Quality Control Techniques and Related Factors for Hydroponic Leafy Vegetables

Abstract

<jats:p>Hydroponics has been an increasingly important field of vegetable production. However, a big issue with hydroponics is that certain crops can quickly accumulate high levels of nitrate-N (NO<jats:sub>3</jats:sub> ± -N) from the hydroponic system. The objective of this research was to decrease NO<jats:sub>3</jats:sub> accumulation and increase the nutritional value and yield of vegetable crops using lettuce and oilseed rape as a model under hydroponic production. In this study, two technologies were applied to leafy vegetable production: 1) using supplementary lighting (blue-violet diode) by manipulating illumination and 2) removing fertilization before harvest for a short term (3 or 5 days), thus providing a practical experiment for improving yield and edible qualities of hydroponic leaf vegetable production. Illumination was applied 4 hours a day (0500–0700 <jats:sc>hr</jats:sc> and 1700–1900 <jats:sc>hr</jats:sc>) during good weather, or 12 hours a day during bad weather with insufficient natural light (&lt;2000 lux) during the autumn and winter seasons. Results showed that the lettuce cultivar Ou-Luo and the oilseed rape cultivar Ao-Guan Pakchoi had increased yield (50.0% and 88.3%, respectively), decreased NO<jats:sub>3</jats:sub> content (26.3% and 30.8%, respectively), and increased total soluble solids (24.1% and 30.6%, respectively). The 5-day fertilizer-free treatment before harvest resulted in 19.2%, 6.4%, and 16.5% yield increases; and 26.0%, 24.3%, and 47.8% NO<jats:sub>3</jats:sub> decreases in oilseed rape cultivar Ao-Guan Pakchoi and lettuce cultivars Da-Su-Sheng and Ou-Luo, respectively.</jats:p>

Hydroponics as an advanced vegetable production technique: an overview

“…Furthermore, to run the system more effectively, an adequate supply of energy and lighting is also required. Despite popular growth, hydroponics system has many disadvantages, viz., few crops can accumulate a higher quantity of nitrate-N (NO3-N) from the system (Guo et al, 2019). The hydroponic system must support around 40 plants, such as tomatoes, and 72 small plants like strawberries and spinach, etc.…”

Opportunities and constraints in hydroponic crop production systems: A review

“…Hydroponics is becoming a more popular method of growing vegetables. However, one of the major drawbacks of hydroponics is that certain crops can quickly accumulate large levels of nitrate-N (NO 3 ± -N) from the system (Guo et al, 2019). According to Tyson et al (2004) the hydroponic structure's world should be able to support at least 40 large plants (tomatoes, banana peppers, and bell peppers) and 72 little plant (spinach, lettuce, and strawberries).…”