegrasses (especially L. perenne), P. tuberosa (more so in the dryland treatment) and P. dilatatum (particularly in summer and autumn). Specifically high aggressivities of P. tuberosa towards P. dilatatum and P. dilatatum towards L. perenne were shown. Under dryland conditions, the P. tuberosa monoculture produced the highest yield in both years, differing markedly from L. perenne × multiforum in response to limited water availability. Under irrigation overall gains of yield were obtained by mixing grasses in the second year, the gains being significant for ryegrass-P. dilatatum mixtures. This response is related to the different growth potentials of the species in different seasons with the proviso that conditions such as water stress or excess suppression do not limit the expression of these potentials. Although P. dilatatum was of lower digestibility than the ryegrass, the difference was not sufficiently large to cancel the gain from mixing when expressed as digestible organic matter (DOM). An unsatisfactory feature of these mixtures was the depressive effect on winter yield of dormant P. dilatatum. By comparison, winter yield stimulation by mixing P. tuberosa and L. perenne, occurring when digestibilities were high, contributed to a significant gain of DOM yield by this mixture. Marked dominance of L. perenne × multiforum under dryland conditions, although appearing to assist the survival of this species in mixture, was detrimental in that by suppressing P. tuberosa, F. arundinacea and P. dilatatum, it restricted the potential of these species to produce in dryland conditions. There was evidence that F. arundinacea depressed yield in mixture, especially when associated with L. perenne.

scholarly journals Characteristics of Extratropical Cyclones That Cause Tornadoes in Italy: A Preliminary Study

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 180
Author(s):  
Eigo Tochimoto ◽  
Mario Marcello Miglietta ◽  
Leonardo Bagaglini ◽  
Roberto Ingrosso ◽  
Hiroshi Niino
Keyword(s):  
Environmental Conditions ◽  
Convective Available Potential Energy ◽  
Static Stability ◽  
Extratropical Cyclones ◽  
Cool Season ◽  
Southeastern Us ◽  
Different Seasons ◽  
The Difference ◽  
Upper Level ◽  
Strong Evaporation

Characteristics of extratropical cyclones that cause tornadoes in Italy are investigated. Tornadoes between 2007 and 2016 are analyzed, and statistical analysis of the associated cyclone structures and environments is performed using the JRA-55 reanalysis. Tornadoes are distributed sporadically around the cyclone location within a window of 10° × 10°. The difference in the cyclone tracks partially explains the seasonal variability in the distribution of tornadoes. The highest number of tornadoes occur south of the cyclone centers, mainly in the warm sector, while a few are observed along the cold front. Composite mesoscale parameters are examined to identify the environmental conditions associated with tornadoes in different seasons. Potential instability is favorable to tornado development in autumn. The highest convective available potential energy (CAPE) in this season is associated with relatively high-temperature and humidity at low-levels, mainly due to the strong evaporation over the warm Mediterranean Sea. Upper-level potential vorticity (PV) anomalies and the associated cold air reduce the static stability above the cyclone center, mainly in spring and winter. On average, the values of CAPE are lower than for US tornadoes and comparable with those occurring in Japan, while storm relative helicity (SREH) is comparable with US tornadoes and higher than Japanese tornadoes, indicating that the environmental conditions for Italian tornadoes have peculiar characteristics. Overall, the conditions emerging in this study are close to the high-shear, low-CAPE environments typical of cool-season tornadoes in the Southeastern US.

scholarly journals High Phosphorus Acquisition and Allocation Strategy Is Associated with Soybean Seed Yield under Water- and P-Limited Conditions

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 574
Author(s):  
Yun-Yin Feng ◽  
Jin He ◽  
Yi Jin ◽  
Feng-Min Li
Keyword(s):  
Water Stress ◽  
Water Supply ◽  
Seed Yield ◽  
Soybean Seed ◽  
Dry Weight ◽  
Water Regimes ◽  
P Acquisition ◽  
Application Rates ◽  
Soybean Genotypes ◽  
Water Treatments

Both water stress and P deficit limit soybean seed yield, but the effects of water regimes and P application rates, their interaction on P status, acquisition, and partitioning, and their roles in yield performance have not been well-studied. Two soybean genotypes (Huangsedadou (HD) and Zhonghuang 30 (ZH)) with contrasting seed yield and root dry weight (DW) were used to investigate the P status, P acquisition, P partitioning, and yield formation under two water regimes (well-watered (WW) and cyclic water stress (WS)) and three P rates (0 (P0), 60 (P60), and 120 (P120) mg P kg−1 dry soil). The results show that increased P and water supply increased the seed yield, shoot and root DW and P concentrations and accumulations in different organs. Cultivar ZH had a significantly higher seed yield than HD at P60 and P120 under WS and at P0 under WW, but a lower seed yield at P60 and P120 under WW. Cultivar ZH had a significantly higher P harvest index and P acquisition efficiency, but a significantly lower shoot and root DW than HD. The interaction between water treatments and P rates had significant effects on leaf and stem P concentration. Cultivar ZH had significantly lower P partitioning to leaves and stems but significantly higher P partitioning to seeds than HD. The seed yield was positively correlated with leaf and seed P accumulations and P acquisition efficiency under WS. We conclude that (1) adequate water supply improved the P mobilization from leaves and stems at maturity, which may have improved the seed yield; and (2) the high P acquisition efficiency is coordination to high P partition to seeds to produce a high seed yield under water- and P-limited conditions.

