The effect of high temperature pretreatments on germination of Townsville stylo seed material

1973 ◽  
Vol 13 (61) ◽  
pp. 190 ◽  
Author(s):  
AM Holm
Keyword(s):  
High Temperature ◽  
Wet Season ◽  
Dehulled Seed ◽  
Dry Heat ◽  
Heat Pretreatment ◽  
Seed Material ◽  
Townsville Stylo

Townsville stylo cv. Gordon dehulled seed and intact pods were exposed to temperatures ranging from 40� to 11 5�C for between 12 and 48 hours in the expectation that a method of reducing hardseededness could be devised. Dry heat temperatures of 75� and 95�C markedly decreased the level of hardseededness in both dehulled seed and intact pods. A temperature of 11 5�C for 12 hours was sufficient to kill all seeds and pods. Fifty per cent germination was achieved after 2.5 days for dehulled seeds and after 5 days for pods exposed to a pretreatment of 95�C. Untreated scarified dehulled seeds took only 1.5 days to achieve 50 per cent germination. It was suggested that a suitable heat pretreatment on Townsville stylo pods should result in a seed material with a soft-seed level similar to dehulled scarified seed, yet with the pods still retaining considerable immunity from 'false starts' to the wet season.

Effect of time of cessation of wet season grazing on Townsville stylo-annual grass pasture at Katherine, N.T

1973 ◽  
Vol 13 (64) ◽  
pp. 544 ◽  
Author(s):  
MJT Norman ◽  
LJ Phillips
Keyword(s):  
Dry Matter ◽  
Recovery Period ◽  
Dry Matter Yield ◽  
Annual Grass ◽  
Wet Season ◽  
Active Growth ◽  
Heavy Grazing ◽  
Stylosanthes Humilis ◽  
Dry Conditions ◽  
Townsville Stylo

A Townsville stylo (Stylosanthes humilis)-annual grass pasture at Katherine, N.T., was subjected to a series of treatments in 1969-70 and 1970-71 under which plots were grazed heavily from the beginning of the wet season for a period and then allowed to recover undefoliated for the remainder of the season. The dates at which heavy grazing ceased were spaced at 2-week intervals from November 24 to March 16. At the end of the wet season, total dry matter yield was linearly related to length of recovery period. Townsville stylo yield declined as recovery period was reduced from 18 to 8 weeks, but showed little response to a further reduction to 4 weeks. In contrast, annual grass yield showed little change as recovery period was reduced from 18 to 8 weeks, but fell with a further reduction to 4 weeks. As a result, the proportion of Townsville stylo in the pasture at the end of the season was high with long and short recovery periods but reached a minimum with an 8 - 10 week recovery period. Dry conditions prevailed in the first half of both seasons. The evidence suggests that young Townsville stylo is sensitive to heavy grazing when under water stress, and that early grazing for grass control should be imposed only during periods of active growth.

Herbicides for weed control in grain sorghum crops in the Northern Territory

1970 ◽  
Vol 10 (46) ◽  
pp. 588
Author(s):  
IMW Wood
Keyword(s):  
Good Control ◽  
Dry Weight ◽  
Grain Sorghum ◽  
Northern Territory ◽  
Research Station ◽  
Wet Season ◽  
Grain Yields ◽  
Stylosanthes Humilis ◽  
Townsville Stylo ◽  
Grass Weed

In experiments conducted in the 1968-69 wet season at the Katherine Research Station, Northern Territory, a number of herbicides gave good control of the grass weed Pennisetum polystachyon in grain sorghum crops. Linuron at 3 lb a.i. an acre and PCP at 20 lb a.i. an acre as pre-emergence applications effectively controlled grasses with no apparent adverse affects on the crop. With both there were significantly higher grain yields than on unweeded control plots containing an average of 1378 lb dry weight of P. polystachyon an acre. Fluometuron at 3 lb a.i. an acre late pre-emergence and early post-emergence and chlorthal at 7 lb a.i. an acre pre-emergence controlled grasses but did not increase grain yields. Further investigations are warranted with these herbicides, as banded applications to the interrow may overcome the apparent problem of crop phytotoxicity. Chlorthal at rates that gave good grass control had no adverse effect on Townsville stylo (Stylosanthes humilis). This could be an important advantage when sorghum is sown in rotation with Townsville stylo pasture or where the crop is undersown with Townsville stylo.

