Comparison of Root-Zone Temperature Profiles and Growth Characteristics of Spinach (Spinacia oleracea L.) under Different Hydroponic Systems for High-Temperature Cultivation

Joo Hee Nam; Se Jin Kim; Hee Seung Hwang; Gyeong Lee Choi; Mi Young Lim

doi:10.12791/KSBEC.2026.35.3.231

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Original Articles

Comparison of Root-Zone Temperature Profiles and Growth Characteristics of Spinach (Spinacia oleracea L.) under Different Hydroponic Systems for High-Temperature Cultivation 고온기 시금치 생산을 위한 수경재배 시스템별 근권 온도 변화 및 생육특성 비교

31 July 2026. pp. 231-240

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Abstract

High air temperature in late summer and early autumn limits greenhouse production of spinach (Spinacia oleracea L.), a cool-season crop with an optimum temperature range of 15–20°C. Three hydroponic systems-aeroponics AP, nutrient film technique NFT, and perlite substrate culture PL-were evaluated for spinach grown in a greenhouse from 19 September to 3 November 2025, with emphasis on characterizing the above-ground environment and system-specific root-zone temperature. Greenhouse air temperature averaged 21.5°C (mean daily maximum 29.7°C, absolute maximum 40.7°C), exceeded 25°C-the threshold for physiological disorders in spinach-for 5.3 h·d^-1 on average, and its daily maximum exceeded 25°C on 40 of 46 days. Daytime vapor pressure deficit averaged 1.32 kPa and daily solar radiation 11.0 MJ·m^-2·d^-1. Mean root-zone temperature was 22.9°C in PL, 22.2°C in AP, and 21.5°C in NFT; the slope of its linear regression on air temperature was steepest in NFT 0.67 and shallowest in PL 0.34, indicating the greatest thermal buffering in the substrate system. Shoot fresh weight tended to be higher in AP 55.5 g/plant and NFT 50.2 g/plant than in PL (24.6 g/plant), about twofold, and leaf area followed the same order 856.8, 791.8, and 395.9 cm²/plant. Net photosynthetic rate at 2,000 µmol·m^-2·s^-1 was highest in AP 15.64 µmol CO₂·m^-2·s^-1, as were stomatal conductance 0.237 mol·m^-2·s^-1 and transpiration rate 2.77 mmol·m^-2·s^-1. Shoot P₂O₅, K₂O and MgO concentrations tended to be higher in the substrate-free systems AP, NFT than in PL, whereas T-N and CaO were similar and Na₂O was higher in PL. Because mean root-zone temperature differed by at most 1.4°C, the difference in shoot biomass is unlikely to be explained by root-zone temperature alone and is more plausibly related to root-zone oxygen supply and water availability, which warrants further study.

Keywords

aeroponics

nutrient film technique

perlite substrate culture

root-zone temperature

vapor pressure deficit

여름철 후반부터 초가을에 걸친 시설 내 고온은 생육적온이 15－20℃인 호냉성 작물 시금치의 재배를 제한한다. 본 연구는 2025년 9월 19일부터 11월 3일까지 온실에서 재배한 시금치를 대상으로 분무경(AP), 박막경(NFT), 펄라이트 배지경(PL) 세 가지 수경재배 시스템을 비교하였다. 재배기간 중 온실 내 기온은 평균 21.5℃, 일최고기온 평균 29.7℃, 최고 40.7℃였으며, 생리장해 한계온도인 25℃를 초과한 시간은 일평균 5.3시간이었고 46일 중 40일에서 일최고기온이 25℃를 초과하였다. 주간 수증기압포차는 평균 1.32kPa, 일적산 일사량은 평균 11.0MJ·m^-2·d^-1였다. 근권부 평균 온도는 PL 22.9℃, AP 22.2℃, NFT 21.5℃였고, 기온에 대한 근권부 온도의 회귀 기울기는 NFT 0.67, AP 0.48, PL 0.34로 배지를 사용하는 시스템에서 열 완충 효과가 가장 컸다. 지상부 생체중은 AP 55.5g/plant, NFT 50.2g/plant로 PL 24.6g/plant보다 높게 나타났다. 순광합성속도는 AP에서 15.64μmol CO₂·m^-2·s^-1로 가장 높았으며 기공전도도와 기공증산속도도 동일한 경향을 보였다. 식물체의 P₂O₅, K₂O 및 MgO 함량은 AP와 NFT에서 PL보다 높은 경향을 보였으나 T-N과 CaO는 차이가 없었다. 처리 간 근권부 평균 온도 차이가 최대 1.4℃에 불과하여 생체중 차이를 근권부 온도만으로 설명하기 어려웠으며, 이는 근권부 산소 공급 및 수분 가용성의 차이와 관련된 것으로 판단되어 이에 관한 추가 연구가 필요하다.

키워드

근권부 온도

대기 수증기압포차

박막경

분무경

펄라이트 배지경

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Information

Publisher :The Korean Society for Bio-Environment Control
Publisher(Ko) :(사)한국생물환경조절학회
Journal Title :Journal of Bio-Environment Control
Journal Title(Ko) :생물환경조절학회지
Volume : 35
No :3
Pages :231-240
Received Date : 2026-06-11
Revised Date : 2026-07-15
Accepted Date : 2026-07-28
DOI :https://doi.org/10.12791/KSBEC.2026.35.3.231

Journal of Bio-Environment Control ISSN:1229-4675(Print) 2765-3641(Online) 생물환경조절학회지

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