CCA - Certified Crop Advisor Crop Growth and Development Questions and Answers 1 — Questions and Answers
Question 1: A corn producer needs to calculate the Growing Degree Days (GDDs) accumulated since planting to predict when the crop will reach the V10 growth stage. Which of the following sets of data is essential for this calculation?
- Daily solar radiation and precipitation totals
- Soil temperature at planting and average wind speed
- Daily maximum and minimum air temperatures (Correct answer)
- Relative humidity and the hybrid's disease resistance score
Correct answer: Daily maximum and minimum air temperatures
The standard formula for calculating corn Growing Degree Days (GDDs) is [(Daily Maximum Air Temperature + Daily Minimum Air Temperature) / 2] - Base Temperature (50°F). Therefore, the daily high and low air temperatures are the essential inputs.
Question 2: Which of the following physiological processes is most directly responsible for creating the 'pull' that moves water from the roots up through the xylem and out of the plant's leaves?
- Photosynthesis
- Transpiration (Correct answer)
- Respiration
- Photoperiodism
Correct answer: Transpiration
Transpiration is the process of water evaporating from the surfaces of leaf cells and exiting through stomata. This water loss creates a negative pressure potential, or tension, in the xylem, which pulls the continuous column of water up from the roots.
Question 3: A soybean field is subjected to a period of severe drought and heat stress. At which of the following reproductive growth stages would this stress cause the most significant yield loss, primarily through flower and pod abortion?
- R1 (Beginning Bloom)
- R7 (Beginning Maturity)
- VE (Emergence)
- R3 (Beginning Pod) to R5 (Beginning Seed) (Correct answer)
Correct answer: R3 (Beginning Pod) to R5 (Beginning Seed)
The period from R3 (Beginning Pod) through R5 (Beginning Seed) is the most critical for soybean yield determination. Stress during this window directly impacts the number of pods per plant and seeds per pod, which are the primary yield components. The plant has a decreasing ability to compensate for lost pods and flowers as it moves through these stages.
Question 4: A wheat crop is at the Feekes 10.5.1 growth stage (beginning of flowering/anthesis) when it experiences a late spring frost of 28°F (-2°C) for several hours. What is the most likely and severe damage a CCA should look for?
- Sterilization of anthers, leading to poor kernel set. (Correct answer)
- Temporary wilting of the flag leaf with full recovery expected.
- Increased development of secondary tillers to compensate.
- A dark green, water-soaked appearance on the lower stem.
Correct answer: Sterilization of anthers, leading to poor kernel set.
During flowering (Feekes 10.5.1), the exposed anthers are extremely sensitive to frost. Temperatures at or below 30°F can kill the pollen or anthers, preventing fertilization. This results in sterile florets, which leads to poor kernel set and empty sections of the wheat head, severely impacting yield.
Question 5: Soybeans are classified as short-day plants. This classification means that the initiation of flowering is primarily triggered by which environmental cue?
- A specific accumulation of Growing Degree Days.
- The plant reaching a genetically predetermined height.
- The length of the uninterrupted dark period exceeding a critical threshold. (Correct answer)
- Soil moisture levels dropping below a certain percentage.
Correct answer: The length of the uninterrupted dark period exceeding a critical threshold.
Photoperiodism in short-day plants like soybeans is controlled by the length of the night. Flowering is induced when the period of uninterrupted darkness is longer than a critical minimum. While called 'short-day', it is the long night that actually triggers the hormonal response for reproduction.
Question 6: In corn, the potential number of kernels per ear is a critical yield component. During which of the following developmental windows is the number of kernels per row primarily determined?
- R3 (Milk) to R5 (Dough)
- VE (Emergence) to V5
- V12 to R1 (Silking) (Correct answer)
- R6 (Physiological Maturity) to Harvest
Correct answer: V12 to R1 (Silking)
The number of potential kernels per row is determined over a period from approximately V12 until about one week before silking (R1). Stress from factors like drought, nutrient deficiency, or pest damage during this critical window can significantly reduce the potential kernel number, thereby limiting yield potential.
CCA - Certified Crop Advisor Crop Growth and Development Questions and Answers 1
A corn producer needs to calculate the Growing Degree Days (GDDs) accumulated since planting to predict when the crop will reach the V10 growth stage.
Which of the following sets of data is essential for this calculation?