Analisis Dinamika Konduktansi Stomata Tanaman Selada (Lactuca sativa L.) pada Fase Terang Fotoperiode Berdasarkan Pengukuran Pertukaran Gas Daun pada Sistem Plant Factory

Aisyah Ramadhani, Ir. Andri Prima Nugroho, S.T.P., M.Sc., Ph.D, IPU., ASEAN Eng., APEC Eng.; Prof. Dr. Mohammad Affan Fajar Falah, S.T.P., M. Agr.

2026 | Skripsi | TEKNIK PERTANIAN

Konduktansi stomata (gs) mengatur masuknya CO? untuk fotosintesis dan keluarnya uap air melalui transpirasi. Pada sistem plant factory, dinamika temporal g? selama fase terang fotoperiode masih belum banyak dikaji secara kontinu. Penelitian ini bertujuan untuk menganalisis pola dinamika temporal g? tanaman selada (Lactuca sativa L.), hubungannya dengan variabel pertukaran gas daun, serta membangun model prediksi gs berbasis parameter mikroklimat. Penelitian dilakukan pada 20 Januari 2026 (28 HST), 21 Januari 2026 (29 HST), dan 24 Januari 2026 (32 HST) selama pukul 07.00–17.00 WIB dengan interval 10 menit. Data g?, laju transpirasi (E), laju asimilasi CO? (A), konsentrasi CO? intraseluler (Ci) diukur menggunakan LI-6800, sedangkan data mikroklimat diamati menggunakan Pulse Pro. Analisis meliputi statistik deskriptif, korelasi Pearson, Partial Least Squares Regression (PLSR), dan regresi linier berganda.

Hasil menunjukkan bahwa gs meningkat sejak pagi, mencapai puncak pada pertengahan fase terang, lalu stabil hingga sore. Tidak ditemukan gejala midday depression yang jelas yang berkaitan dengan kondisi VPD di dalam plant factory yang moderat dan stabil. Hubungan gs dengan E sangat kuat (r = +0,99), sedangkan dengan A relatif lemah (r = +0,42), yang menunjukkan adanya diskoneksi temporal antara respons stomata dan laju fotosintesis. Variabel yang paling erat berkaitan dengan gs adalah E_Leaf, VPD_Leaf, RH_mikro, dan Suhu_mikro. Model PLSR menunjukkan performa sangat baik dengan R² = 0,996 dan RMSE = 0,0049 mol m?²s?¹. Model mikroklimat sederhana menghasilkan persamaan gs = ?0,044(Suhu_mikro) + 0,022(RH_mikro) ? 0,0003(CO2_mikro) ? 0,329, dengan R² = 0,880 dan RMSE = 0,0255 mol m?² s?¹. Hasil ini menunjukkan bahwa g? dapat diprediksi dengan cukup baik menggunakan sensor mikroklimat sederhana.

The conductance of the stomata (gs) regulates the entry of CO2 for photosynthesis and the release of water vapor through transpiration. In the plant factory system, the temporal dynamics of gs during the bright phase of the photoperiod have not been continuously studied. This study aims to analyze the temporal dynamics of lettuce plants (Lactuca sativa L.) and their relationship with leaf gas exchange variables, and to build a gas exchange prediction model based on microclimate parameters. The research was conducted on January 20, 2026 (28 DAT), January 21, 2026 (29 DAT), and January 24, 2026 (32 DAT) from 07:00 to 17:00 WIB with an interval of 10 minutes. gs data, transpiration rate (E), CO2 assimilation rate (A), and intercellular CO? concentration (Ci) were measured using LI-6800, while microclimate data were observed using Pulse Pro. Analysis included descriptive statistics, Pearson correlation, Partial Least Squares Regression (PLSR), and multiple linear regression.

The results showed that gs increased from morning, peaking in the middle of the bright phase, then stabilizing until the afternoon. No obvious symptoms of midday depression were observed, likely due to the moderate and stable VPD conditions in the plant factory. gs had a very strong relationship with E (r = +0.99), whereas its relationship with A was relatively weak (r = +0.42), suggesting a temporal disconnect between stomatal response and photosynthesis rate. The variables most closely related to gs include E_Leaf, VPD_Leaf, RH_mikro, and Suhu_mikro. The PLSR model exhibits excellent performance, with an R² value of 0.996 and an RMSE of 0.0049 mol m?² s?¹. A simple microclimate model yields the equation gs = ?0.044(Suhu_mikro) + 0.022(RH_mikro) ? 0.0003(CO2_mikro) - 0.329, with R2= 0.880 and RMSE = 0.0255 mol m?² s?¹. These results show that gs can be predicted quite well using a simple microclimate sensor.

Kata Kunci : konduktansi stomata, selada, plant factory, fase terang fotoperiode, pertukaran gas daun, mikroklimat