This set of Irrigation Engineering online test focuses on “Water Requirements of Crops – Consumptive Use of Evapotranspiration”.
1. The value of consumptive use may be different for different crops and different for the same crop at different times and places.
Explanation: Consumptive use is defined as the total amount of water used by the plants in transpiration and evaporation from soils, in specific time. So, therefore the values of consumptive use vary for different crops, and vary for same crops at different places or times.
2. What is the process of a plant called, through which it leaves water?
Explanation: Transpiration is the process of the plant through which water leaves the plant, through its leaves as water vapor and enters the atmosphere.
3. Transpiration process is an integral part of the main process called photosynthesis.
Explanation: Yes, photosynthesis is an important process of the plant through which the plant produces carbohydrates for its growth, and it is during this process transpiration occurs as an integral process in the whole photosynthesis process.
4. Which protein in the leaf of the plant utilize carbon dioxide and produce carbohydrates?
Explanation: Water enters the leaves of the plant through the roots, where photosynthesis happens. During this, air enters the stomata of the leaves. The protein chloroplasts present here takes the carbon dioxide in air and uses it to produce carbohydrates.
5. Total transpiration about 95% occurs during the day alone.
Explanation: Preparation of food, i.e carbohydrates is done during daylight alone, as photosynthesis process occurs only during sunlight. Therefore most of the transpiration occurs during the day alone.
6. On which factor does the transpiration loss also depends on?
a) Available Moisture
b) Type of Soil
c) Type of Irrigation
d) Method of Irrigation
Explanation: Availability of moisture also affects the transpiration losses because plants transpire moisture according to its availability. That is plants transpire less moisture when moisture is scarce, and transpire more moisture when it is more available.
7. On what factor does transpiration ratio depends on?
Explanation: Transpiration ratio is directly proportional to water requirement of the plant. So, therefore if amount of water increases the ratio increases, and if amount of water decreases the ratio decreases.
8. In transpiration ratio what type of crop is considered to be weighed, for mass of dry matter produced?
a) Marketed Crop
b) Cash Crop
c) Horticulture Crop
d) Plantation Crop
Explanation: Mass of dry matter is taken as the weight of the entire plant including its roots. And also sometimes only marketed crop like wheat, gram etc is weighed.
9. Given information is that total mass of water required for the growth of a plant is 285 kgs, and mass of the marketed crop is 19 kgs. Find the transpiration ratio?
Explanation: We have transpiration ratio (TR) = (total mass of water transpired by the plant during its growth / mass of dry matter produced)
10. A crop is being tested in the lab to its loss due to transpiration. Given that initial weight of instrument is 100 kgs, and final mass of instrument is 150 kgs. The amount of water added during full growth of plant is 70 kgs. Find the loss due transpiration when the method used is phytometer method?
a) 20 kgs
b) 15 kgs
c) 25 kgs
d) 10 kgs
Explanation: When phytometer method is used the formula for transpiration loss (T)
= (M1 + M) – (M2)
M1 = initial mass of instrument
M = mass of water added during full growth of plant
M2 = final mass of instrument
Therefore (T) = (100 + 70) – 150 = 170 – 150 = 20 kgs.
11. By what number should the value from the phytometer method be multiplied when it comes to obtain possible field results?
d) A Constant Number
Explanation: Since the phytometer method is tested in lab in artificial conditions, the obtained result is only relevant to the lab due different soil conditions in the open field. So, therefore in order to get or obtain exact field results we need to multiply the value of transpiration loss obtained from the method with a constant number.
12. Which type of soil has less ratio of AET/PET than the other?
a) Clayey Soil
b) Sandy Soil
c) Alluvial Soil
d) Black Soil
Explanation: The ratio AET/PET is directly proportional to available moisture. Sandy soil has less availability of moisture than the other type of soils like clayey soil, alluvial soil, and black soil. So, this gives that sandy soil has less AET/PET ratio.
13. On what factors Potential Evapotranspiration critically depends?
a) Climatological Factors
b) Types of Crop
c) Types of Soils
Explanation: Potential Evapotranspiration (PET) involves transpiration process. As this process consists of transpiration losses through leaves of plant, and evaporation losses from surroundings of the plant and this directly dependent on availability of moisture which when is sufficiently available to meet the needs of the vegetation then it is called PET. Therefore this clearly states PET critically depends on climatological conditions.
14. On what factors Actual Evapotranspiration depends?
a) Climatological Factors
b) Types of Crop
c) Types of Soils
d) Characteristics of Soil and Vegetation
Explanation: Actual Evapotranspiration (AET) is actual and real evapotranspiration that occurs in any specific situation of the field. The specific situation of the field directly depends on the characteristics of soil and the type of vegetation present in that particular soil. So, therefore AET indirectly depends on the characteristics of soil and vegetation, in the field.
15. Which type of method is adopted for research studies on crops?
a) Phytometer Method
b) Lysimeter Method
c) Furrow Irrigation Method
d) Drip Irrigation Method
Explanation: Actually lysimeter method is used to determine the AET. This method consists of a tight tanker filled with a block of soil and is installed in a field of growing plants. The conditions to maintain this tanker on par with conditions of the field and the measurement of water added to the tanker to maintain moisture content are time-consuming and costlier field studies.
Sanfoundry Global Education & Learning Series – Irrigation Engineering.
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