Analisis Impedansi Listrik sebagai Indikator Non-Destruktif Status Fisiologis Selada Hidroponik (Lactuca sativa L.) akibat Cekaman Nutrisi dan Air

Les' Aullian Achmad Argito, 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

Pemantauan status fisiologis selada hidroponik secara cepat dan tanpa merusak jaringan masih menjadi kendala pada sistem plant factory, sementara sensor optik konvensional hanya membaca sifat permukaan daun. Penelitian ini menganalisis perbedaan respons spektrum impedansi listrik antara selada bernutrisi normal (1.200 ppm), defisiensi nutrisi (600 ppm), dan cekaman air, didukung karakterisasi dan pemodelan rangkaian ekuivalen, serta keterkaitannya dengan indeks SPAD. Spektrum impedansi diukur dengan spektroskopi impedansi listrik (EIS) menggunakan modul AD5933 (1.000-101.000 Hz, 501 titik) pada ketiga kondisi tersebut, lalu dimodelkan dengan lima rangkaian ekuivalen yang dipilih berdasarkan kriteria informasi Akaike, dan perbedaan antar perlakuannya diuji menggunakan Kruskal-Wallis, model efek campuran, PERMANOVA, serta klasifikasi bebas-kebocoran. Model Cole Ganda (Double-Cole) merupakan model paling sesuai (median R² 0,943; MAPE 3,04%; terpilih pada 76,9% spektrum) dan didukung dua puncak distribusi waktu relaksasi, sehingga mendukung penggunaan EIS berbasis AD5933 untuk karakterisasi non-destruktif jaringan daun. Perbedaan antar perlakuan bersifat spesifik-parameter dengan ukuran efek sedang hingga besar (Cohen's d 0,6-0,9): ?? paling responsif terhadap cekaman air, sedangkan ?? dan ?? paling responsif terhadap cekaman nutrisi, dengan frekuensi paling diskriminatif 4.000 Hz (air) dan 1.000 Hz (nutrisi). Namun, perbedaan tersebut belum signifikan secara statistik (PERMANOVA p=0,92) akibat ukuran sampel biologis yang kecil; analisis daya menunjukkan diperlukan sekitar 21-41 tanaman per perlakuan. Keterkaitan impedansi-SPAD tergolong lemah (R² validasi silang terbaik 0,24). Berdasarkan hasil tersebut, EIS dengan model Cole Ganda memadai untuk karakterisasi non-destruktif jaringan daun, sedangkan perbedaan antar perlakuan masih bersifat indikatif dan memerlukan ukuran sampel lebih besar untuk validasi.

Rapid, non-destructive monitoring of the physiological status of hydroponic lettuce remains a challenge in plant factory systems, whereas conventional optical sensors only read leaf surface properties. This study analyzed differences in the electrical impedance spectrum response among lettuce under normal nutrition (1,200 ppm), nutrient deficiency (600 ppm), and water stress, supported by characterization and equivalent-circuit modeling, together with its relationship to the SPAD index. Impedance spectra were measured by electrical impedance spectroscopy (EIS) using an AD5933 module (1,000-101,000 Hz, 501 points), fitted with five equivalent circuit models selected by the Akaike information criterion, and treatment differences were tested using Kruskal-Wallis, linear mixed-effects models, PERMANOVA, and leakage-free classification. The Double-Cole model was the most suitable (median R² 0.943; MAPE 3.04%; selected for 76.9% of spectra), supported by two relaxation-time peaks, supporting the use of AD5933-based EIS for non-destructive tissue characterization. Treatment differences were parameter-specific with medium-to-large effect sizes (Cohen's d 0.6-0.9): ?? was most responsive to water stress, whereas ?? and ?? responded most to nutrient stress, with the most discriminative frequencies at 4,000 Hz (water) and 1,000 Hz (nutrient). However, these differences were not statistically significant (PERMANOVA p=0.92) owing to the small biological sample size; a power analysis indicated that about 21-41 plants per treatment would be required. The impedance-SPAD relationship was weak (best cross-validated R² 0.24). Overall, EIS with the Double-Cole model is adequate for non-destructive tissue characterization, whereas treatment differences remain indicative and require a larger sample for validation

Kata Kunci : impedansi listrik, model Cole Ganda, indeks SPAD, selada hidroponik, pemantauan non-destruktif