Some effects of heat waves on grain sorghum at the stage of head emergence

1969 ◽  
Vol 9 (41) ◽  
pp. 636 ◽  
Author(s):  
D Pasternak ◽  
GL Wilson
Keyword(s):  
High Temperature ◽  
Grain Yield ◽  
Seed Set ◽  
Heat Waves ◽  
Pollen Viability ◽  
Grain Sorghum ◽  
Heat Treatments ◽  
Grain Production ◽  
Dry Heat ◽  
Heat Application

Sorghum plants were exposed at head emergence to simulated heat waves for five days, and subsequent grain production observed. Comparisons were made between relatively dry heat (108�F, 41 per cent RH by day and 90�F, 53 per cent RH by night), more humid hot conditions (107�F, 70 per cent RH-90�F, 70 per cent RH), and ambient (81�F, 64 per cent RH-71�F, 85 per cent RH). Whole inflorescences or portions that had emerged before heat application were little affected, whereas most enclosed flowers were killed. High temperature was responsible, humidity having little effect. Grain yield depended on the resulting number of grains. There was some loss of pollen viability in the dry heat treatments, but not sufficient to affect seed set.

scholarly journals Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

2013 ◽  
Vol 80 (5) ◽  
pp. 1739-1749 ◽  
Author(s):  
Yun Xing ◽  
Alex Li ◽  
Daniel L. Felker ◽  
Larry W. Burggraf
Keyword(s):  
High Temperature ◽  
Bacillus Anthracis ◽  
Exposure Time ◽  
Mechanical Analysis ◽  
Mechanical Stresses ◽  
Heat Inactivation ◽  
Content Type ◽  
Dry Heat ◽  
Wet Heat ◽  
Dry Heating

ABSTRACTEffective killing ofBacillus anthracisspores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivatedBacillus anthracisspores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating.

scholarly journals Characterizing the Synoptic Expression of the Angola Low

2018 ◽  
Vol 31 (17) ◽  
pp. 7147-7165 ◽  
Author(s):  
Emma Howard ◽  
Richard Washington
Keyword(s):  
Southern Africa ◽  
Sea Breeze ◽  
Wet Season ◽  
Cyclonic Vorticity ◽  
Tropical Regions ◽  
Dry Heat ◽  
Anabatic Wind ◽  
Low Precipitation ◽  
Low Pressure Systems ◽  
Heat Low

The Angola low is a key feature of the southern Africa wet season atmosphere that influences precipitation across the continent. This paper uses ERA-Interim to show that the synoptic expression of the Angola low is a combination of dry heat lows and moist tropical low pressure systems. The Angola heat low and Angola tropical low composites are contrasted against similar lows observed in other continental tropical regions and found to be broadly comparable. The implications that the distinction between dry and moist events has for the interannual relationship among the Angola low, precipitation, and ENSO are examined. The tropical lows exhibit unusual semistationary behavior by lingering in the Angola region rather than traveling offshore. This behavior is proposed to be caused by an integrated sea breeze–anabatic wind that enhances (inhibits) cyclonic vorticity stretching and convection inland (near the coast). The combined effect of the heat lows and the anchored tropical lows creates the Angola low in the climatological average. By elucidating the mechanisms of the Angola low, this research improves the foundation of process-based evaluation of southern Africa present and future climate in CMIP and AMIP models.

scholarly journals Dry Heat and Hot Water Treatments for Disinfesting Cottonseed of Fusarium oxysporum f. sp. vasinfectum

