Kajian Fungi Mikoriza Arbuskula dan Fungi Non-Simbiosis Indigenous Serta Asam Humat-Fulvat Pada Akumulasi PB Umbi Bawang Merah (Allium cepa var. ascalonicum) di Media Tanam Tercemar

SUMMARY Based on the results of research at the Brebes shallot production center, information was obtained that the Pb content in the soil and plants was high, exceeding the threshold set by the Indonesian Ministry of Health. Efforts to restore land with environmentally friendly methods need to be made to improve environmental quality and production of shallots. Bioremediation using indigenous microbes potentially polluted land is used to achieve this goal. Several research and literature results state that as a bioaccumulator, fungi are more effective than bacteria, and are economical. This study aims to: 1) obtain information on the level of Pb contamination in shallot cultivation land in Larangan and Wanasari Districts, Brebes Regency; 2) to obtain information on the diversity of Arbuscular Mycorrhizal Fungi (AMF) and non-symbiotic fungi in Pb contaminated shallot cultivation land; 3) obtaining indigenous non-symbiotic fungi of Pb-polluted shallot crop areas which were effective in the in vitro test; 4) obtaining a consortium and single spores of Arbuscular Mycorrhizal Fungi indigenous shallot area contaminated with Pb which is effective in vivo on Pb accumulation of tubers; 5) Obtaining indigenous non-symbiotic fungi on shallot crop areas polluted with Pb and humic-fulvic acid which are effective in Pb accumulation of tubers. Before the first phase of the experiment was carried out, land characterization and analysis of the Pb content of shallot tubers were carried out with soil and plant samples from 6 shallot fields in 3 villages in Wanasari District namely, Kupu Village, Wanasari Village, and Sigentung Village, as well as in Larangan District, namely, Karangbale Village, Slatri Village, and Larangan Village. Land characterization (soil analysis) includes: soil class, N total (%), C-organic (%), organic matter%), C/N ratio, total P2O5 (%), total K2O (%), pH H2O, P2O5 available (ppm ), CEC (me%), KB (%), total Pb (ppm), Ca (me%), Mg (me%), K (me%), Na (me%), sand (%), dust ( %), clay (%). The first stage of the experiment was to isolate and identify Arbuscular Mycorrhizal Fungi and non-symbiotic indigenous fungi onion rhizosphere contaminated with heavy metal Pb. The second stage of the experiment was to test the potential infective propagules of the shallot rhizosphere with different levels of heavy metal contamination. Tests were carried out on a consortium and single spores of Arbuscular Mycorrhizal Fungi in vivo with Pb-contaminated shallot media, and non-symbiotic fungi with Pb-contaminated media in vitro. The third stage of the experiment was to test the interaction of non-symbiotic fungi and humic-fulvic acid in the cultivation of Pb contaminated media. The results showed that the mean total soil Pb content of the soil in Wanasari District ranged from 17.10 to 20.68 ppm and the total soil Pb content of the soil in Larangan District ranged from 21.11 - 26.31 ppm. While the content of heavy metal Pb in shallot bulbs in Wanasari District is in the range of 1.54 - 3.43 ppm and the content of heavy metal Pb in shallot bulbs in Larangan District ranges from 1.47 - 2.53 ppm. The majority of soil and shallot tuber Pb content was above the required threshold. The results of regression analysis showed that the contribution of soil Pb was only 4% in the heavy metal content of the tubers, while the rest was influenced by other variables with a value of 96% (y = -0.0541x + 3.2641). Arbuscular Mycorrhizal Fungi were isolated and identified 4 genera of fungi, namely Gigaspora, Glomus, Acaulospora, and Scutellospora.Glomus was found at 16 out of 17 rhizosphere sampling sites. In the single spore test, giving different Glomus species did not significantly affect the growth and yield of shallots on all observation variables, except for the number of leaves at 35 DAS. Glomus sp5 species showed the best role in the growth of Pb-stressed onion plants, especially the number of leaves (35 dd) compared to other Glomus species. The decrease in Pb accumulation was highest in Glomus sp. 12 of 99.353%. Providing AMF from different locations showed a good response to the percent of infections where AMF treatment from Slatri L14 Village showed the highest percentage of infections at 93.33%. AMF treatment was able to reduce the Pb content of tubers compared to without treatment, up to 83.660%, and increase the Pb accumulation mostly in shallot roots. The AMF consortium test of 17 different Pb contaminated land locations on shallot plants showed no significant effect on the fresh tuber weight and leaf weight variables. The results of isolation and identification from shallot agricultural land in Larangan and Wanasari Districts, Brebes Regency, found 8 identified non-symbiotic fungal species, namely Penicillium oxalicum, Trichoderma harzianum, Aspergillus niger, Penicillium dangeardii, Penicillium citrinum, Penicillium sp., Aspergillus terreus and Dichotomomyces cejpii. The non-symbiotic fungal isolates identified had the ability to survive in the medium with the highest Pb concentration, as indicated by the highest tolerance index value and significantly different from 7 other isolate species, namely Trichoderma harzianum. The decrease in tuber Pb content was highest in the Trichoderma harzianum fungal treatment without humic-fulvic acid, namely 50.282% compared to the control treatment. Growth and yield of shallots in planting media contaminated with heavy metal Pb with the treatment of the fungi Penicillium dangeardii and Aspergillus terreus and humic acid fulvic at a dose of 750 ml / polybag, showed the best treatment. The general conclusion obtained is that the Arbuscular Mycorrhizal Fungi (Glomus sp. 12) and non-symbiotic fungi (Trichoderma harzianum) indigenous shallot land contaminated with Pb have the potential to be used to reduce Pb accumulation in shallot bulbs. The addition of humic-fulvic acid compounds to non-symbiotic fungi showed the same potential to reduce the Pb accumulation of shallots on Pb contaminated media. Keyword: Arbuscular Mycorrhizal Fungi, humic-fulvic acid, indigenous, non-symbiotic fungal, P