Nitrogen plays a critical role in plant growth. It is present in various parts of a plant and affects many physiological functions. For example, nitrogen is a significant component of the amino acids in the proteins and enzymes involved in plant metabolism and transport of water and mineral nutrients across the membranes of plant cells. It makes up a large part of the chlorophyll found in plants, which is used to make sugars that feed the plant. In addition, nitrogen impacts plant growth regulation as well as the development of proteins present in a crop's grains, fruits, and seeds.
Balance, of course, is essential. Too little nitrogen and crops may not thrive, and too much nitrogen can harm plants and the environment. Because certain conditions are necessary to facilitate the roots' ability to uptake nutrients that are present in the soil, crops can experience nutrient deficiencies when growing conditions are poor. Very acidic or alkaline conditions, extreme temperatures, drought, and heavy rains can all influence nutrient availability in soil and its subsequent absorption by crops. This means that at times nutrients may be present in the soil, however not available to the plants.
The Nitrogen Balancing Act
Nitrogen deficiency negatively affects all plant functions and results in poor growth and fruiting. This deficiency can often be detected via the pale green or yellow-colored leaves due to the lack of nitrogen's impact on chlorophyll production.
Nitrogen levels that are too high also negatively affect the chemical balance of a plant. When there is an oversupply of mineral nitrogen, the plant's response is to divert energy, carbohydrates, water, and minerals to metabolize it, thereby leading to weak plants, delayed fruiting, uneven ripening, and trace element deficiencies. Moreover, excessive nitrogen availability can lead to poor quality of product by inducing the accumulation of antinutritional factors (i.e., nitrates, oxalic acid) and lowering the shelf-life.
When it comes to nitrogen, growers face a balancing act – with real economic consequences.
The quality of soil affects how well nutrients and water are retained. Nitrogen in the form of nitrate can quickly dissolve in water, and, as water drains, it may take the nitrogen along with it. This leaching of nitrates can have severe environmental effects, such as eutrophication, which is an accumulation of nutrients in a body of water, frequently caused by run-off, which results in a thick growth of algae and other organisms and a depletion of oxygen in the water. Moreover, nitrogen can be lost from the soil surface as ammonia gas via the process of volatilization. Flooded soils can also result in pulses of nitrogen losses through denitrification which is a microbial process of reducing nitrate and nitrite to gaseous forms of nitrogen, principally nitrous oxide (N2O) and elemental nitrogen (N2).
With the propensity of nitrogen to volatilization, denitrification, leaching, surface runoff, thereby polluting the air, water, and land in the process, smart nitrogen management can help reduce these threats and positively contribute to a grower's bottom line. Nitrogen fertilizers can be expensive and wasteful. Nitrogen loss means more pollution, lower yields, and higher costs to growers. One way to improve nitrogen efficiency is with the use of biostimulants like vegetal-derived protein hydrolysates.
Nitrogen Use Efficiency
Protein hydrolysate based biostimulants have been shown to improve nitrogen use efficiency, which is the fraction of applied nitrogen that is absorbed and used by the plant, by helping crops increase the ability to uptake and metabolize nitrogen quickly and effectively. It does so by regulating specific metabolic pathways and enzymes within the plant structure, thereby maximizing the benefits of nitrogen applications (wet or dry). Protein hydrolysates increases nutrient use efficiency by regulating key enzymes involved in nitrogen assimilation and intervening with hormone-like activity to increase nitrogen metabolism.
In a recent study, Sestili et al1 concluded:
• The increase in plant biomass was associated with the stimulation of the root growth, thus inducing a “nutrient acquisition response” that favors nitrogen uptake and translocation.
• Results highlighted the potential benefits of using this technology to increase growth and N-nutritional status of plants grown under both high and low nitrogen regimes.
• This technology mediated an increase of total nitrogen content in leaves that can be explained by the stimulation of root growth and the upregulation of genes involved in the N assimilation.