No abstract

The resistance level of several national superior corn varieties to the primary disease of corn is still varied and unstable. Therefore, evaluating the resistance of hybrid corn varieties candidate to the primary disease of corn is deemed necessary as an initial step in managing the disease. This study aimed to evaluate the resistance reaction of the hybrid corn varieties candidate against the primary disease of corn. This study was conducted at two different locations. The first location was at the Agricultural Technology Research and Assessment Installation (ATRAI) of the Indonesian Cereals Research Institute in Bajeng District, Gowa Regency, South Sulawesi first, where the test for P. phillipinensis downy mildew, leaf blight, and leaf rust was conducted. The next location was at the ATRAI of Muneng of the Research Institute for Various Nuts and Tubers in Probolinggo, East Java, where the test for the P. maydis downy mildew was conducted. The tests were carried out using plants as the source of the test pathogen inoculum planted around the experimental block. The four corn genotypes tested were CHC1, CHC02, CHC3, CHC5, and CHC5. Meanwhile, the comparison varieties used were P36, Pertiwi-6, PAC339, BISI18, Anoman, and Pulut. The test results showed the two hybrid corn varieties candidate that were moderately resistant to P. philipinensis, namely CHC1 and CHC2, with attack intensities of 30.94% and 32.07%, respectively; one variety candidate resistant to P. maydis, namely CHC1 with an attack intensity of 15.92%. Meanwhile, the five hybrid corn varieties candidate, namely CHC1, CHC02, CHC3, CHC5, and CHC5, showed a moderately resistant reaction to maydis leaf blight and leaf rust with an attack intensity of 35%.

Indigenous fungi can suppress infection by pathogens and produce secondary metabolites that directly or indirectly affect plant growth. This study aimed to test indigenous fungi collected from corn plants as biological control agents and their effects on the viability and vigor of corn seeds. Purposive sampling method was used for sampling where soil samples taken from the rhizosphere zone, corn stem and leaf tissue from three locations namely Maros-South Sulawesi, Bone-South Sulawesi, Sigi-Central Sulawesi, Indonesia. Rhizospheric fungi were isolated from soil collected at the rhizosphere and rhizoplane using a serial dilution technique, while the endophytic fungi isolated from the leaves and stem tissues using surface sterilization method. The isolated fungi were cultured on a potato dextrose agar (PDA) medium. An antagonism test was performed using the dual culture method on PDA media with F. verticillioides as target pathogen. Pathogenicity test and the effect of fungi on corn seed germination was carried out using the blotter test method. Parameters observed were; necrotic symptoms on seedlings, growth potential, germination, growth rate, growth simultaneity, vigor index, germination rate, and time needed for 50% of the total germination. The effect of the isolated indigenous fungi on corn growth was carried out in-planta using seedling trays. The results of the blotter test and in-planta test were further confirmed by a physiological characteristic test. And assessing the fungi's ability to dissolve potassium, phosphate, and produce protease enzymes. A total of 89 fungal isolates were isolated and collected from various parts of the corn plant. Nineteen of the 89 fungal isolates showed inhibitory activity against F. verticillioides by ! 50% inhibition. The fungal isolates JRP 5 MRS, JRP 9 MRS, JRP 10 MRS, JRP 7 MRS, and JEDF 1B BN were selected based on the tests and showed a consistently positive effect on seed viability and vigor with a value of !90%. The isolates did not cause necrosis in corn, and had the ability to suppress the growth of pathogenic F. verticillioides by ! 50%.

ABSTRAKMeloidogyne spp. merupakan salah satu penyebab penurunan produksi wortel di Indonesia. Nematoda ini telah dilaporkan menjadi penyebab penyakit umbi bercabang di beberapa sentra produksi wortel di Pulau Jawa. Penelitian ini bertujuan mendeteksi dan mengidentifikasi karakter morfologi dan molekuler spesies Meloidogyne pada tanaman wortel asal Dataran Tinggi Malino, Kecamatan Tinggimoncong, Kabupaten Gowa, Sulawesi Selatan. Identifikasi morfologi dilakukan dengan pengamatan karakter pola perineal nematoda betina. Identifikasi molekuler dilakukan dengan teknik polymerase chain reaction (PCR) untuk mengamplifikasi DNA ribosom menggunakan primer spesifik spesies (Rjav/Fjav untuk M.arenaria ditemukan berasosiasi dengan kejadian penyakit umbi bercabang. PCR menggunakan primer spesifik berhasil mengamplifikasi pita DNA M. incognita dan M. arenaria dengan ukuran berturut-turut ± 999 pb dan ± 420 pb, sedangkan PCR dengan primer multipleks tidak berhasil mengamplifikasi pita DNA. Analisis sikuen nukleotida menunjukkan isolat M. incognita asal Malino memiliki kekerabatan yang dekat dengan isolat asal Bangka-Indonesia, Cina (isolat JS2), dan Malaysia (isolat JIK4, FIK4, JIT19, dan FIT19) dengan nilai homologi berkisar 99.2-100.0%. Sikuen nukleotida M. arenaria asal Malino-Indonesia telah didaftarkan pada GenBank dengan nomor aksesi KP234264 dan menjadi data pertama yang tersedia di GenBank. Kata kunci: Meloidogyne arenaria, M. incognita, umbi bercabang ABSTRACTMeloidogyne spp. was reported as the cause of branched tuber disease on several carrot production areas in Java, Indonesia and may potentially cause yield loss. This research aimed to use morphological and molecular characters to detect and identify Meloidogyne species on carrot from Malino Highland, Sub-district of Tinggimoncong, District of Gowa, South Sulawesi. Morphological identification was done based on character of the female perineal pattern. Molecular identification was based on amplification of r-DNA by polymerase chain reaction technique using species specific primers (Fjav/ Rjav for M. javanica, Far/Rar for M. arenaria, and Finc/Rinc for M. incognita) and multiplex primer (JMV1/JMVhapla/JMV2 for M. hapla, M. chitwoodi, and M. fallax).Two of Meloidogyne species, i.e. M. incognita and M. arenaria were detected associated with the incidence of carrot branched tuber. The specific primers amplified two DNA bands, i.e. ± 999 bp of M. incognita and ± 420 bp of M. arenaria, while multiplex primer was failed to amplify DNA bands. Nucleotide sequence analysis showed M. incognita isolate of Malino was closely related to M. incognita isolate from