Skrining Awal Semai Klon Acacia Crassicarpa Tahan terhadap Ceratocystis spp.

Eva Lutfiana, Prof. Dr. Ir. Sri Rahayu, M.P.; Dr. Ir. Eko Bhakti Hardiyanto, M.Sc.

2023 | Tesis | S2 Ilmu Kehutanan

Acacia crassicarpa dikembangkan untuk produksi kayu bahan baku pulp dan kertas; di Indonesia spesies ini banyak ditanam lahan gambut. A. crassicarpa  dilaporkan terserang beberapa patogen khususnya jamur Ceratocystis spp. Namun, informasi mengenai resistansi klon A. crassicarpa terhadap penyakit ini masih masih sangat terbatas karena dianggap relatif resistan terhadap jamur Ceratocystis spp. Penelitian dilakukan dengan tujuan untuk 1) mendeskripsikan karakter morfologi dan pertumbuhan serta mengevaluasi virulensi isolat Ceratocystis spp., 2) menskrining klon A. crassicarpa yang resistan terhadap Ceratocystis spp., 3) mengestimasi heritabilitas klon A. crassicarpa untuk sifat-sifat resistan terhadap Ceratocystis spp., dan 4) mendeskripsikan histologi jaringan batang klon A. crassicarpa resistan yang diinokulasi buatan jamur Ceratocystis spp.  
    Uji virulensi pada semai A. crassicarpa dilakukan di Laboratorium Perlindungan dan Kesehatan Hutan Fakultas Kehutanan UGM menggunakan 8 isolat Ceratocystis spp. (AC1, AC2, AM1, AM2, AM3, AM4, EP1 dan LA1) sebanyak 4 ulangan dengan desain uji Rancangan Acak Lengkap Blok (RALB). Parameter uji virulensi yang diamati adalah panjang lesi luar, panjang lesi dalam, persentase kematian dan waktu kematian semai. Isolat paling virulen digunakan untuk skrining 44 klon A. crassicarpa dengan metode inokulasi buatan. Skrining klon dilakukan di persemaian PT Arara Abadi Perawang, Riau dengan desain uji RALB menggunakan 3 unit sampel sebanyak 4 ulangan. Heritabilitas klon ?(H?_c^2) diestimasi untuk karakteristik: persentase kematian, Intensitas Gejala pada Daun (IGD), Luas Serangan (LS), Panjang Relatif Lesi Luar (RLL), dan Panjang Relatif Lesi Dalam (RLD). Persebaran dan intensitas hifa jamur Ceratocystis spp. serta adanya lignin di sekitar titik inokulasi pada masing-masing penampang melintang batang klon A. crassicarpa yang berstatus respons tahan, toleran, dan moderat diamati secara kualitatif deskriptif.
    Hasil uji virulensi menunjukkan isolat AC1 merupakan isolat paling virulen dengan panjang lesi luar 30,7 cm, panjang lesi dalam 31,6 cm, dan persentase kematian 75?n waktu kematian tercepat 21 Hari Setelah Inokulasi (HSI).  Skrining klon berhasil mengindentifikasi 32 klon berstatus tahan, 8 klon toleran, 3 klon moderat, dan 1 klon rentan. H_c^2  untuk  IGD, RLL, RLD dan persentase kematian berturut-turut sebesar 0,70; 0,64; 0,64; dan 0,55. Histologi batang klon A. crassicarpa berstatus tahan menunjukkan persebaran dan intensitas miselia Ceratocystis spp. kurang intensif dibandingkan dengan klon toleran dan klon moderat. Klon tahan membentuk lignin di sekitar titik inokulasi sebagai respons ketahanan terimbas.

    Acacia crassicarpa has excellent wood properties for producing pulp and paper, it is widely grown on peatlands in Indonesia. Ceratocystis spp. has been reported to harm this species. Although A. crassicarpa is regarded relatively resistant to Ceratocystis, the information on clone resistance to the disease is very limited. A study was conducted aiming to: 1) describe morphological characteristics and growth of Ceratocystis spp. as well as to evaluate the virulence of selected fungi isolates; 2) screen A. crassicarpa clones resistant to Ceratocystis spp.; 3) estimate clone heritability of resistant characteristics of A. crassicarpa to Ceratocystis spp., and 4) describe the histology of A. crassicarpa clone stem tissue resistant to Ceratocystis spp. through artificial inoculation.
The virulence test on A. crassicarpa seedlings was carried out at the Forest Health and Protection Laboratory, Faculty of Forestry UGM, using 8 isolates of Ceratocystis spp. (AC1, AC2, AM1, AM2, AM3, AM4, EP1, and LA1) with 4 replications with a Randomized Complete Block Design (RALB) test design. The virulence test parameters observed were length of outer and inner lesion,  survival, and time to death of the seedlings. The most virulent isolate was used to screen 44 clones of A. crassicarpa using artificial inoculation method. A RALB test design with 3 sample units and 4 replications was used for clone screening at the PT Arara Abadi Perawang nursery in Riau.  Clonal mean heritability ?(H?_c^2) values  estimated in the clones screening test were survival, leaf symptom intensity (LSI), disease incidence (DI), relative length of outer lesions (RLOL), and relative length of inner lesions (RLIL). In each cross-section of the stem with the status of high, moderate and low resistance, fungal hyphae distribution and intensity, as well as the presence of lignin around the inoculation point, were qualitatively and descriptively examined.
The AC1 was the most virulent isolate with outer lesion length of 30.7 cm, inner lesion length of 31.6 cm and survival of 25%, with the shortest death time being 21 days after inoculation. Screening results of the tested clones indicated that 32 were resistant, 8 tolerance, 3 moderately resistant, and 1 susceptible.  H_c^2   estimates for LSI, RLOL, RLIL and survival were 0.7, 0.64, 0.64 and 0.55 respectively. The histology of stem of resistant clones revealed that Ceratocystis spp. spread less intensively than tolerance and moderately resistant clones. The resistant clones formed lignin around the inoculation point as an induced resistant response.

Kata Kunci : Acacia crassicarpa, Ceratocystis spp., skrining klon, heritabilitas klon; Acacia crassicarpa, Ceratocystis spp., clone screening, clone heritability