scholarly journals Forest biomass and wood consumption In the lower course of the Amazon: a case study of rhe Urubueua Island

1999 ◽  
Vol 29 (1) ◽  
pp. 79-79 ◽  
Author(s):  
Akio TSUCHIYA ◽  
Mario HIRAOKA
Keyword(s):  
Water Stress ◽  
Forest Structure ◽  
Forest Biomass ◽  
Human Intervention ◽  
Terra Firme ◽  
Wood Volume ◽  
The Difference ◽  
Várzea Forests ◽  
Wood Consumption

Várzea and terra-firme forests in the lower course of the Amazon were compared in terms of forest structure, wood volume increments and forest biomass. The wood volume of várzea forests was smaller than that of terra-firme forests, particularly when severe human intervention such as the cultivation of açaí palm occurred. The difference was even greater in the forest weight comparison because of the lower wood density of várzea trees. These trees are not directly influenced by water stress during the dry season, while late wood with a high density is formed in the terra-firme trees. The annual forest disappearance area due to firewood for tile factories was estimated to be about 276 ha on the island investigated, which had an area of 36,200 ha. Assuming that the forests are rotatively cultivated every 25 to 30 years, the total deforestation area is 6,870-6,948 ha in 25 years and 8,244~8,337 ha in 30 years. This result means that the balance between forest biomass and utilization is not in crisis, however, this balance might be lost as long as substitutive energy such as electricity is not supplied.

scholarly journals A Comparative Study of Growth and Nutrition in Barley and Rye As Affected by Low-Water Treatment

1955 ◽  
Vol 8 (4) ◽  
pp. 435 ◽  
Author(s):  
RF Williams ◽  
RE Shapter
Keyword(s):  
Water Stress ◽  
Water Treatment ◽  
Comparative Study ◽  
Plant Parts ◽  
Stage Of Development ◽  
Growth And Nutrition ◽  
Water Treatments

A comparative study of growth and nutrition in barley and rye was made with two water treatments. The low-water treatment was of an intermittent character and harvests were made after each of the five periods of water stress. Yield reductions due to low-water treatment were highly significant at all five harvests and for both species. The severity of the effects on various plant parts was conditioned by the stage of development of those parts.

scholarly journals Water-Stress Influences on Three New Promising HLB-Tolerant Citrus Rootstocks

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 336
Author(s):  
Lidia Aparicio-Durán ◽  
Frederick G. Gmitter ◽  
Juan M. Arjona-López ◽  
Rocío Calero-Velázquez ◽  
Áurea Hervalejo ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Abiotic Factors ◽  
Dry Weight ◽  
Emerging Diseases ◽  
Carrizo Citrange ◽  
Citrus Rootstock ◽  
Chlorophyll Index ◽  
Stress Influences ◽  
Water Treatments

Drought and flooding conditions are increasingly common abiotic factors that affect citrus crops in both the Mediterranean Basin and Florida. Furthermore, emerging diseases, such as Huanglongbing (HLB), are a potential risk for these crops in those producing areas. This study aimed to evaluate the behavior under water-stress treatments of three new citrus rootstocks (UFR-6, B11R5T60, and 2247 x 6070-02-2) with reported tolerance of HLB, comparing them with a common commercial citrus rootstock (Carrizo citrange). Four water conditions were established: Control, Medium Water Stress (MWS), Drought, and Flooding. Chlorophyll index (SPAD), growth in height, relative growth rate, biomass (fresh and dry weight) and plant water status were evaluated. Citru rootstock response were different for each genotype; Carrizo citrange was negatively affected by all water treatments in the chlorophyll index (SPAD) and biomass production. By contrast, UFR-6 showed a positive response in SPAD and growth under MWS and Drought, B11R5T60 displayed similar behavior to Control under all water stresses, and the response of 2247 x 6070-02-2 under MWS treatment was adequate but was not under Drought or Flooding conditions. Our study describes the behavior of these promising new citrus rootstocks against water stress; B11R5T60 exhibiting the best performance. These results can be useful for the citrus industry to address water-stress problems in these crops.