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1469-1475 ◽  
Author(s):  
Rebecca S. Bennett ◽  
Patrick D. Colyer
Keyword(s):  
High Temperature ◽  
Fusarium Oxysporum ◽  
Heat Treatments ◽  
Seed Vigor ◽  
Hot Water ◽  
Seed Infection ◽  
Fusarium Spp ◽  
Dry Heat ◽  
Incubation Temperatures ◽  
Water Treatments

The potential of low- and high-temperature dry heat, and hot water treatments, for disinfesting cottonseed of Fusarium oxysporum f. sp. vasinfectum was investigated. Naturally infected seeds from Louisiana were air-heated at 30, 35, and 40°C for up to 24 weeks. Seed harvested from bolls inoculated with race 4 of F. oxysporum f. sp. vasinfectum were incubated in dry heat at 60, 70, and 80°C for 2 to 14 days, or were immersed in 90°C water from 45 s to 3 min. The effects on seed germination and vigor of hot water treatment and a subset of the high-temperature dry heat treatments were also examined in seeds of a Pima (Gossypium barbadense) and an Upland (G. hirsutum) cultivar. Low- or high-temperature dry heat did not eliminate Fusarium spp. from the seed, although seed infection declined more rapidly with higher incubation temperatures. High-temperature dry heat treatments effective in eliminating fusaria also significantly reduced seed vigor in both the Pima and Upland cultivars. Seed from all times of immersion in hot water were less frequently infected with Fusarium spp. than nontreated seed. Incidence of seed infection did not differ significantly among immersion times ranging from 75 s to 3 min. Immersion in 90°C water did not reduce germination or vigor at exposure times ≤120 s and ≤150 s for seeds of Pima and Upland cotton, respectively. Results from the hot water treatments suggest that thermotherapy may be optimized to provide a tactic to prevent the spread of virulent F. oxysporum f. sp. vasinfectum genotypes into uninfested areas through infected seed.

Effect of pasture type and supplementary feeding on the reproductive performance of cattle in the dry tropics of north Queensland

1977 ◽  
Vol 17 (85) ◽  
pp. 197 ◽  
Author(s):  
RG Holroyd ◽  
PJ Allan ◽  
PK O'Rourke
Keyword(s):  
Reproductive Performance ◽  
Dry Season ◽  
Conception Rate ◽  
Wet Season ◽  
Lactating Cows ◽  
Dry Tropics ◽  
Stylosanthes Humilis ◽  
Native Pasture ◽  
Conception Rates ◽  
Townsville Stylo

A study was made over a four year period ( 1970-1 973) on the reproductive performance of cows grazing either native pasture stocked at 1 breeder 4.9 ha-1 or native pasture oversown with Townsville stylo (Stylosanthes humilis) and fertilized with superphosphate, stocked at 1 breeder 2.4 ha-1. Animals were supplemented on each pasture type with combinations of molasses, urea and phosphorus at various times of the year. Mating from September 1 to January 31 resulted in animals lactating during the dry season. At double the stocking rate, lactating cows on fertilized pastures had similar conception rates to those on native pasture. During a prolonged dry season, lactating cows on fertilized pasture had twice the conception rate and fewer required survival feeding. Urea compared with non-urea based supplements produced significant increases in conception rates of cows grazing native pasture especially during a dry year. Calves were born earlier, had shorter intercalving intervals and fewer cows had to be fed a survival ration when urea was available. On fertilized pasture, urea based supplements caused only a marginal increase in conception rate except in a dry year, when there was a significant increase. Over the four years, there was a diminishing response in the conception rate of lactating cows grazing native pasture and supplemented with phosphorus during the wet season compared with the control. On fertilized pasture, there was a variable but non-significant response. The addition of phosphorus either as a wet or dry season supplement to urea caused variable responses on each pasture type, but none differed significantly from that of urea.

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