Cow-Calf Certification Practice Exam

Under drought conditions, where are the highest nitrate concentrations found in the corn plant?

1. Upper leaves

2. Middle portion of the stalk

3. Lower portion of corn stalks

4. Roots of the plant

The correct answer is: Lower portion of corn stalks

The correct answer points to the lower portion of the corn stalks as the area where the highest nitrate concentrations are typically found under drought conditions. During drought, the plants often experience stress that affects their nutrient assimilation and transport mechanisms. As a result, the plant may mobilize stored nitrates from the upper parts to mitigate the effects of reduced nutrient uptake. When drought occurs, the lower part of the stalk tends to accumulate nitrate due to the lack of water necessary for efficient uptake and transport to the upper parts. The lower stalk may retain higher concentrations of nitrates because the plant's physiological responses under stress can lead to the accumulation of these nutrients in areas that are not actively growing or are less efficient in uptake. In contrast, the upper leaves and middle portion of the stalk do not typically accumulate nitrates to the same extent because these areas are associated with active photosynthesis and nutrient usage, which could deplete the available nitrate concentrations. The roots, while crucial for nutrient absorption, do not typically have high concentrations of nitrates themselves, as they are more involved in uptake rather than storage. Thus, considering these dynamics, the lower portion of the corn stalk becomes a reservoir for nitrates during drought conditions, leading to its identification as the area with the highest