Wetenschap - 1 januari 1970

Nitrogen and light interact in lettuce growth

Nitrogen and light interact in lettuce growth

Nitrogen and light interact in lettuce growth

Hydroponically-grown lettuce thrives well on lower nitrogen inputs at times of lower radiation, such as during the winter months. However, at times of high light intensity, such as during the summer months, the amount of nitrogen becomes a more important factor for growth. These were the main conclusions made by Andreia Henriques after a year of greenhouse experimentation at the Research Institute for Agrobiology and Soil Fertility (AB-DLO). The first conclusion was good news to Henriques: We are always looking for ways to reduce the amount of nitrogen applied in agriculture as nitrates can be harmful to the environment and health. Her experiments form part of a joint AB-ATO research institute project on precision plant nutrition which aims at more efficient nutrient recycling. According to Henriques, using a combination of two factors (light intensity and nitrogen supply) to determine dry matter production is unusual. When three levels of radiation were tested against three amounts of nitrogen input, nitrogen proved to be the limiting factor. Henriques' experiments showed that all the plants were equally efficient in their use of radiation, regardless of how much nitrogen was added, except for one combination: at high light intensity and low nitrogen input (70% of normal plant needs), quality and growth of the lettuce heads declined. For lettuce grown under low radiation, an increase in nitrogen input resulted in only negligible improvement in lettuce quality and growth. Am.S

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