For years now farmers and researchers have understood the value of applying water to crops during periods when the temperature drops below 32oF (0oC). The temperature of 32oF is the freezing point of water and is the temperature at which crops start to become damaged due to the formation of ice crystals in their tissue cells. The point that this starts to occur is considered the crops critical temperature. The critical temperature usually is slightly lower than the freezing point of water and depends on the duration at the temperature. For example, in citrus the critical temperature at four hours is 28oF. This means that a citrus tree can stand a temperature of 28oF for four hours before sustaining damage. After four hours the damage is proportional to the time that the temperature remains below the critical temperature. Temperatures below 28oF for a short period of time (one or two hours) will cause only minimal damage. Temperatures over 28oF can be tolerated for extended periods of time with only minor damage (partial leaf burn, partial defoliation, etc., but no wood damage). Other factors such as stage of growth (if the plant is in early stages of growth or mature), fruit set (whether the crop is still on the plant or not), dormancy (whether the plant is actively growing or is dormant), plant water content (whether the plant is under water stress or not) and overall plant health will influence the critical temperature for a specific crop.
There are three ways that water can transfer heat for freeze protection. The first way is through radiation. Water pumped from wells will be introduced into the field at a much higher temperature than the surrounding air temperature (in Florida the temperature for water coming from a well is...
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References
Hochmuth, G.J., S.J. Lacascio, S.R. Kostewicz, and F.G. Martin. 1993. Irrigation Method and Rowcover Use for Strawberry Freeze Protection. J. Amer. Soc. Hort. Sci. 188(5):575-579.
Miller, F. 1977. College Physics. Harcourt Brace Jovanovich, Inc. New York.
Parsons, L.R., and T.A. Wheaton, 1987. Microsprinkler Irrigation for Freeze Protection: Evaporative Cooling and Extent of Protection in an Advective Freeze. J. Amer. Soc. Hort. Sci. 112(6):879- 902.
Parsons, L.R., T.A. Wheaton, N.D. Faryna, and J.L. Jackson. 1991. Elevated Microsprinklers Improve Protection of Citrus Trees in an Advective Freeze. Hortscience. 26(9):1149-1151.
Rieger, M., F.S. Davies, and L.K. Jackson. 1986. Microsprinkler Irrigation and Microclimate of Young Orange Trees During Freeze Conditions. Hortscience. 21(6):1372-1374.
Some say that the only reason glaciers are melting is because of low evaporation and not hot temperatures. That is one of the reasons , but the other is because there is some mu...
The problem of water shortage is one of the major limiting factors in food production and agriculture development in the arid and semi arid regions. Reclaimed water is one of the most significant available water resources that shall be consumed in agriculture and urban landscape maintenance. In order to investigate the impact of water quality and its application method on olive trees this experiment was carried out during 2010-2012 in the semiarid central part of Iran on young olive trees. The trees were irrigated by a new subsurface-leaky irrigation (SLI) system and surface irrigation in line with irrigation with recycle and clean water for 24 months. The results revealed that SLI system could enhance trees growth, leaf area, Fv/Fm and photosynthesis by68, 26, 4 and 42% respectively, although it decreased leaves soluble sugars (47%). In addition, irrigating trees by SLI system using reclaimed water could increase N and Mg uptake 138 and 8% respectively. Plants irrigated with RW showed improved growth (42%) leaf area26% and photosynthesis 23.4% compared with CL water. Furthermore Mg, Na, K, P and N surprisingly increase 12, 59, 30, 7, and 92 % respectively in leaf tissue in application recycle water. In overall, this experiment showed that recycled water could be a favorable resource for olive trees irrigation and SLI irrigation system was more efficient in irrigation in this research.
The rise in temperature is having a significant impact on levels of rainfall, which in turn effects water run-off. Satellite observations since 1987 have shown that, as global temperatures have increased, global mean precipitation has increased in parallel at a rate of 7.4 ± 2.6% per ◦C ...
Following the fall of the great Roman Empire a new age was born, the age of knights in shining amour and the great kings in stone castles. Yet, it was also a chaotic time, War and plague was a disease upon Europe. Countries fought for land, resources, and above all, the attention of God. The world was young and so was the English Language. Few writers wrote in English, the language of the commoners, as French and Latin was the Language of the powerful élite. Yet one writer dared to speak against the feudal society of which he was born into. Geoffrey Chaucer served most of his life in the employment of the crown, as both a soldier and a clerk. Yet through all of these titles, Chaucer would be forever immortalized as Geoffrey Chaucer the writer, and the Satirist. The true goal of any Satire is to point out the flaws in certain aspect of society, while also inspiring reform to that very same aspect in one way or another. In Chaucer’s Canterbury tales, Chaucer satirizes the corruption Catholic Church and those associated. Chaucer saw that hypocrisy polluted the pureness of the church and expressed his disillusionment through the use of satire. Fearless of discommunication Geoffrey Chaucer, the father of satire, dared to speak openly of the absolute corruption of the medieval church.
The Big Freeze article discussed the detrimental effects that frost and freezes can have on agriculture and plant production. The article went on to provide examples of devastating frost and freezing events that wiped out agricultural yields and the dollar amounts that came with it. What confused me is that the article only explains the cost that was lost, they do not discuss the other impacts that a loss in crop yield had. Such as food shortages, it seems in our society those in power only consider money as a driving force. I wonder if anyone went hungry because of a heavy reliance on grocery stores. I learned that damage occurs due to water inside the plant freezing. I learned the difference between a frost and a freeze. These two can cause
Many pilgrims in Geoffrey Chaucer’s Canterbury Tales held a religious position. Some of these people’s personal ideas have caused debates and criticism over Chaucer’s opinion of the Catholic Church. Critics have discussed the ideas that were presented both subtly and openly. Two of the pilgrims and their tales will be discussed: the Prioress and the Pardoner. Both of these tales offer points of criticism in the Catholic Church.
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Also, when we put the insulation cans in warn water the water heated up the can. And lastly, in the insulated can experiments, both cooling and heating, when the cans temperature was changed it in turn changed the air temperature
The table below shows the men pole vault gold medalists at various Olympic games between 1932 and 2008.
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Although the right to privacy has been used to sway the outcome of many U.S court cases, including the famous Supreme Court ruling of Roe vs. Wade, there is still some debate over how the “right to privacy” should be viewed. For example both Judith Jarvis Thompson, and James Rachels agree that the right to privacy is indeed a right that is bestowed upon citizens, however their perception of how one is granted this right is quite different.
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