scholarly journals Under-vine cover crops: impact on weed development, yield and grape composition

OENO One ◽  
2020 ◽  
Vol 54 (4) ◽  
pp. 975-983
Author(s):  
Javier Abad ◽  
Marín Diana ◽  
Santesteban L. Gonzaga ◽  
Cibriáin José Félix ◽  
Sagüés Ana
Keyword(s):  
Water Stress ◽  
Cover Crops ◽  
Drip Irrigation ◽  
Vegetative Growth ◽  
Cover Crop ◽  
Sustainable Management ◽  
Arid Regions ◽  
Management Tool ◽  
Second Year ◽  
Semi Arid

This study aims to evaluate the interest of using an under-vine cover crop as a sustainable management tool replacing herbicides or tillage to control weeds, evaluating its effects on yield and berry parameters in a semi-arid climate. The performance of Trifolium fragiferum as an under-vine cover crop was evaluated in 2018 and 2019 in a Merlot vineyard in Traibuenas (Navarra, Spain). This trial showed that the soil under the vines was covered by 80 % of the cover crop in August 2018 and 100 % in Aug 2019, with clover (T. fragiferum) comprising around 26 % and 70 % of the cover crop surface, respectively. The presence of the cover crop only reduced the number of shoots in the second year, although both years there was an increment in water stress. Neither yield, cluster weight nor berry weight were affected by the presence of the under-vine cover crop. Similarly, no changes in grape composition were observed. The use of T. fragiferum-like cover crops under the vine allows for better control of weeds, provided a good installation is achieved. In the first two years, this cover crop reduced vegetative growth and increased water deficit slightly. However, no changes in yield and grape composition were observed.In a context of herbicide suppression and search for sustainable management, under-vine clover cover crops constitute a viable alternative in semi-arid regions provided drip irrigation can be applied. 

scholarly journals Ruderal succession starting at different seasons

2014 ◽  
Vol 55 (3) ◽  
pp. 403-419 ◽  
Author(s):  
Reinhard Bornkamm
Keyword(s):  
Poa Pratensis ◽  
Floristic Composition ◽  
Clayey Loam ◽  
First Year ◽  
Conyza Canadensis ◽  
Senecio Vulgaris ◽  
Different Seasons ◽  
Winter Annual ◽  
Second Year ◽  
Different Soils

Succession experiments were carried out in 1 m<sup>2</sup> sized plots on three different soils (S = sand. SCL = silty clayey loam, CL = clayey loam). Vegetation was allowed to grow for 9 years, starting at different dates between 18.06.1969 and 1.04.1971. The greatest part of the variation of floristic composition and cover was brought about by the different soils. Direct effects of the starting season were detected only in the first two years. On sand in the first year the winter annual <em>Conyza canadensis</em> was well developed on the plots that had started in spring, but was poorly developed on the summer and fall plots. In the second year it decreased in the spring plots but increased in the summer and fall plots. The same was true for the winter annual <em>Sonchus asper</em> on CL. On SCL, however., <em>Senecio vulgaris</em>, belonging to the therophyta epeteia (overwintering in summer habit), was well developed in both the spring and summer plots, and showed an increase towards the second year in the fall plots only. In the later years of the experiment plots that had been started early in the year mostly were dominated by <em>Poa pratensis</em> ssp. <em>angustifolia (or Quercus rubra)</em>, whereas plots that had been started late in the year mostly were dominated by <em>Solidagn canadensis</em> together with <em>Artemsia vulgaris</em>. The analyses of the transition events between the (sub)dominant species showed a variety of replacement patterns, but no determinated series of species following each other. It remains, therefore, unclear in what manner the differentiation between the terminal dominants may be related to the starting season.

An assessment of the quality of forage from its cell-wall content and amount of cell wall digested

1972 ◽  
Vol 78 (3) ◽  
pp. 355-362 ◽  
Author(s):  
K. W. Moir
Keyword(s):  
Cell Wall ◽  
Organic Matter ◽  
Ammonium Oxalate ◽  
Physical Structure ◽  
Tropical Species ◽  
Average Amount ◽  
Lignin Concentration ◽  
Digestible Organic Matter ◽  
The Difference

