Why does plant respiration occur during the night and not during the day?

Because photosynthesis ioccurs only during the day and not at night

Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar. This process occurs in plants and some algae (Kingdom Protista). Plants need only light energy, CO2, and H2O to make sugar. The process of photosynthesis takes place in the chloroplasts, specifically using chlorophyll, the green pigment involved in photosynthesis.

Carbohydrates made during photosynthesis are of value to a plant when they are converted to energy. This energy is used for cell growth and building new tissues. The chemical process by which sugars and starches are converted to energy is called oxidation and is similar to the burning of wood or coal to produce heat. Controlled oxidation in a living cell is called respiration

C6H12O6 + 6 O2 => 6 CO2 + 6 H2O + Energy

This equation is essentially the opposite of photosynthesis. Photosynthesis is a building process, while respiration is a breaking-down process (Table 2).

Photosynthesis

* produces food
* stores energy
* uses water
* uses carbon dioxide
* releases oxygen
* occurs in sunlight

Respiration

* uses food
* releases energy
* produces water
* produces carbon dioxide
* uses oxygen
* occurs in the dark as well as light

Unlike photosynthesis, respiration does not depend on light, so it occurs at night. Respiration occurs in all life forms and in all cells. Now cactus are a whole new ball game - To limit water loss many desert adapted plants have very small or vestigial leaves. This presents a trade-off problem because reducing water loss with smaller leaves also reduces the number of chloroplast containing cells in the leaves. To compensate,
the photosynthesis function is transferred to cortical cells in the fleshy stem, and so their green color. This is not so unusual because many plants have green stems when they are young. Photosynthetic stems must also have stomates, pores, through which gas exchange takes place. Again there is a functional tradeoff problem because while gas exchange is necessary for
photosynthesis, water is lost through the pores. Cacti are among a group of plants that solve this problem by capturing solar energy by day, and finishing the photosynthesis by night when the stomates can be open with minimal water loss.

exciting isn't it.

I've read a few times that plants typically respire at night so that they can prevent water loss. In order to go through respiration they need to open their stroma, so that they can release oxygen and bring in co2. If they did this during the day, the heat would encourage more water loss than if they did this at night.
I'm pretty sure (though not 100%) that there are also implications with C3 vs C4 leaves in terms of the time of respiration.

Plant respiration occurs during the night AND during the day. The ATP generated by photosynthesis stays in the chloroplast then the plant still needs to do cellular respiration to generates ATP.

Wow!! great!!

It only respires during the night

The process of respiration in plants in the day is defrent then the respiration at night
The respiration of plants and human are opposite to each other in the day but the some at night the plants capture the oxygen from the air and release the carbon dioscide

The people who have said that respiration in plants doesn't occur during the day are totally incorrect. All plants, and all animals for that matter, require ATP for cellular processes. ATP is made via respiration at all times in plants and animals.

It is true that during the day when there is available solar energy, the so-called light reactions of photosynthesis are what the plant is "focusing" on. If you ever investigated this in the lab, you would see that while in the light plants are net producers of O2 due to photosynthesis, and in the dark they are relative net producers of CO2 due to it being a biproduct of cellular respiration. But keep in mind, those are NET outputs meaning that both exist at the same time, just in different proportions. Make no mistake, plants are performing both photosynthesis as well as cellular respiration in the daytime.

The plant (just as an animal) would die unless its cells were able to respire throughout the day and night.

Respiration occurs only in the night as it needs to open up its stomata to allow excess water to be released into the surroundings. If this process occurs during the day, the heat would allow more water to be released into the surroundings, causing a huge amount of water to be lost in the plant. The plant also takes in oxygen and releases carbon dioxide in the night, which is just what we breathe in.

PLease look at the post dates before answering... this was originally a homework question (meaning site rules prohibit it being answered directly without the OP giving their answer first) but it was original posted in 2009, it is currently 2015.