Substrates and Importance of Water Flashcards
Quiz 3
Osmosis creates the turgor pressure in plant cell’s that help the cell maintain its shape, and expand its size. TRUE OR FALSE
True
Please select all that apply. Water is important to plant growth because…
-it carries the dissolved nutrients that the plant needs for growth and development
-it is needed for the process of respiration
-it helps plant cells keep their shape and their size.
Compost is commonly added to substrates for what reason?
providing a starter change of nutrients to the media
Please select all that apply. Which of the following statements about Rockwool are true?
-It has 0 cation exchange capacity
Dolomitic Lime is commonly added to substrates for what reason?
To raise pH and provide some pH buffering capacity
The ratio of the total volume of water that is held in a saturated substrate after all the excess water has drained, to the substrate’s total volume is called
Water Holding Capacity
Engineered wood fibers are being used more frequently in growing mixes becuase…
-it generally costs less than perlite and coir
-it is a renewable resource unlike peat
Please select all that apply. Which of the following statements about Sphagnum Peat Moss are true?
-requires a wetting agent
-is susceptible to compaction over time
-needs dolomitic limestone added because naturally low pH
The ratio of the dry weight of the solid particles in a substrate to its total volume is called
Bulk density
The optimal substrate pH for maximum nutrient availability is 6.2 - 7.3. TRUE OR FALSE
True
Vermiculite is often incorporated into growing mixes because it will greatly increase the air porosity and drainage of the mix. TRUE OR FALSE
False
Adding vermiculite to to a mix increases the growing medias water holding capacity.
Perlite will often be used as a top coat in plug trays. TRUE OR FALSE
False
Perlite typically added to increase air porosity and reduces the water holding capacity.
Mycorrhizal fungi are commonly added to substrates for what reason?
Added to improve the plant’s ability to uptake nutrients
The ratio of the total volume of air space in a saturated substrate (after the excess water has drained) to its total volume is called
Water holding capacity
Active transport uses energy to move solutes across membranes that they are not permeable to, or against a natural concentration gradient. TRUE OR FALSE
True (**)
It is important to maintain the pH of a substrate in the optimal range to limit the amount of nutrients that plant will take up at one time. TRUE OR FALSE
False
Outside of the optimal range the plant will experience deficiency, pH levels affect that plants ability to uptake nutrients.
Substrates used in the greenhouse are also called growing media. TRUE OR FALSE
True
Cation Exchange Capacity, or CEC, is a measure the the substrates ability to hold water. TRUE OR FALSE.
False.
Cation Exchange is the soils ability to hold positively charged nutrient ions. A higher cation exchange rate the more nutrients available to plants.
The ratio of the total volume of pore space in a substrate to its total volume is called
Total Porosity
Biological organisms like Trichoderma spp. are commonly added to substrates for what reason?
to provide protection against soil borne pathogens like Pythium, Rhizoctonia and Fusarium spp.
Which of the following statements about osmosis is correct.
Osmosis involves the movement of water from areas of low concentration to high concentration.
The movement of water from the roots to the shoots of plants occurs because…
Osmosis draws water into the roots and transpiration evaporates water from the leaves.
Please select all that apply. Which of the following statements about Coconut Coir are true?
-It needs to be washed and buffered with Calcium Nitrate prior to planting
Leaching Fraction is…
the amount of extra irrigation water that must be applied above the amount required by the crop in order to maintain an acceptable root zone salinity
