Lupines are sometimes sown in the working rows of vineyards as `n cover crop. Now, besides the obvious benefits of erosion control, soil temperature regulation, soil moisture control and weed suppression, these legumes have something very special about them.
On the roots of these Lupines, nitrogen-fixing bacteria are "binded" to the roots. They work in symbiosis with the plant. This bacterium is called Bradyrhizobium japonicum. It is a nodulating, microsymbiotic nitrogen-fixing bacterium species.
Approximately 80 percent of the atmosphere is nitrogen gas (N2).Plants cannot use nitrogen in this form. They use NH3 (ammonia) to manufacture amino acids, proteins, nucleic acids and other nitrogen-containing components.
Legumes nitrogen-fixation starts with the forming of a nodule on the root.
The plant supplies all nutrients and water for the bacteria to grow, and the nodule multiplies very fast from here on. Young nodules are usually grey to white on the inside. This is due to the fact that they are not fixating nitrogen yet. As they get older, the inside turn pinkish-red. This indicates that they are fixating nitrogen. The pink or red color is caused by Leghemoglobin (similar to hemoglobin in blood) that controls oxygen flow to the bacteria.
The nitrogen fixing doesn't come free. The plant still needs to donate a substantial amount of energy and nutrition towards the bacteria to help it with the fixation process. If the plant is stressed (due to too cold weather, drought or nutrient deficiency), nitrogen fixation will will be stalled or progress at a slow pace.
The nitrogen doesn't "leak" into the soil so that other plants can use it. When the legume dies and decomposes, it releases the nitrogen into the soil in a usable form, so that other plants (grapevines in this case) can use it.
On the roots of these Lupines, nitrogen-fixing bacteria are "binded" to the roots. They work in symbiosis with the plant. This bacterium is called Bradyrhizobium japonicum. It is a nodulating, microsymbiotic nitrogen-fixing bacterium species.
Approximately 80 percent of the atmosphere is nitrogen gas (N2).Plants cannot use nitrogen in this form. They use NH3 (ammonia) to manufacture amino acids, proteins, nucleic acids and other nitrogen-containing components.
Legumes nitrogen-fixation starts with the forming of a nodule on the root.
The plant supplies all nutrients and water for the bacteria to grow, and the nodule multiplies very fast from here on. Young nodules are usually grey to white on the inside. This is due to the fact that they are not fixating nitrogen yet. As they get older, the inside turn pinkish-red. This indicates that they are fixating nitrogen. The pink or red color is caused by Leghemoglobin (similar to hemoglobin in blood) that controls oxygen flow to the bacteria.
The nitrogen fixing doesn't come free. The plant still needs to donate a substantial amount of energy and nutrition towards the bacteria to help it with the fixation process. If the plant is stressed (due to too cold weather, drought or nutrient deficiency), nitrogen fixation will will be stalled or progress at a slow pace.
The nitrogen doesn't "leak" into the soil so that other plants can use it. When the legume dies and decomposes, it releases the nitrogen into the soil in a usable form, so that other plants (grapevines in this case) can use it.
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