Articles
Growth of lettuce plants cultivated hydroponically with organic fertilizers under continuous light and high humidity conditions
Article number
1423_19
Pages
141 – 148
Language
English
Abstract
The rising interest in organic farming in Japan aims to reduce environmental impacts and ensure stable agricultural production.
Organic fertilizers are expected to be utilized in plant factories with artificial lighting (PFALs), which are generally managed using hydroponics with chemical fertilizers.
PFALs offer flexibility in setting day length, with longer day lengths facilitating accelerated growth.
However, longer day lengths also increase the likelihood of physiological disorders such as tipburn.
Unlike chemical fertilizers, organic fertilizers frequently include additional substances beyond plant nutrients.
Consequently, employing organic fertilizers for hydroponics in PFALs is deemed to necessitate more meticulous management of nutrient solutions compared to chemical fertilizers.
This study examined temporal changes in lettuce growth and conducted growth analysis using lettuce plants cultivated with organic fertilizers under 24- or 12-h photoperiods.
Nutrient solutions with organic fertilizers including waste liquid from dried bonito production and oyster shells commonly used in hydroponics in Japanese greenhouses were employed following the method developed at the National Agriculture and Food Research Organization by Shinohara et al. (2014). The relative humidity around the plants was set to at least 85% during treatment, to simulate the high-humidity environments found in large-scale PFALs.
As a result, there was no significant difference in the relative growth rate between chemical and organic fertilizers except for the 24-h photoperiod grown plants at 21 days after treatment, suggesting that the net assimilation rate compensated for the decrease in leaf area ratio.
On the other hand, phenomena such as a higher dry matter content, a higher dry matter distribution to roots and inhibition of leaf expansion were observed in the plants cultivated with organic fertilizers, which were thought to be due to water stress or nutrient deficiencies.
Organic fertilizers are expected to be utilized in plant factories with artificial lighting (PFALs), which are generally managed using hydroponics with chemical fertilizers.
PFALs offer flexibility in setting day length, with longer day lengths facilitating accelerated growth.
However, longer day lengths also increase the likelihood of physiological disorders such as tipburn.
Unlike chemical fertilizers, organic fertilizers frequently include additional substances beyond plant nutrients.
Consequently, employing organic fertilizers for hydroponics in PFALs is deemed to necessitate more meticulous management of nutrient solutions compared to chemical fertilizers.
This study examined temporal changes in lettuce growth and conducted growth analysis using lettuce plants cultivated with organic fertilizers under 24- or 12-h photoperiods.
Nutrient solutions with organic fertilizers including waste liquid from dried bonito production and oyster shells commonly used in hydroponics in Japanese greenhouses were employed following the method developed at the National Agriculture and Food Research Organization by Shinohara et al. (2014). The relative humidity around the plants was set to at least 85% during treatment, to simulate the high-humidity environments found in large-scale PFALs.
As a result, there was no significant difference in the relative growth rate between chemical and organic fertilizers except for the 24-h photoperiod grown plants at 21 days after treatment, suggesting that the net assimilation rate compensated for the decrease in leaf area ratio.
On the other hand, phenomena such as a higher dry matter content, a higher dry matter distribution to roots and inhibition of leaf expansion were observed in the plants cultivated with organic fertilizers, which were thought to be due to water stress or nutrient deficiencies.
Authors
M. Eguchi, B. Lin, K. Nakamura, Y. Kitaya
Keywords
plant factory with artificial lighting, vertical farm, organic fertilizer, continuous lighting, lettuce cultivation
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