PENGARUH POLA TANAM BAWANG MERAH DI LAHAN SAWAH DAN PASIRTERHADAP KERAGAMAN KOMUNITAS MIKROB, NUTRISI TANAH, DAN KEJADIAN PENYAKIT MOLER

Ary Virgianti Setyaningrum, Prof. Ani Widiastuti, S.P., M.P., Ph.D.

2025 | Tesis | S2 Fitopatologi

Pertanaman bawang merah di pesisir Bantul, Yogyakarta dilakukan pada dua tipe tanah dengan rotasi tanam berbeda, yaitu sawah (padi–bawang–bawang) dan pasir (cabai–bawang–bawang). Perbedaan agroekosistem ini memengaruhi kandungan nutrisi, komunitas mikroba, serta kejadian penyakit moler yang disebabkan Fusarium spp. Penelitian ini bertujuan membandingkan insidensi penyakit moler, komunitas mikrob, nutrisi tanah, dan hubungan keduanya pada kedua agroekosistem. Pengamatan dilakukan melalui survei kejadian penyakit moler dan pengambilan sampel tanah untuk analisis DNA serta uji nutrisi. Komunitas bakteri dianalisis menggunakan primer 16S V4 (515F–806R), sedangkan komunitas jamur menggunakan primer ITS2 (2024F–2409R). Uji nutrisi mencakup pH, C-organik, N, P, K, S, kapasitas tukar kation (KTK), kandungan anion–kation utama, serta tekstur tanah. Hasil penelitian menunjukkan insidensi penyakit moler tidak berbeda signifikan antar tanah, namun di tanah pasir gejala muncul satu minggu lebih cepat. Tanah sawah memiliki KTK, NO??, dan NH?? lebih tinggi, sedangkan tanah pasir lebih kaya Fe, Ca, Mn, Cu, Mg, S, dan Zn. Bakteri Marmoricola merupakan biomarker dan core microbe pada tanah sawah yang berperan dalam siklus N. Bakteri Lysinibacillus merupakan biomarker dan core microbe pada tanah pasir yang berperan dalam peningkatan kandungan nutrisi tanah untuk pertumbuhan. Jamur Fusarium merupakan core microbe pada tanah sawah dan tanah pasir pada seluruh pertanaman bawang merah. Pyrenochaetopsis merupakan biomarker pada tanah sawah yang bermanfaat sebagai biofertilizer. Biomarker pada tanah pasir adalah Sordariales yang berperan dalam penguraian bahan organik. Komunitas jamur dan bakteri lebih kompleks pada tanah pasir daripada tanah sawah. Secara umum, komunitas mikrob berhubungan erat dengan kondisi nutrisi, terutama pH.

Shallot cultivation in the coastal area of Bantul, Yogyakarta, is carried out on two soil types with different crop rotations, namely paddy soil (rice–shallot–shallot) and sandy soil (chili–shallot–shallot). These agroecosystem differences influence soil nutrient composition, microbial communities, and the incidence of basal rot disease caused by Fusarium spp. This study aimed to compare the incidence of basal rot, microbial communities, soil nutrients, and their relationships across the two agroecosystems. Observations included a field survey of basal rot incidence and soil sampling for DNA-based microbial analysis and nutrient testing. Bacterial communities were assessed using the 16S V4 region (primers 515F–806R), while fungal communities were analyzed using the ITS2 region (primers 2024F–2409R). Soil nutrient analyses included pH, organic C, N, P, K, S, cation exchange capacity (CEC), major anions and cations, as well as soil texture. The results showed that basal rot incidence did not differ significantly between the two soil types; however, symptoms appeared one week earlier in sandy soil. Paddy soil exhibited higher CEC, NO??, and NH?? levels, whereas sandy soil was richer in Fe, Ca, Mn, Cu, Mg, S, and Zn. Marmoricola was identified as a biomarker and core microbe in paddy soil, functioning in the N cycle. Lysinibacillus was identified as a biomarker and core microbe in sandy soil, contributing to enhanced nutrient availability for plant growth. Fusarium was a core microbe in both soil types across all shallot fields. Pyrenochaetopsis was identified as a biomarker in paddy soil, with potential as a biofertilizer. In contrast, the fungal order Sordariales was identified as a biomarker in sandy soil, playing a role in organic matter decomposition. Both fungal and bacterial communities were more complex in sandy soil than in paddy soil. Overall, microbial community composition was closely associated with soil nutrient conditions, particularly pH.

Kata Kunci : Rotasi tanam, tanah sawah, tanah pasir, amplicon metagenomic sequencing, penyakit moler.