SUMMARYGrasses and legumes comprising poor to good quality temperate and tropical species were fed to either cattle or sheep in 36 digestibility experiments. Cell wall in these forages was the ash-free and protein-free residue after sequential extraction with acidpepsin, organic solvents and either water for grasses or ammonium oxalate for legumes. The average amount of cell wall digested per 100 g forage OM was 40·0±0·59 g in grasses and 19·8±1·85 g in legumes. It was considered that within grasses and within legumes the physiology of ruminant digestion, rather than forage quality, was the main determinant of the average amount of cell wall digested and the difference between grasses and legumes was due to interaction of the ruminant digestion process with the physical structure of the cell wall. Of forage factors governing variation about the physiological average, the total cell wall had some effect on the amount of cell wall digested, but the lignin concentration in the cell wall had no effect.Among grasses and legumes the average, apparently undigested, protein-free non-cell-wall component was 6·2±0·13 g per 100 g forage OM. This component and digestible protein relative to total protein varied among different sets of data. It was concluded that only the component of digestible organic matter which was governed by the relative proportions of cell walls and cellular contents was predictable from chemical composition. It was considered that selection in plant breeding should be based on both digestible cell wall and cell-wall content instead of digestible organic matter.

scholarly journals Differences in Faculty and Standardized Patient Scores on Professionalism for Second-Year Podiatric Medical Students During a Standardized Simulated Patient Encounter

2018 ◽  
Vol 108 (2) ◽  
pp. 145-150
Author(s):  
James M. Mahoney ◽  
Vassilios Vardaxis ◽  
Noreen Anwar ◽  
Jacob Hagenbucher
Keyword(s):  
Medical Students ◽  
Faculty Member ◽  
Real Time ◽  
Assessment Tool ◽  
Simulated Patient ◽  
Standardized Patient ◽  
Patient Encounter ◽  
Second Year ◽  
The Difference ◽  
Share Information

Background: This study examined the differences between faculty and trained standardized patient (SP) evaluations on student professionalism during a second-year podiatric medicine standardized simulated patient encounter. Methods: Forty-nine second-year podiatric medicine students were evaluated for their professionalism behavior. Eleven SPs performed an assessment in real-time, and one faculty member performed a secondary assessment after observing a videotape of the encounter. Five domains were chosen for evaluation from a validated professionalism assessment tool. Results: Significant differences were identified in the professionalism domains of “build a relationship” (P = .008), “gather information” (P = .001), and share information (P = .002), where the faculty scored the students higher than the SP for 24.5%, 18.9%, and 26.5% of the cases, respectively. In addition, the faculty scores were higher than the SP scores in all of the “gather information” subdomains; however, the difference in scores was significant only in the “question appropriately” (P = .001) and “listen and clarify” (P = .003) subdomains. Conclusions: This study showed that professionalism scores for second-year podiatric medical students during a simulated patient encounter varied significantly between faculty and SPs. Further consideration needs to be given to determine the source of these differences.

The Influence of a Gonadotrophin on the Seasonal Changes in the Testis and Deferent Duct of the Chaffinch (Fringilla coelebs)

1949 ◽  
Vol s3-90 (9) ◽  
pp. 1-11
Author(s):  
J. W. SLUITER ◽  
G. J. van OORDT
Keyword(s):  
Interstitial Cells ◽  
Seminiferous Tubules ◽  
Control Bird ◽  
Interstitial Tissue ◽  
Fringilla Coelebs ◽  
Large Numbers ◽  
Different Seasons ◽  
The Difference ◽  
In The Beginning ◽  
Progressive Stage

1. Male chaffinches (Fringilla coelebs) were treated with gestyl, a gonadotrophin prepared from pregnant mare serum, in different seasons; using different techniques their testes and deferent ducts were histologically studied after autopsy on 11 August, 30 November, 28 January, and 5 May. 2. After Champy-fixation and Altmann-staining two types of interstitial cells can be distinguished in the intertubular tissue of sexually active chaffinches: lipoid cells. (= Leydig cells) and secretion cells. 3. Results of gestyl-administration: In summer- and winter-birds (PI. I) whose testes are in the resting stage, the testis-tubule diameter shows a strong enlargement, which is partly due to the plasma of the cells being distinctly inflated; spermatogenesis does not take place. In the intertubular tissue lipoid and secretion cells appear in abnormally large numbers. In 10 days the deferent ducts pass over from the quiescent into the fully-activated stage. In spring-birds (Pl. III), being in the reproductive stage, the administration of gestyl has practically no effect. In this stage the intertubular tissue also contains both lipoid and secretion cells. 4. From the results mentioned under 3, and the fact that in the control bird of 28 January, being in the beginning of the progressive stage (Pl. II), many lipoid cells were found, whereas its deferent ducts were still quiescent, it is concluded that only the secretion cells produce the male sex-hormone. The lipoid cells, which amongst others contain cholesterol, possess only a trophic function. 5. The difference in reaction of the seminiferous tubules of birds to chorionic and hypophyseal gonadotrophins as well as the function of the interstitial cells are discussed. Most opinions on the last-mentioned subject are not sufficiently well founded, as the investigators used routine techniques only for the cytological investigation of the interstitial tissue.

Sign in / Sign up

Export Citation Format

Share Document